World War 2 saw the airplane rise to even greater importance than in the first World War. Air superiority became a crucial component of battlefield operations and air forces were massively expanded during the conflict.The Allied and Axis sides of the war developed enormous war machines, capable of developing and rolling out unprecedented numbers of advanced new military equipment in rapid response to changing conditions on the battlefield, as well keeping up with the technological advances of adversaries.
High altitude bombing raids and night fighting were hallmarks of the War for Europe, whilst aircraft carrier battles pitched the American and Japanese fleets against one another. The technology of the day was pushed to it’s limit with the use of superchargers in aircraft engines, the introduction of radar, and the rapid development of the jet engine by the war’s end.
The period ended as the Nuclear Age and subsequent Cold War were ushered in by the tremendous and tragic blows to Japan’s wearied people.
USSR (1938-1940) Experimental long-range bomber – One prototype
With the rapid expansion of Soviet aviation in the 1930s, radical new design concepts were constantly being developed, producing a number of eccentric designs that hoped to break the mold. Among the many different concepts, one particularly unusual design emerged in the form of a twin-fuselage, bat-winged aircraft created by Viktor Nikolayevich Belyayev.
This aircraft, known as the Belyayev DB-LK, featured two fuselages, connected by a central wing section with a glazed rear cone. Despite its unconventional layout, testing showed that the DB-LK was a stable and reliable aircraft. However, the Soviet aviation industry at the time prioritized more conventional designs for long-range bombers with the onset of war, which ultimately doomed the project before it could progress further.
Belyayev DB-LK was an unusual twin-fuselage long-range bomber prototype. Source: Reddit
History
Following the end of the First World War and the later Russian Civil War, a new nation emerged from the remnants of a once-mighty empire: the Soviet Union. During the 1920s, it began the slow process of rebuilding its shattered industry. In order to recover, the Soviet political and military leadership decided to prioritize large-scale industrial development, and enormous financial resources, manpower, and raw materials were committed to achieving this goal. As a result, new technologies were quickly introduced, leading to a period of rapid industrial expansion.
The aviation sector also benefited from this renewed focus. A series of new projects, both civilian and military, were initiated to rebuild and modernize the nation’s air capabilities. Before the First World War, in the now-lost Russian Empire, there had been considerable developments in airliner design. However, progress was halted by the outbreak of the First World War, and the devastation caused by the subsequent Civil War. By the early 1920s, the aviation industry’s infrastructure was in ruins, and many of its original engineers and experts had either fled the country or been killed.
By the 1930s, new experts were eager to test various ideas and concepts. Among them was Viktor Nikolayevich Belyayev. Born in 1896 (Moscow, Russian Empire), Belyayev showed a strong interest in aviation from an early age and was an enthusiastic engineer. During the late 1920s, he worked with Andrei Nikolayevich Tupolev’s Experimental Design Bureau, and later with Aeroflot, the Soviet civil aviation operator.
Viktor Nikolayevich Belyayev was a Soviet aircraft designer and aviation enthusiast who was particularly keen on finding ways to minimize aerodynamic drag while improving overall flight performance. Source: en.wikipedia.org
Belyayev had a particular fascination with a bat-wing, sometimes also described as a butterfly wing shape, design, featuring a slightly forward-swept wing with tips that curved gently backward. At the time, aviation worldwide was marked by the introduction of numerous experimental and innovative concepts. With such rapid technological progress, there was plenty of room for improvement and innovation, and eccentric ideas found fertile ground for development. Belyayev believed that this bat-wing configuration could significantly improve longitudinal stability while also reducing overall drag.
Like many other aircraft engineers who often lacked adequate funding, he decided to test his ideas using simple and inexpensive gliders. In 1920, he built a fully operational glider. In 1933, he managed to construct a glider designated BP-2. It used the bat-wing layout and also featured an unusual twin-tail assembly connected by an extended elevator. The glider was tested in a flight from Crimea to Moscow, towed by a Polikarpov R-5. The tests were successful, which encouraged Belyayev to continue experimenting with new fuselage designs. He was particularly interested in an unconventional twin-fuselage arrangement.
The Belyayev BP-2 was used to test some of his concepts. It successfully flew from Crimea to Moscow while being towed in 1933. Source: airwar.ru
The Development of a New Project
Following his research and experimentation with glider design, Belyayev eventually felt that he had gathered enough knowledge and design experience to put his ideas into practice. In 1934, he began working on a new twin-fuselage, 10-seat transport aircraft. Each fuselage was fitted with a 750-hp engine.
In addition to developing new wing designs, Belyayev also theorized methods to significantly reduce aircraft drag. Conventional twin-engine aircraft had their engines mounted on the wings, which inevitably created drag that could not be eliminated. Belyayev’s new concept was to extend the engine nacelles and use them as the fuselage itself. This meant that no additional structural elements had to be attached to the wing, thereby removing unnecessary drag and creating a more aerodynamically efficient aircraft.
In the late 1930s, the Soviet Air Force issued a requirement for a new long‑range bomber. Belyayev decided to take this opportunity. He essentially reused his original civil aircraft design and adapted it for military use. In 1938, he approached the Soviet Air Force with his proposal for a new long-range bomber. This time, he received approval to construct a working prototype, which was completed rather quickly by November 1939. The resulting aircraft made use of his earlier concept: it featured two fuselages that, technically speaking, functioned more like elongated engine nacelles.
The aircraft received a simple designation: DB-LK. While not entirely clear, this was most likely an abbreviation of Dalniy Bombardirovshchik – Letayushcheye Krylo, meaning Long-Range Bomber — Flying Wing. It is also often referred to by its designer’s name as the Belyayev DB-LK. During the testing phase, it also carried the nickname Kuritsa (Eng. Chicken), given by the test pilot who was afraid to fly it.
Experimental Flights
Once the DB-LK prototype was completed, it was cleared for its first flight tests. While Belyayev may have had doubts about the realization of the entire project, he likely never expected that, despite the vast size of the Soviet Union, not a single test pilot was willing to fly his plane. At this time, most pilots were still flying older biplane designs, and many were often reluctant to test newer aircraft. For example, some even hesitated to fly low-wing monoplanes, which were still unfamiliar to many aviators. This hesitation stemmed both from a general fear of experimental aircraft and, to an even greater degree, from an ingrained belief that proven older designs were superior to new, untested ones. In any case, Belyayev unexpectedly found himself unable to secure a willing test pilot.
This situation dragged on until 1940. That year, the Soviet Directorate of the Air Scientific Test Institute issued an official order assigning pilot M. A. Nyukhtikov to test the aircraft. There was little point in keeping a fully functional machine sitting idle on the ground. To support the pilot during the trials, lead engineer T. T. Samarin and test observer N. I. Shaurov were also assigned to the project.
After several initial flights, Nyukhtikov reported that the aircraft’s controls were heavy and difficult to operate. In addition, he noted that the landing gear should be strengthened. A commission of the Scientific Test Institute, led by A. I. Filin agreed that the control system needed refinement but rejected the pilot’s concerns regarding the landing gear. This decision proved premature, as only a few days later, during a flight test involving Filin himself, one of the landing gear legs collapsed.
Despite test pilots repeatedly pointing out that the landing gear was too fragile, it ultimately took an accident for their superiors to finally realize that this was something that needed fixing and improvement. Source: militarymatters.online
Sudden End of the Project
After a series of test flights, the DB-LK, despite its unconventional, inverted-gull twin-fuselage design, proved to be an airworthy and well functioning aircraft. During testing, the DB-LK could easily reach speeds of up to 488 km/h (303 mph) at an altitude of 5 km (16,400 ft). When fully loaded, it was also capable of climbing to around 8.5 km (28,000 ft). In total, more than 100 test flights were conducted without any major incidents, demonstrating that the overall design was sound.
Complaints from the test pilots focused on the limited visibility experienced by both the pilot and the navigator. Despite this, the DB-LK was viewed as an aircraft with significant potential for future service within the Soviet Air Force.
Then, suddenly, the project was shut down. This occurred for several reasons, though not necessarily because of flaws in the design. By late 1940, war was raging in Western Europe between Germany and Britain, and a wider conflict seemed increasingly possible. The Soviet leadership did not want to take risks with an aircraft considered highly unorthodox. The DB-LK’s twin-fuselage layout likely contributed to these concerns. Instead, the authorities decided to focus production efforts on the more conventional and already-established IL-4 bomber. With that decision, all work on the DB-LK stopped. Its final fate is unclear, but it was likely scrapped.
Technical characteristics
The DB-LK featured an unconventional overall layout, lacking a traditional central fuselage. Instead, the crew stations, armament, and most of the onboard equipment were housed inside two elongated engine nacelles that terminated in glazed tail cones (gondolas), somewhat reminiscent to the aft section of the later German Fw 189. In practical terms, these extended nacelles functioned as the aircraft’s fuselage. Each semi-monocoque structure was built from a framework of metal frames and longerons, covered with duralumin skin. The two glazed cones could be mechanically rotated 360°, boosted by small electric motors mounted on top of the fuselages. This was designed to provide the best possible angle for the rear gunners, while retaining aerodynamic shape.
The DB-LK’s wings featured a distinctive layout. In addition to the characteristic “batwings,” the aircraft incorporated a central wing section positioned between the two fuselages. The wings were slightly forward-swept and ended in backward-curved tips. Structurally, they consisted of a light metal stressed-skin construction over a conventional airframe. The outer wing panels used a Göttingen 387 airfoil profile, while the center section employed a CAHI (TsAGI) MV-6bis profile. The wing leading edges were curved at an angle of –5° 42′.
The aircraft’s rather unusual wings were slightly forward-swept and finished with backward-curved tips. Structurally, they featured a light metal stressed-skin construction built over a conventional airframe. Also note the glazed rear fuselage cone section, where the rear gunner would have been positioned. Source: forum.warthunder.com
The rear tail assembly was mounted on the central wing section between the two fuselages. It consisted of a single vertical fin with a large rudder. Above the rudder, a small horizontal stabilizer was installed, fitted with two large elevators, one on each side.
The rear tail section was also unusual, being positioned in the middle of the central wing section and featuring a large rudder with a small tailplane. Source: wikipedia.org
The landing gear retracted rearward, with one wheel (900 × 300 mm) housed in each fuselage section. During later testing, this arrangement was redesigned, and the gear was modified to retract forward instead. The entire landing gear system was hydraulically operated. A small fixed tailwheel (450 × 150 mm) was installed at the bottom of the tail unit.
The DB-LK was powered by two Tumansky M-87B 14-cylinder radial engines, each delivering 950 hp. These drove three-bladed variable-pitch propellers. It was planned to replace them with the more powerful 1,100 hp M-88 engines, or even the 1,700 hp M-71, but these upgrades were never implemented as the project was ultimately cancelled. Fuel was stored in both the wing and fuselage tanks, with a total capacity of 3,444 liters (910 US gallons)..
Behind each of the two engines, a cockpit with a rear-sliding canopy was installed. The DB-LK was designed to be operated by a crew of four: the pilot, navigator, and two rear gunners. The pilot occupied the left cockpit, and the navigator the right. The gunners were positioned in the two rear glazed cones, with one of them also serving as a radio operator. Crew members entered their positions through the roof hatch doors.
Given its role as a long‑range bomber, Belyayev intended for the aircraft to have a fairly respectable defensive armament for its day, consisting of six machine guns. Both rear glazed tail cones were fitted with mounts for twin 7.62 mm (.30 in) ShKAS machine guns. These weapons had a firing arc of –10° to +10° in all directions. However, the gunner could rotate the glazed cones themselves, allowing him to reposition the guns and further increase the weapon’s effective defensive arc.
The interior of one of the two fuselages. On the right, the rear machine-gun mount is visible, while on the left side, you can see the radio equipment and the mechanism used to rotate the entire glazed tail cone. Source: forum.warthunder.com
In addition to these four rear-mounted machine guns, two more were installed in the leading edge of the center section and operated by the pilot. Altogether, approximately 4,500 rounds of ammunition were carried for all six weapons.
For attacking ground targets, bombs were to be employed. The bomb bays were located behind the landing‑gear doors in each of the nacelles. Each of the two bomb bays could carry up to 1 tonne (2,200 lb) of bombs, or alternatively four 250 kg (550 lb) or two 500 kg (1,100 lb) bombs per bay, four in total. In addition, a container with 59 smaller bombs could have been used instead. Lastly, an additional external bomb rack capable of carrying up to one tonne could be attached to the central wing section.
Cocnlusion
The Belyayev DB-LK is one example where the overall visual design essentially killed the project. The aircraft itself had no unresolvable flaws. In fact, it demonstrated generally good flight performance. It carried a large bomb payload, and its defensive armament, while not covering every angle, was still respectable. Most importantly, it did not suffer any major problems during the initial test flight phase.
Its main downside was its unusual overall appearance, which may have caused significant concern among industry decision-makers when it came time to consider a production order. It can be assumed that this was one of the key reasons it was cancelled, along with its prototyping being interrupted by the start of the Second World War. Soviet authorities preferred more conventional, proven designs and did not want to commit to a highly unorthodox aircraft that had no equivalent or prior service experience anywhere in the world.
Belyayev DB-LK specifications
Wingspan
21.6 m / 70 ft 10 in
Length
9.8 m / 32 ft 1 in
Wing Area
56.9 m² / 612 ft²
Engine
2x Tumanskii M-87B 950 hp 14 cylinder radial engines
Experimental Fighter Program: Six Prototypes Built
The Höhenjäger 2 project would spawn one of the strangest-looking, and most troubled experimental aircraft during the second world war. (Smith & Creek)
As the Second World War progressed, the development of high altitude aircraft became of critical importance. At the beginning of the war, extreme altitude flights were conducted only by highly specialized reconnaissance aircraft, prompting many nations to scramble for a means of shooting them down. With little investment before the war into high altitude interceptors, 1941 and 1942 would be critical years in the development of planes capable of fighting at once unthinkable heights. At Focke Wulf, the new Fw 190A would go through a number of modifications, eventually resulting in six turbo supercharged test aircraft under the program title Höhenjäger 2. The program would be fraught with technical challenges at every turn, was undermined by the disastrous politics within the Luftwaffe’s developmental offices, and would fail to deliver a badly needed high altitude fighter to the Luftwaffe.
Threats from on High
In early 1941, the Luftwaffe deployed the Ju 86R reconnaissance plane over Britain. With its specialized high aspect ratio wings, and GM-1 nitrous oxide injection for its engines, it could operate at extreme altitudes. Flying at nearly 14km, it was almost untouchable at the time, and only when specially modified Spitfires were fitted out could it be intercepted. The first of these Spitfires could only reach the Junkers by shedding all excess, its armor plates, much of its armament, and even its radios, with the fighter needing another aircraft to guide it towards the target before the final climb. There would soon be specialized marks built for this exact mission, the Spitfire Mark VI would incorporate a pressurized canopy to spare the pilot the worst effects of flying at extreme altitudes, and the Mark VII would be further modified with a addition of a better wing for maneuvering in thin air, and they would receive an oxygen boost system, to increase the available engine power in the thin air where its targets would be found. The Mk VI was delivered to the RAF only about a year after the first Ju 86R had flown over Britain, such was the rate of fighter evolution.
In Germany, the Luftwaffe had to contend with the Mosquito, which first flew over Germany in the summer of 1941. It did not reach the heights of the specialized Junkers bomber, but flying over 560 km/h at an altitude of 7km, it was enough to outrun anything the Luftwaffe could dispatch to bring it down. Improvements to this aircraft would only boost its already impressive performance, and new, specialized designs were posing even greater threats. As was the case, when German intelligence services revealed the development of the Vickers Wellington V, which possessed high altitude Merlin engines and a pressurized cabin, allowing the aircraft to operate at altitudes beyond 12km. Technical difficulties prevented its employment, but it nonetheless presented a threat which the Luftwaffe had no answer to. Likewise, the declaration of war against the United States would entail fighting their advanced bomber fleet, which had made major investments in the technologies that would enable them to conduct raids from high altitudes.
In the spring of 1942, the Messerschmitt Bf 109F had a full throttle height of roughly 6.2 km, and the Focke Wulf 190A’s was roughly the same. There were versions of the Bf 109 which utilized a nitrous oxide injection system to allow them to regain engine power lost at high altitudes, but as a system, the GM-1 boost was inconvenient as it could not be stored in aircraft for long, due to leakage, and it was a logistical burden beyond its deployment in Western Europe, where the infrastructure for supplying and handling the nitrous oxide existed. It was very useful aboard high altitude recon aircraft, and in interceptors that pursued high flying reconnaissance aircraft, but it was unusable as a means of giving high altitude performance to a large force of fighters which were on call around the clock. Thus came a top down push for a new high altitude fighter.
The Bf 109E, F, and G could make use of GM-1 nitrous oxide boosting, though it added dead weight to the aircraft below an altitude of around 7km, where it provided little to no benefit. (Asisbiz)
In May of 1941, the Reichsluftministerium, or Reich air ministry, convened a conference at the Messerchmitt plant at Augsburg to discuss the requirements for a new high altitude fighter, or Höhenjäger. The requirements were sent out to Messerchmitt, Focke Wulf, and a number of other firms. Their goals were ambitious, and pursued at a very inopportune time.
Working Conditions
At the start of 1942, there were few practical engines available for high altitude use in Germany. To make matters even more complicated, most firms were struggling to modify their engines to work with the new economy alloys and synthetic fuels available to them. Nickel was in short supply, leaving engines more vulnerable to corrosion, and chrome was soon to become scarce, so heat resistant alloys were less effective. Their stocks of aviation gasoline had transitioned to synthetic derivatives, whose differing properties from the original petroleum derived stock were causing great difficulty in the DB 601 engine, which powered the Bf 109, among other aircraft. In addition to the many technical challenges facing engine designers, the political situation was equally disastrous. In short, there were too many competing engine manufacturers vying for production, and the Luftwaffe’s technical offices badly managed what resources it had. The Luftwaffe’s chief of the relevant offices, Ernst Udet was a very capable pilot, but an incompetent administrator.
At this stage, neither of the primary fighter power plants in Luftwaffe service would permit acceptable high altitude performance, without significant modification. While both were advanced, they were geared to low and medium altitude use, and the supercharger impeller design on the Fw 190’s BMW 801 engine, was already quite dated. New models of these engines were forthcoming, but were being developed in parallel with a number of new high performance engines. Resources were accordingly spread very thin. The most important of these new engines were the Daimler Benz DB 603 and Junkers Jumo 213 V-12s. The DB 603 was similar to the preceding DB 601, and was a considerably larger design with its output eventually reaching the 2000hp class. The Jumo 213 was a further development of the Jumo 211, but with a pressurized cooling system for high altitude use, and it was designed to operate at significantly higher RPMs. The Junkers engine was the more advanced model, but was experiencing harsher developmental difficulties. In spite of their problems, they would represent an important second generation of fighter engines during the latter half of the war.
The DB 603 wasn’t a particularly advanced V-12, though it presented a fairly small profile, and had a high displacement of some 44.5L. (DB 603 Manual)
The Contenders
At Messerschmitt, the Bf 109 was not chosen to pursue the Höhenjäger program, but rather the Me 155. High altitude versions of the Bf 109E and F were already in service, but as specialized GM-1 boosted interceptors, and not air superiority fighters. Originally a project to develop a carrier based fighter, the Me 155 was repurposed for use as a Höhenjäger. Dubbed Me 155B, it was soon transferred to the a S.N.C.A.N. in Paris, as Messerschmitt was totally committed to existing projects. The project would eventually be brought to Blohm und Voss for assistance, before finally fully transferred to the firm, with a handful of aircraft being created in 1944. More modest attempts to build high altitude versions of the Bf 109 failed when the necessary high altitude engines failed to materialize. With Messerschmitt unable to produce a new high altitude fighter, what prospects remained lied with Focke Wulf’s efforts.
Focke Wulf would instead choose to try and modify their existing Fw 190 fighter, rather than take on the high developmental burdens of a new design. This took the form of three proposals which were proposed to the RLM. The Fw 190B, which would be powered by the BMW 801, featuring air frame modifications to improve high altitude performance, and a pressurized cockpit; the Fw 190C, the same but with a new DB 603 V-12 power plant; and the Fw 190D, which would utilize the Jumo 213. These projects would not only pursue the high altitude goal, but also produce new high performance standard fighter models of the Fw 190. All three programs would be developed in parallel, and were supplied with a series of pre-production Fw 190A-0’s for testing.
The Fw 190A proved a tremendously successful fighter, combining the powerful BMW 801 engine with an rugged, and aerodynamically clean air frame. Pre-production Fw 190A-0 aircraft like these were often converted into prototype and research aircraft. (traces of war)
From an early date, the engineers at Focke Wulf were convinced that they needed to transition to one of the new V-12’s for the high altitude project. Fw 190 lead designer, Kurt Tank, favored the DB 603 as it was likely to be available sooner, though the RLM did not. The engine was not originally ordered at the behest of the military and it had its opponents within Luftwaffe R&D circles. Tank was however, able to convince the Technisches Amt, the Luftwaffe technical office, to continue Fw 190 development with the engine, but only as a back up design to the BMW 801, and Jumo 213, powered models. In any case, these would be available in greater supply, and there was a considerable risk that the Fw 190C could have been reliant on an engine the firm might be denied a supply of.
The Fw 190C
Kurt Tank’s highest hopes were placed on the DB 603 engine, the initial output of which was some 1500hp, with later developments hoping to push the engine into the 2000hp class. This engine would be selected to power both standard, and high altitude fighter projects. The engine was lighter than the BMW 801 and had good developmental potential. They were not however, without issue, as they were still running roughly at the start of 1942, with six out of ten engines in flight testing only surviving some 60 to 100 hours. There had been interest in equipping the Fw 190 with this engine at an earlier date, with the first proposals being drawn up in March of 1941, well before the high altitude fighter conference. This early proposal did little to advance the development time tables, as the engines themselves were not forthcoming, and the program awaited delivery for testing for quite some time. The new Fw 190C had been designed with the new engine in a new modular power unit, but it was not available for testing until March 1942.
The first three prototypes were Fw 190V13, V15, and V16, all built on old air frames and equipped with pressurized cockpits. To follow were over a dozen prototypes to test various configurations. V-17 through 33 were to test the performance of the aircraft with the DB 603 and Jumo 213 engines, along with pressurized canopies, a new tail section, and GM-1, all in various arrangements.
Tthe C series, hoped to install a much more powerful DB 603 engine. Harsh teething issues with the engine plagued the project. (grafiq)
V13 was originally a Fw 190B prototype, and was tested at the Luftwaffe experimental unit at Rechlin between the 18th and 22nd, achieving a top speed of 650 km/h at 5.9km. V15 was modified by moving the air intake to the port side of the engine, rather than at the nose of the aircraft, to test cooling capacity. Performance was markedly improved despite continued issues with overheating, with the prototype making for 696km/h at 6.9 km, in June of 1942. This last figure represents good performance, but still not a significant enough improvement from the BMW 801D engine on the Fw 190A. The Daimler Benz engine had its advantages, but the DB 603 variant that was available was not a high altitude engine, even if its supercharger design was by far superior.
Regardless, development continued. The prototypes V15, and V16 were sent to the Luftwaffe research center at Rechlin, leaving Focke Wulf with only the V13 for DB 603 testing, but V17 and V18 were taken off Jumo 213 testing to be fitted with the Daimler Benz engine. This was until an engine failure caused the loss of V13 in July, as attested to by the test pilot. Focke Wulf continued testing and designed two standard fighter production variants, Fw 190C-1, with an armament of two cowl mounted MG 131 13mm machine guns, two inner wing mounted MG 151/20’s; and the Fw 190C-2, which included a pressurized cockpit, and provisions for a centerline cannon, being either a 30mm Mk 103 or Mk 108, or a MG 151, in either a 20mm or 15mm caliber. Both variants were equipped with a DB 603A engine. The Luftwaffe ordered the production of 727 Fw 190C’s in December 1942, but this order was quickly canceled, as the performance increase over the BMW 801D equipped Fw 190A was not significant enough to warrant its replacement, and the engine was still running very roughly. The new twin engine He 219 nightfighter, the Do 217 bomber, and Me 410 Zerstorer were less threatened by an engine failure, and it was against them that the new fighter would have to compete with for a supply of engines.
The DB 603A on the Fw 190C provided little improvement over the BMW 801D, and would not be running well until near the end of 1943. Re-engining the Fw 190 with this engine proved a fruitless prospect. (Laursen)
The project was shelved, but two of the prototypes, V15 and V16, were retained to test experimental, high altitude models of the DB 603 engine. In 1943 they utilized the experimental 1900hp, DB 603G, which replaced the single stage, variable speed supercharger, with a two stage supercharger. It showed a significant performance increase, with V-16 achieving 722km/h at 9km during testing in mid 1943. It later mounted the DB 603E in 1944, which used an improved model of the single stage, variable speed supercharger, which brought the engine’s critical altitude from 5.7km to 7.4km, and its maximum output rose to 1800hp, with water injection. Its overall performance was inferior to the DB 603G, but nevertheless allowed the aircraft to reach 12km during tests in the summer of 1944. However, neither engine saw mass production as they were unable to reach the minimum threshold for 100 hours between overhauls.
Höhenjäger 1
Despite the promise of a new V-12 engine, the BMW 801 radial was the standard power plant of the Fw 190A, and the new high altitude project, christened Höhenjäger 1, was to use it. The designation for this new high altitude model was Fw 190B, and the aircraft was proposed to the Luftwaffe in August of 1942.
The Fw 190B would be an extremely modest attempt at a high altitude design, comprising a new 12.4m wing, up from 10.5m, and incorporating a pressurized canopy. The new fighter would also include the GM-1 nitrous system, more or less as an expedient measure, as the BMW 801 had poor high altitude performance. It was quickly modified, with ground testing beginning in December of 1942, and flight tests were conducted in January the following next year. The capabilities of the Fw 190B were only modestly improved over the nitrous boosted Fw 190A, with the new model having its service ceiling raised to 12.5 km, an increase of only .7km. The four pre-production aircraft would later have their wings reverted to the standard Fw 190A span, and along with the only production model B-1, would be used to test the troublesome pressurized cockpit design in the following years.
Highly automated, and quite powerful, the standard C, and much more powerful D, variants of the BMW 801 would prove totally unsuited for high altitude use given their dated supercharger design. (BMW 801 manual)
The BMW 801C&D would not prove an acceptable power plant in a high altitude fighter, and the turbo supercharger arrangement proposed for the aircraft was in a pod directly under the engine, which was utterly unacceptable. BMW was developing a specialized turbo supercharged engine in the form of the BMW 801TJ, however, it was designed for bombers and the exhaust gate for the integrated turbine would have been in front of the cockpit. Any high altitudes variants of the BMW 801 for the Fw 190 would prove even less forthcoming than those of the DB 603. The failure of the Fw 190B thus made the DB 603 and Jumo 213 projects essential. Progress, however, remained slow and difficult, and through 1943, neither engine was running very well.
Where are the Engines?
The engineering and political chaos which dominated engine development in 1941 would hold true for the following year, and the rest of the war to come. The Jumo 213 was, on paper, still the planned premier high performance power plant for fighter use. However, the project was pursued alongside the need to improve the existing Jumo 211, in use with a number of Luftwaffe bombers, and the completion of the Jumo 222, an experimental 6-bank 24 cylinder inline engine which boasted extremely high performance. Likewise, at Daimler Benz, the further development, and re-engineering, of the existing DB 601/605 series of engines, along with delivering a workable DB 603, and completing the new DB 628, had pushed their developmental capacity to the limit. To further complicate matters, the DB 603 had begun as a private venture before the war by Daimler Benz, with the RLM initially being frustrated with them, that they had started work on an engine they had not requested. Daimler Benz was initially on the line for all resources spent on the project, and it was shelved, only to be restarted in 1940 with military approval and funding. To add insult to injury, neither the Jumo 222 nor the DB 628, would materialize in any useful capacity, in spite of the considerable efforts and resources spent on their development. The situation was abysmal, and, three years into the war, neither the new DB 603 or Jumo 213 engines were in reliable state for single engine fighter use.
The two stage Merlin engine would supply the Americans with the P-51B, a long range fighter with excellent high altitude performance. Only after many brutal months following its debut, did the Luftwaffe possess fighters which could face it on roughly equal terms. (P-51B manual)
In Britain and America, new technological breakthroughs led to the production of much improved radiators, and the use of new two-stage superchargers. Turbo superchargers had also been incorporated into new fighter designs with good high altitude performance, namely the P-38 and the P-47, the latter being judged a very dangerous opponent above 9 km. Across the board, the new British and American fighters were becoming leaner, mounting lighter, better cooling gear, and were faster at high altitudes, making use of the next generation, two stage Merlin, and a number of turbo supercharged engines. The RAF and USAAF would be receiving superlatively improved designs in 1943, perhaps best exemplified with the new Spitfire Mk IX, which shifted the balance of forces across the English Channel, and the European low countries.
In comparison, German manufacturers were still largely occupied with modifying existing engines on lower quality materials. The DB 605A would only be fully released to run at its full power settings in 1943, and the BMW 801D, in early 1942. The DB 603A would enter mass production, in a very rough state, at the end of 1942, with the Jumo 213 not being available until well into 1944.
How had this happened? Much of the blame can be placed on Generaloberst Ernst Udet, and the man who placed him in the role of the Air Master General, Reichsmarshall Herman Göring. The Aircraft Master General’s Office was enormous, once consisting of twenty six departmental heads and some four thousand officials. This sprawling office, which oversaw Luftwaffe procurement, and its research and development efforts, was utterly unmanageable in the early years of the war. It was dominated by confusion, unable to maintain the necessary supervision, and resource management, for its many new projects, and with its many heads, it had extremely poor communication with the Luftwaffe’s General Staff. Perhaps the greatest example of Udet’s shortsightedness are in his celebratory remarks in June of 1940, when he exclaimed to his staff, “The war is over! All our plans can be tossed into the waste-basket. We don’t need them any longer!” Such delusions were quickly dispelled following the RAF’s victory over the Luftwaffe later that year, and Udet himself was sent into a deep, personal crisis when Reichsmarshall Göring placed much of the fault of the Luftwaffe’s shortcomings during the invasion of the Soviet Union, on him.
Reichsminister Albert Speer (left), and Luftwaffe General Inspector Erhard Milch (right) attempted to rationalize aircraft development and production from 1942 onwards. They succeeded in boosting production, but difficulties in the Aircraft Master General’s Office were never fully resolved. (Bundesarchiv)
Generaloberst Udet dithered in trying to reorganize his office, and only with the intervention of Luftwaffe State secretary, Erhard Milch, in October of 1941, were the department’s many heads reduced to four. In no uncertain terms, Milch dismissed the Luftwaffe’s Engineer-General, “Your plans are inaccurate. Your attitude is one of constant negativism. I have been ordered to inform you of these facts and let you know of his (Göring’s) displeasure. You are herewith relieved of your assignment, and you are expected to tender your resignation.” Milsch would be later be given Udet’s post, following his suicide, and curb the worst of the office’s dysfunction. Along with the efforts of Albert Speer, Reichsminister of Armaments and War Production, there would be considerable improvements in the development, and procurement, of Luftwaffe projects.
The confusion lessened, but many Luftwaffe projects, like the Me 210 and He 177, failed to deliver on time, if at all. Very promising power plants suffered the same fate, with the Jumo 213 and DB 603, competing for resources with projects that had little hope of delivering an engine in any relevant time frame. Two years following its reduction in staff, Reichsmarshall Göring would state “There’s still many a scoundrel there…You’ll find people there who have been thrown out on their ears three times already, and they come to light in some other department again, only bigger and stronger than ever”. As the chief of the Luftwaffe, it was, of course, his responsibility to ensure the office was well staffed, and it was his appointment of Udet, and continued administrative neglect, that effectively doomed it.
Höhenjäger 2
In August of 1942, a much more ambitious project was initiated to produce a high altitude fighter, under the title Höhenjäger 2. It was developed concurrently with the extremely modest Höhenjäger 1 project as a more technically ambitious alternative. The new fighter was to incorporate a number of features, notably the longer span wing of the Fw 190B, the pressurized cockpit, and with the addition of a new 2000hp turbo supercharged DB 603S engine.
Turbochargers, like superchargers, compress air before feeding it into the engine’s intake manifold, allowing for an increase in overall power, and can provide truly excellent high altitude performance. A supercharger is typically still required if one is using a turbocharger on an aircraft, and this arrangement of a supercharger, supplied charge air by a turbo charger, is referred to as a turbo supercharger. This type of system can be very challenging to incorporate in an aircraft. The turbocharger requires ducting to supply the exhaust to the turbine, then back to the engine, and it presents new cooling requirements, as the temperature of charge air from the turbine will be high, and some form of cooling will be needed before the charge air is sent to the supercharger.
As exemplified by the General Electric turbo supercharger on the American P-47, installing this gear required an enormous amount of space, and additional cooling capacity. This arrangement was excellent, adding very little drag to the fighter. (P-47N manual)
On the Fw 190, this would prove challenging. There was simply not enough space available within the air frame to accommodate the ducting, cooler, and turbine. The turbine and exhaust ducting would also require high temperature alloys to build, which were in short supply. Despite these challenges, the project engineers would study ways of incorporating the Hirsch TK 11 turbocharger in the Fw 190, while receiving assistance from the Deutsche Luftfahrtforschungsanstalt, or German Aeronautical Research Institute.
While studies were underway, one of the first practical tests involved the development of the exhaust tubes which would lead from the engine to the turbine. These were first added to one of the earlier prototypes Fw 190V15 sometime during the latter half of 1942. The first of the true Höhenjäger 2 prototypes would be constructed from Fw 190V18, one of the aircraft transferred from Jumo 213 testing to the DB 603. It did not feature the long span wing, or the pressurized cockpit. The TK-11 turbocharger was mounted behind the cockpit, below the fuselage within a fairing. It would prove impossible to mount the turbine fully within the aircraft itself, and its cooling requirements demanded a large intercooler be installed in a ventral scoop. In addition to the large radiator, the ducting for the turbine was almost entirely outside the fuselage, giving the aircraft a very unique appearance, and adding considerable drag generating surfaces.
Fw 190V18/U-1 would prove anything but ideal, the inadequate space within the Fw 190 fuselage required external piping and an ventral scoop. The plane was nicknamed “Kangaruh”, or kangaroo. (Luis Lopez-pinterest)
Fw 190V18/U-1 was completed by December, 1942, and took to the air on the 20th. After the first test flights numerous issues began to arise, mostly related to cooling, but also general reliability issues. A larger oil cooler was also subsequently fitted to the aircraft, along with a four bladed VDM propeller and a pressurized cockpit, as continuous testing was conducted to refine the turbo supercharger arrangement. Months later, after some 42 flying hours, V18/U-1 was able to achieve a top speed of 670 km/h at 11km, and had a ceiling of 14 km with the use of the turbocharger. The setup still proved troublesome, with continued issues with overheating. The exhaust piping was also prone to rapid wear, being consistently subjected to very high temperatures, and being made of an inadequately heat resistant alloy. It would be a fatal weak point of the program, in addition to the overheating, and the teething issues of the temperamental DB 603 engine. The turbine itself, however, seemed to be operating well enough.
The program was expanded in the hopes of finding a means of improving the design, and delivering a high altitude fighter to the Luftwaffe. To this end, several new prototypes were constructed from pre-production Fw 190A’s, V-29 through 33. These aircraft were all fitted with the pressurized cockpit, and enlarged vertical stabilizer. Fw 190V29 was delivered in March of 1943, with more to come in the following months. Of note, was Fw 190V32, which was the only example of these aircraft that had a provisional armament, featuring a pair of MG 151/20’s in the inner wing roots. This particular aircraft was completed in November, 1943. Despite the construction of several more test aircraft, the engineers failed to find a means of solving the issues which plagued the design. The inadequate supplies of heat resistant alloys, and the already rough running DB 603, would prove an insurmountable combination of challenges for the engineering team. Testing continued into January of 1944 before the program was canceled and the prototypes were converted to test the new Ta 152 fighter series.
The Höhenjäger 2 project conducted test flights on four prototypes for nearly a year before the planes were repurposed. (GeorgeThomas-Pinterest)
The new series of fighters would be derived from the Fw 190, with a number of new features, namely more powerful engines. Among them was the Ta 152H, a high altitude design, and the only aircraft in the series to enter production. The Ta 152H would entirely dispense with the turbo supercharger arrangement, and utilize a Jumo 213E high altitude engine, with a two stage, three speed supercharger. Its development was rushed and it entered pre-production after a very short prototyping phase that saw few modifications to the design. It did however see service in the last weeks of the war. Very little of the Höhenjäger 2 project would make its way into the Ta 152H, save for the enlarged wooden vertical stabilizer, and the pressurized cockpit, which was modified considerably between the two programs.
Comparisons
The Fw 190 Höhenjäger compared poorly with aircraft already in Luftwaffe service. Despite the considerable effort expended, the aircraft did not present much of an improvement over the Bf 109G carrying a GM-1 nitrous boost system. The Höhenjäger 2 was faster at extreme altitudes, and had a theoretical ceiling of nearly 14km, but in practice the limitations of the turbo supercharger made sustaining this difficult. Simply put, it wasn’t capable of reliably achieving its most impressive test results given the inability to run the engine at high settings for extended periods. Beyond this was the fact that the test aircraft did not carry a full combat load. The 670 km/h record at 11km was achieved by Fw 190V18/U-1, which did not carry a FuG 16 fighter radio set, a FuG 25 IFF, armor plates, or any weapons. All of which rendered the aircraft several hundred kilograms lighter than any fighter aircraft that might have been based on its design.
The Bf 109G used GM-1 for high altitude reconnaissance missions, flying top cover for more heavily armed fighters during strategic bomber intercepts, and intercepting the high altitude variants of the Mosquito. (wwiiaircraftforum)
On a practical level, the Bf 109G with GM-1 was able to largely match the combat capabilities of the Fw 190 Höhenjäger 2. The Fw 190 would have likely held some advantage in speed, but it had a projected service ceiling some 800 meters below the 13.2 km ceiling of the Bf 109G. The turbo supercharger also failed to create a fighter that could match the performance of a nitrous boosted aircraft, and eliminate its weaknesses. Namely, the added weight of a boost system, its ineffectiveness in providing any advantage at low altitude, and the inability to store the nitrous in the aircraft without it leaking out via evaporation. Only in the last factor could it really boast of an advantage. The turbo supercharger system also added considerable drag, which GM-1 did not impose on any aircraft. The scoop for the intercooler, and the turbine’s associated piping, were aerodynamically unsound features, creating enormous amounts of drag, and created a serious handicap at lower altitudes, where the turbo supercharger also offered very little advantage. Even without comparisons to specialized aircraft in foreign service, the Fw 190 Höhenjäger 2 had failed to exceed the performance of the expedient high altitude fighter model already in use with the Luftwaffe.
Construction
The Fw 190 took shape under the direction of Dipl.-Ing Kurt Tank, of Focke Wulf Flugzeugbau. In designing the aircraft, Kurt Tank sought to make a rugged fighter, a “work horse” rather than the “race horses” that were the Bf 109 and Spitfire. In his mind, these aircraft were too focused on pursuing performance over more practical concerns, like how well they could operate out of ill-prepared forward airfields, or being designed with ease of production in mind. Kurt’s Fw 190 would also feature considerable attention given to making the aircraft as convenient to fly as possible.
Fw 190A core fuselage. (Fw 190A manual)
The core of the Fw 190 is a conventional, and rugged fuselage composed of two sections. The main fuselage is composed of a pair of sub assemblies. The forward section is of a semimonocoque construction and contains the engine firewall, cockpit, and fuel tanks, with the forward tank containing 232 liters, and the rear, 292 liters. Behind the front fuselage section is a monocoque rear section which connects to the tail unit. The tail unit is bolted to the fuselage and contains the horizontal and vertical stabilizers. On the Höhenjäger 2, the tail section included a fuselage extension to balance the added length of the longer DB 603, and a new enlarged vertical stabilizer. The new stabilizer was made of wood, with the rest of the aircraft being composed of duralumin, save for the fabric-covered control surfaces. The use of a wooden tail unit was carried over into the Ta 152 program.
The wing was of a single spar, monolithic construction. The tips were removable, but the wings were a single unit which was a single sub assembly. Doing so made them easier to produce, and in the event of damage, were replaced entirely, rather than have repair crews go through the time consuming process of repairing, and realigning the wings. The wide set landing gear made landings in rough, ad-hoc fields easier. The undercarriage lowered under its own weight, and was retracted by means of steel cables driven by electrically actuated drums. The Höhenjäger 2 project made use of an original wing with a 10.5 meter span with an area of 18.3 m2, and it was hoped to test a later set with a 12.4 meter span with an area of 20.3 m2.
Fw 190A wing. (Fw 190A Manual)
The use of these sub assemblies made the aircraft much easier to produce. The sub assembly components could be produced with unskilled labor as the production steps kept the work as easy and simple as possible until wiring and final assembly, and the assembly process itself kept fitment and alignment to an absolute minimum. The wings were attached to the forward fuselage via flanges, requiring no fitting work, which was a time consuming and expensive step. Much of this was achieved by forgoing any complex or sensitive systems that were woven through the air frame, for example the wing mounted radiators on the Bf 109, or unfortunately, the ducting on for the turbo supercharger on these test aircraft.
The Hirth TK-11 turbocharger unit was half embedded in the lower fuselage, it was supplied by exhaust gas delivered from the engine through a set of pipes made of Sicromal 8, which was contained by an outer sheet metal tube at a separation of 5mm, to keep it from being in contact with the fuselage and the air flow across the skin of the aircraft. The alloy was totally inadequate for enduring exhaust temperatures of around 800 degrees Celsius, at some two atmospheres of pressure. In tests they could fail in as low as ten hours of use, and last as long as 20, after improvements were made to the design. The exhaust pipes extended across the fuselage, and were semi faired over to reduce drag, they went over over the wings, and into the turbocharger unit aft of the cockpit. The turbine itself proved adequate in its use, though the inability to mount it in the fuselage itself proved problematic. Hollow turbine blades served to adequately give the device adequate heat resistance when the materials alone would not have. The turbine waste gate was at the rear of the scoop. The charged air was sent through the intercooler in the air scoop, and directed in a pipe along the underside of the aircraft, before it entered the fuselage ahead of the cockpit. The charge air was then directed into the integral supercharger on the DB 603S engine.
The internal layout of the Höhenjäger 2. (johnbr-wwiiforum)
The pressurized cockpit took a number of forms, never working quite right. The original layout consisted of reinforcement brackets along the canopy hood, a rubber canopy seal, stoppers around the electrical cables entering the cockpit, and a DVL air compressor. The windows could blow out and needed reinforcement, the cockpit frame could cut the rubber seal, and the various plugs around the cockpit had a tendency to fail. It wasn’t until December of 1943 that the pressurized cockpit was satisfactory, though the program’s cancellation followed soon after. The later Ta 152H included a much improved, and modified, pressurized cockpit.
The otherwise clean and workman-like cockpit of the Fw 190 was complicated considerably with the inclusion of the liquid cooled engine and turbocharger. The new powerplant required the installation of more instruments to allow for the display of the liquid coolant temperature of the DB 603, and the output of the turbine blower.
The Fw 190 typically made use of a unitary power unit which contained the motor and all its associated accessories and cooling systems. It was designed for ease of installation and removal through brackets attached to the fuselage. The Fw 190 Höhenjäger 2 represented a significant break from the design with the incorporation of the turbo supercharger. The Fw 190 prototypes it was based on used a DB 603A in a Kraftei unitary power unit, which was connected via a bracket to the firewall on the fuselage. The engine’s liquid cooling was facilitated by an annular radiator at the nose of the aircraft, a remarkably efficient layout in regards to drag, if somewhat inadequate in cooling capacity. Beneath the cowling was the scoop for the oil cooler.
The DB 603A is an inverted V-12, it was relatively straight forward for a German fighter engine, and its supercharger was its only true novelty. The single stage supercharger was mechanically driven by the engine and used a hydraulic coupling for variable transmission, effectively making it infinitely variable. Compared to the fixed gears on most fighter engines, this eliminated the performance gaps when an aircraft was flying at an altitude that was between the critical altitude for its otherwise fixed supercharger speeds. Like the DB 601/605 series, it featured a high degree of automation which adjusted the propeller RPM, mixture, and radiator flaps through a series of pre-set linkages, which were reactive on inputs from the throttle. The engine was otherwise only an interest to the Luftwaffe for its 44.5L displacement and relatively compact form. Unlike the more cutting edge Jumo 213, it was somewhat dated, though still powerful and possessed similar dimensions.
The DB 603A had a length of 2680mm, a width of 77.5 mm, and a height of 1067 mm It had a bore and stroke of 162 mm x 180 mm. It had a dry weight of 910 kg. It also used a Bosch direct fuel injection system. The DB 603S was the turbo supercharged model on the Höhenjäger 2 Fw 190.
The DB 603 was considerably larger than the DB 601’s and 605’s that powered the Bf 109. It was not particularly novel, but was a potential means of getting a more powerful engine into Luftwaffe aircraft. (DB 603 manual)
While it was claimed the engine had a rating of some 2000 PS, its extreme unreliability and propensity for overheating meant that there was likely no stable upper level output. Overheating remained a chronic issue with the aircraft, and both the intercooler, and the engine liquid coolant temperatures were too high. A test pilot noted the engine temperatures were consistently elevated above what were typical on the Fw 190C prototypes, which already ran hot.
Pilot’s Notes and Handling
The Fw 190 has a well established pedigree of being a pilot’s plane. Everything that could be done to lessen the pilot’s workload, and generally make the aircraft as convenient to fly as possible, had been done. It was very stable, provided excellent visibility for a fighter of its day, had a cleanly laid out cockpit and instrument panel, and used a push-rod control system in place of more conventional cables, as they were more responsive and didn’t have any tension or play to them. In the case of the Höhenjäger 2, many of these conveniences were lost.
Fw 190V15, featuring similar instrumentation to later series. (destination’s journey)
The cockpit was considerably more complicated as new instrumentation and controls for the turbo supercharger were installed. The BMW 801 and Jumo 213 engines were almost entirely automated, and required the pilot to do little more than adjust the throttle lever to bring the aircraft to the desired power setting. The DB 603S engine, in comparison, required constant supervision. Not only did the turbine management add to the otherwise light pilot workload, but the unreliability of the base engine, and the overtaxed cooling systems, required the pilot to remain highly attentive to the engine at all times.
With test pilots having flown the aircraft for roughly a year, from early 1943 to early 1944, there must have been considerable frustration among them. Its critical failings were never fully addressed, and the plane was still ill functioning through nearly all its test flights, the last of which was only two minutes long. For the considerable effort expended, it seems the only saving grace of the aircraft is that it remained stable. Only one major accident resulted in an air frame loss, being V-31, which overturned on landing on April 29, 1943.
Prototypes
The Fw 190 Höhenjäger 2 never entered mass production, nor did it possess a standard design under a military designation, as the Fw 190C had. The program delivered six prototypes in various configurations. They were built from Fw 190A-0’s, before being modified at Focke Wulf Workshops, and sent off to the Hirth motor works in Stuttgart to be fitted with the turbo supercharger equipment. It does not appear these aircraft were referred to as either Fw 190B or Fw 190C, with no defined model of either type having a DB 603S engine. Given the enormous troubles involved in this program, it does not seem to have reached a stage where a potential fighter design was proposed.
Fw 190V18/U-1: This was the first of the prototypes constructed, and transferred from Jumo 213 testing, first flown in December of 1942. It had the standard Fw 190A span wing, the enlarged vertical stabilizer, and was only later fitted with a pressurized cockpit, an enlarged radiator for the intercooler, and a metal four bladed VDM propeller. By May of 1943, it had flown 44 test flights, and was later passed on to the Hirth, and Daimler Benz test centers in Stuttgart in June of 1944.
Fw 190V29: Same as V18/U-1 and all the later additions it received. This aircraft carried fighter communication and identification gear, the FuG 16P and FuG 25A, respectively. The first of the freshly converted prototypes, and first flown in March of 1943. The turbo supercharger failed to function after being installed at the Hirth facilities in Stuttgart, and the prototype had to be rebuilt to begin testing.
Fw 190V30: The same as the V29, save for it testing a wooden four bladed VDM propeller manufactured by Schwarz. This prototype had considerably worse overheating problems. Completed in April, 1943.
Fw 190V31: Same as V29, this prototype was soon lost after engine failure during one of its early test flights. It overturned during a forced landing, and was written off on May 29, 1943.
Fw 190V32: Same as V29 and V31, with the addition of a pair of Mg 151/20 cannons in the wing roots. Completed in November 1943.
Fw 190V33: Same as V29. Completed in time to be turned over to the Ta 152 program.
Conclusion
The Höhenjäger 2 project can categorically be stated to be a failure. It was unable to produce a design which could have been offered for service, given the completely unworkable state of its turbo supercharger system. Both the victim of resource shortages, and the chaotic and dysfunctional Luftwaffe offices which oversaw new technical developments, the task set before the engineers was impossible. In the end, the program’s test aircraft were turned over to the more successful, if very short lived, Ta 152 project. Its only contribution seems to have been the enlarged, wooden tail section and pressurized cockpit.
Specification
Höhenjäger 2 (Proposed)
Specification (Projected)
Engine
DB 603S
Engine Output
2000 PS
Gross Weight
3585 kg
Maximum speed
685 km/h at 11,800 m
Height
3.95 m
Length
9.50 m
Wingspan
12.30 m
Wing Area
20.3 m2
Note: These figures do not depict any aircraft constructed by Focke Wulf, the prototypes have roughly the same dimensions and have a 10.5 m wing with an area of 18.3 m2
Illustration
Fw 190V18/U-1. The aircraft was left in a natural metal finish, and received the typical Luftwaffe ID markings and registry code.
Poland (1934-1939) Type: Light Bomber/Reconnaissance, Number built: 240
In the early 1930s, the Polish Air Force began modernizing its fleet as tensions rose in central Europe. Among its top priorities was acquiring a specialized class of aircraft capable of performing both reconnaissance and bombing missions. The goal was to develop a modern, all-metal aircraft that could fulfill both vital combat roles. This ambition materialized in the form of the PZL.23, produced in two main variants: the PZL.23A, and the improved PZL.23B. A total of 250 aircraft were built, and the design even achieved modest export success. These aircraft went on to serve in the early stages of the Second World War II, seeing combat against both Germany and the Soviet Union, with some measure of success.
The Polish Bomber/reconnaissance plane PZL.23 Source: https://en.wikipedia.org/wiki/PZL.23_Kara%C5%9B
History
At the start of the 1930s, the Polish Air Force was primarily equipped with outdated aircraft. This was the case with its bomber formations, which mostly relied on French canvas-skinned, biplane bombers, such as the Breguet 19. These aircraft were fragile, had a relatively small bomb-carrying capacity, and were intended more to harass the enemy than to inflict significant damage.
The role of the light bomber/reconnaissance aircraft was mostly taken by the French Breguet 19 biplane in the post war years. Source: https://commons.wikimedia.org/wiki/File:Samolot_Breguet_19_B2_NAC_1-W-1555-2.jpg
In 1931, the Polish Air Force initiated the development of a new bomber designed to provide close support to ground forces. In addition, it was also to perform the role of reconnaissance operations, this request being primarily based on the experience gained during the Russo-Polish War of 1919–1920. During that conflict, both sides employed a limited number of aircraft, mainly for reconnaissance and bombing operations. As a result, the Polish Air Force sought to replace its aging fleet with new aircraft capable of effectively performing both roles.
In 1931, the Polish Air Force issued a requirement for a new single-engine, monoplane aircraft. It was to accommodate three crew members and be capable of carrying several hundred kilograms of bombs, serving the dual roles of bomber and reconnaissance platform. Few proposals were submitted, including the high-wing PSW.19 and the Lublin R.XVII biplane. Of the two, only the PWS.19 was built and tested, but it was ultimately not accepted for service.
The PSW.19 was a proposal from Podlaska Wytwórnia Samolotów (Eng. Podlachian Aircraft Factory) for a new bomber/reconnaissance plane. However, the design was not accepted for service. Source: https://www.armedconflicts.com/PWS-19-t185849#valka_group-2
The winning design came from a young engineer named Stanisław Prauss, working at Państwowe Zakłady Lotnicze (PZL, or State Aviation Works). Prior to this project, Prauss had worked on the PZL.13, a single-engine passenger aircraft, which was a modern design for its time, featuring an all-metal structure. Despite its innovative features, the project was ultimately canceled in 1931.
Following that setback, Prauss and his team dedicated much of late 1931 to drafting design plans, and performing critical calculations for the new military aircraft. In order to accelerate development, Prauss chose to incorporate several elements from his earlier PZL.13 project into the new design.
To expedite development, Prauss decided to incorporate several elements from his earlier PZL.13 project. The overall shape of his earlier design was clearly reflected in the later production aircraft, including the fixed landing gear, engine configuration, and fuselage design. Source: http://www.samolotypolskie.pl/samoloty/2296/84/PZL-13
By early 1932, a full-scale wooden mock-up of the fuselage was completed. Both the drawings and the mock-up were presented to the Polish Aviation Department in the spring of that year. After analyzing the wooden construction and technical documentation, the department approved the project and ordered the construction of three prototypes for testing.The first prototype was completed by 1934, powered by a 593 hp Bristol Pegasus II M2 radial engine. Although not of Polish origin, the engine was produced under license in Poland, with the original rights obtained from the United Kingdom. The overall design was simple: a conventional linear crew arrangement with a weapons bay between them. The rear gunner was also expected to serve as the bombardier, for which a small under-fuselage compartment was provided. For defense, the rear gunner operated two machine guns, one mounted dorsally and the other ventrally. Lastly, another crew member was tasked with aiming and releasing the bombs. A forward-firing machine gun was also planned for the pilot’s use, though it remains unclear whether this was ever actually fitted to the prototype.
The prototype, designated PZL.23/I, was flight-tested in early April 1934. Interestingly, it received the nickname Karaś, meaning Crucian-carp, a species of fish. Its performance in the was rather poor, and several design flaws became apparent, such as a cramped interior, limited crew visibility, and vibrations in the rear section. Bombing trials were also problematic: when released, the bombs would shift from a vertical to a horizontal position, then back to vertical, as they fell from the aircraft. This erratic behavior significantly reduced bombing accuracy.
Further tests were carried out to refine the overall design throughout 1934 and into 1935. Eventually, the prototype was handed over to the Polish engineering college, where it was used for training new engineers. It remained there until the fall of Warsaw in September 1939.
The first prototype, although successfully flight-tested, was found to have several design flaws. As a result, after 1934, it was eventually repurposed as an instructional airframe.Source: https://jmodels.net/de-hombres-y-maquinas/aire-air/pzl-23-karas/
In late 1934, work began on a second prototype, designated PZL.23/II. The most notable change was the removal of the centrally located bomb bay. Instead, bombs were mounted under the wings, and the former bomb bay space was expanded to provide more space and improve visibility for the crew. Additionally, the engine was lowered by 10 cm to improve the pilot’s forward view. Other improvements included the addition of new leading-edge slats and flaps.
Testing revealed that many of the previously identified issues had been resolved; however, forward visibility was still considered unsatisfactory. Unfortunately, testing of the PZL.23/II came to a sudden and tragic end. At the end of July 1935, all three crew members were killed in a crash landing. The investigation concluded that the pilot had made a serious error, with some speculating it may have been a deliberate act of suicide.
Following the loss of the previous aircraft, another prototype (designated PZL.23/III) was constructed in 1935. This version incorporated several improvements over its predecessor, including an enlarged canopy and a raised pilot’s seat. These modifications significantly enhanced the pilot’s forward visibility, addressing a major flaw in earlier designs.
An especially interesting feature of the PZL.23/III was the addition of a hydraulically operated rear machine gun mount. This system allowed the rear gunner, if necessary, to engage targets approaching from the front by raising the machine gun above the forward fuselage. However, while seemingly innovative, this setup was likely difficult to use effectively in combat.
Production and Service Problems
Following the successful testing of the third prototype, the Polish Air Force placed an order at the end of 1935 for the production of 200 aircraft. These were to be manufactured at the PZL factory in Warsaw-Okęcie, with the first batch of 40 aircraft scheduled to begin production at the start of 1936. However, after only a few units were built, production was abruptly halted due to a critical issue: the unreliability of the Bristol Pegasus engines.
These engines, produced under license in Poland, were plagued by numerous mechanical problems that required extensive troubleshooting and rework. To make matters worse, the engines were not manufactured in the UK, which meant acquiring replacements or parts from abroad was not an option, given differences in manufacturing tolerances. It wasn’t until September 1936 that these issues were finally resolved, allowing production to resume. The aircraft entered service under the designation PZL.23A, and the initial order of 40 aircraft was finally completed in November 1937.
Unfortunately, matters only worsened once the aircraft entered operational service. The planes delivered to the Polish Air Force proved deeply disappointing, bordering on unusable. The engines were underpowered, limiting the aircraft to a maximum altitude of just 3,000 m. Additionally, the automatic leading edge slats frequently malfunctioned, often deploying mid-flight without warning and causing severe stability problems. As a result, the aircraft was ultimately deemed unsuitable for combat roles and relegated primarily to reconnaissance duties.
Need For Improvements
Abandoning the PZL.23 at that point would have seemed a waste of both resources and time, two things the Polish military could ill afford. Starting from scratch would have required significant time, with no guarantee that a new design would be any more successful. In the face of rising threats from both Germany and the Soviet Union, officials in the Polish Air Force sought ways to salvage the PZL.23 project.
One of the first PZL.23A production aircraft. Source: https://tvd.im/aviation/1666-pzl-p-23-karas.html
The first option considered was installing a stronger engine. PZL engineers decided to equip the aircraft with the newly produced Bristol Pegasus VIII engine, which had just entered production in Poland. This engine offered the advantages of its greater performance and a reliable local supply of parts, making it a logical choice. A prototype designated PZL.23/III was fitted with this engine and tested.
The third prototype was equipped with the new engine. Source: T. J. Kopanski PZL.23 Karaś
Although the speed increased only slightly (from 263 km/h to 274 km/h), the upgraded aircraft could now reach an altitude of 7.3 km, a significant improvement over the previous 3 km ceiling. In addition to the new engine, several other modifications were introduced: the leading-edge slats were removed, the elevator was redesigned, and an extended antenna mount was added to the observer’s gondola for in-flight radio use.
Lastly, the new variant received two machine gun mounts in the forward engine compartment, compared to only one in the earlier model. However, due to a shortage of available machine guns, only one was actually installed in most aircraft. With these improvements, production of the updated model continued under the designation PZL.23B (sometimes referred to as Karaś II). With the introduction of the B variant, the remaining A variant aircraft were mainly employed as trainers. Some of them were thus equipped with dual controls.
The most common variant was the PZL.23B, which resolved many issues with the previous model. Source: https://www-airwar-ru.translate.goog/enc/bww2/pzl23.html?_x_tr_sch=http&_x_tr_sl=ru&_x_tr_tl=en&_x_tr_hl=enNearly all PZL.23A aircraft were converted into trainers by rebuilding them with dual controls, as was likely the case with this example, which probably belonged to the training school at Krosno. Source: https://www-airwar-ru.translate.goog/enc/bww2/pzl23.html?_x_tr_sch=http&_x_tr_sl=ru&_x_tr_tl=en&_x_tr_hl=en
Production
After the production of 40 PZL.23A aircraft, the remaining 160 units were built exclusively in the upgraded PZL.23B variant, and the initial order for 200 aircraft was completed by September 1937. Due to high demand, the Polish Air Force secured additional funding and requested the construction of 50 more aircraft. This follow-up order was fulfilled by February 1939.
In total, 240 aircraft of the Variant A and B (in addition to three prototypes) would be built.Source: https://panssarivaunut.blogspot.com/2016/02/pzl23-karas.html
Experimental Project
Dive Bomber
While the PZL.23 shared some visual similarities with the German Ju 87 dive bomber, the Polish Air Force initially did not consider employing it in this role. However, by 1936, the idea of using the aircraft as a dive bomber began circulating among Air Force officials. To test the feasibility of this concept, one PZL.23A was modified to serve as a prototype, designated PZL.23/IV. This prototype could be easily identified by the removal of the bombardier’s gondola.
The proposed armament included two forward-firing and two rear-mounted machine guns. The estimated bomb load was 300 kg, though it was hoped that this could be increased to 800 kg for potential export customers. Testing was carried out by the Air Force Technical Institute (ITL) in August 1936. Despite the modifications, it’s overall performance did not improve significantly, and the aircraft proved unsatisfactory in dive-bombing operations.
PZL.42
In April 1937, the prototype was further modified by replacing the single vertical stabilizer with twin vertical tails. This change aimed to improve the gunner’s field of fire. Bombing trials conducted with this version were somewhat more promising. However, for unclear reasons, the aircraft remained at the prototype stage, with only one example ever built. It was later used as a training aircraft until it was destroyed in a bombing raid in September 1939.
The PZL.42 prototype was tested with the new tail design. Source: https://jmodels.net/de-hombres-y-maquinas/aire-air/pzl-23-karas/An aircraft lost in one of many German bombing runs during September 1939. Source: T. J. Kopanski PZL.23 Karaś
In Service
As the first PZL.23A aircraft became available, they were issued to units for familiarization. The first units to be equipped, in September 1936, included the 11th and 12th Flights of the 1st Air Regiment. The 21st Flight of the 2nd Regiment also received some of these aircraft. However, due to the poor performance of the PZL.23A, they were soon relegated to training duties.
With the introduction of the improved PZL.23B variant in early 1937, more than a dozen units received the updated aircraft. The Polish pilots experienced some difficulty adapting to the new type. This was not due to any inherent flaw in the aircraft or deficiencies in training, but rather because most pilots had been accustomed to flying older biplanes. This issue was not unique to Polish pilots—air forces across Europe faced similar challenges during this period of transition to more modern monoplanes.
Nonetheless, the aircraft was involved in numerous accidents. Between early 1937 and August 1939, a total of 23 aircraft were involved in various incidents, resulting in the tragic loss of 55 lives.
The PZL.23 would be dispatched in small groups of up to 10 aircraft to various units of the Polish Air Force. Source: https://en.wikipedia.org/wiki/PZL.23_Kara%C5%9B
In Action
Border Actions
The PZL.23 saw its first operational use against Poland’s neighbors in the year 1938, a particularly turbulent moment in this part of Europe. Nearly all the nations in central Europe had once formed much of the German and Austro-Hungarian Empires (including Poland), were embroiled in long-standing border disputes. These tensions escalated rapidly following 1938 as political pressure continued to mount across the continent.
Poland, eager to assert control over territories it considered historically its own, sought to occupy several neighboring provinces. In March 1938, a border clash between Poland and Lithuania triggered considerable alarm, prompting the partial mobilization of the Polish Air Force. However, the operation was poorly organized, hastily executed, and ultimately too late to have any significant impact.
To make matters worse, the relocation of several PZL.23 aircraft to an unprepared airfield near Wilno led to the crash-landing of three planes. By the 20th March, the brief conflict had subsided. Nonetheless, in an effort to intimidate Lithuania, the Polish military carried out a large-scale demonstration flight of over 100 PZL.23 bombers near the Lithuanian border.
The PZL.23 was deployed again in September 1938, this time against Czechoslovakia. At that point, part of Czechoslovakia had already been occupied by Germany with the approval of the Western Allies. Seeing an opportunity, Poland moved to occupy the Zaolzie region. Once again, the PZL.23 aircraft were used primarily as a show of force and did not engage in actual combat.
However, this show of force came at a significant cost. The frequent deployments accelerated the wear and tear on the PZL.23 fleet. Limited availability of spare parts meant that many planes had to be withdrawn from service due to being worn out beyond repair. As a result, some units were disbanded, while others had only a handful of operational aircraft of this type remaining.
Downfall of Poland
By July 1939, tensions between Germany and Poland had reached a boiling point, and the possibility of war between the two nations was becoming increasingly likely. In response, the Polish Air Force conducted several reconnaissance flights along the German border, primarily using PZL.23 aircraft.
On the 23rd of August, the Polish Air Force began mobilizing. According to Poland’s war contingency plan, in the event of conflict with Germany, the air force was to be divided into two main groups. One group would be placed under the direct control of the Polish High Command, while the other would be attached to various ground formations. By the end of August, nearly all PZL.23-equipped units had been mobilized and prepared for potential combat operations.
On the 31st of August, the Polish Air Force issued orders to implement the pre-war organizational distribution plan. The group under the High Command’s direct control consisted of five fighter flights and the Bomber Brigade. The Bomber Brigade included five flights of PZL.23 aircraft, which were at that point renamed Light Bomber Flights. These were supported by seven reconnaissance flights, each equipped with an average of eight PZL.23 aircraft.
The aircraft allocated to direct ground support roles for the army were dispersed in small groups across various units. Although in theory, they were meant to cover vast territories and participate in reconnaissance or bombing raids, in practice, this deployment strategy significantly reduced their effectiveness. Their numbers were too few in each location to have any real impact in combat.
As of 1st September 1939, the Polish Air Force could field only 114 PZL.23 aircraft. Of these, 50 were allocated to the Bomber Brigade and 64 were assigned to various ground forces. An additional 10 were held in reserve. At least 55 more aircraft were in storage awaiting repairs, and another 45 PZL.23s were being used as training aircraft. Some of these would be pressed into combat as a replacement when nothing else was available. The small number of available aircraft meant that the PZL.23 was a generally rare sight during the war in Poland.
Despite many misconceptions about the war, the belief that the Polish Air Force was destroyed on the first day, is simply not true. While many aircraft were indeed destroyed on the ground, many survived and saw continued use through the conflict. The PZL.23, in particular, saw considerable action in both reconnaissance and bombing roles.
The PZL.23s of the 21st Bomber Flight first entered combat on 2nd September. A single aircraft was tasked with locating a German column near Lubliniec. It successfully identified a German motorized unit and carried out an attack against it. Another aircraft was shot down while on a similar reconnaissance mission, having been engaged by four Bf 109 fighters. On September 3rd, the unit suffered further losses, with several planes downed by superior German fighters and anti-aircraft fire. By 11th September, the unit handed over its remaining four aircraft to the VI Bomber Squadron, and the surviving pilots and crew were evacuated to Romania. Between September 1st and 11th, the 21st Bomber Flight dropped approximately 10 tonnes of bombs and lost six aircraft.
The 22nd Bomber Flight saw its first action on September 3rd, attacking a German column. The bombers were engaged by enemy fighters and anti-aircraft fire, resulting in the loss of three aircraft. Two more were lost in a follow-up attack later that same day. Over the following days, the unit continued to carry out bombing raids against German forces. By 10th September, the 22nd had transferred its remaining aircraft to the VI Bomber Squadron and evacuated its personnel to Romania. By that time, the unit had dropped around 12 tonnes of bombs and lost a total of five aircraft.
A PZL.23B from the 22nd Bomber Flight, easily identified by the painted emblem of a flying dragon holding a bomb on the fuselage sides. Source: https://tvd.im/aviation/1666-pzl-p-23-karas.html
The 55th Independent Bomber Flight was another unit that saw heavy action in both bombing and reconnaissance missions. It was almost completely wiped out on 11th September, losing nine of its aircraft. Despite the losses, the unit managed to drop 14 tonnes of bombs in 40 combat sorties. The 64th Light Bomber Flight also suffered significant losses during the war, losing 21 aircraft to German fighters and anti-aircraft fire.
The 24th Reconnaissance Flight was engaged from the very beginning of the conflict, tasked with spotting enemy formations and tracking their movements. On the 3rd September, six of its aircraft took part in a bombing run against a German armored column near Rabka. Polish pilots reported scoring several hits on enemy targets, although one aircraft was lost to anti-aircraft fire.
Despite sustaining losses, the unit still had operational aircraft by the 14th September. The following day, one aircraft was assigned the dangerous task of delivering a message to the Polish High Command in besieged Warsaw. The pilot had to fly 360 km over enemy-held territory and land in a city under siege, with no guarantee that the airfield was still secure. Against the odds, the mission was successful. The aircraft even managed to take off again and return, despite German attempts to shoot it down. The unit remained active until 17th September, when it was forced to evacuate to Romania due to the Soviet invasion from the east.
The 41st Reconnaissance Flight operated a small number of improved PZL.43A aircraft (an export version of the PZL.43 that had been sold to Bulgaria). While most of these aircraft were delivered to Bulgaria before the outbreak of war, a few remained in Poland awaiting final delivery. Initially, they could not be used due to missing components.
Interestingly, on the 6th September, an element of this unit engaged a German reconnaissance balloon near Przasnysz. Despite being protected by anti-aircraft guns, the Polish aircraft managed to shoot it down. By the 10th September, the unit had only two PZL.43As remaining. On that day, during a reconnaissance mission, one of the aircraft was hit by anti-aircraft fire and crashed, killing its crew. The following day, the last remaining aircraft was damaged by an enemy fighter and subsequently lost in a crash landing.
A PZL.23B from the 41st Reconnaissance Flight. Source: https://www-airwar-ru.translate.goog/enc/bww2/pzl23.html?_x_tr_sch=http&_x_tr_sl=ru&_x_tr_tl=en&_x_tr_hl=en
By the time of Poland’s surrender on the 6th October, 1939, the PZL.23 aircraft of the Bomber Brigade had conducted over 186 sorties, during which they dropped approximately 64 tonnes of bombs. Meanwhile, the independent flight units assigned to the Army saw even more combat activity, flying around 260 sorties. However, these units dropped only about 20 tonnes of bombs, as their missions were primarily focused on reconnaissance rather than bombing enemy positions and forces on the move. Of the 140 aircraft deployed, over 100 were eventually lost in combat during the war. Far from the myth that the Polish Air Force was destroyed on the first day of the war, they fought with every tool at their disposal until the end.
By the end of the war in Poland, some 120 PZL 23 would be lost in combat. Source: https://www.reddit.com/r/WWIIplanes/comments/12bnmuw/german_personnel_examine_the_remains_of_a_polish/
In the Foreign Service
As soon as the first PZL.23 aircraft left production facilities, the Polish authorities were eager to generate foreign interest. In the spring of 1936, the PZL.23/III was presented at the air fair in Stockholm. Later that year, in November, another aircraft was exhibited at the Paris Air Show. Despite these efforts, Poland failed to attract any significant foreign interest in the design.
One PZL.23B was modified with a more powerful 925 hp Pegasus engine and equipped with a three-bladed, variable-pitch propeller. This variant was intended for export, but it failed to generate any interest, and was eventually reverted to the standard PZL.23B configuration.
The PZL.23B was modified with a 925 hp Pegasus engine, equipped with a three-bladed, variable-pitch propeller. Source; T. J. Kopanski PZL.23 Karaś
Bulgaria
The PZL.23 would see some export success. In March 1936, a delegation was sent to Poland by Bulgaria to evaluate and potentially acquire aircraft for their own use. Following a series of negotiations, Poland agreed to sell them 12 PZL.23 bombers.
However, the Bulgarians requested that the aircraft be powered by Gnome-Rhône engines, which presented a design challenge. The positioning of the Gnome-Rhône radial engines and their cylinders prevented the installation of the forward-firing machine gun originally housed within the engine compartment. Polish engineers had to overcome this by finding a new, suitable position for the machine gun within the fuselage, an issue that took some time to resolve.
By the end of summer 1936, the modified variant was ready. Due to changes in both the engine and fuselage design, the new aircraft was given a different designation: PZL.43. Although the contract between Poland and Bulgaria was signed on the 9th April 1936, actual production faced delays. The main issue was the engine: the requested Gnome-Rhône 14N had to be imported from France.
Bulgaria was the only country that showed interest in this aircraft, acquiring around 50 of a modified variant designated as PZL.43. Source: https://jmodels.net/de-hombres-y-maquinas/aire-air/pzl-23-karas/
It was not until May 1937 that the last of the ordered aircraft arrived in Bulgaria. The Bulgarians were satisfied with its performance and placed a new order for 42 additional aircraft. These were to be powered by the Gnome-Rhône 14N engine and received the new designation PZL.43A. Most of these aircraft were delivered by late August 1939.
Following the German occupation of Poland, the few PZL.43A units that had not yet been delivered were briefly tested by the Germans before being sent on to Bulgaria. In total, Bulgaria acquired 50 aircraft, comprising both the original PZL.43 and the updated PZL.43A variant.
During the war, these aircraft were primarily used for training purposes, though they were occasionally employed in operations against Yugoslav partisans. By September 1944, due to a lack of spare parts, most had been withdrawn from service. A few remained operational until 1946, when they too were finally scrapped.
Romania
Besides Bulgaria, Romania also operated some of these aircraft. They came into Romanian possession following the defeat of Poland in September 1939, when a group of 21 aircraft managed to escape German forces by fleeing to Romania. Of these, the Romanians were able to restore 19 to operational status, using the remaining two for spare parts. The aircraft saw extensive action against the Soviets, serving both in bombing, and reconnaissance roles, until 1943, after which they were reassigned to secondary duties. The last of these aircraft remained in service until 1946, when it was finally scrapped.
Romania operated at least 19 fully operational aircraft until 1943 when they were relocated for second line duties. Source: https://ww2aircraft.net/forum/media/a-crashed-pzl-23-karas-no-12-romanian-af.25926/
Germany
After their victory in Poland, the Germans managed to capture several PZL.23 aircraft, most of which were either in poor condition or heavily damaged. They repaired a few PZL.43s and used them for testing purposes. Beyond that, however, they showed little interest in these aircraft.
Germans tested some captured aircraft but showed little interest in them. Source: T. J. Kopanski PZL.23 Karaś
Soviet Union
The Soviets also managed to capture several PZL.23 aircraft, some of which were actually in working condition. These appear to have been put to some use by the Soviets; however, beyond that, nothing else is known about their ultimate fate.
Technical characteristics
The PZL.23 was a single-engine, low-wing aircraft intended for both bombing and reconnaissance missions. The fuselage featured an oval-shaped fuselage cross-section built using a framework of stringers and struts. The tail section employed a semi-monocoque construction for added strength and reduced weight. The entire fuselage was then skinned with duralumin sheeting.
An excellent illustration of the PZL.23 internal component and crew’s positions. Source: https://panssarivaunut.blogspot.com/2016/02/pzl23-karas.html
The wings were constructed in three main sections. The first section consisted of two spars that formed an integral part of the structure. In addition to serving as the attachment point for the rest of the wing structure to the fuselage, this central section also housed the mounting points for the two landing gear units. It was further reinforced to support a bomb rack installed beneath the aircraft fuselage.
Following this were the two outer wing sections, which were built using an innovative method. These outer parts featured a torsion box design, constructed with corrugated heavy-gauge duralumin sheets. These were connected spanwise by additional corrugated, stress-bearing duralumin plates with a smooth finish. Finally, the wing tipsand trailing edge slats were attached to complete the wing. The tail assembly was built using spars and ribs, all of which were covered in duralumin for structural strength and aerodynamic efficiency.
The wing was made up of three sections. The first section was directly attached to the fuselage and housed the landing gear and fuel tanks. This central section was flanked by the two remaining outer wing panels. Source: https://www-airwar-ru.translate.goog/enc/bww2/pzl23.html?_x_tr_sch=http&_x_tr_sl=ru&_x_tr_tl=en&_x_tr_hl=en
The cockpit was positioned at the front of the aircraft. In its early development phase, the PZL.23 suffered from poor forward visibility. This issue was eventually addressed in the B variant by lowering the engine and raising the pilot’s seat. Directly behind the pilot sat the observer and bombardier, who was provided with a glazed canopy offering fairly good all-around visibility. Beneath the fuselage was the bombardier’s gondola. Finally, at the rear of the aircraft was the gunner’s position
Close-up view of the aircraft glazed crew compartment. Source: https://panssarivaunut.blogspot.com/2016/02/pzl23-karas.htmlThe instrument panel. Source: https://jmodels.net/de-hombres-y-maquinas/aire-air/pzl-23-karas/At the bottom of the fuselage, a small bombardier’s gondola was installed. Source: J. B.Cynk The P.Z.L.23 Karaś
The first variant was powered by a 670 hp Bristol Pegasus II M2 engine. Later production aircraft were equipped with the more powerful 710 hp Bristol Pegasus VIII. In both versions, a two-bladed fixed-pitch propeller was used.
The fuel load consisted of 740 liters stored in six fuel tanks located within the central section of the wings.
The landing gear comprised two front-mounted fixed wheels (775×240 mm), each enclosed in aerodynamic spats. On many training aircraft, these spats were removed. To absorb shock during landings, shock absorbers were mounted on the landing gear legs. At the rear, a small tail skid with a shock absorber was installed.
The defensive armament included one forward-mounted 7.92 mm Wz.33 (Karabin lotniczy wz. 37) machine gun. The rear was protected by two 7.92 mm Wz.36 machine guns. Each machine gun was supplied with 600 rounds of ammunition. The B variant was designed to accommodate two forward-firing guns, but due to a lack of mounts, only one was typically installed. A ventrally mounted machine gun was also present, with an elevation and traverse range of 60 degrees.
For self-defense from rearward attacks, two machine guns were installed. Source: T. J. Kopanski PZL.23 Karaś
Initially, the aircraft’s bomb bay was located just behind the cockpit. However, during early testing, this design proved to be inefficient and was soon eliminated. Instead, bombs were mounted on an external rack positioned under the central fuselage.
This bomb rack could carry a payload ranging from 300 to 700 kilograms, typically using one of the following configurations: six 100 kg bombs, eight 50 kg bombs, or twenty-four small 12.5 kg bombs. In practice, however, loads exceeding 400 kg were rarely employed.
Production and Proposed Versions
PZL.23 I-III Prototypes – A small series of three prototypes
PZL.23A – An experimental version created by combining the Re.2002’s fuselage with the Re.2005’s wings. One built but never used operationally.
PZL.23B – possibly one modified for this role.
PZL.43 – Variant developed for Bulgaria
PZL.43A – Further improvement over the previous variant
PZL.23/IV – Proposed dive-bomber variant remained at prototype stage
PZL.42 – Future modification with new tail assembly, used as training aircraft until destroyed in September 1939,.
Operators
Poland – Operated fewer than 50 aircraft.
Bulgaria – Purchased 50 PZL.43 and PZL.43A aircraft, with a few remaining in service until 1946.
Romania – Acquired 21 aircraft from Polish pilots who escaped to Romania. Of these, 19 were put into service and used against the Soviet Union until 1943.
Germany – Captured numerous PZL.23 aircraft, though most were in poor condition. The Luftwaffe showed little interest in utilizing them.
Soviet Union – Also captured several PZL.23s, but there is no known record of their operational use.
Conclusion
The PZL.23 has developed something of an unfair reputation as a poorly designed aircraft. While it was far from perfect, it was not as ineffective as it is often portrayed. The aircraft did manage to inflict some losses on German forces, conduct many reconnaissance missions, and remained in service with Poland until almost the end of the campaign. However, like many of its contemporaries, it was too slow to effectively evade or counter enemy fighters. While capable in its designed role, it was adapted for various missions, some of which it was neither designed for nor particularly suited to, such as dive bombing, and it often flew missions without fighter escort. This left the aircraft highly vulnerable and with little chance of survival. Ultimately, nearly all PZL.23s were lost by the time the war in Poland came to an end.
Kingdom of Italy (1940-1943) Twin-engine maritime reconnaissance aircraft. Number built: 2 prototypes and 8 production aircraft
During the 1930s, Italian aviation made considerable strides, marked by the introduction of numerous new aircraft designs and technologies, such as all-metal air frames. However, not all of these designs were successful. Some, like the Ba.65 and Ba.88, ultimately proved to be failures, despite showing promise in their initial evaluations. However, a number would go on to prove incredibly successful despite troubled origins, with one notable example being the FIAT CR.25. In the late 1930s, FIAT proposed the development of a twin-engine fast bomber that could also serve in reconnaissance roles. After a fraught and meandering development cycle, only a small number of CR.25 were produced, they proved to be reliable and capable during the war.
The FIAT CR.25. Source: https://en.wikipedia.org/wiki/Fiat_CR.25
History
In 1936, FIAT approached the Italian Air Ministry with a proposal for a modern, light bomber. In addition to its primary role, they suggested that the aircraft could also serve as a reconnaissance platform. A FIAT representative assured the Ministry that the aircraft’s exceptional speed and robust defensive armament would enable it to excel in both roles, with a maximum estimated speed above 500 km/h.
The Air Ministry found the proposal promising and approved the project. As FIAT worked on developing the first prototype, the Air Ministry made an additional request: the aircraft should also be capable of fulfilling the role of a heavy fighter, alongside its initial design purposes.
In April 1937, a meeting was held between FIAT and Air Force representatives to discuss the overall characteristics of the aircraft. One key question was whether the aircraft should include a dedicated bombardier’s station or prioritize a more streamlined design. The precise details of the armament were also debated. After a series of discussions, it was agreed that the initial plan for four forward-mounted heavy machine guns would be reduced to three. Additionally, the rotating turret on the lower fuselage would either be removed or completely redesigned. Lastly, it was decided to retain the dedicated bombardier and observation position.
As work progressed, it was decided to remove the rear machine gun gondola to achieve a more aerodynamic shape and save weight. However, the project encountered its first major issue when the designers, despite all efforts, failed to reach the required maximum speed of 500 km/h. At best the prototype recorded a speed of 450 km/h. The Air Ministry began to lose interest in FIAT’s design, as the Breda Ba.88 appeared to be a more promising alternative. During its initial tests, the Ba.88 managed to achieve speeds exceeding 550 km/h.
Ironically, despite this promising start, the Ba.88 turned out to be a disastrous design, with only a few aircraft ever seeing combat. Further testing of the Ba.88 revealed additional flaws, raising concerns among the Italian Air Force’s leadership. As a precaution, FIAT was granted permission to prepare for the production of 40 of their twin-engine bombers, which were then designated as the CR.25.
The production order was issued before the first prototype was even fully completed. This prototype, designated MM.332, underwent flight testing in July 1937, followed by extensive flight and endurance trials. Meanwhile, work on the second prototype, designated MM.333, and the first aircraft from the production order, was slowly progressing. However, before any of them could be fully completed, the situation surrounding the aircraft changed dramatically.
In the late 1930s, as tensions in Europe rose and the prospect of a new war loomed, the Italian Air Ministry began selecting aircraft for mass production. They carefully evaluated each design to determine its intended role and operational performance.
The FIAT CR.25 first prototype registered as MM.332. Source: https://en.wikipedia.org/wiki/Fiat_CR.25
A debate emerged regarding the future of the CR.25. Despite its promising overall performance, the aircraft failed to meet the required maximum speed, a flaw considered critical in its design. The earlier decision to reduce its bombload had also already cast doubt on its viability as a fast bomber. Furthermore, its initial intended role as a fast heavy fighter had also been abandoned. In essence, the Air Ministry was inclined to terminate the project.
However, with approximately 40 units already in production, halting construction entirely would have resulted in wasted time, resources, and production capacity. In order to make good on the cost of producing these planes, the CR.25 was repurposed in 1938 as a dedicated reconnaissance aircraft, instead of a fast bomber.
This new role also presented challenges. The Air Ministry first wanted to properly evaluate the aircraft’s suitability for reconnaissance missions. Additionally, there was a shortage of suitable engines, and introducing another aircraft into service risked further straining the already limited supply of critical engine components.
Trials of the CR.25 were conducted alongside a modified Ba.88, and a Caproni Ca.312. During these evaluations, the Ba.88 was quickly dismissed due to persistent mechanical issues. While the Ca.312 was not without its flaws, it was ultimately favored for the reconnaissance role.
Production
In August 1939, a decision was made to scale back the CR.25 production order to just eight aircraft, in addition to the two existing prototypes. The remaining 32 units were canceled, with the incomplete airframes being set aside for replacement parts.
The A.74 engines were also salvaged from incomplete aircraft, as new engines would not be available for the production line. The final CR.25 from the initial order of eight aircraft was completed in early 1940.
Despite the initial order for 40 aircraft of this type, only 8 were ever fully completed beside the two prototypes. Source: https://comandosupremo.com/fiat-cr-25/
Sources slightly disagree on the exact number of aircraft built. The previously mentioned production figures are based on G. Apostolo’s (FIAT CR.25). However, other sources, such as D. Nešić (Naoružanje Drugog Svetskog Rata – Italija), suggest that a total of 12 aircraft were produced.
In Service
The 10 available CR.25 aircraft were allocated to the 173rd Squadriglia (Eng. Squadron), and the two prototypes were used as training aircraft. The personnel assigned to equip this unit were drawn from the 31st and 35th Stormi B.M. (Eng. Maritime Bombing Wing). For most of 1940, the unit saw no operational use. It was not until 1941 that the squadron began intensive training for its pilots and crew. Aircrew training was conducted in Turin, while ground personnel were stationed at Palermo-Boccadifalco.
Pilot training officially began in April 1941, but problems arose almost immediately. The most significant issue was that the pilots selected for this unit had only flown maritime aircraft and lacked experience with land-based planes. Another major challenge was the absence of suitable training aircraft with dual controls, which slowed the entire process considerably. Matters were further complicated when one of the prototypes caught fire during a training flight. Fortunately, the pilots and crew managed to bail out in time, but the aircraft crash-landed and was destroyed.
The first prototype was lost in an accident when the aircraft caught fire and crash-landed. Both the pilot and the passenger survived the incident as they managed to escape the plane in time. Source: G. Apostolo FIAT CR.25
By July 1941, only four aircraft and their respective crews were considered trained and ready for frontline deployment. The squadron’s first operational missions, primarily submarine reconnaissance flights, began later that month. On 25th July, four additional CR.25 aircraft arrived at the base in Palermo-Boccadifalco.
These eight aircraft saw extensive use throughout 1941 and early 1942. Despite their limited numbers, they were employed in wide-ranging reconnaissance and escort missions over the Mediterranean. However, three aircraft were sent to be scrapped after suffering damage in landing accidents that rendered them irreparable.
In 1940, only eight CR.25 aircraft were produced, and deployed for frontline use as maritime reconnaissance aircraft. Source: https://comandosupremo.com/fiat-cr-25/
From February 1942 onward, the 173rd Squadriglia was permanently attached to the 10th Stormo, operating out of the same base. This unit included SM.79 and Ca.314 aircraft in its inventory. On 6th February, the first recorded action involving the CR.25 against enemy aircraft took place. One of the 173rd’s CR.25s intercepted a British Blenheim bomber during a patrol. The bomber, heavily damaged during the encounter, was subsequently shot down by a German Bf 109.
On 21st June, two CR.25s were conducting an escort mission for an Axis convoy. During the mission, Allied aircraft attacked the convoy. The CR.25s managed to shoot down two enemy planes, while three more were downed by the convoy’s destroyer escort.
By October, the combination of landing accidents and a lack of spare parts meant that only three CR.25 aircraft remained operational. To prevent the unit’s disbandment, additional Ca.314 aircraft were assigned as replacements. However, these planes were poorly received by the pilots due to their inferior performance compared to the CR.25.
By 1943, the chronic shortage of spare parts effectively marked the end of the CR.25’s operational service life. The aircraft’s last recorded patrol occurred in mid-January 1943. The remaining four planes were subsequently withdrawn from service and placed in storage, likely awaiting scrapping.
Berlin Attaché Transport CR.25
Interestingly, one of the eight procured CR.25 aircraft found its way into service as the personal transport of the Italian military attaché in Berlin. Visually, it differed from the remaining aircraft by lacking the glazed nose typically seen on the model. Additionally, the interior was extensively modified to suit its specialized mission.
The first production aircraft was repurposed for military use as a transport aircraft, primarily serving to ferry politicians and ambassadors between Italy and Germany. Although it was essentially the same model as the original design, it lacked the glass-enclosed nose section. Source: https://www.vvsregiaavions.com/RegiaHTML/rcr252.htm
The redesigned interior featured seating for four passengers and dual controls. This aircraft was actively used by the Italians during the war. However, after the Italian capitulation in September 1943, it was seized by the Germans. They temporarily repurposed it as a training aircraft, but its service ended once spare parts became unavailable.
Some sources have referred to this aircraft as the CR.25A, though there is no evidence to suggest that the Italians officially used this designation.
Technical characteristics
The CR.25 fuselage was constructed using four tubular longerons, secured by a combination of crossbars, braces, and diagonal metal tubes. These components were assembled into three sections to form the complete fuselage. The wings and tail units were built using a similar construction method. However, unlike the fuselage, which was entirely made of metal, the tail and wing surfaces were covered with fabric.
The cockpit was located directly behind the aircraft’s nose and accommodated the pilot’s position. To the pilot’s right was the position originally intended for the bombardier. However, as the aircraft was rarely used in a bombing role, the second crew member performed various other tasks, such as navigation, observation, operating the radio, and managing the onboard camera. In practice, the second crew member was often overburdened with multiple responsibilities.
For observation and other tasks, the second crew member could use the cockpit’s side windows or the lower section of the nose, which was glazed to provide a clear view of the area below. Interestingly, the Italians incorporated an auxiliary control stick located behind the pilot. This allowed the second crew member to partially operate the aircraft if the nose sustained severe damage or if the pilot was incapacitated.
The lower part of the CR.25’s nose was enclosed in glass, allowing the crew members tasked with identifying targets for bombing runs to have a clear view. Source: G. Apostolo FIAT CR.25Close up view of the CR.25 cockpit command board. Source: https://www.vvsregiaavions.com/RegiaHTML/rcr252.htm
The CR.25 was powered by two 840-horsepower FIAT A.74 RC.38 engines, each paired with 3-meter-long FIAT automatic pitch propellers. The aircraft’s fuel load consisted of 1,600 liters, distributed among six smaller fuel tanks located in the wings. These tanks were protected by armored plating, offering protection against weapons up to 12.7 mm caliber.
The primary armament included two 12.7 mm SAFAT heavy machine guns mounted in the aircraft’s nose. For defense against enemy aircraft, another heavy machine gun was positioned in a small, rotating Breda Type M.2 turret located on the rear upper fuselage. This turret was operated by a third crew member.
The fuselage of the CR.25 featured a small bomb bay capable of carrying up to 300 kilograms of bombs, though this capacity may vary according to different sources.
The CR.25 armament consisted of two nose-positioned and one in the rear turret 12.7 mm heavy machine guns. Source: https://comandosupremo.com/fiat-cr-25/
Conclusion
Unlike a number of Italian aircraft that failed to live up to their expectations, and were produced in limited numbers, the CR.25 stood out as a success despite its short service life and limited production run. While it was certainly no extraordinary aircraft by any measure, it performed well in its intended role, and despite being produced in relatively small quantities, it saw significant use in the Mediterranean theater, and was favored by its crews over other comparable aircraft.
Though never employed as a bomber, the CR.25 was predominantly used as a reconnaissance aircraft with great success. Remarkably, no aircraft of this type was ever shot down by the enemy. By 1943, however, they ran out of spare parts, which effectively marked the end of the CR.25’s long service career.
Operators
Kingdom of Italy – Operated 10 aircraft
Germany – Briefly operated the one captured aircraft for training purposes
Kingdom of Hungary (1943) Reconnaissance aircraft – Over 28
During the Second World War, Hungary aligned itself with the Axis powers, and in 1941, they dispatched their armed forces to support the German invasion of the Soviet Union. Initially, the Hungarian Army, particularly its Air Force, was poorly equipped for this conflict and lacked many vital military resources, particularly modern weapons and aircraft. For example, its Air Force had to conduct tactical reconnaissance using obsolete biplane aircraft. In 1943, to support their ally, the Germans supplied a small group of the modern Fw 189 reconnaissance aircraft to the Hungarians. Although these aircraft were limited in number, they saw extensive action until the end of the war.
Hungarian-operated Fw 189. Source: G. Punka Focke-Wulf Fw 189 in Action
History
Despite many attempts to improve its Air Force during the 1930s, Hungary faced numerous obstacles that hindered its progress. The most significant challenge were the restrictions on developing certain military technologies, including aircraft, imposed by the Treaty of Trianon in June 1920. Although the geopolitical landscape in Europe had changed considerably by the 1930s, rendering the Western Allies incapable of enforcing this ban, it did little to assist Hungary. The country simply lacked the financial resources and could not find any potential sources from which they could purchase a large number of new aircraft from.
As a result, the Hungarian Air Force had to rely on the Weiss Manfred WM 21 Sólyom, a biplane developed domestically in the late 1930s, for reconnaissance operations. Fewer than 130 of these aircraft were built. To supplement the WM 21, Hungary acquired the Heinkel He 46 from Germany. However, by the time Hungary entered the war with the Soviet Union in 1941, both aircraft were clearly obsolete. Nevertheless, with no better alternatives available, they had to continue in their reconnaissance roles.
The Weiss Manfrédfrom WM 21 two-seat reconnaissance aircraft. Source: lasegundaguerra.com
By 1943, it had become clear to Hungarian Air Force officials that the two aging aircraft in their fleet needed to be replaced. With limited options available, they turned to the Germans for assistance. At that time, Germany was deeply entangled in the conflict with the Soviet Union and was in desperate need of support from its allies. Realizing the necessity of keeping Hungary well-equipped in the fight against the Soviets, the Germans agreed to supply a small contingent of the well-known Focke-Wulf Fw 189 reconnaissance aircraft to reequip the Hungarian forces.
A Brief Fw 189 History
The history of the Fw 189 dates back to 1937, when the German Ministry of Aviation initiated the development of a new tactical reconnaissance aircraft. The role of the aircraft was to survey the front line, and carry out army liaison duties. One of the companies that responded to this competition was Focke-Wulf, which presented the Fw 189. This aircraft won the contract, leading to a production order that began in 1940. The Fw 189 was a twin-engine aircraft with a heavily glazed central fuselage which gave its crew excellent visibility. It was well-liked in service and generally performed well, with most of them being employed on the Eastern Front. By the time production ended in 1944, some 900 of these aircraft had been built.
The German Focke-Wulf Fw 189. Source: Wiki
Operational Service Life
While the Fw 189 aircraft were allocated to the Hungarian Air Force, they operated under German command. This was not irregular; in fact, to better coordinate their efforts, large parts of the engaged Hungarian Air Force were placed under German operational control. In May 1943, Germany supplied the Hungarians with a group of 12 Fw 189A models, which were assigned to the 3rd Hungarian Flying Squadron under the command of Captain Lorand Telbisz. This squadron was subordinate to the German 4th Air Fleet.
The first aircraft operated from airfields near Harkow, where they undertook over 224 reconnaissance missions against Soviet forces. Some of these missions even targeted Soviet partisans in the Pripet Marshes. During one of these operations, the Hungarians lost their first Fw 189, when it was shot down in late May.
The aircraft also saw heavy action during the Battle of Kursk, performing reconnaissance missions and, in many instances, conducting light bombing attacks against enemy forces. However, with the failure of the German offensive, the Hungarian forces were forced to retreat as well.
The Fw 189 was the first Hungarian modern reconnaissance aircraft, employed first in 1943. Source: G. Sarhidai, G. Punka, and V. Kozlik Hungarian Eagles
In September 1943, a lone Hungarian Fw 189 achieved remarkable success against Soviet fighters. On the 21st, during a reconnaissance mission, the Hungarian Fw 189 was engaged by a group of three Yak-9 fighters. To evade the enemy, the Fw 189 pilot descended sharply, making abrupt turns. Despite intensive enemy fire, the rear gunner managed to shoot down one of the fighters. A second Soviet fighter was lost when its pilot misjudged his altitude and crashed into the ground. The last surviving fighter disengaged and retreated. While the Fw 189 lacked for a heavy defensive armament, its spindly form and exceptional maneuverability made it a difficult target for interceptors, when an experienced pilot was at the controls.
Later that same day, another Fw 189 was attacked by at least six La-5 fighters. After extensive maneuvering and exchanging of fire, the rear gunner of the Fw 189 claimed two of the attackers. In both cases, the Fw 189s successfully returned to their bases.
During this period, the Germans added a few more aircraft to the unit to replace losses and worn-out planes. By the end of October 1943, the 3rd Flying Squadron had completed its 1,000th flight mission. However, while it remained active until the end of the year, a lack of fuel and spare parts greatly reduced the number of operational flights. By March 1944, the unit had only one operational aircraft left. That same month, the unit was officially disbanded, and the surviving personnel were sent back to Hungary.
Despite the small number operated, the Fw 189 saw extensive use by the Hungarian military. By the end of October 1943, the 3rd Flying Squadron had completed its 1,000th flight mission. Source: G. Punka Focke-Wulf Fw 189 in Action
The story of the Fw 189 in Hungarian service did not end there. In April 1944, the 4th Reconnaissance Squadron was relocated to Hungary and stationed at Bydgoszcz. The squadron’s crew underwent training in night reconnaissance operations, which were completed by May. Following their training, the unit engaged in extensive action on the Eastern Front, ranging from Poland to Hungary. They remained active on the frontline until September, when it was disbanded. Following the unit’s dissolution, the surviving aircraft were returned to the Germans. While the exact number of Fw 189s operated by this unit is unclear, they are known to have lost between 10 and 11 aircraft of this type to all causes. This marked the end of the Fw 189’s service within the Hungarian Air Force.
It is not clear precisely how many aircraft of this type were operated by the Hungarians. Author G. Punka (Hungarian Air Force) places the number of 28 aircraft of this type, while in another book, Hungarian Eagles, written by Sarhidai, G. Punka, and V. Kozlik, a figure of 21 is given. While most of these received Hungarian Air Force markings, many of them retained the original German markings, which makes identification somewhat confusing, likely contributing to this ambiguity.
After 1943, the Fw 189 would still see service within the Hungarian Air Force but primarily for night reconnaissance operations. Source: https://old-forum.warthunder.com/index.php?/topic/490017-visegrad-group-aviation-tech-tree/page/3/
Technical Specification
The Fw 189 was designed as a twin-engine reconnaissance aircraft with a unique construction. Its central fuselage featured extensive glazing, with the cockpit at the front of the compartment, followed by a small crew area, and a gunner’s station at the rear. The fuselage was bulkier at the front and tapered toward the rear. Access to the crew area was provided through two hatches above the cockpit and a larger hatch at the rear. Although the extensive glazing left the crew more exposed to enemy fire, it was ideal for its reconnaissance role, offering excellent all-around visibility.
The wings are composed of two distinct sections. The central, square-shaped panel connects the nacelle and engines, while the second section extends outward from the booms. The wings feature a metal base covered with duralumin, though the ailerons and split flaps are clad in fabric.
The aircraft was powered by two 465 hp Argus As 410 A-1 12-cylinder air-cooled V-12 engines. These engines demonstrated remarkable effectiveness and reliability, even under the harsh winter conditions of the Eastern Front. With these engines, the Fw 189 achieved a maximum speed of 335 km/h, though exact figures may vary between sources. Each engine drove a two-blade, constant-speed propeller. Fuel was stored in two 110-liter tanks, which were housed in the tail booms. The Fw 189 had a maximum operational range of approximately 670 km.
The landing gear consisted of two landing gear assemblies that retracted into the engine nacelles. The rear smaller tail wheel was located inside the vertical stabilizer and was retracted in flight. While nominally a reconnaissance aircraft, the aircraft could be armed with machine guns for strafing targets, and had four underwing shackles for bombs, or flares.
Conclusion
The Fw 189 was a well-designed aircraft that excelled in its intended role. Given its effectiveness, it’s no surprise that the Hungarians made extensive use of the few aircraft they were supplied with. These planes were deployed exclusively against the Soviets, primarily in 1943 and late 1944.
The Raiden proved to be an oddity during the Second World War. Beset by numerous technical challenges and a meandering developmental cycle, it nonetheless entered mass production, and saw service amidst the most brutal air campaigns of the Second World War. (Phillip Jarrett)
Intro
The J2M Raiden, Japanese for Thunderbolt, was developed to provide the Japanese Navy with an interceptor for the defense of its bases in China and across the Pacific. While it was designed with many of the most advanced technologies available to Japanese aviation, its development was fraught with technical issues and resource competition with the Navy’s premier fighter, the A6M Zero. After several years in troubled development, it entered service in the last line of defense against the American Army Air Force and Navy, which had taken the war to the skies over Japan itself.
Foundations
Japanese military aviation began early, but ambitiously, with the Navy launching its first naval air attacks from the seaplane carrier Wakamiya against various German targets during the First World War. There was little damage done with these light, and very crude, seaplane bombers, yet it was clear that as the technology matured, aviation would take a key role in any future conflict.
Following the end of the first world war, Japan claimed former German territories across the pacific, and sought greater control over China, then embroiled in a brutal civil conflict. The Washington Naval treaty would affirm the integrity of Chinese territory regardless of the wars, and assure equal economic rights for those wishing to trade in the region, and the Empire of Japan would not contest these principles through the 1920’s. However, its armed forces nonetheless planned and lobbied for ambitious policies that would wrest control of most of Asia from the Chinese, and the Pacific from the Europeans and United States of America. However, as a still nascent industrial power, Japan had much to learn regarding the cutting military technologies that they would need to challenge their many planned opponents.
A longstanding alliance with the United Kingdom had brought rapid advancements in both military and related civil fields. This was only one part of a military partnership that had once challenged Russian ambitions in Asia, and had led them against the Germans in the Great War. By the end of that war, this alliance was wearing thin, with both sides now holding opposing goals across Asia and the Pacific. Yet one final major transfer of technology would catapult Japanese aviation ahead, before military coordination with Britain finally lapsed. Following a request for technological assistance in aviation in 1920, the Sempill mission was organized to bring Japanese expertise in aircraft design and development up to modern standards. While there were clear concerns that this technology might be used to challenge British interests in the future, major economic partnerships and sales with Japan proved a stronger motivation.
The mission arrived at Kasumigaura in 1921, led by former RAF officer Baron Sir Williams Frances-Forbes. Along with a cadre of experts in airplane design, construction, and use, the mission brought a collection of aircraft. Over a hundred planes in total were delivered to Kasumigaura, accounting for modern military aircraft of every type available to the mission planners. To the Japanese military, this technology exchange was as generous as they could have hoped for, and put them on a faster track to self-sufficiency. This massive leap in technical abilities would define Japanese aviation moving forward, giving their industry a firm grasp on modern construction techniques and technologies, but still lacking depth in manufacturing.
While they would continue to be reliant on licensed equipment for the years to follow, they now had a strong technical foundation from which to build on. Just as this assistance ended, so too did the alliance with Britain, which lapsed in 1923. The very same year, the Navy would select the United States as its chief ‘hypothetical enemy’, against which future war plans would be focused.
War Games
The aviation industry was slow growing, beginning with cottage industries that eventually grew into major enterprises, that later made the leap from licensed equipment to their own designs. The largest of these manufacturers were Mitsubishi, Nakajima, and Kawasaki, which provided the nucleus for the rest of the cottage industry based aviation sector. Arguably the largest of these was Mitsubishi Heavy Industries, through its branch, the Mitsubishi Internal Combustion Engine Co. at Kobe. Concurrent with the Sempill mission, the company’s aircraft manufacturing effort was shifted to Nagoya, which would remain the center for Mitsubishi’s aircraft development and production. In the years to come, additional production plants would sprout from the main facilities in Nagoya, with separate air frame and engine departments being founded by 1935.
Given the state of aviation in Japan in the late twenties, the first major war plans against the United States made very little use of aircraft, with the plan being to draw the US fleet into Japanese territorial waters where it could then be devastated in a decisive battle, the outcome of which would decide the fate of untold millions. The rationale and foundation for these plans was to develop superior technologies in key areas, and in all others, the supposed superior qualities of the Japanese soldier would allow them to persevere, confident in the belief that material shortcomings were minor impediments to seizing a victory that was destined. In practice, they initially sought to out-match the enemy in the areas of long range gunnery and torpedo warfare, to claim a decisive edge against an enemy which was beginning to eclipse them. Yet, in time, the need to master the air would come before all else, as it became clear air power could make up for disparities elsewhere.
The battleship defined naval might for nearly half a century. Against these behemoths, the airplane would maintain a small supporting role, before the technology matured and it took center stage. (oldtokyo)
Battleships defined the plan until the mid 1930’s, with aviation playing a very small role until several crucial technical developments were rolled out. Aircraft at the time had a very limited range of action, had small payloads, and were very fragile. The coming war for the Pacific would be waged against a number of very powerful opponents, and such a battlefield would be vast and feature the most powerful pieces of military equipment in existence, modern warships. It was the development of all-metal, streamlined, monoplanes that proved to be the deciding factor in shifting the idea of the airplane as a defensive weapon and reconnaissance tool, to a deadly offensive weapon. The ability to conduct strikes of greater power, and scout ever larger swaths of ocean continually pushed the boundaries of military planning. The hypothetical decisive battle was taking place further than the originally conceived battlefield in Japanese home waters, and by the late 1930’s, it was judged to take place around the Marianas.
In the Navy’s plans, torpedo and dive bombing aircraft were pursued enthusiastically, with fighters far less so. Seen as a mostly defensive weapon, there was little development in their advancement or tactics between the Sempill mission and the end of the 1920’s. This changed after a pair of RAF officers were invited to present a five month fighter course in 1930, and a larger fighter maintenance and employment course was provided the next year, again with RAF personnel. The naval air combat program would soon grow under Lt. Kobayashi Yoshito, Lt. Genda Minoru, and Lt. Okamura Motoharu at the Yokosuka Naval Air Base. By this time, there were two major issues with the program, the first being the general reluctance for defensive tactics by the Japanese Navy, and the fact that bombers by this time were capable of out-pacing their pursuers. With their relatively crude Nakajima Biplane fighters, there was little that could be done to face and bring down modern bombers. Yet the fighter advocates held out, and waited for new planes, ones that could demonstrate their necessity on carrier flight decks and naval air bases.
Horikoshi and the Zero
By the mid 1930’s, there was a swell of engineers who had been schooled in the advancements brought forth by the Sempill Mission, and a good number who had traveled abroad to see new technologies and techniques in use with the forerunners of aviation. It was this latter group that was the most pessimistic about Japan’s ability to wage war against the US, as they were witness to America’s vast manufacturing potential and technological expertise in all the fields relevant to the war in which their own work would one day contribute. During this time, Japan had invaded Manchuria, and planned for a greater war which could place China in their orbit. Needing to modernize, the Navy sought to push past the old Nakajima N4A, which had become very dated by 1934, and obtain a fighter which could match the performance of the bombers it chased. New high speed fighter requirements were prepared by Lt. Cmdr. Sawai Hideo from the Department of Engineering at the Naval Air Arsenal, and released to the industry.
Horikoshi Jiro had studied at the brand new Department of Aeronautics at the University of Tokyo, which at the time, numbered only 39 people, staff and students. From there he went on to work at the Mitsubishi Internal Combustion Engine Co. at its aircraft department, working first on the basic, yet essential tasks of running performance and strength calculations, and designing various components. In time, he would be selected to study foreign methods of aircraft construction, and would travel to Germany, France, Britain, and the United States to tour factories and study the planes they built. While Japan was clearly still lagging behind the leaders in aeronautics, he knew a quick path to design parity was only a few leaps away.
However, despite his belief Japan could find a way to produce its own cutting edge military aircraft, Jiro remained pessimistic about the Empire’s chances in a war with the United States, having toured the aircraft manufacturing plants in America himself. He would remark in later years, after learning of the attack on Pearl Harbor, that “-The majority of us who had truly understood the awesome industrial strength of the United States never really believed that Japan would win this war. We were convinced that surely our government had in mind some diplomatic measures which would bring the conflict to a halt before that situation became catastrophic for Japan.” Yet well before the dawning of the Pacific War, he continued his work in pushing the boundaries of aeronautics in Japan.
The Mitsubishi Ka-14 test aircraft would be developed into Japan’s first modern fighter, it was nothing less than the leap Horikoshi envisioned for Japanese aviation. (Aviation of Japan)
Understanding that the monowing fighter would be the future of its class, with its obvious advantages in drag reduction and strength, he would pursue designs of this type from his first attempt. It would not go well, as there were many technical challenges that had to be overcome, but overcome he would, and his next design would prove phenomenal. For the 1934 Naval requirements for the year 9 carrier fighter, he would submit the Mitsubishi Ka-14, later modified into the A5M fighter. A superlative modern fighter, it impressed the Navy enough to purchase a large number of the aircraft.
The A5M would prove to be the start of an exceptional career for one of the era’s foremost aeronautical engineers, a major leap for the Japanese aero industry, and it gave the Japanese Navy proof that fighters were an essential investment in any future war. It proved a decisive success in China, but as is always the case, a successor needed to be planned for. For the next carrier fighter, the Navy released the planning requirements for the year 12 carrier fighter. They had effectively asked for the impossible, a plane that needed to be able to act as an interceptor, a long range escort, and air superiority fighter. To make a long story short, Horikoshi managed to design a plane which met the requirements, and produced the A6M Type 0 fighter.
Horikoshi Jiro, pictured center. His meteoric rise with the A5M and A6M would see him at the center of a number of new projects. Soon overworked, he found himself trying to design two new fighters for the navy, while keeping the Zero up to date. (wikimedia)
In addition to this aircraft, which would become the primary fighter of the Japanese Navy, another design would be requested in October of 1938. A local fighter, a dedicated interceptor to defend Japanese positions in both China and the Pacific from enemy bombers. While a seemingly simple request, it represented a rapid and enormous shift in naval strategy. At the outset of the 1920s, the airplane was little more than a novelty which played a supporting role. Experience in the agonizing war in China showed that bombers could now threaten the Navy’s ports and airfields, such that a specialized aircraft was needed to counter them. Gone was the reluctance that dogged officers like Lt. Genda in pursuing a purely defensive aircraft.
The fact that the Navy was developing a land based fighter at all, while the Army had several designs at its disposal, was a factor of the vicious inter-service politics that defined their relationship. Both vied for supremacy over control of national politics and industrial resources, and so competitive that they denied each other use of the same designs. Concurrent with the Navy interceptor project, the Army was also seeking an aircraft for the same role, in their case the Ki 44 Shoki. Resources spent on these parallel efforts were a major handicap to both the Army and Navy, and would prove catastrophic to the overall Japanese war effort as later events would show.
The Navy’s request for the interceptor called for a maximum speed of 323 kts at an altitude of 6 km, a landing speed no greater than 70 kts, an endurance of 45 minutes, a take off run of 300 m at full load and with no wind, and it had to have the same armament as the A6M fighter, being two 20 mm machine guns, and a pair of 7.7mm guns. It was also the first Japanese fighter required to carry an armored plate behind the seat back to protect the pilot.
It was in many respects the reverse of the Zero, where maneuverability and range were sacrificed to achieve the highest possible rate of climb. However, unlike the Zero, significantly fewer resources would be available for the engineers working on the aircraft. With the Zero being made the premier fighter of the Japanese Navy, a constant stream of improvements would be ordered over the next several years, straining both the development of the Raiden, and other Mitsubishi aircraft, namely the G4M bomber.
A Troublesome Development
The original design of the Raiden featured only two exhaust stacks, and a cooling fan driven by airflow. Like many of its early features, they proved inadequate in their purpose and were replaced. (japanese-warship)
The first major design decision came in the form of the choice of engine, with two major contenders. The Aichi Atsuta, a 1200 hp V-12, and the Mitsubishi Kasei 13, a new 14 cylinder radial. The Atsuta was a licensed development of the Daimler Benz DB 601A, and as was the case with most licensed foreign designs, was being sold as it was no longer a cutting edge design in its own country. Nevertheless, the Army would use the licensed engine in their own Ki 61 fighter, developed by Kawasaki as the Ha40. Despite both engines looking identical, and being derived from the same common model, they had few interchangeable components and fittings due to conflicting Army and Navy requirements, and the differing manufacturing practices between the firms. This level of parallel effort was both extremely expensive, and not at all uncommon. For the Raiden design team, the DB 601 derivative presented a light, streamlined engine, but also one with more limited paths for improvement.
The Kasei was still in its teething period, but was substantially more powerful and had better prospects for further development. While the engine’s higher fuel consumption was not problematic given the short range requirements, its size forced some compromises. To reduce drag, the engine was set much further back from the nose of the aircraft, with an extension shaft running through the tapered cowling to the propeller. The space was also shared by the oil cooler, supplied with air from an air flow driven fan. Further aerodynamic streamlining came from setting the canopy in a shallow frame, and the use of an advanced high-speed wing with aerofoils incorporating research in laminar flow. While maneuverability was not a primary concern of the aircraft, it would receive ‘fowler flaps’ which could be deployed via a button on the yoke, enabling the aircraft to make tighter turns in combat, at the cost of speed.
The Raiden incorporated a number of advancements in aerodynamics, most notably “laminar flow” aerofoils. As with other nation’s attempts, they did not achieve laminar flow, but reduced drag and improved dive performance. (Lancero99)
The Raiden’s development was plagued by numerous technical issues from a very early stage. There were issues with the engine, the cooling system proved inadequate given the small inlet for air at the nose, and the canopy proved to be extremely cramped with major restrictions in visibility. Worse, it competed for resources with the Zero, which included the already overworked engineer Horikoshi himself, who was also tasked with designing its successor. While being developed well before the coming war with the United States, the prototype wasn’t ready until February, 1942.
The Raiden first flew on March 20, 1942 at Kasumigaura, revealing a number of major faults. Numerous engine related issues cropped up, most notably trouble with the propeller’s constant speed governor and heavy vibration. Navy pilots who went on to test the aircraft were also extremely frustrated with the curved canopy, which not only restricted the range of view, but also caused optical distortions at certain angles, which were especially pronounced on the landing approach.
However, it flew notably well, featuring high stability and responsive controls. These were not able to overshadow the aircraft’s more visible faults, and inability to meet project goals. It failed to exceed 311 kts at its target altitude, and failed to reach its time to altitude requirements. Beyond the need to increase its overall performance, members of the IJNAF’s Air Arsenal required a redesign of its canopy, and improvements to its constant speed propeller mechanism, which proved to be one of the most troublesome issues in their several weeks of testing.
The canopy was most easily remedied, replaced with a more conventional design with flat windscreen panels. However the engine remained a more vexing problem. Several issues were intertwining to make further development far harder. First was the relatively new Kasei 13 engine itself, with its own teething issues, second was the inadequate oil cooler, and there was the fact that the engine itself was to be replaced with an even newer model to allow the plane to reach its required performance, which brought its own uncertainties. The Kasei Model 23 would prove much more powerful, and a later model would add methanol-water injection, the anti-detonation properties of which allowed the engine to run at higher manifold pressures, allowing it to produce 1800 hp. There were also more minor improvements, such as the introduction of a new oil cooler beneath the nose, the air driven cooling fan was replaced with a mechanically driven one, and the addition of exhaust stacks for each cylinder. Along with the engine came a new four bladed VDM propeller with a re-balanced governor, to address the unreliability of the previous model. There was much confidence in the new engine, which was premature.
The J2M1 also had a low set canopy with a curved front windshield. While it was aerodynamically clean, it proved a serious handicap to pilots. The fowler flaps are shown deployed. (Aces Flying High)
Operating the engine at a high output would prove troublesome, with excessive exhaust smoke, and extreme vibration being apparent from the outset. The smoke proved simple enough to address via the fuel injection system, but the vibration would remain with the aircraft through its entire career. It was brought up to Horikoshi that the use of the extension shaft might be the cause, though he adamantly denied this. He was at least partially correct, as the propeller design left much to be desired. In time, the vibration issues were addressed through the use of rubber buffers on the engine mounts, which along with the redesigned propeller governor, reduced vibration to manageable, but still noticeable levels. While Japanese aviation had a number of enviable technologies at its disposal, its propeller designs lagged behind that of the US. Harmonics were thus an issue that limited the performance of all Japanese high performance engines, but were particularly harsh on the J2M.
The J2M2 resolved the canopy issues, added additional exhaust stacks, and an engine driven cooling fan. Later in its development an additional nose mounted oil cooler was added to improve cooling during long climbs in tropical heat. (zbiam)
The aircraft was re-designated J2M2, but prototyping and pre-production continued at an extremely slow pace. To make matters worse, a pair of J2M2 were lost in early testing, just as the aircraft was being prepared for large scale introduction. One was lost on a basic test flight on June 16, 1943. The test pilot, Lt. Hoashi Takumi, lost control of the aircraft and struck a barn after trying to regain control after take off. He died when the aircraft caught fire shortly after the crash. In a non-fatal incident that occurred a month later, test pilot CPO Sasakibara Masao managed to land the J2M2 after encountering major handling issues. This incident offered no explanation for its cause, which was only discovered weeks later. On another test flight, a Mitsubishi test pilot, Shibayama Eisaku, found that the yoke was pulled forward when the landing gear was retracted. Being at a higher altitude than Lt. Takumi was when he started to retract the gear, he was able immediately lower it, and regained control of the aircraft. On some aircraft, it was found that the retracting tail wheel was coming to rest against the elevator controls. The problem was remedied, though only by late 1943.
While technical issues continued to plague the development of the Raiden, the Navy was still conducting tactical and performance tests with the prototypes. In the autumn of 1943, the Navy had several prototypes of the new fighter at its disposal, a number of them the older J2M1. The Yokosuka Air Corps would put these aircraft in mock dogfights against their A6M3 Zeros, finding the J2M1 was at a serious disadvantage when using the typical Navy fighter tactics, which favored horizontal maneuvering over climbing and diving. Its true strength was in energy fighting, with the pilot keeping to a high speed and expending little energy through more aggressive horizontal maneuvers, and outmaneuvering them by attaining a higher energy state. Unfortunately, this point was not stressed in their reports, and pilots stuck to the more traditional tactics that the aircraft was less suited to.
Their attempts in mock interceptions of bombers also proved troublesome, not for any purely performance related reasons, but that the J2M1 fighters they were using were very unreliable. As was the case in earlier tests, the propeller governor failed when the aircraft was put through harsh maneuvers, and in another instance, a throttle had gotten stuck in the forward position. Veteran pilot and Ace, CPO Oh-hara Ryoji, experienced both such failures, and performed multiple unpowered landings in the fighter.
The J2M2 and J2M3 eventually resolved into a serviceable, but still rough around the edges interceptor. Its development was slow, as Mitsubishi was primarily concerned with producing the vital G4M bomber, and A6M fighter for the Navy, whose fortunes had turned for the worse. (Japanese-warship)
Troubles aside, development of the fighter continued, resulting in a new J2M3 model with a heavier armament of four 20 mm guns, and an improved oil cooler. The weight of the new equipment would again put it behind the performance figures set in place then five years ago, though the heavier armament would prove important in facing the resilient heavy bombers in service with the US. These improvements aside, they were unable to trace the issues of the harsh vibrations from the engine, and proceeded to production regardless, believing the measures in place to be sufficient. After much delay and considerable frustration, the Raiden was moved toward mass production at the end of 1943, at a relatively low figure of some 20 aircraft per month. Only 90 would be built in 1943, with only another 274 the following year, most being the J2M3 Model 21.
Its production was mostly motivated out of desperation. The Navy had at its disposal only one major fighter model at that time, the Zero, which had gone from dated, to obsolete, from mid 1943 to early 1944. It was supposed to have been succeeded by the A7M, which failed to proceed past prototyping. Making matters far worse, in the land based land interceptor role, the Raiden was now years behind schedule, leaving vital forward anchorages to be defended by the aging Zero. The Navy’s alternative to the troubled Raiden was the N1K-J Shiden, though it would not materialize in the numbers needed for many months. Thus the Raiden was to be produced in limited numbers, being the only fighter the Navy was confident could intercept American bombers, especially the newly discovered B-29 which intelligence services had identified well before its debut.
In dealing with this particular threat, there were attempts to fit the Raiden with a high altitude engine. A J2M4 was thus created with a turbo-supercharged Kasei engine, and a J2M5 was built with a three speed supercharger. The turbo-supercharger proved far too unreliable for service, with the three speed supercharger proving to be somewhat more manageable. While both experimental models did have much better high altitude performance, neither were able to be employed, leaving the Navy without a high altitude interceptor.
The Whirlwind
By the start of 1944 the war had been fully reversed against the fortunes of the Japanese. The long, grueling Solomons campaign had drained them of the corps of elite airmen they had carefully cultivated since before the start of the war, and US industry was producing enormous amounts of war materiel. The situation was soon to grow even worse as the United States began to prepare the deployment of one of its newest, and most advanced weapons.
Japanese intelligence services first became aware of the B-29 after reading of the death of a test pilot flying a new Boeing bomber in early 1943. They would soon produce speculative performance capabilities for the new bomber based on what they knew of the known abilities, and likely new improvements, of the US aviation industry. They proved to be reasonably correct in their efforts, and concluded that major raids against Japan could be expected by early summer 1944. The bomber was first deployed to a base in China, at the Chengtu complex, a distant and difficult to reach airfield, which proved to be far from ideal to keep supplied, and offered a limited ability to strike at the Japanese mainland. They first raided the rail lines in Bangkok in June of 1944, as they prepared for a greater offensive. Their first raid over Japan took place on the night of June 15/16, and mirrored the operations of RAF Bomber Command, with pathfinders going ahead of a long, dispersed line of bombers to mark targets. This effort, and the many that would follow would prove unsuccessful, night raids were an exceedingly difficult affair that demanded the highest levels of flying proficiency, and high altitude operations would be complicated by the powerful jet stream, which also reduced the accuracy of daylight raids considerably.
Basing the B-29’s would prove to be a challenge, with most locations being either too exposed, or too remote. American victories in the central Pacific opened the route for raids against Japan. (National Archives)
These many issues aside, the B-29 made a considerable impression across Japan. It was an opponent that was advanced as it was elegant, its tendency to catch fire due to the use of a magnesium alloy accessories case, was unknown to those who faced it in combat, or the civilians who endured its presence. Author Kosaka Masataka would note its “beauty and technological perfection” which to his mind symbolized the mark of “higher civilization” achieved by the United States. One of the first Japanese airmen to encounter the new bombers, ace and night fighter pilot 1st Lt. Isamu Kashiide, would be awestruck at the sight of a B-29 that had been coned by searchlight. Remarking, “I was scared! It was known that the B-29 was a huge plane, but when I saw my opponent it was much larger than I had ever expected. There was no question that when compared with the B-17, the B-29 was indeed the ‘Superfortress’!”
These encounters would grow in frequency and lethality as the raids mounted. The Chengtu complex was supplemented by new bases in the Western Pacific, notably the enormous base on Tinian, and the appointment of a new, aggressive commander, General Curtis LeMay. Against them was the dwindling cadre of experienced Japanese airmen, who had relatively few advanced interceptors to call on.
The Raiden In Combat
With the end of its less than ideal development cycle, the Raiden made its service debut with the 381st Air Group, in October of 1943. However, after constant teething issues with the aircraft, and a fatal accident resulting from an unidentified air frame failure, the squadron would have its Raidens exchanged for Zeros before their deployment to the Philippines, and the Dutch East Indies, in March of the following year. In September, after several months in combat, they received some ten J2M3 Raidens while deployed to the Celebes. The combat debut of the new aircraft came with some success, as during an intercept of a large number of American B-24 bombers, one victory was credited to the new fighter. They continued their service there, and found the new aircraft to be a potent combatant, with noted success against American P-47 and P-38 fighters, as unlike the zero, Raiden pilots could escape them at lower altitudes and were still able to comfortably outmaneuver them.
Long accustomed to the Zero, many struggled to make use of a plane whose strengths lay in its energy retention and dive speed. (Japanese-warship)
The 381st continued its service through the Battle for the Philippines, defending Japanese positions around Manilla, and later, the oil industries in the region. There were also Raidens in service with other units, notably the 301st Air Group which served in the central Pacific, which struggled, making use of the older and less reliable J2M2, and facing considerable opposition from massed American air power in the region. There were otherwise a handful of other aircraft serving in outlying theaters on a mostly provisional basis, with very little known of their use.
Aluminum Overcast
The American air raids against Japan were to enter their penultimate and most brutal stage in early 1945. Earlier raids were done from high altitude, and did so with the difficulties of having to juggle the difficult basing situation in Chengtu China, and the weather. The weather proved frustrating for lack of access to intelligence gathering in the region, save for the Soviets who refused the use of their services to maintain their neutrality, and whose broadcasts were shrouded by constantly changing codes. However, General Curtis LeMay would employ new tactics allowing him to side-step the issue of the weather, and the Americans had constructed new bases in the Marshall Islands which would allow for the comparatively easy amassing of bombers. LeMay chose low altitude, incendiary saturation bombing, the most blunt, and brutal of the methods available to him. Earlier, smaller scale incendiary raids, including one against the Mitsubishi works at Nagoya had proven successful, though they soon pivoted toward targeting cottage industries in urban areas, and the civilian population. This shift in tactics can occurred rapidly, seen in a single raid on February 25 of 1945, where some 200 B-29’s raided Tokyo which saw fires burn uncontrolled across a large swath of the city.
The B-29 was among the most advanced aircraft of the Second World War. Once they ranged over the skies of Japan in large numbers, the Pacific war was to enter its final phase. (National Archives)
To make a desperate situation worse, when LeMay’s XXI Bomber Command began raiding Japan in force, they weren’t alone. On February 16th, a major incursion performed by carrier based aircraft swept across the shores of Honshu, launched from Task Force 58, which accounted for 16 fleet carriers, and 116 warships in total. Admiral Mitscher would sortie 1,187 planes; 895 fighters, 201 torpedo bombers, and 91 dive bombers. They would contest control of Japanese airspace, and strike at the targets LeMay had not, mostly factories producing materiel for the Japanese war effort. The next day, he launched another 1,574 sorties before departing southward to engage the Japanese forces on Iwo Jima. In this uneven fighting, he lost only 80 planes to all causes with the Japanese claiming 134 kills. With the subsequent loss of Iwo Jima, came the first encounters with P-51 mustangs, now based from that island. They first came north on April 7th, where they quickly showed themselves to be a dangerous opponent.
The Japanese defensive situation during this time period grew from difficult to dire. The quality of the aircrews had declined even further after the disastrous encounter in the Philippine sea, and the following American invasion of the Philippines itself. There, the Navy had spent its last strength in an attempt to prevent American forces from staging a landing, following a plan which could never have hoped to succeed. The merchant marine had also been decimated, and the heart of the Empire was thus seeing shortages of every kind. There were no offensive means by which the war could be fought, and the enemy was closing in from all sides. Despite a situation which could only resolve itself in a painful defeat, the Japanese armed forces chose to continue the war in the hope for a conditional end to hostilities.
There was little hope for anything approaching a favorable outcome in continuing the war, yet fatalism ruled, and the country marched on. The exuberance of the early victories was gone, the hopeful energy of the early Solomon campaign had faded, and China remained vast and unconquered. In the Autumn of 1944, ace Navy Pilot Lt.jg Sakai Saburo returned to Tokyo, after several years on campaign and the loss of an eye. “The city appeared drab and lifeless. – Most of the stores were closed, their windows empty. The significance was clear. There were no goods to sell, and the owners were away, working in war plants. The few stores that remained open hardly resembled the colorful and well-stocked establishments I once knew. Few goods were on display, and for the most part these were crude substitutes.” It was this city that was to become a battleground in the months to come.
Just as pressing as the approaching American forces, the division between Japan’s air forces, Army and Navy, would prove a critical fault which saw them face this storm almost totally unprepared. Despite the early warning of the B-29 threat, there was no comprehensive plan for the defense of the Japanese mainland from air attack, the strategic outlook of both forces was one defined by delusion and self-sabotage. From the outset, the Army and Navy each had their own jealously guarded industrial complexes, possessed few compatible munitions, and operated aircraft with no common base for components. Army and Navy aircraft of similar design did not even possess a common voltage. They pursued aircraft development and research separately, further dividing the pool of expertise and industrial base, which were dwarfed by their rivals in America. The Navy commissioned some 53 models of aircraft for which there were 112 variants, and the Army 37 models with 52 variants. Making matters worse was the failure to prepare, and expand aircraft production in wartime. The Ministry of Munitions was only finally established in 1943 to better convert Japanese industries for military use. In 1944, its head, Fujihara Ginjiro, found that with the ideal utilization of Japan’s industries, the level of annual aircraft production could have been as much as 53,000, rather than the 8,000 to 10,000 which were being turned out. While the figure is purely theoretical, it nonetheless demonstrates the widely impractical decision making that dominated Imperial Japan’s industrial planning.
The P-51 would become a major threat to Japanese defenders, just as it had been over the skies of Germany. Here a fighter squadron flies assembled alongside a B-29. (National Archives)
Even critical pieces of equipment, such as early warning radar, were developed separately, and hoarded to build separate networks with little collaboration. The Army used its Tachi-6’s and 7’s, and the Navy its ground based Mark I radar system, serving only to divide the already relatively small Japanese radio industry. Any real potential for the defense of Japan had been sacrificed in favor of inter-departmental politicking. When the Americans returned to the skies of Japan in strength, the two Japanese air forces would meet them with too few aircraft, too poor early warning capabilities, and no real strategic plan.
What few hopes there were could be found in a new generation of fighters. During 1943 and 1944, Japanese fighters had lagged behind considerably their American opponents, largely due to their engines being less powerful. In the last months of the war, there were new models in service which gave some parity with the Allies. These new fighters were the Ki 84, N1K-J, Ki 100, and to an extent, the J2M3 Raiden, which was at one point to be phased out by the Navy’s new N1K-J fighter. Given the desperate situation over the looming bomber offensive, and concerns over shortfalls in the supply of fighters, its production was instead boosted. With the proper planning, one or two of these fighter types could have taken up the bulk of the defensive effort in greater numbers, but the division of resources and the lack of any coherent strategy would prove fatal. In early 1945, the Japanese Air Forces had only some 500 fighters between acting in the defense of the homeland.
The Last Line – 302nd Air Corps
The 302nd Air Group would be the longest serving of the three units supplied with the Raiden to serve in the defense of Japan. The unit was formed March first, 1944, and was to be equipped with 48 Raidens, and 24 J1N1 night fighters, which was not irregular, as many other Japanese air corps operated more than one type of aircraft. This was often a mix of fighters and maritime bombers, though in the case of the home defense units, the combination of interceptors and night fighters was to give them a 24 hour, all weather defense capability.
Japan’s defenders employed a bewildering number of single-engined fighter types, mostly spawned from the total non-cooperation between the Army and Navy in developing and procuring aircraft. Left to right: J2M, N1K-J, A6M, Ki 44, Ki 61, Ki 84, Ki 100. The top three are Navy aircraft, the rest belonged to the Japanese Army Air Forces (wikimedia, rodswarbirds)
The 302nd was deployed to Kisarazu, and later Atsugi, in Tokyo, to act in the defense of the Kanto region. The 302nd was the first, and among the most colorful of the three Raiden units established for the defense of Japan. It was a mix of mostly green airmen with a few veterans, among whom was possibly the most irregular officer in the service of the Japanese navy. Lieutenant Junior grade, Akatsumaki Saadaki had nearly a decade of service under his belt, and had built a steady reputation for disorderly conduct, drinking, womanizing, casual violence, and being an otherwise first rate combat pilot. His stories of his combat prowess and carousing were legendary, and according to fellow airman Lt.jg Sakai Saburo, all lies. Nevertheless, he would be a pillar of the unit alongside CPO Nakamura Yoshio, a veteran of the withering Solomon Island campaign, and Ensign Isozaku Chitose, an ace pilot with over ten years experience, from China to Rabaul. The unit was led by the fiercely patriotic Captain Kozono Yasuna, another Solomon island veteran, and a night fighter pilot with considerable experience.
Along with its odd mixture of experience, the 302nd also lacked for its new aircraft, with the priority of new Raidens being the 301st, elsewhere in the central pacific. The unit thus initially flew a considerable number of zeros, and older Raidens that had remained in Naval inventory, these being old preproduction J2M2’s, delivered in their orange test liveries. These proved to be a more challenging aircraft for the green pilots that made up much of the air group, and Lt.jg Akamatsu set aside the Raidens for his veterans, ensuring they were well versed in emergency procedures and dead stick flying. This would prove vital, given the poor quality of many of the aircraft they were given. It was only in May of the following year that they would eventually receive their 48 Raidens, though the Zeros would remain to substitute for unserviceable planes, and for the use of pilots not experienced enough for the more powerful Raiden.
The self proclaimed “King of Aces”, Lt.Jg Akamatsu Sadaaki. (wikimedia)
The 302nd attempted several intercepts through 1944, most of these being lone, high flying F-13’s. They typically ended in failure. These aircraft were the photo reconnaissance model of the B-29 bomber, and free of a heavy bomb load, could prove very difficult to intercept without ample warning thanks to their high speed, and operating altitudes at and above 9 km. Other attempts to intercept larger formations also proved difficult, and success wasn’t noted until late in the year. On December 3, 1944, the 302nd sent 24 of its Raidens amongst the 74 Japanese fighters sortied against a raiding force of B-29’s. They saw some success, bringing down three B-29’s, with another two lost to the 244th Sentai’s “special attack” unit of the Japanese Army Air Force. Flying specially prepared, and armored, Ki-61’s, they performed ramming attacks against the American bombers. The ramming pilots survived their attacks, but Lt.jg Saadaki was deeply frustrated by these tactics, enough to discourage their use among his younger, and more impressionable airmen. There would be considerably more of these novices in their number, as many older veterans were eventually transferred away to establish new fighter units. In time, Lt.jg Akamatsu would also be transferred near the end of the war to train for a posting for a potential rocket-powered interceptor unit.
Shorn of some of its most venerable airmen, including Ens. Chitose, the 302nd would also soon find that following February, 1945, B-29 raids would be conducted at night, when only the unit’s J1N1s could pursue them. Despite the reduction in daylight raids, they would still have to contend with the presence of American fighters which began constant operations over Japan. The first encounters came as a result of Admiral Mitscher’s raids in mid February, 1945. Against them the Raiden crews proved their worth, claiming to have brought down eight Hellcats, for the loss of two Zeros, and three damaged Raidens. On the second day, they claimed a further seven Hellcats for the loss of two zeros, though the Raidens did not see combat that day. While they could contend well with the Hellcats, they would find a more dangerous opponent in the F4U Corsair, and the P-51D Mustangs, which they first encountered on April 7th.
In addition to the 302nd near Tokyo, two other Raiden units were raised for the defense of Japan, this included the 332nd near the Kure Naval arsenal, and the 352nd, near the Sasebo Arsenal. Here airmen of the 332nd pose before one of their interceptors. (rods warbirds)
Flying long sorties from Iwo Jima, American airmen fought cramps and the Pacific heat during their seven hour missions. Fatigued and bored, they nonetheless made for deadly opponents over Japan. The Mustang’s Packard Merlin engine was powerful from the sea level to high altitudes thanks to its two stage supercharger, its aerodynamic form saw it lose little speed in performing acrobatic maneuvers, and its laminar flow wings and sealed and balanced control surfaces gave it near unparalleled maneuverability at speeds other aircraft had stiff, and even unworkable controls. On the day they were first seen over the Kanto plain, they claimed three J1N1 night fighters, one D4Y2 dive bomber, and a Raiden. The heavier aircraft were capable bomber hunters when enemy fighters were of no concern, but as the Mustang had done in Germany when it made its appearance the previous year, it denied the use of these otherwise effective aircraft.
Despite complaints from Japanese Airmen, the Raiden could outperform the Hellcat comfortably, and its combat flaps gave it an edge in close-in maneuvers over the newer American P-51 and F4U Corsair. (Japanese-warship)
The 302nd would struggle to cope with the influx of Mustangs which made their presence immediate, and known. On April 12, while XXI Bomber Command was raiding the Musashino aircraft plant, they were joined by 104 P-51, who engaged Japanese fighters attempting to scramble, and strafed their airfields. Around the Kanto region, it thus became very difficult to actually reach the bombers given the presence of the P-51s, who were tasked with engaging the Japanese interceptors before they had a chance to make contact with the B-29s.
A small detachment of the 302nd was also sent to the southern home island of Kyushu, where they had more success against the smaller formations of raiders, which flew with a more modest escort. They still remained difficult targets, as bringing down a B-29 could take three passes, and the bombers were well defended by computer-assisted defensive guns.
In the last months of the war, the 302nd continued to take action against the American air forces which had become an immovable presence over Japan. However spirited the defenders may have been, they were contending almost exclusively with American fighter forces, and the B-29s were left to put entire cities to the torch by night. Between poor command and control facilities, crude early warning radar, and the constant inter service rivalry between the Navy and Army Air Forces, the defense of the Home Islands was failing. Despite having nearly two years to prepare for a potential strategic bombing campaign, there was no effective plan for the air defense of the Home Islands. In the final accounting, interceptors brought down a confirmed 74 Superfortresses, which flew some 31,300 sorties.
In the face of a disintegrating effort against an enemy that was only growing more numerous, the Japanese air forces continued their defense, largely without success. The Mustang, Hellcat, and Corsair, continued to roam the skies of Japan. On August 15th, In the last major battle between the air forces of the Japanese and US Navy’s, four Raidens and eight Zeros took off to engage a detachment of F6F Hellcats. Incensed by the declaration of surrender, the airmen of the 302nd ambushed the flight. Outnumbered and weighed down by external fuel and munitions, the Hellcats fought to escape, and in the ensuing dogfight, two Raidens and a Zero were lost for four of the US Navy’s fighters. An ace pilot was made in one Lt. Morio Yutaka, and the flight returned to base, concluding the final combat mission of the Raiden. The 302nd would mutiny in an attempt to continue fighting, but were discouraged when their messengers to other units were rebuffed and their commander fell ill. Divided and disheartened, they returned home.
Flight Characteristics and Pilot’s Remarks
Many Japanese Navy fighter pilots were unsure what to make of the stout, yet, powerful fighter. (lancero99)
The Raiden was fairly unique in that it was viewed very poorly by most Japanese airmen, yet American test pilots gave a fairly glowing account of it. Before all else, it must again be said that the strengths of the aircraft were not impressed upon Japan’s Naval Airmen before they were issued their planes. Its excellent rate of climb and impressive dive characteristics were noted in technical evaluations, but they were not emphasized enough in training. However, throughout its service, it did gain some good marks from Japanese pilots, notably from pilots in the Philippines who engaged American bombers at lower altitudes and found it far superior in this task than the other fighters available to them.
Both Japanese and American pilots were complimentary of the spaciousness of the cockpit. Of note is the large armor glass pane above the instrument panel, combined with the 8mm steel headrest, the Raiden provided considerably more protection than most Japanese fighters. (rods warbirds)
Most Japanese airmen coming to this aircraft did so with experience on the supremely agile, if slow, A6M Zero. The Raiden was practically the antithesis of this aircraft, with their strengths and weaknesses reversed. It thus proved categorically unpopular among Japanese Naval Pilots. The Raiden’s vibration at cruise and the poor build quality of the aircraft did nothing to improve its reputation. Poor visibility over the nose, rear, and the higher landing speed also presented challenges to those familiar with flying the Zero. They did, however, recognize it made for a superior interceptor over the A6M Zero, featuring an impressive rate of climb, and powerful armament. Its vertical maneuverability was also among the highest of all late war Japanese fighters, giving it a number of strengths over its allied opponents that the Zero lacked.
A wartime TAIC calculated performance report claims the Raiden was capable of climbing 4700 feet per minute (23.9 m/s) at its highest for its first supercharger speed at 4000 ft (1220 m), and 4100 feet per minute (20.828 m/s) at its second at 15,000 ft (4572 m). Its top speed was projected at 304 knots at sea level, 321 knots at 6,000 ft, and 369 knots at 17,500 ft. These figures are likely suspect and calculated based on an incomplete model, disagreeing considerably with other claims elsewhere.
A figure of top speed of 330 kts at 6km appears elsewhere in numerous, including Japanese publications, likely with better access to resources on the aircraft. It is also likely that its true performance lies somewhere in the middle. While this top speed isn’t particularly impressive, its maximum climb rate of approximately 4650 feet per second at sea level, was. This is considerably higher than the Mustang’s maximum rate of climb of 3600 feet per minute, when running at 67” manifold pressure and with a bomb rack on each wing, which would have been the case for those over Japan. These figures are likely more in line with its true performance, given that the aircraft was designed to achieve a very high climb rate, rather than the highest speed in level flight. Concurrently, its sustained turn performance was excellent compared to allied fighters, thanks to high power to weight ratio.
A veteran with over a decade of experience, Lt.jg Akamatsu taught the Raiden pilots of the 302nd how to best employ their fighter, ensuring his pilots knew how best to pursue their targets, and how to disentangle from unfavorable engagements. (TooBadAtNamingAccounts)
One of the most notable pilots to use the Raiden in combat was Lt.jg Akamatsu Sadaaki of the 302nd Air Group, who was as far removed from the picture of a Japanese wartime officer as was possible. He received his wings in the Naval Air Force in 1932, was a borderline dysfunctional alcoholic who was prone to insubordination, womanizing, striking those who irritated him, managed to survive the war without major injury, and he was said to have flown combat sorties drunk, among other wild claims. He would claim to have shot down over 200 enemy aircraft when sober, and 300 after a few drinks. He was officially credited with 27 victories. His eccentricities aside, he proved the Raiden was a capable combat aircraft in his role at the 302nd. In one engagement, he showed the excellent energy-fighting capabilities of the Raiden on April 19, 1945 when he and his wing man encountered a flight of five P-51s. With a height advantage, he dove beneath, and crept behind the enemy, shooting one fighter down, then and brought down another in a head-on pass before both sides broke away. His only real complaint was that the aircraft’s radius of action was short, but was otherwise seemingly the only advocate of this troubled aircraft.
A Raiden in American colors alongside a Seafire Mk IX, and an F6F Hellcat. In spite of its roughness, the aircraft was given favorable remarks by American evaluators. (National Archives)
With several airworthy Raidens having been captured in the battle for the Philippines, American evaluators were able to give an alternate perspective on the aircraft. Overall, it earned good remarks. The cockpit was spacious and well ventilated, especially valuable in the tropical climates of the pacific. The plane was judged stable on all axes, with good stall characteristics. Apart from a lack of warning, recovery was easy with no inclination to go into spins. Maneuverability was judged good, especially with the deployable fowler flaps that allowed for tighter turns. Harmony of control was acceptable but less than ideal, as the ailerons were heavy at cruise and became very stiff at 325 mph, the elevators also being noted for being light up to this speed, and with the rudder being judged effective at all speeds.
The engine ran roughly at the RPM’s for cruise, but at combat and takeoff power this was less pronounced. However, this rough running caused vibration and considerable noise, not enough to be considered excessive or uncomfortable, but enough to be noteworthy. The poor workmanship of the engine would make itself known during testing when an oil delivery hose failed during a long flight, causing the engine to seize and force the pilot to make a dead stick landing.
One Allied evaluation pilot, who filed a detailed report on the plane, would claim it to be the best of the Japanese aircraft he’d flown, which notably included the Ki 84. Overall, the aircraft judged well thanks to its good stability, stall characteristics, comfort, good combat related performance, and its combat flaps. Ironically, it was also said to have had good landing characteristics, which suggests much about the different expectations in aircraft handling between American and Japanese airmen.
Construction
Featuring numerous new advancements in aviation, the Raiden would be a remarkable, if flawed, interceptor. (rods warbirds)
The fuselage of the J2M was of a traditional construction, save for the deeper placement of the aircraft’s engine. This resulted in the spindle-like shape of the aircraft’s fuselage, allowing for the fitment of a larger engine while still retaining a clean aerodynamic shape. It was of a typical duralumin monocoque construction, with 18 structural bulkheads and former sections from the engine to the tail. It was, however, noteworthy for the use of Sumitomo Super Duralumin, which could boast of higher strength than its contemporaries, comparable with post war 7075 grade aluminum alloy, and late war American alloys which had been developed in response to captured Japanese examples.
It was among the few Japanese fighters to incorporate protection for the pilot, though compared to foreign designs it was very lightly armored. This consisted of an armored steel headrest with a thickness of 8mm, and an armored glass screen, 50mm thick, at the front of the cockpit. In service, these plates were occasionally removed to lighten the aircraft.
From the prototype to the production models there were two major fuselage alterations, namely the addition of a canopy which sat higher atop the air frame to improve visibility and resolve optical issues, and the addition of an additional oil cooler for the engine. A more minor, yet essential, alteration was to shift the position of the tail wheel retracting mechanism, as on early models it could press against the elevator control, and render the aircraft uncontrollable.
The wings incorporated laminar flow theories into their design, which gave the aircraft improved dive performance, and provided high drag reduction. They also improved control through high speed ranges by keeping the destabilization of airflow across the wing’s surface, known as compressibility, from occurring up until the aircraft reached higher mach numbers. Each wing had landing gear which deployed outward, driven by an electric motor which also actuated the tail wheel and flaps. Fowler flaps were used to give the aircraft a tighter turning circle at the cost of speed, they could be deployed via a button on the control yoke, and set the flaps at a 16 degree deflection so long as the button was held.
Cooling was originally provided by an airflow, and later engine driven, fan which drew air through a small annular radiator at the nose of the aircraft. This proved to be inadequate due to the small inlet at the nose of the aircraft and the limitations of the engine driven cooling fan, forcing the addition of an under-nose radiator on the J2M2 model. This cooler was also enlarged on the next model, the J2M3, to provide better cooling for the longer, higher power climbs these interceptors would be making.
The plane was powered by various models of the Mitsubishi Kasei, a 42.1 liter, two-row, 14 cylinder radial engine equipped with a Mitsubishi fuel injection system, and a single stage, two speed supercharger. The original was the Kasei 13, MK4C, which operated at a reduced output of 1,420hp, this was done to try and keep issues of vibration to a minimum, but this failed due to issues with the constant speed propeller governor, which drove a three bladed propeller. It was noteworthy for its air driven cooling fan which sat at the front of the engine, and a 50cm extension shaft which was shrouded in an elongated reduction gear housing unit. Technical issues with this engine, and its insufficient output saw it abandoned for the Kasei 23.
The Kasei 23, note the propeller shaft extension and mechanically driven cooling fan. (sagamiharaheikishou)
The Kasei 23, MK4R, reduced the length of the extension shaft to 30cm, incorporated an engine driven cooling fan. Vibration issues were eventually relieved through the use of rubber buffers on the engine mounts and adjusting the propeller balancing mechanism along with replacement of the constant speed unit, which then drove a four bladed Sumitomo metal propeller. Some vibration was still noted in flight, but not enough to significantly affect the combat performance of the aircraft. It likely had an impact on the serviceability of Raiden, but far less so than most of the aircraft being produced by an inexperienced workforce.
This engine was further developed into the Kasei 23a, MK4R-A, with the addition of a methanol-water injection system. The anti-detonation properties thus allowed the engine to run at higher manifold pressures, allowing for an output of 1800hp. It was also equipped with individual exhaust stacks, providing thrust augmentation. This was the primary engine for the J2M2 and J2M3, after the Raiden’s protracted development. The engine had a bore and stroke of 150x170mm. It had a diameter of 134 cm, with a length of 274.32 cm.
At an RPM of 2600 and +450 mmhg over atmospheric pressure, the engine produced 1800 hp at takeoff. It produced 1575 at its first supercharger speed at 1800 m (5905 ft), and 1410 hp at its second speed at 4800 m (15748 ft). It could hold its maximum power setting for 1 minute, and military power, 2500 RPM at +300 mm hg, for 30. Its maximum continuous rating was at 2300 RPM and +150 mm hg of manifold pressure.
Fuel tankage comprised a pair of tanks at the wing roots containing 90 liters of aviation gasoline, along with a fuel tank ahead of the cockpit which initially contained 410 liters, later reduced to 390 liters after plane 3003. A centerline detachable drop tank could also be carried, increasing fuel supply by 250 liters. The oil tank was mounted aft of the engine and had a capacity of 60 liters. The methanol-water tank was sandwiched between the oil and fuselage fuel tank for a capacity of 120 liters. The aircraft was serviced with 92 octane aviation gasoline.
A Raiden carrying the more or less standard armament of four 20 mm Type 99 machine guns. (Japanese-warship)
The initial armament of the J2M2 Raiden comprised a pair of 7.7mm Type 97 machine guns mounted in the engine cowling, and a pair of wing mounted 20mm Type 99 Model 2 machine guns. The Type 99 was designated a machine gun, as compared to other calibers in use by the navy it was quite small and did not warrant being referred to as a “cannon”.
The Type 97 was a derivative of the Vickers class E aircraft machine gun. Each weighed 11.8 kg, was 104 cm in length, was belt fed, and had a rate of fire of 900 rounds per minute. The Type 99 no.1 model 4 20mm machine gun weighed 23 kg, measured 133 cm in length, was belt fed, and fired 520 rounds per minute, supplied with a 210 round belt.
This armament was also to be used for the J2M3 before the cowling machine guns were removed and a second pair of wing mounted 20 mm machine guns were added. These Type 99 no.2 model 4 20mm machine guns were mounted inboard of the initial guns, weighed 34 kg, measured 189 cm in length, were belt fed, and fired at 490 rounds per minute, with a 190 round belt. These featured a longer barrel and had a higher muzzle velocity.
A rare Raiden sporting a heavier 30 mm armament, a considerable upgrade in firepower though one that saw little to no operational use. (japanese-warship)
A very small number of J2M3’s were equipped with a pair of 30 mm Type 5 machine guns in place of the Type 99 no.2’s. These each weighed 70 kg, had a length of 207 cm, fired 500 rounds per minute, and were belt fed.
A very small number of Raidens received an upward firing 20mm mounted behind the cockpit for use against bombers. It was used only with the 302nd air group, and installed at the insistence of its commanding officer, a night fighter pilot who thought it would be useful against heavy bombers. Little has been written of its configuration or use, with the modification being stated to have been very unpopular with pilots who disliked the added weight of the questionable weapon.
A pair of 60 kg general purpose aviation bombs could be carried on outer wing shackles. They were compatible with air to air phosphorous bombs, though this capability was likely never used.
Attempts to produce high altitude series were made, though none produced a combat ready aircraft. The J2M4 possessed a turbosupercharged Kasei 23c engine with a slightly lengthened fuselage to accommodate the turbine, but it proved too unreliable for service. It proved capable of reaching 315 kts at 9.2 km. A second high altitude series was attempted in the J2M5, which took a more modest path in using a Kasei 26a, utilizing a three speed supercharger. It proved a far more reliable means of boosting high altitude performance, allowing it to make 331 kts at 6.8 km. It had a fairly small production run, but the escalating bombing raids against the Japanese mainland made any major modifications to the Raiden unacceptable, as they would have reduced the production output of an already much needed aircraft.
Variants
J2M1: Prototype series, Kasei 13, early windscreen. 3 produced. First aircraft completed March, 1942, flown March 23.
J2M2 Model 11: Kasei 23, new canopy design, air driven cooling fan replaced with engine driven, chin oil cooler added, propeller changed with new governor, numerous other mechanical improvements. Two Type 97 7.7mm guns in cowl, two Type 99 20mm guns in wings. Kasei 23a later retrofitted, vibrations issues reduced. First aircraft completed October 1942, first flown October 13.
J2M3 Model 21: Kasei 23a, oil cooler enlarged. Four Type 99 20mm guns in wings. Most produced type. First aircraft built October 1943.
J2M4 Model 32: Prototype series, Kasei 23c turbosupercharged engine, unreliable. Only 2 produced. First aircraft built August 1944, first flown September 24. Project canceled in February 1945.
J2M5 Model 33: Production series, finished trials May 1944, shelved. Kasei 26a with three speed supercharger. Enlarged cockpit frame to improve rearward visibility. 34 produced. First flown May, 1944.
J2M6 Model 31: Prototype, J2M3 with canopy and cockpit from J2M5. First aircraft built February 1944.
J2M7 Model 23: J2M3 with fuselage modifications to improve rearward visibility. None built.
Production
The Raiden was built at Mitsubishi Airframe Works No. 3 at Nagoya, and later at dispersal facilities and the Naval depot at Kanagawa. Production varied drastically, especially early on when cancellation of the program was being considered, only for it to be brought back when the need for interceptors of any kind became dire. The relationship between the plant and government was deeply strained during wartime, production decisions with long term impacts were judged to have been made too often by post war American evaluators, and the plant officials were disparaging of the government’s involvement in their business. Stress was felt strongest over production orders, where the military changed its mind too often in regards to order sizes and modifications. Where Mitsubishi would have preferred large orders with little modifications between batches, the military vacillated in their procurement.
The main works at Nagoya were a prime target for allied air raids, and the failure to properly disperse production had major effects on the supply of aircraft for the Navy. (National Archives)
As the war continued, more and more conscripted labor was used, and in its last year, a large number of teenage workers. They were not only inexperienced, but were categorized by the plant managers as “inefficient, inept, and indifferent”. To complicate matters, they had friction with the regular plant employees, a factor that was likely also cultural as these conscripts often came from territories outside Japan. Morale at the plant was low.
Nagoya Airframe Works No. 3, and its dispersal facilities produced 493 aircraft, with a further 128 being produced by the Koza Naval Air Arsenal in Kanazawa. Unlike in Germany, dispersal efforts largely failed due to poor long term planning and the USAAF’s ability to track the progress of alternate production sites. Production never ceased, but the quantity and quality of the aircraft that left the production lines was heavily impacted. According to Horikoshi Jiro, the efforts to disperse the factory were conducted too blatantly, and had the effect of dividing up experienced plant personnel and construction crews at a time where they were already spread too thin. The build quality of the J2M was thus fairly dubious during 1944 and 1945, which was well understood by aircrews.
Production Mitsubishi, Nagoya, All Types
January
February
March
April
May
June
July
August
September
October
November
December
1942
1
1
1
2
2
1
1
1
1
2
1943
0
0
1
2
0
0
3
4
5
16
21
22
1944
17
26
9
22
39
44
34
22
16
20
18
7
1945
17
12
29
16
0
8
7
27
Production Koza, Kanagawa Naval Depot
January
February
March
April
May
June
July
August
September
October
November
December
1944
1
0
0
1
2
3
4
6
1945
13
8
23
15
10
20
22
0
Specifications
J2M3 Raiden
Specification
Engine
Kasei 23a MK4R
Engine Output
1800 hp
Gross Weight
2861 kg
Empty weight
2191 kg
Maximum Range
968 nmi (calculated)
Maximum speed
330 kts at 6km
Armament
4x 20mm Type 99 Model 2, no.’s 1&2
Crew
1, Pilot
Length
9.69264 m
Height
3.93192 m
Wingspan
10.78992 m
Wing Area
11.7058 m2
Conclusion
The only fully intact Raiden, at the Planes of Fame museum in Chino, California. (Planes of Fame Air Museum)
Few full-scale production aircraft had the developmental difficulties of the J2M Raiden, and of those that did, few of those ever reached the front line in appreciable numbers. Despite its development running through nearly the entire war, Horikoshi’s troubled plane did eventually find its way into service. Unfortunately it did so without pilots being well informed of the aircraft’s strengths, with most taking a dim view of the aircraft, one which ran roughly and was less maneuverable than the Zeros they traded it for. Yet, in service, the aircraft proved quite capable in combat, and received glowing endorsements from Allied evaluators.
Illustration
J2M3 Model 21. Flown by Akamatsu Saadaki of the 302nd Air Corps. He claimed 2 P-51 Mustangs in this aircraft.J2M3 Model 21. Flown by Aoki Yoshihiro of the 352nd Air Corps.
Flight Tests on the North American P-51D Airplane, AAF No. 44-1534. Memo Report No. TSCEP5E-1908. 15 June 1945.
Mitsubishi Heavy Industries, Ltd (Mitsubishi Jukogyo KK) Corporation Report No. 1 (Airframes and Engines). United States Strategic Bombing Survey Aircraft Division. 1947.
Army Air Arsenal And Navy Air Depots. Corporation Report No.XIX (Airframes and Engines). United States Strategic Bombing Survey Aircraft Division. 1947.
Japanese Air Weapons and Tactics. Military Analysis Division. 1947.
Japanese Aircraft Performance and Characteristics TAIC Manual No. 1. Technical Air Intelligence Center. 1944.
Secondary:
Price, Alfred. Instruments of Darkness: the History of Electronic Warfare, 1939-1945. 2017.
Overy, Richard. The Air War 1939-1945. 2005.
Francillon R.J. Japanese Aircraft of the Pacific War. 1970.
Goodwin, Mike. Japanese Aero Engines. 2017.
Williams, Anthony G. Flying Guns of World War II. 2003
In the late 1930s, the British Royal Navy was in desperate need of a modern carrier-based fighter. No existing aircraft in the British inventory could effectively fulfill this role; fortunately, the aircraft manufacturer Fairey was developing a versatile light bomber. Upon closer examination, it became clear that this aircraft could be adapted for carrier operations. The result was the Fairey Fulmar, which entered service in 1940.
With little time or resources on hand as a new World War loomed, the Royal Navy’s need for a carrier-based fighter was the found in the Fairey Fulmar. (wikimedia)
History
By the late 1930s, Japan was expanding across Asia, and there were increasing signs that a new war in Europe was on the horizon. This prompted nations such as the United Kingdom to invest in new military developments, focusing on new weapons, aircraft, and nascent technological fields which might yield decisive advantages. The Royal Air Force (RAF) saw a surge of new aircraft designs, some of which would prove to be war-winning weapons, such as the Spitfire and Hurricane fighters.
In contrast, the British Royal Navy struggled to find a suitable fighter aircraft to protect its ships. Few existing designs met the requirements, and while some older designs still had some use left in them, like the venerable Gloster Gladiator, the need for modern fighters was becoming apparent. The main airborne threats were maritime patrol aircraft that could reveal the position of the Royal Navy’s fleets, but with rapid advancements in aviation happening year over year, new dangers were soon to emerge.
Ruggedness, endurance, and advanced navigational equipment were key aspects of carrier-based fighters, but for a short-legged, landbased day fighter, these design goals were secondary at best. As a result, the Royal Navy’s requirements for a new fighter prioritized long-range radio navigation equipment and a multi-crew design. While these additions reduced the aircraft’s speed, the trade-off was considered necessary for the sake of improved coordination and operational effectiveness. In addition, the new fighter needed to carry enough fuel for a flight of at least three hours.
Developing an entirely new design was likely to take years, and given the rising tensions in Europe, the Navy wanted a solution as soon as possible. Fortunately for them, the RAF had been experimenting with a high-speed light bomber concept. In response, several companies, including Fairey Aviation and Hawker Aircraft, submitted proposals, the Fairey P.4/34 and the Hawker Henley.
However, before either of these designs reached flight testing, the RAF abandoned the fast bomber concept altogether. The Navy, on the other hand, remained highly interested in a potential fighter based on the designs. Both aircraft demonstrated impressive speed and an endurance of over four hours, making them strong candidates for the naval fighter role the navy was seeking.
To further improve their options, a third aircraft, the Phillips and Powis M.9 Kestrel, was included in the evaluation as a private venture. However, as it was initially intended as a trainer, it lacked the long-range capabilities required for naval operations and was quickly rejected.
In January 1938, after meeting with representatives from the Air Ministry, it was suggested that the Navy select the Fairey entrant as the winner. This recommendation was not based primarily on overall performance, but rather on Hawker’s already overloaded production schedule. The company was heavily engaged in manufacturing the much-needed Hurricane fighter and could not afford to divert time and resources to another project.
After analyzing its limited options, the Navy agreed to the proposal but issued a series of requirements for the new fighter. Among these were an endurance of six hours at a speed of 220 km/h (138 mph) and three hours at 427 km/h (265 mph), all at an altitude of over 3,000 meters (10,000 feet). The aircraft’s armament was to consist of at least eight 7.62 mm (0.303 in) Browning machine guns. Navy officials determined that a rear-mounted machine gun would not be necessary. While not specifically intended for attacking enemy ships, the aircraft was to be capable of carrying two 113 kg (250 lb) bombs if needed.
A more significant requirement was that the fighter should be adaptable for floatplane operations, with the ability to be equipped with floats in the field by a four-man crew in a relatively short time. Additionally, the aircraft had to be built with a sufficiently strong structure to allow for carrier landings and catapult launches.
In February, representatives from the RAF and the Navy met to discuss the proposal further and refine the specifications. During these discussions, several additional modifications were agreed upon, including raising the canopy to improve visibility during landings, and the rear observer/navigator’s compartment was to be equipped with the necessary navigational instruments. If these requirements were met, production was estimated to begin in September 1939, with a planned output of 8 aircraft per month. The new fighter was designated as Fairey Fulmar.
In March 1938, Fairey was informed of the Navy’s request for a new fighter aircraft. After examining the details, Fairey’s engineers began assessing whether the necessary modifications could be made without compromising the aircraft’s performance. By May, they informed Navy officials that their P.4/34 prototype could be adapted for the role. Following this, Fairey received a production order for 127 aircraft. Interestingly, the contract did not include the construction of an additional P.4/34 prototype for testing.
However, the project came to a halt that same month. The main issue was that Fairey was already overwhelmed with other commitments. The P.4/34’s designer, Marcel J. O. Lobelle, was instead assigned to work on the Fairey Barracuda and Albacore torpedo bombers. With his focus diverted, he was unable to dedicate time to yet another project. Despite this setback, work on the fighter continued, albeit at a slow pace.
The Munich Crisis of September 1938, in which Britain and France negotiated the fate of Czechoslovakia with Germany, further heightened tensions in Europe. With the possibility of war increasing, the order for the new fighter was expanded to 250 aircraft. However, given the existing delays, Fairey informed Navy officials that production could not commence before March 1940, seven months later than originally intended. To compensate for lost time, the monthly production was to be increased to 25 aircraft and carried out at the newly constructed Stockport factory.
First Production Aircraft
During the spring of 1939, the P.4/34 prototype was modified and tested as a potential new fighter. Following its success, two more pre-production aircraft were completed in late 1939. The first of these underwent flight testing in January 1940, while the second was not tested until May of that year. The delay occurred because the designers wanted to evaluate the installation of the Rolls-Royce RM3M engine. However, despite this test, the production aircraft that were to be gradually introduced were to be powered by the Merlin VIII engine instead.
One of the five pre-production aircraft was used as a test prototype. (D. Brown Fairey Fulmar Mks I and II Aircraft Profile 254)
Testing of the first aircraft revealed that its performance was below expectations. It achieved a maximum speed of 410 km/h (255 mph), which was lower than intended, and its climb rate was also deemed insufficient. More importantly, its operational endurance was an hour below the originally promised six hours. The primary issue was that once armament and additional equipment were installed, the aircraft’s weight increased considerably, which negatively impacted its overall performance.
On the 6th of April 1940, the first production aircraft underwent flight testing at the Aeroplane & Armament Experimental Establishment in Boscombe Down, Wiltshire. The aircraft was described as pleasant to fly and highly responsive. However, much like the prototype, its performance was subpar compared to modern land-based fighters.
Further testing was conducted by No. 770 Squadron, a trial unit stationed at Lee-on-Solent Naval Air Station. The aircraft arrived at its unit on May 10, 1940—the same day Germany launched its invasion of Western Europe. There, it was used for takeoff and landing trials, both on solid ground and on a wooden dummy flight deck designed to simulate aircraft carrier runways.
In early June 1940, the aircraft underwent flight tests aboard the newly built HMS Illustrious. The Fairey Fulmar proved easy to land, thanks to its excellent forward visibility and responsive controls. However, during takeoff, pilots noticed a tendency for the aircraft to veer to the left.
Despite its mediocre capabilities, and with no viable alternative available, the Fairey Fulmar was put into production. Manufacturing began in April 1940, and between April and December of that year, approximately 159 aircraft of this type were built.
Despite the urgent need for such fighters, production was delayed. When it finally began, it began at a slow pace, meaning the aircraft were never available in significant numbers during the war. (https://hushkit.net/2020/03/24/fairey-fulmar-how-an-absurd-lumbering-thing-became-britains-top-scoring-naval-fighter/)
Improved Mk. II Model
As Fulmar production was underway, Fairey proposed an improved variant. Essentially, it was the same aircraft but powered by a 1,260 hp Merlin 30 engine. Additionally, it was estimated that the new model could have its weight reduced by approximately 160 kg (350 lb). Once approval was granted, Fairey modified one of its already-built Fulmar aircraft to create the prototype for the new version, designated as the Fulmar II (Mk. II). The prototype modification was completed by the end of 1940, and flight testing began after nearly a month. The conversion proved successful and straightforward, requiring no major retooling of the production process. As a result, manufacturing soon transitioned to the new Fulmar II. However, despite the more powerful engine, its overall performance saw only marginal improvement. The aircraft built using older airframes, but fitted with the new engine, were designated as Fulmar I/II. By February 1943, a total of 600 aircraft of both variants had been produced.
Night Fighter Role
When the war in Europe began, Britain was among the many countries that lacked a dedicated night fighter. By 1940, the situation had not improved significantly. In particular, night raids by the Italian Air Force inflicted damage on several British ships stationed in the Mediterranean. The Royal Navy’s Fulmar fighter was ill-equipped to counter these nighttime attacks, and naval officials requested Air Interception Radar Mk. VI sets from the RAF. However, the experiment proved disappointing, as the radar performed poorly at the low altitudes where anti-ship attacks were conducted.
From 1942 onward, the older Mark IV radar system replaced the Mk. VI. This upgrade involved installing three antenna masts on the wings and in front of the aircraft. Unfortunately, this installation further reduced the Fulmar’s already slow speed by an additional 32 km/h (20 mph). Due to these challenges, none of the 100 modified aircraft were deployed to the front lines until February 1944, and it remains doubtful whether they ever saw combat.
While the Fulmar failed in its night fighter role, approximately 50 aircraft were repurposed as night-fighter trainers, making up half of the originally modified night-fighter fleet.
Long-Range Reconnaissance Role
Beginning in April 1942, some Fulmars were tested with lightweight H/F W/T radio sets. The installation proved successful, leading to further modifications for use as long-range reconnaissance aircraft equipped with improved radio equipment. These aircraft were primarily deployed for extended patrols over the Indian Ocean.
In Combat
Northern Europe
As the first Fairey Fulmars entered service in 1940, Europe was already engulfed in war. The first operational unit to receive the aircraft was No. 806 Squadron. Initially, Fulmars operated from airfields in the UK, from which they were deployed to support the defense of Norway, and later played a role in the evacuation of Allied forces from Dunkirk. Their first assigned aircraft carrier deployment was aboard the newly commissioned Illustrious, beginning in August 1940.
Later in 1941, Fulmars were used to patrol, and escort convoys bound for the Soviet Union in the North Sea. While engagements with enemy fighters were rare, one notable encounter took place in late July 1941. During this engagement, a group of Fulmars intercepted German aircraft, resulting in the destruction of two Bf 109s and one Me 110. However, the Fulmars suffered losses as well, with two aircraft being shot down in the process.
Additional units were formed as more aircraft became available. Interestingly, some Fulmars from No. 804 Squadron were assigned to operate from Fighter Catapult Ships, escorting Atlantic convoys. These were actually modified merchant ships equipped with catapult rams. Once the fighter was launched, the pilot was to fly it until he ran out of fuel. After that, the pilot would use his parachute or ditch the aircraft in the path of a ship that could recover him.
While they were intended to function as carrier-based fighters, their early operational life saw them deployed from coastal airfields in the UK. (https://www.reddit.com/r/WeirdWings/comments/c2ivcq/fairey_fulmar/)
The last recorded sortie from an aircraft carrier occurred on the 8th of February 1945. On that day, a Fulmar night fighter was dispatched to intercept an enemy aircraft approaching a convoy destined for the Soviet Union. However, en route to its target, the Fulmar’s radar equipment malfunctioned, forcing the pilot to return to the carrier. During landing, the aircraft missed the arrestor wire and instead crashed into the safety barrier.
Mediterranean Theater of War
As production increased, additional units were formed. Such as No. 804 Squadron, which was assigned to operate Fulmars from merchant ships fitted with catapults, escorting Atlantic convoys. These vessels would launch the aircraft when an enemy target was identified. Between June and September 1940, this tactic saw limited use, with the Fulmars managing only to inflict minor damage on a German Fw 200 bomber. The Fulmars also participated in the hunt for the German Bismarck battleship but played a minor reconnaissance role.
Their combat service was primarily seen in the Mediterranean, and in September 1940, HMS Illustrious was deployed to that theater of war. At the time, the British Navy operating there lacked any form of fighter support. This role was then fulfilled by the 18 aircraft of No. 806 Squadron.
For the remainder of the year, the squadron was mainly tasked with targeting Italian reconnaissance aircraft and enemy bombers. Despite their limited numbers, they managed to shoot down 26 Italian aircraft by the end of 1940. This success was achieved by effectively coordinating their operations with Illustrious‘ radar system.
However, the situation changed drastically in 1941 when the German Luftwaffe arrived in greater numbers. Illustrious was heavily damaged, forcing No. 806 Squadron to relocate—first to Malta and then to Crete in February 1941. There, they were attached to another carrier, Formidable, and effectively merged with No. 803 Squadron.
The squadron continued operations from Formidable until May 1941, when the carrier was severely damaged by German attacks. By that time, the Fulmars had managed to shoot down at least 56 enemy aircraft, but these successes came at a cost—more than half of their already limited numbers were lost.
In April 1941, the aircraft carrier Ark Royal was tasked with protecting Gibraltar, supported by No. 807 and No. 808 Squadrons. These squadrons remained active until August 1941, when Ark Royal was sunk. Following its loss, No. 808 Squadron was disbanded, while No. 807 Squadron continued operating in the area. They were primarily assigned to patrol missions, occasionally engaging German submarines. In June, while conducting operations around Malta, they managed to shoot down five enemy aircraft but suffered the loss of three of their own. Afterward, they were redeployed to the United Kingdom.
During August 1942, No. 807 Squadron played a role in protecting a supply convoy to Malta. The British forces were supported by 18 Fulmars from No. 809 and No. 884 Squadrons. Between the 11th to 12th of August, intense battles with Axis fighters took place. The Fulmars successfully shot down at least two enemy aircraft but lost three of their own in the process.
On a few occasions, they also engaged Vichy French aircraft near Syria. In one such encounter, a group of Fulmars clashed with French D.520 fighters. Although they failed to bring down any of the French aircraft, the British lost three of their own.
The Fairey Fulmar was predominantly employed in the Mediterranean against Axis maritime patrol aircraft. (https://www.armouredcarriers.com/fairey-fulmar-models)
Deployment to China Bay
In February 1942, a small contingent of Fairey Fulmar aircraft was dispatched to China Bay to support the Royal Air Force’s General Reconnaissance No. 273 Squadron. The Fulmar equipped two squadrons, No. 803 and No. 806. No. 803 Squadron suffered heavy losses in April 1942 when four of its six aircraft were shot down during an engagement with Japanese fighters. However, the squadron managed to achieve one air victory during the battle.
On April 9, the Fulmars saw action again when they engaged Japanese bombers attacking the British aircraft carrier HMS Hermes. Despite being at a disadvantage, they successfully shot down three enemy bombers but lost two of their own aircraft in the process.
End of Service
By 1943, most Fulmar aircraft that had been deployed as day fighters were withdrawn from frontline service. The remaining aircraft were repurposed for training or used as second-line night fighters for the remainder of the war. As the war in Europe neared its end, nearly all Fulmars were replaced by the improved Fairey Firefly. In total, approximately 40 Fulmars were lost in combat by the war’s conclusion.
Technical characteristics
The Fulmar was a single-engine, all-metal carrier-based fighter. Its monocoque fuselage was constructed using metal panels placed over a tubular framework. A similar design approach was employed for the rest of the aircraft, including the wings and tail assembly.
Since the aircraft was intended to operate from smaller aircraft carriers, where space was limited, its wings needed to be foldable to maximize available room. As a result, the inner section of the wings was fixed to the fuselage, while the outer sections were designed to fold back efficiently against the sides of the aircraft. The tail assembly followed a more conventional design, featuring two horizontal stabilizers and a single vertical stabilizer.
Since it was designed to operate from an aircraft carrier, where space was limited, its wings were modified to fold. (https://www.armouredcarriers.com/fairey-fulmar-models)Its landing gear consisted of two main wheels that retracted inward into the fuselage, along with a small fixed tail wheel. (https://en.wikipedia.org/wiki/Fairey_Fulmar)
The first prototype developed from the P.4/34 was powered by a 1,030 hp Rolls-Royce Merlin II V-12 engine. It was later replaced with a slightly more powerful Merlin VIII engine, producing 1,080 hp. With this upgrade, the aircraft achieved a maximum diving speed of 724 km/h (450 mph) and a cruising speed of 398 km/h (247 mph). The final improved variant was instead equipped with a Merlin 30 engine, delivering 1,300 hp. This modification increased the cruising speed to 417 km/h (259 mph).
Initially powered by a 1,030 hp engine, it was soon replaced with a later variant that produced 1,300 hp. While this upgrade didn’t significantly increase its maximum speed, it was certainly a welcome improvement in its rate of climb and sustained turn rate. (https://www.armouredcarriers.com/fairey-fulmar-models)
Beneath the fuselage, there were sets of catapult spools along with an arrestor hook. These components were essential for launching the aircraft from a carrier. The arrestor hook featured a V-shaped design and was secured in place by a snap lock. The pilot could release it when needed, and when not in use, only a small portion of the hook remained exposed.
The cockpit consisted of a position for the pilot and a rear, extended radio operator/observer cabin. To provide the best forward visibility, the pilot’s canopy was slightly elevated. The remaining crew compartment was fully glazed to ensure the best possible view of the surroundings. Given the distance between them, the crew communicated using a speaking tube or, when necessary, a sidetone. However, due to engine noise, the latter method was not always the most effective.
The Fulmar featured a raised pilot’s canopy, providing an excellent forward view. Additionally, its rear crew compartment was fairly long and enclosed by a glazed canopy, offering a good all-around view. (https://hushkit.net/2020/03/24/fairey-fulmar-how-an-absurd-lumbering-thing-became-britains-top-scoring-naval-fighter/)
The armament of this aircraft consisted of eight 7.62 mm machine guns mounted in the wings. Each gun was initially supplied with 750 rounds of ammunition, which was later increased to 1,000. While eight machine guns may sound formidable, in practice, they lacked the firepower needed to inflict serious damage on larger targets, given their relatively small caliber.
The ground crew in the process of loading each gun with 750-round belts. Later, this was increased to 1,000 rounds per machine gun. (https://www.destinationsjourney.com/historical-military-photographs/fairey-fulmar/)
For example, the British recorded an incident in which three Fulmar fighters engaged a single Blohm & Voss BV 138, a long-range maritime reconnaissance aircraft. Despite firing nearly 18,000 rounds at it, the German aircraft suffered no significant damage and managed to escape.
To address this issue, the British considered equipping the Fulmar with heavier 12.7 mm (0.5 in) machine guns. While the installation proved feasible, a shortage of these weapons meant that very few aircraft were ever fitted with them. Around 100 units were slated for modification to carry four of these heavy machine guns, but only a small number actually received the upgrade.
Despite having enough space, no attempt was made to mount a rear-positioned machine gun, despite the crew’s insistence on doing so. Instead, the crew improvised with whatever defensive weapons they could find. Some used Thompson submachine guns, while others relied on signal pistols. The most unusual weapon employed for self-defense was a bundle of standard-issue toilet paper, secured with an elastic band. When thrown out of the aircraft, the band would snap, creating an explosion of paper that, on rare occasions, helped distract or deter enemy pursuers.
The Fulmar was originally designed to carry a bomb load consisting of either two 45 kg or 113 kg (100-250 lbs) bombs. However, this was never actually implemented, as no bomb racks were installed to accommodate such a load. On rare occasions, small 9 to 18 kg (20-40 lbs) bombs were carried to engage enemy anti-aircraft batteries during support missions.
Production
Production of this aircraft began in May 1940 and ended in February 1943. During that time, 250 units of the Mk. I variant was built, followed by 350 of the later Mk. II variant. In total, approximately 600 aircraft of this type were produced during the war.
Production Versions
Fairey Fulmar Mk.I– First production variant
Fairey Fulmar Mk.II– Second production variant equipped with a Merlin 30 engine
Night Fighter/trainer– Modified to act as a night fighter, supplied with radio equipment. In total 100 were converted to this role of which half were reused as night fighter trainers
Long-Range Reconnaissance – Equipped with long-range radio equipment
Surviving Aircraft
Only one of the approximately 600 aircraft of this type has survived to this day. This surviving example is actually the first prototype, which was later used for civilian purposes after the war. Today, it is on display at the Fleet Air Arm Museum in Yeovilton.
The only surviving Fairey Fulmar can be seen at the Fleet Air Arm Museum in Yeovilton. (https://en.wikipedia.org/wiki/Fairey_Fulmar)
Conclusion
The Fairey Fulmar was an attempt to adapt an existing aircraft design into a fighter type that was in high demand by the British Royal Navy. While it met most of the required specifications, it was too slow and heavy to compete effectively against faster, purpose-built fighters. Its
armament, despite featuring multiple machine guns, was also still somewhat underpowered. However, this did not prevent the Fulmar from achieving remarkable success for a relatively large fighter. Despite its small production numbers, it proved effective against Italian aircraft and, on occasion, even German fighters. By 1943, however, it was becoming obsolete, and by the end of the war, all remaining Fulmars had been retired from service. Nonetheless, it paved the way for later, more advanced naval aircraft.
United Kingdom (1943-1944) Rotor Kite Transport – One prototype
During the Second World War, airborne troops became an essential component of modern military strategy. They allowed armies to wreak havoc on unprotected rear areas by destroying critical targets, such as the enemy’s vital command structures, and the infrastructure supporting their army. However, one major drawback was that once on the ground, these troops were lightly equipped and moved at a walking pace. However, an engineer named Raoul Hafner proposed an innovative solution: airlifting light vehicles using unpowered rotary wings, similar to those later used in helicopters. His concept involved towing the vehicle, behind a truck or light aircraft until lift off. Once airborne, it would be released, and the pilot would use autorotation to fly the vehicle to the landing zone. A prototype was built and tested, but with the advent of larger gliders, the project was ultimately abandoned.
With the abundance of US-supplied military vehicles, the British sought ways to incorporate them into various roles, and experiments. Among those interested was Raoul Hafner, a rotor kite enthusiast. Rotor kites were essentially unpowered rotary-wing aircraft that shared many design features with later helicopters. While helicopters can take off under their own power, rotor kites cannott, instead, they need to be towed by a larger aircraft, or a suitable ground vehicle. Once airborne, they rely on airflow over their rotary wings to generate lift and remain airborne. This can be achieved by descending to generate speed and lift, having a strong wind to keep the rotor wing turning, or remaining tethered to another vehicle for the entirety of the flight. Although this technology was inexpensive to build, it was never implemented on a larger scale.
Hafner was born in Austria in 1905. In his early twenties, he developed an early interest in rotorcraft design, and in 1928, he collaborated with Bruno Nagler on an early helicopter prototype. In the early 1930s, Hafner emigrated to the United Kingdom, where he began working on gyroplanes there, he designed and built a functional prototype known as the Hafner A.R.III Gyroplane. Hafner continued refining his designs, but with the outbreak of World War Two, he was briefly held in state custody due to his Austrian origin.
Raoul Hafner would go on to play a vital role in the history of helicopter development. However, his early work was primarily focused on an unpowered variant known as the rotor kite. Source: en.wikipedia.org
Upon his release, Hafner began working on a solution to Britain’s shortage of materials needed for parachute construction. His goal was to develop an inexpensive, one-man rotor kite to carry an infantryman deep behind enemy lines. The core principle behind his concept was that, given the scarcity of materials required for parachute production, a small, easy-to-build, and simple-to-control rotor kite could serve as a cost-effective alternative. These kites were designed to be towed into the air by another aircraft and then released near the designated target. Once released, the pilot/paratrooper would glide down slowly before proceeding to their objective. Hafner followed with a small prototype series of these aircraft, designated the Hafner Rotachute. While his work showed promise, it ultimately resulted in only a limited number of experimental prototypes, with no further large-scale implementation.
The so-called Hafner Rotachute was an experimental attempt to develop an alternative to parachutes. While the concept was intriguing, it never progressed beyond a small prototype production run. Source: en.wikipedia.org
He soon expanded on that idea, if he could devise a way to land soldiers, why not include light vehicles as well? Paratroopers, who were often dropped behind enemy lines to wreak havoc among key targets, were frequently left vulnerable as they were lightly armed and had limited mobility. The challenge, however, was that airdropping even light vehicles was no simple task. Hafner theorized that his rotor kite design could be expanded and enlarged to allow for the airlifting and deployment of light vehicles. If successful, this would provide paratroopers with a means of transportation, increasing their effectiveness in combat.
The overall design was intended to be as simple as possible. A standard light vehicle, left mostly unmodified, would be partially enclosed within an aerodynamic fuselage, likely made of plywood, to provide lift and protect the crew from the tow aircraft’s propeller wash, and the wind. A rotary assembly would be mounted on top, while a large tail section at the rear would ensure lateral stability. Upon landing ,assuming a safe descent, the crew would discard the fuselage, leaving the vehicle fully operational and ready for use without issue.
In 1942, with this idea in mind, he approached the Central Landing Establishment, later renamed the Airborne Forces Experimental Establishment, to present his proposal. While, at first, the concept of attaching a makeshift rotary wing to a lightweight wheeled vehicle may seem dangerous and wasteful, it would be phenomenally valuable should it succeed. Developing an effective method for transporting such vehicles over long distances would have provided significant combat advantages. This was especially crucial at a time when the Allies were considering various plans and strategies for invading occupied France, plans where airborne units played a star role. Thus the Central Landing Establishment saw potential in this idea, and Hafner received approval to move forward with its development. Now, Hafner needed to find a suitable light chassis for the job. Fortunately for him, he didn’t have to search for long, the answer was already in the hands of the UK’s ally across the Atlantic.
A Well-Known Icon
In the 1930s, the leadership of the US Army closely observed the rapid military developments unfolding in Europe and the Pacific. In response, the Army sought to modernize its forces, starting with an increase in mobility for its reconnaissance units and couriers, which at the time primarily relied on horses.
Initially, as in Germany, motorcycles were introduced for this role. While they were an improvement over horses, they had significant limitations, primarily their limited carrying capacity, as they could only transport the driver, one additional passenger, and a very small amount of cargo. It became clear that a larger, more capable vehicle was needed.
This led to the development of small, relatively inexpensive, all-wheel-drive light vehicles. Throughout the 1930s, the Army conducted extensive testing and evaluation of several different designs. After these trials, a final decision was made to adopt Willys-Overland Motors’ design, known as the Willys MB, but generally, it was simply referred to as the Jeep, as the Army’s standard lightweight reconnaissance vehicle. Unbeknownst to them at the time, they had just created one of the most iconic military vehicles in history.
The Willys MB would become one of the most iconic military vehicles in history. Source: en.wikipedia.org
While Willys was set to produce these new vehicles, the immense demand and the need to utilize the vast production capacity of its competitor, Ford, led to the company also receiving orders to manufacture the vehicle. Although Ford was allowed to make some modifications, the overall design had to remain to ensure all mechanical components for the vehicles were interchangeable. Between 1941, when production began, and 1945, over 600,000 of these vehicles were produced. They saw widespread service across the globe during and after the war, with a significant number still in use today.
Initially designed for reconnaissance operations, their sheer numbers and popularity led to their adaptation for various roles. These included medical evacuation, combat, self-propelled rocket launchers, and long-range raiders for missions against enemy rear positions. They were also used as command vehicles, among many other roles.
The vehicle was widely exported to Allied nations, including the UK, which received tens of thousands. Even the Soviet Union acquired them and eventually developed its own variant. Given the vast stockpile of these vehicles, it is unsurprising that Hafner chose to test his idea using one of them.
The Jeep saw extensive use by British special forces in North Africa, where it played a crucial role in raids targeting enemy rear positions. Source: wikipedia.org
Name
The unusual vehicle was known by many nicknames. It received the Air Ministry designation ML 10/42 Special Rotating Wing Glider. It was also called the Malcolm Rotaplane, Flying Jeep, and Blitz Buggy. Eventually, it became best known simply as the Hafner Rotabuggy. For the sake of simplicity, this article will refer to it as the Rotabuggy.
Building and Testing the Vehicle
After receiving approval, the next task was to find a suitable chassis, and someone capable of building the vehicle or aircraft. Given the abundance of options, Hafner decided to utilize the US-supplied Jeep light reconnaissance vehicle. For the construction of the working prototype, he approached R. Malcolm Ltd., a small company that had been building aircraft components during the war.
Once the base components were selected, the construction of the working prototype began. It was likely completed by mid-1943. The first flight trials of the Rotabuggy were scheduled for November 1943. These trials were planned to be conducted using a Diamond T 4-ton 6×6 truck as a tug vehicle. This was seen as a simple, cost-effective, and safe option, given the prototype’s early development stage, far too early for tests with aircraft. The flight tests were carried out on the 16th November, 1943. Despite numerous attempts, the crew was unable to get the Hafner Rotabuggy off the ground, as they could not achieve the necessary speed to generate lift.
The Rotabuggy’s shape in its early experimental phase was still evolving. Experimenting with the design led to many changes, such as the introduction of much larger tail fins. Source: www.nevingtonwarmuseum.com
Further tests were carried out on 27th November. This time, a stronger, albeit unspecified, tug vehicle was used. The initial test was successful, as they managed to lift the Rotabuggy into the air. The first flight test using a tug aircraft, specifically a Whitley Bomber, was conducted in December 1943. However, the first design problems were identified during this test flight. At a speed of 80 km/h (50 mph), the vehicle experienced strong vibrations, forcing an early end to the flight.
Subsequent tests with a similar tug vehicle showed that the vibrations persisted at speeds of 70 km/h (45 mph) and higher. Additionally, during one test flight, one of the rotors struck the tail fin, damaging it in the process. Following these tests, the Rotabuggy was temporarily grounded for various repairs and modifications.
By February 1944, the Rotabuggy achieved a speed of 112 km/h (70 mph), and many more tests were carried out throughout 1944. On September 11th, 1944, the first major test flight was undertaken. At a height of 120 m (400 feet), after being towed by a Whitley bomber, the small buggy was released. After some brief difficulty controlling the aircraft, the pilot managed to land the vehicle, though with some effort.
In later stages, it would look visually much different, having a fully enclosed cockpit. Source: www.macsmotorcitygarage.com
Fate
Given the extensive testing, it was clear that there was significant interest in this project. However, despite more than a year of development, the project was ultimately canceled. The primary reason for this was not the new concept itself but rather the fact that the British had begun mass-producing gliders, such as the Waco CG-4, which could carry a Jeep within its fuselage. As a result, the Rotabuggy was no longer needed.
While his Rotabuggy project reached an unsuccessful dead end, this was not the end of Hafner’s story. Given his expertise in rotor aircraft development, he was appointed Chief Designer and head of the newly established Helicopter Division at Bristol. Hafner’s work at Bristol was highly successful, and he played a pivotal role in advancing early British helicopter design. His contributions were instrumental in the development of aircraft such as the Type 171 Sycamore, and the large tandem-rotor Bristol Belvedere.
He was also among the first aircraft engineers to receive the Dr. Alexander Klemin Award, a prestigious honor in the field of vertical flight aeronautics. Tragically, in 1980, Hafner disappeared at sea when his boat went missing and was never found.
Technical characteristics
The Rotabuggy fuselage was an extension added to the U.S. Jeep, designed to enable controlled flight. During testing, it was concluded that the Jeep could be dropped from a height of up to 2.35 m (7.7 ft) without suffering any major mechanical breakdowns. It could thus theoretically survive rough landings on unprepared ground.
Essentially, it consisted of a standard Jeep with four metal bars arranged in a pyramidal shape at its base. To enhance structural integrity, two additional metal bars connected the front and rear pairs. Atop this framework, a rotor unit was intended to be installed.
Another metal frame was attached to the rear section, consisting of at least four long stringers reinforced with smaller crossbars. Surrounding this structure, a series of almost circular frames, decreasing in size toward the tail section, were added to shape the fuselage.
A clear view of the Rotabuggy’s internal framework, which consists of at least four long stringers reinforced with smaller crossbars and enclosed in a plywood skin. Source: www.macsmotorcitygarage.com
The structure forming the base of the fuselage was then covered with plywood for aerodynamics. The sides and top were essentially flat, without any noticeable features. Large windshields were added at the front and on the crew’s side doors, providing excellent, almost all-around visibility. This gave the crews a clear view, more than sufficient for landing the aircraft. While little data for its flight characteristics survive, its estimated rate of sink at a speed of 77 km/.h (48 mph) was 4.9 m/s (960 ft/min)
Large windshields were added at the front and on the crew’s side doors, providing excellent, almost all-around visibility. This gave the crews a clear view of their surroundings. Source: rafbeaulieu.co.ukThe rear part of the fuselage was essentially flat, featuring only a slight curve. Source: /www.nevingtonwarmuseum.com
To help provide lateral stability, a large tail assembly was added to the vehicle’s rear. It consisted of two fairly large vertical stabilizers. Interestingly, there were no rudders on these fins. Lastly, a small landing skid was located at the end of the vehicle’s tail.
The tail assembly features two large fins that provide much-needed lateral stability. Source: www.nevingtonwarmuseum.com
The crew consisted of two members: a driver and a pilot. The driver was seated on the left side, as in the original Jeep configuration. The pilot sat in the opposite seat and was responsible for controlling the rotor blades, which were used to lift the vehicle off the ground. To control the vehicle, the pilot was provided with a control column, a rotor tachometer, and a set of basic and glider navigational instruments. Once on solid ground, the vehicle would be driven like a regular Jeep.
The Rotabuggy used rather long rotor blades, with a diameter of 14.22 meters (47 feet). There were some issues with this length, as on at least one occasion, they damaged the rear tail assembly, luckily without injuring its crew.
The control column for the aircraft. Source: aviadejavu.ruThe Rotabuggy used rather long rotor blades. There were some issues with this length, as on at least one occasion, they damaged the rear tail assembly. Source: aviadejavu.ru
Surviving Aircraft
Since it never progressed beyond the prototype stage, it is not surprising that the vehicle did not survive to the present day. The prototype was eventually refurbished back to a standard Jeep . However, being such an intriguing design concept, a replica was built by the Wessex Aviation Society. can now be seen at the British Museum of Army Flying in Middle Wallop, Hampshire.
While the prototype did not survive, the Wessex Aviation Society managed to modify a Jeep and create a modern replica of the Hafner Rotabuggy. Source: www.reddit.com
Conclusion
The Hafner Rotabuggy was surely an interesting and unique attempt at utilizing the relatively new rotorcraft design. In theory, this concept would allow for an alternative method of airdropping men and materials, including vehicles.
While the Rotabuggy had some issues, such as severe vibration during flight, it was generally considered a mechanically sound design. However, its main drawback was that, despite its novelty, it did not offer significant improvements over the gliders already in use. As stronger and more capable gliders were developed, which could transport both personnel and lightweight vehicles, the Rotabuggy became obsolete.
Although its service life was short, the project played a vital role in shaping Hafner’s future work in rotary-wing aircraft, ultimately contributing to the development of various helicopter designs.
Close-support ground attack aircraft : Two prototypes built
The Luftwaffe (Eng. German Air Force) entered the Second World War without a dedicated close air support aircraft, with their more infamous dive bombers carrying out their missions independently of ground forces. As this need became increasingly apparent, attempts were made to identify a suitable design, but any new aircraft would have to be as inexpensive as possible, as other aircraft projects were prioritized. With limited options, Focke-Wulf proposed adapting its Fw 189 reconnaissance aircraft for this role. While promising in theory, the adaptation proved flawed and ultimately unsuccessful in practice. Despite this, two prototypes were built and tested, but by 1940, the project was abandoned.
The rise of Nazism in Germany during the 1930s led to a massive military buildup, defying the limitations imposed by the Treaty of Versailles, which by this time was little more than a formality, with few parties motivated to uphold it. Among the most rapidly expanding branches was the Luftwaffe, which received substantial investment and development, leading to the introduction of a series of modern aircraft designed for various military roles.
One of these roles, tactical reconnaissance, was initially assigned to the Henschel Hs 126. Despite its somewhat outdated design, this high-wing aircraft proved reasonably effective for its intended purpose. However, its relatively low speed and the absence of a dedicated observer limited its effectiveness in reconnaissance missions.
Even as the Hs 126 entered service, the Reichsluftfahrtministerium (RLM), or German Air Ministry, took steps to develop a more advanced replacement. In 1937, they initiated a program to explore new designs. Although multiple projects were tested, the Focke-Wulf Fw 189, headed by the engineer Kurt Tank, ultimately emerged as the chosen design. While RLM officials were initially uncertain about the Focke-Wulf proposal, they eventually placed an order for three prototypes. Construction on the first prototype designated the Fw 189V1, began in April 1937 and was completed in 1938. It was soon followed by two additional prototypes.
As preparations for production were underway, the RLM initially decided to rely solely on the Hs 126. However, after the successful conclusion of the Western campaign against the Allies in France in June 1940, Luftwaffe officials reconsidered their stance on the Hs 126. It became evident that this aircraft would soon be extremely obsolete in its intended role, necessitating an urgent search for a replacement. The only aircraft that could potentially fulfill this role within a short timeframe was the Fw 189. Production began in the summer of 1940, and by 1944, fewer than 900 units of this aircraft had been built. Despite the limited production, the Fw 189 saw extensive service and proved to be both popular and highly effective throughout the war.
A Modern Air Force With No Ground Attack Aircraft?
While the rearmament of the German military forces was underway, Luftwaffe officials recognized the need for a dedicated ground-attack aircraft to provide close air support. Although the Ju 87 Stuka was designed for precision bombing to neutralize fortified targets, it was clear that they needed a heavily armed and well-protected aircraft for close-in support near friendly units. Despite this need, early Luftwaffe development in this area lagged, for reasons that remain unclear. Kurt and his team at Focke-Wulf saw a potential business opportunity and decided to repurpose their Fw 189 aircraft to meet this demand.
Recognizing that the Fw 189’s glazed, unarmored fuselage was not equipped for the ground-attack role, the Focke-Wulf team set out to develop a more protected fuselage design, which would house both a pilot and a rear gunner. Eager to proceed quickly, Focke-Wulf engineers decided to modify the first prototype of the Fw 189. The aircraft was returned to the Focke-Wulf factory in 1938 so that work on the modifications could begin immediately. After several months of redesign and construction, the new prototype designated Fw 189V1b (later marked with the code NA+BW) was completed and underwent its first flight tests in 1939. It was powered by the two 430 hp Argus As 410 engines.
The results of these tests were disappointing, to say the least. The prototype was difficult to control, and its overall flight performance was poor. The added weight significantly affected its handling and maneuverability. Furthermore, the small armored glass windshield provided a limited view for the pilot, making it challenging to fly. To make matters worse, the rear gunner’s visibility was almost nonexistent.
Only two prototypes of this variant would be constructed. (Source: planehistoria.com)
With few other options, the aircraft was returned to Focke-Wulf for further modifications. Both the pilot’s and rear gunner’s visibility issues had to be addressed, necessitating adjustments to the overall design. After a series of modifications, the aircraft was deemed ready and submitted to the Luftwaffe for evaluation. Despite the promise of close-support ground attack aircraft, it attracted little interest from major German aircraft manufacturers, leaving the Henschel Hs 129 as its only real competitor.
After a series of test flights with both aircraft, Luftwaffe officials grew increasingly annoyed and disappointed. The Fw 189 and the Hs 129 performed quite poorly. As a result, both aircraft were sent back for further improvements. However, the story of the Fw 189V1b came to an abrupt end shortly after this competition. During one demonstration flight, the pilot miscalculated his approach and collided with a building while attempting to land. Although he survived with injuries, the prototype was so severely damaged that it was written off entirely.
Future Development
Despite a rough start, the project was not abandoned. Though the initial prototype failed, it still held interest with some Luftwaffe officials, leading to an order for Focke-Wulf to produce another prototype for further testing. Expectations were high, as this version was intended to enter production as the Fw 189C and to have corrected all the faults of the disappointing first attempt. To meet these demands, Focke-Wulf developed the Fw 189V6 prototype, which carried the code D-OPVN.
In appearance, the Fw 189V6 closely resembled the previous model, but it featured a slightly modified fuselage and was powered by a more powerful 465-horsepower Argus As 410 engine. The prototype was completed and tested in 1940, with trials conducted by the 5 Staffel of Lehrgeschwader 2. During testing, pilots who had the chance to fly both the Fw 189V6 and its competitor, the Henschel Hs 129, overwhelmingly favored the Focke-Wulf design.
However, the pressures of the ongoing war and reduced production capacity meant that the Luftwaffe needed an option that was quicker and cheaper to mass-produce. Ultimately, the Hs 129 was chosen, despite its reputation as a more cumbersome design. The fate of the Fw 189V6 is unclear, though it was likely scrapped. The close support role was later taken up by the Fw 190, with special fighter bomber variants being created to take up the mission and phase out the dated dive bombers.
The Fw 189V6 prototype was to serve as the base for the anticipated C variant, but in the end, nothing came of it. (Source: www.airwar.ru)
Although the Fw 189C never entered production, some Fw 189A models were modified for ground-attack roles during the war. Designated as the Fw 189A-4, these variants were armed with two forward-mounted 20 mm cannons and two MG 17 machine guns. Additional armor was installed to protect vital components, including the fuel tanks, engines, and fuselage. An unknown number of these modified aircraft were produced starting in late 1942.
Technical characteristics
The Fw 189C prototypes incorporated several components from the original Focke-Wulf design. The original glazed fuselage was replaced with a fully enclosed, two-man armored compartment. This updated cockpit featured an armored, pointed nose, designed to provide an improved forward view while maintaining some degree of aerodynamic efficiency. The canopy had three small windows, and directly behind it was a compact compartment for the rear gunner. The aircraft’s overall construction consisted of rounded metal frames covered with a stressed duralumin skin. The new fuselage was reinforced with armor plating, though specific details about the placement and thickness of the armor are not mentioned in available sources. Unfortunately, the design proved to be cramped and lacked consideration for the comfort of both the pilot and the gunner.
The aircraft’s wings consist of two primary sections: a central, square-shaped segment connecting the nacelles and engines, and an outer section extending from the booms. The wing structure has a steel spar framed by duralumin, while the ailerons and split flaps are covered in fabric. At the rear, the twin-tail assembly includes two large rudders connected by a single, extended elevator, with both tail control surfaces also being fabric-covered. Since the wing root was designed to support heavy armament, the central part of the wing had to be reinforced to withstand the recoil forces.
The first prototype was powered by a 430-horsepower engine, while the second prototype featured 465-horsepower Argus As 410 A-1, both 12-cylinder air-cooled engines. Unfortunately, specific details about the aircraft’s flight characteristics were not mentioned in available sources. It is known, however, that the added weight of the armor and armament degraded its flight performance, though the extent of this impact remains unclear.
The main landing gear extended from beneath each engine nacelle, with smaller wheels extending from the rear tail assembly. Later in the war, the second prototype received reinforced landing gear to improve durability.
As it was intended for ground attack operations, the second prototype was armed with two 20 mm MG 151/20 cannons and four 7.92 mm MG 17 machine guns. For rear self-defense, a dual MG 81 machine gun mount was installed. Had it entered production, it is likely that bomb racks would have been added
Close up view of the Fw 189’s experimental fuselage. (Source: www.airwar.ru)Top view of the new fuselage with the canopy removed. (Source: www.airwar.ru)The two prototypes were provided with single-leg landing gear. (Source: www.airwar.ru)
Conclusion
The Fw 189C was an intriguing attempt to develop a ground-attack aircraft based on the successful reconnaissance version. While it performed effectively in its original reconnaissance role, the ground-attack variant proved far less successful, proving cumbersome and difficult to fly. Only two prototypes were ever built before the project was discontinued in 1940, with the Hs 129 deemed a more cost-effective alternative.
Type: Ground anti-aircraft rocket – 83 Launchers Built
By late 1944, the Germans were losing on all fronts and the Allies were steadily advancing into Germany itself. To make matters worse, the extensive losses in manpower and equipment had become irrecoverable. As a result, various makeshift, improvised, and even obsolete weapons were brought to the front lines in a desperate attempt to halt the Allied advance. One such last-ditch effort was the creation of a 73 mm rocket launcher, intended as a close range anti-aircraft weapon by firing a volley of small rockets. While the official project name has been lost to history, it is often referred to as the 73 mm Föhn-Gerät.
Throughout history, rockets in combat were typically a cheap complement to artillery. While early rocket designs lacked the destructive power of conventional artillery, their primary role was to disrupt enemy lines and instill chaos, acting more as psychological weapons than as tools of mass destruction. By the onset of the Second World War, however, rocket technology had advanced significantly, rockets could now fire over greater ranges and deliver larger payloads, making them far more effective in both tactical and strategic contexts.
In Germany, early rocket development was largely driven by civilian efforts to explore new technologies and their potential applications. Much of this work focused on using rockets to power aircraft, exemplified by Fritz von Opel’s experimental work in the 1920s. Von Opel was assisted by another prominent aircraft designer Alexander Martin Lippisch. While technically speaking these were not real rocket-powered flights, given that these gliders did not take to the sky using purely the rocket engine but were towed to altitude. Nevertheless, these flights showed that considerable investment was going into rocketry, with the desire for it to break into new roles.
The early German rocket program was mainly intended for civilian use, such as its use in Fritz von Opel’s experimental rocket-powered glider. Soon, the Army saw a potential use of rocket technology and tried to implement it for its own use. (Source: L. Warsitz The First Jet Pilot The Story of German Test Pilot Erich Warsitz)
Over the following years, Lippisch became quite interested in rocket technology and joined the Deutsche Forschungsinstitut DFS, where he worked as an engineer. There, he developed a series of new glider designs, like the DFS 40, to test rocket propulsion. This work would eventually lead to the creation of the Me 163 rocket-powered aircraft. Another major stepping stone in rocketry was the work of Wernher von Braun. In 1932 and 1934, von Braun managed to successfully launch two rockets using liquid-fuel rocket engines. In 1935 he managed to come into contact with Dr. Ernst Heinkel 1935. With financial and infrastructure support, von Braun would participate in the creation of the first operational rocket-powered aircraft, the He 176.
The He 176 Source:luft46.com
In the early 1930s, the German military began to take an interest in using rockets to produce new artillery systems. The Germans had a unique motivation to develop rocket technology, as it was not prohibited by the terms of the Treaty of Versailles. The pioneering work of engineers like Hauptmann Dr. Ing. Walter Dornberger and von Braun played a significant role in advancing German rocket programs. Their work made it possible to create rockets that rotated around their longitudinal axis, effectively stabilizing them during flight. This innovation reduced the need for specialized wings and fins that would otherwise be required to maintain stability. As a result, a simpler, smooth-barreled launcher could be used, significantly lowering production costs while also creating lightweight launchers.
Due to its unique characteristics and capabilities, the artillery rocket held great potential as a formidable weapon. With the ability to fire over long ranges, multiple rockets could be launched rapidly from a single launcher, allowing it to carry outa rapid salvo compared to contemporary artillery pieces. Additionally, rockets could carry a larger payload than artillery shells of the same caliber, increasing their impact. However, they lacked precision and were less effective against fortified targets.
The German army formed its specialized Nebeltruppe (Eng. Smoke Troops) in 1929. These were initially equipped with large caliber mortars. As rocket launchers became available, these were then integrated in Nebeltruppen. Initially, rockets were used primarily to obscure enemy positions with smoke-generating rounds, rather than for direct attacks. Although chemical rounds were also developed, these were not employed in combat. Interestingly, they also employed rocket launchers to deliver propaganda leaflets, although they were rarely employed.
The first mass-produced rocket launcher was the 15 cm Nebelwerfer (Eng. Smoke Thrower) 41. Development of this weapon began in 1934, and it officially entered service in 1940. Designed to be simple and cost-effective, the Nebelwerfer utilized existing components to streamline development. The base of the launcher was adapted from the 3.7 cm PaK anti-tank gun carriage, and with the gun and shield removed, it was fitted instead with a six-tube launcher, each tube 15 cm in diameter. A folding pad was added to the front of the carriage for stabilization during firing.
The 15 cm Nebelwerfer 41 was one of the first, and one of the most common, rocket artillery systems. It was a towed weapon and needed a prime mover to transport it over longer distances. (Source: en.wikipedia.org)
A Literal Propaganda Weapon
Besides using rockets to deliver deadly payloads or smoke, the Germans also employed them in a rather unconventional manner: distributing propaganda leaflets over enemy lines. In 1941, they introduced the Propagandagranate 41 (Eng. propaganda grenade), a specialized 7.3 cm rocket designed for this purpose.
The Propagandagranate 41 was slightly over 3 kg in weight and about 40 cm long. It was launched from a metal frame stabilized by three fixed spades. After setting the correct firing angle, the rocket was placed into the mount and at a distance from the base of the tube. This arrangement was necessary because the rocket was ignited using a percussion-firing system, essentially functioning like a mortar.
To fire the rocket, the operator would retreat to a safe distance and pull a string to release the captive rockets. This action allowed the rocket to slide down into the base, striking a firing pin that ignited the percussion primer located at the rear.
These rockets were assigned to specialized propaganda units known as Propagandatruppen. While it is difficult to assess the exact effectiveness of this method, it was undoubtedly a unique way to distribute propaganda leaflets during the war.
The 73 mm rockets were originally designed to distribute leaflets over enemy lines (Source: www.lonesentry.com)
A New Life For The Failed Propaganda Weapon
While rockets developed during the war were primarily forms of artillery, they were not limited to this role. The flexibility of unguided rockets allowed them to be adapted for use against aerial targets and even ships. Once again, the Germans tested various such weapons when their fortunes declined, including ground-to-air missiles, intended to counter the escalating Allied bombing raids. These projects mixed results and failed to achieve the level of success their designers had hoped for. Notably, attempts to build various surface-to-air missiles were met with only limited success. As resources became scarce and the war more desperate, the Germans sought simpler, cheaper, weapon systems designed to saturate the sky with numerous rockets in the hope of bringing down enemy aircraft. One such project appears to have been initiated in 1942.
Starting such a project from scratch was not considered an option at this stage of the war. Instead, the Germans attempted to repurpose what they already had. This is where the 73 mm propaganda rocket came into play. Since the tooling for its production still existed, it was feasible to use it for creating new anti-aircraft rocket launchers. The overall design was quite simple, consisting of a box launcher, rail cages, and a control cabin, and was set on a fixed or mobile carriage.. By 1944, work on this project ran at a slow pace and not many such launchers were built.
As this was a late-war project produced under desperate conditions, not much is known about who precisely initiated it. It is known that they were developed by the Waffenprüfstelle der Luftwaffe Tarnewitz (Weapons Testing Center of the Air Force Tarnewitz). Based on several sources, it appears that the launchers were constructed by Rheinmetall. Other sources claim that Henschel built and developed it. What is certain, however, is that these weapons entered production and service in late 1944.
To provide a cost-effective means of defending vital installations, the Germans introduced the 73 mm Föhn-Gerät rocket launcher in late 1944. (Source:www.landmarkscout.com)
Production
The production of the launchers progressed at a slow pace. By 1944, only 50 units had been completed. By February 1945, this number had increased by 83, or increased to 83, though sources are somewhat unclear on the exact figure.
Designation
No official designation for this system is known to have survived. In available sources, it is often mentioned that the Germans simply referred to it as the 73 mm Föhn-Gerät. The word Föhn refers to a certain type of wind, while Gerät translates to Device.
Some internet sources also designate it as the Henschel Hs 297. Interestingly, captured systems examined by the Western Allies were designated as the 7.5 cm Multiple Fortress Rocket Launcher. This designation is incorrect in both caliber and intended purpose. For the sake of simplicity, throughout this article, we will refer to the system as the 73 mm Föhn rockets.
In Combat
A small number of these launchers were built and deployed for frontline use near the end of the war. They were primarily used to protect bridges over the German rivers on the Western Front. In particular, a few were defending the area around the Remagen bridge in 1945.
The 73 mm Raketen Sprenggranate was introduced to service near the end of the war. (Source: en.wikipedia.org)
Design
Cradle and Carriage
The 73 mm Föhn cradle features a simple conical base, above which is a saddle with two trunnions that securely hold the rocket rail box in place. The entire system could either be bolted to a concrete base, or mounted on an older 3.7 cm Flak 18, two-wheel carriage for mobility. The stationary configuration was chosen for defending critical ground targets where mobility was unnecessary. In contrast, the mobile version was likely intended for use by ground forces as a standard anti-aircraft weapon. When deployed in the field, the rocket system would be lowered to the ground, and the crew would unfold two sheet metal plates designed to provide them with a standing platform.
The 73 mm Föhn-Gerät in mobile (left) and static configuration. (Source: www.lonesentry.com)Side view of the mobile launcher variant. This version seems to be much rarer, as significantly more photographs exist of the static variant. (Source:www.armedconflicts.com)
Controls
The controls for the 73 mm Föhn system were located on the left side of the assembly and housed within a partially enclosed cabin. The front and the right side, which faced the rocket launcher, were shielded by thin sheet metal plating. This housing was not designed to protect against enemy aircraft fire but rather to guard against the exhaust generated when firing the rockets.
At the upper front of the cabin, there was a large, curved glazed window, providing the operator with a mostly field of view. The controls themselves were straightforward; elevation was adjusted using a handwheel, while traversal was managed with a simple flat metal bar, likely welded to the right-side armor of the cabin. To traverse the system, the operator would push the bar forward or backward with their left hand, pivoting the box launcher on its mount.
This greatly illustrates the position of the operator and the two control units (a bar and hand wheel) for elevation and traverse. Interestingly this weapon appears to be a prototype, as it has more launchers than those found at the frontline. (Source: www.armedconflicts.com)A rear view of the operator’s partially protected cabin. The armor was too light to provide effective protection against enemy return fire; instead, its primary purpose was to shield the operator from the rocket’s exhaust. (Source: www.armedconflicts.com)
Armament
The project was based on the 73 mm propaganda rocket but required several modifications. The rocket’s steel body was shortened to 28.2 cm, and weighed 2.74 kg, including 0.48 kg of propellant, and a 0.28 kg explosive charge. Propulsion was achieved through seven small venturi nozzles, which provided rotational stability during flight. This rotation ensured the rocket’s stability without the need for fins.
Two types of explosive charges were available. The first consisted of a mixture of 60% cyclonite (RDX) and 40% TNT, while the second comprised 55% cyclonite, 40% TNT, and 5% wax. The rocket’s 73 mm nose warhead was equipped with a percussion fuze, meaning it had to strike the target to detonate in mid-air. Although not intended, they could be used against ground targets in case of an emergency.
To prevent unexploded ordnance from littering the battlefield, the Germans incorporated a self-ignition detonator. This safety feature ensured that unused rockets would not remain a hazard after missing the intended target. The rocket had a velocity of 380 m/s, and could reach a maximum height of 1.2 km.
A close-up view of a surviving 73 mm anti-aircraft rocket. (Source: www.landmarkscout.com)
The rockets were launched from box-shaped launchers, each equipped with 35 guide rail tubes arranged in a grid of five rows horizontally and seven columns vertically. The dimensions of the launcher were 58.4 cm in width, and 81.3 cm in height, with each guide rail tube measuring 78.7 cm in length. The launchers had an elevation range of -12° to +90° and a full 360° traverse capability.
The loading process for the 35 rocket remains somewhat unclear. However, the launcher tubes were constructed in two distinct parts. The front section serves as a guide for the rocket, while the rear section is loaded separately, already containing the rocket inside.
Side view of the rocket guide rails. (Source: www.landmarkscout.com)This photograph suggests that the launcher tubes were constructed in two distinct parts. The front section serves as a guide for the rocket, while the rear section is loaded separately, containing the unfired rocket. (Source: www.luftarchiv.de)
Once the system was prepared and a target identified, the operator aimed at the approaching enemy aircraft. Upon sighting the target and ensuring it was within range, the operator activated the rockets. All 35 rockets were fired in a single salvo. The idea behind this approach was to saturate the area around the target, increasing the chances that some rockets would hit.
However, this method had significant drawbacks. The rockets were low-velocity and imprecise, making them an unreliable means of bringing down aircraft beyond extremely close range. Additionally, the smoke generated during firing revealed the launch position. While mobile launchers could relocate after firing to avoid detection, stationary ones were left exposed and vulnerable to Allied aircraft.
Reloading the launcher was likely a tedious process, requiring considerable time to prepare all 35 rockets for another volley, or reload from additional racks. Once the rockets were expended, the ground crew could do little but wait for the enemy aircraft to move on. Theoretically, operators could control the number of rockets fired by removing or securing the rockets’ safety pins. How practical this would be is another question.
It was hoped that the 73 mm Föhn could be employed as a relatively cheap anti-aircraft weapon. As demonstrated, its accuracy could be suspect. (Source: www.armedconflicts.com)
Crew
The exact number of crew members required to operate this launcher is not specified in the limited available sources. However, at least one operator would have been necessary to operate the launcher. Additional crew members were likely stationed nearby to assist with loading the rocket launcher or preparing it for transport, and it is reasonable to assume that a commander was also part of the team.
Ground Attack Variant
During their advance toward Germany in 1945, the Allies managed to capture a vast collection of abandoned vehicles and weapons. Many of these were outdated and obsolete, brought into action out of desperation. Among the captured equipment were several improvised weapons, including a 73 mm rocket launcher that appeared to be designed to provide fire support against ground targets. However, little is known about this particular weapon, as it seems to have been a hastily constructed, improvised device created as a last-ditch effort.
An improvised launcher for the 73 mm rocket captured by the Allies at the end of the war. (Source: www.lonesentry.com)
Surviving Systems
Despite its rarity and late introduction during the war, a few of these launchers have survived to the present day. One example is preserved at the Russian Military Historical Museum of Artillery in St. Petersburg, while another is housed at the Swedish Army Museum in Stockholm.
One surviving system can be seen at the Swedish Army Museum in Stockholm. (Source: www.stronghold-nation.com)Another partially preserved launcher is located at the Russian Military Historical Museum of Artillery in St. Petersburg. (Source: www.landmarkscout.com)
Conclusion
The effectiveness of these weapons in combat remains uncertain, but they likely performed poorly. The rockets had a short range and produced excessive exhaust fumes which marked the position of the weapon. They could only be fired in single salvos, meaning that if they missed their target, enemy aircraft could return and engage them without fear of retaliation. Additionally, the rockets were notoriously imprecise, making the chances of hitting an enemy aircraft quite low despite the large salvo the weapon could deliver.
73 mm Föhn-Gerät Specifications
Caliber
73 mm
Crew
One (likely more but it is unspecified in the soruces)
USSR (1938-1940)
Poland 
Kingdom of Italy (1940-1943)
Kingdom of Hungary (1943)
United Kingdom (1940)
Nazi Germany (1939)
