Tag Archives: Experimental

Official classification tag

Fieseler Fi 103 A-1/Re4 Reichenberg

Nazi flag Nazi Germany (1944)

 Piloted flying bomb: 175-200 built

Despite the major advances in military aviation during the 1930s, one persistent problem still lacked a truly satisfying solution: the accuracy of aerial bombing. Hitting a ground target from an aircraft was never easy, and given the technical limitations of the time, accuracy could only be improved to a certain extent through the use of more sophisticated bombsights.

When the Second World War broke out, this issue became even more important. Striking and destroying enemy strategic targets, such as industrial centres, military installations, shipping, or rail communications, was crucial. This was usually attempted using high-altitude bombers that dropped large payloads over the target area, using saturation to overcome the inaccuracy of their weapons. Despite the sheer number of bombs released, these aircraft often missed their intended objectives.

Alternatively, ground-attack aircraft could engage targets somewhat more precisely through the use of rockets, bombs, and gunfire, but they were highly vulnerable to ground fire during such operations and could not carry enough ordnance to destroy larger targets in a single strike.

Near the closing stages of the war, in desperation and hoping to create a system that was both accurate and carried a heavy payload, the Germans tried to modify their V-1 flying bomb into a man-guided missile known as the Fieseler Fi 103R Reichenberg. Fortunately for the pilots who were supposed to fly these bizarre contraptions, the entire idea was abandoned, even though around 175 examples had already been built.

The Fieseler Fi 103 A-1/Re4 piloted variant of the V-1 flying bomb. Source: reddit

History

With the rise of Nazism in Germany during the 1930s, large funds were poured into the development of Germany’s armed forces, including the Luftwaffe (Eng. German Air Force). This allowed for the rapid development of new technologies and a series of modern aircraft designs. Like other air forces of the period, the Luftwaffe employed twin-engine bombers capable of delivering heavy payloads against enemy targets. Conventional bombers, which released their payloads from straight and level flight, were effective against large, stationary targets such as urban centers, industrial facilities, and infrastructure. However, this method proved far less effective against smaller, hardened targets such as bunkers or bridges.

The Germans also showed great interest in improving the precision of bomb strikes. In particular, the concept of dive bombing attracted considerable attention from high-ranking Luftwaffe officials. Through extensive study and testing during the 1930s, the Germans developed a specialized class of dive-attack aircraft known as Sturzkampfbomber, more commonly known as Stukas. Earlier designs came in the form of the biplane Henschel Hs 123. Eventually, however, the focus shifted toward designing a more modern aircraft for this role.

For precision strikes against tactical targets, the Germans adopted dive bombers like the Ju 87, which used a steep dive to engage designated targets with a high degree of accuracy. However, these aircraft were too slow for modern fighters, and even with sufficient protection, they were relatively easy targets. Source: wikipedia

After a series of experiments and experience with the light Hs 123, the Junkers Ju 87 was ultimately adopted as the Luftwaffe’s primary diver bomber. It was specifically designed to attack enemy targets at angles approaching 90 degrees while still being able to safely pull out of the dive after releasing its bomb. These aircraft proved notoriously effective against enemy ground targets and were also devastating to enemy morale. However, once more modern and better-equipped opposing air forces appeared, the Ju 87 became an easy target for enemy fighters when flying without a heavy escort.While they remained in use up to the last days of the war, by late 1941, it was becoming evident that a more precise aerial-attack solution would be necessary.By 1944, the rapid advance of both the Allies’ fronts, combined with the depletion of the Luftwaffe’s strength, meant that there were fewer and fewer options for attacking strategic targets in enemy territory. A particular example was the Luftwaffe’s growing inability to hit targets in the United Kingdom, where Allied air power dominated, and their bombers were steadily reducing German industry to rubble with constant air raids.

Unable to strike back effectively, the Germans turned to alternative solutions. One of these was the creation of a cheap flying bomb, better known as the V-1, launched from occupied territories in Western Europe against various targets across the English Channel. However, these were not precise weapons. Carrying a heavy warhead, they were unmanned aircraft that, once launched, could not correct their course to hit targets more accurately.

By late 1944, the idea emerged to use these flying bombs as manned missiles. Essentially, engineers would add a small cockpit with the minimal instruments necessary to guide the weapon as closely as possible to the target. Once the missile was aimed at its objective, the pilot was expected to bail out.

A New Weapon

The history of the V-1 flying bomb dates back to 1939, when the Reichsluftfahrtministerium short RLM (Eng. German Air Ministry) began showing interest in jet-engine development. One of the companies involved in these early efforts was the Argus Motoren Gesellschaft of Berlin. Argus was particularly interested in developing the so-called pulsejet engine, a simple form of jet propulsion that operated through a series of rapid combustion pulses within a tube-shaped chamber.

In this engine, a mixture of air and fuel was ignited repeatedly, producing a sequence of explosions that expelled hot gases through the exhaust and generated the necessary thrust. As each explosion created a brief vacuum that drew in fresh air, the pulsejet did not require complex compressor assemblies like standard turbojets, making it significantly cheaper and easier to produce. However, it also had major drawbacks: it consumed far more fuel than a turbojet and was incapable of producing comparable levels of thrust, limiting its potential speed and altitude.

By 1941, Argus had completed its first operational pulsejet and needed to find an appropriate application for it. The opportunity came in 1942, when the RLM proposed using the engine to power a new project, an unmanned, automatically guided flying bomb. Argus was to supply the engine, while the Fieseler aircraft company would design and construct the airframe.

The new weapon, designated the Fi 103 (also referred to as the V-1), was a very simple and rugged design. It consisted of an aerodynamically clean fuselage carrying an 850-kg warhead, along with short, straight wings and a basic tail unit. To prevent heat damage from the pulsejet exhaust, the engine was mounted above the fuselage on a short pylon. Although the design work was largely completed by 1942, it took additional time to refine the weapon for reliable mass production. It finally entered large-scale service around the time of the Allied landings in Normandy in June 1944. Thousands of V-1s were launched from sites along the occupied coasts of Western Europe, aimed at a variety of strategic and civilian targets, with mixed operational success. While they drew Allied resources from other efforts to try and shoot them down, their inaccuracy prevented them from doing serious damage to any strategic targets.

 

The V-1 was intended to be a cheap and disposable weapon designed to engage long-range targets that, by 1944, were far beyond the reach of German bombers due to Allied air supremacy. Source: wikipedia

A Piloted Variant 

While work on the V-1 was being carried out during 1943, a new idea began to take shape within parts of the German armed forces: using a piloted guided flying bomb. It should be specified that the V-1 was not initially considered for this purpose. Who exactly first proposed this concept is unclear. Today, there are two versions of its development history, both of which are quite different from each other.

Hanna Reitsch’s Proposal 

One of the two leading versions regarding the historical event and the explanation for this report is closely connected to Hanna Reitsch. Born in 1912 into a wealthy family in Silesia, Hanna Reitsch developed a strong interest in aviation early on, beginning in 1930 when she joined a gliding school.

By the mid-1930s, she had become a skilled and nationally renowned pilot. Over the next few years, she was involved in various test flights and participated in numerous German and foreign aviation exhibitions across Europe and even in Brazil. She was also one of the first pilots to fly over the Alps and was among the first to fly the Focke-Wulf Fw 61, the first practical helicopter.

 

The general idea of using manned piloted bombs is often attributed to one of the most famous German pilots of the war, Hanna Reitsch Source: blue-stocking

When the war broke out in Europe in 1939, she joined the Deutsche Forschungsanstalt für Segelflug (DFS; Eng. German Institute for Glider Research) as a test pilot. She became immensely popular in Germany and even developed a close relationship with Hitler, who praised her highly.

By 1943, the situation for Germany was slowly becoming desperate, with huge losses in both men and materiel that could no longer be easily replaced. To make matters worse, there were growing fears that the Allies might open a new front by landing in France. As a result, many within the German military began theorizing about how best to stop, or at least inflict as much damage as possible on, a potential Allied landing.

This was the question that Reitsch and her two companions, one was Theo Benzinger, a medical research officer at Rechlin; the identity of the second remains unknown but is described as being a skilled glider pilot ,asked themselves when they met in August 1943 in Berlin.

They theorized that if the Allies intended to land in occupied France, they would have to do so using a huge number of ships. These vessels would be a vital part of the invasion, transporting troops and matériel. If sufficient damage could be done to them, the Allied invasion force would be greatly diminished, potentially to the point where they could be easily defeated in combat. The question, however, was how to attack them given the overwhelming Allied superiority on the ground and in the air.

They came up with the initial idea of using pilots to fly a specially designed, man-piloted bomb directly toward a vital Allied installation, ship, or other target. The pilot would guide the aircraft onto the designated objective and then bail out shortly before impact. Although its proponents insisted that this was not intended to be a desperate, suicidal tactic, in practical terms, it essentially was.

Over the next few months, as she spoke with more people, the idea began to gain traction. Soon a volunteer group of around 70 to 80 pilots who were willing to fly the proposed “flying bomb”, was formed. Although Reitsch never claimed to have initiated the creation of this group, nor to have been a member of it, she strongly supported the idea. Her belief was that her vocal support might help accelerate the realisation of the proposal.

The next step was to present this idea to Luftwaffe officials for approval, but they had little success in that regard. This idea was eventually presented to Generalfeldmarschall Erhard Milch, the Luftwaffe’s Inspector General, who was responsible for deciding which projects would be approved or rejected. After reviewing the pilots’ proposals, he firmly opposed the notion of using such aircraft, seeing it as a suicidal mission. Even though Reitsch rejected the idea that it would be a one-way trip, the reality was clear. It is important to understand that while German military leaders accepted that soldiers died in war, they were neither willing to endorse nor incorporate suicide missions into German military doctrine.

Possibly due to the urging of several test pilots, the DFS became involved in the project. Although the DFS was primarily focused on designing and constructing gliders, it played an important role in training early German pilots and also participated in projects such as the rocket-powered Me 163.

Its representatives, together with others from related fields, held a meeting to discuss the possibility of using a piloted bomb. While they ultimately concluded that such attack operations were technically feasible, they avoided using the term suicide mission. It appears that many saw potential in the concept, but few were willing to overlook the fact that the pilot’s chances of survival were very low and their chances of recovery by friendly forces non-existent.

However, with an Allied landing in France expected at any moment, the idea of a high-speed attack aircraft capable of striking targets with much greater precision became an appealing option. Eventually, Hitler was informed of the concept at the end of February 1944. After discussing it with Reitsch, even though he was not a particularly enthusiastic supporter, he nonetheless permitted development to begin.

To test the concept, KG 200 (Kampfgeschwader 200), a special Luftwaffe unit responsible for covert operations and the testing of new technologies, conducted a series of flights in April using Fw 190s. These aircraft were loaded with the heaviest bombs that a pilot could theoretically deliver in a steep dive. Tests showed that the pilot could escape from the cockpit in time to survive the attack. However, since Allied fighter cover was expected to be too strong, the proposal to use the Fw 190 in this manner was rejected

The first aircraft chosen for the role of piloted flying bomb was the Me 328. The idea was that this small and inexpensive pulse‑jet‑powered fighter was already in an experimental stage, and that the necessary tooling and equipment for its construction could be assembled quickly. Initial proposals regarding the use of the Me 328 in this role suggested outfitting it with a torpedo for attacking enemy ships, but this was dropped early on. In the concept of using the Me 328 as a guided bomb, it was intended to be carried aloft by a larger bomber. Once near the designated target, it would be released and, at high speed (estimated to reach nearly 710 km/h), it was supposed to strike the target with a warhead weighing up to one tonne.

Despite promising early expectations, the Me 328 proved to be a disappointing project and was eventually abandoned. Although preparations were made to develop this variant, all work on it was discontinued by May 1944.

 

At an early stage, the small and inexpensive Me 328 pulse-jet-powered fighter was seen as a likely candidate for the project. However, since it remained at the prototype stage, the idea was dropped in favor of the V-1. Source: aviastar

What happened next is not entirely clear, especially regarding who first proposed that the V‑1 should be employed in this manner. However, given that it was cheap to build, available in large numbers, and capable of carrying a substantial payload, it appeared to be an excellent candidate for a piloted bomb.

According to some accounts, Reitsch later contacted the head of the DFS, Professor Walter Georgi, requesting that he and his team of engineers design such a device. After fourteen days, the team managed to construct four prototypes for testing.

Otto Scorceny Side Of The Story 

A second version of the story portrayed the German commando Otto Skorzeny as the inventor of the entire concept. He was one of the best-known German commando officers, most famous for rescuing Benito Mussolini from his imprisonment at the mountain hotel on Gran Sasso in September 1943. The following text is sourced from his personal memoirs, and we must take some of the information with a grain of salt, as it may have been exaggerated or even fabricated.

 

A well‑known German commando, Otto Skorzeny, claimed after the war that he was involved in designing and building the first prototype of a man‑piloted flying bomb. However, how completely true this claim is remains unclear. Source: wikipedia

In early 1944, Skorzeny became involved in finding ways to delay or cause damage to the Allied preparations for the invasion of France, which the Germans knew was coming soon. During this period, he became interested in the idea of using man-piloted flying bombs to strike vital Allied installations and targets during the anticipated invasion. He even had the opportunity to speak with personnel from KG 200, who supported the concept, as well as with Hanna Reitsch. They all confirmed to him that such attacks, despite being suicidal, could inflict serious damage on key Allied targets.

Following this, during a visit to Peenemünde (a municipality in the Baltic region) where the Germans conducted secret research and testing of the V-1 and V-2 weapons, Skorzeny experienced a moment of inspiration while observing a V-1. He had previously been involved in another project that used small explosive boats against Allied shipping in the Mediterranean with some success. He theorized that the same principle could be applied to the V-1: it could be modified and equipped with a cockpit to be used as a more precise striking weapon. He immediately requested the technical specifications of the V-1 and assembled a team of aviation engineers to determine whether his idea had any merit. After a day of deliberation, they gave a positive answer, stating that the concept was theoretically feasible and that such an aircraft could be constructed fairly quickly and cheaply.

With this knowledge, Skorzeny approached Erhard Milch, who was previously firmly opposed to any such idea. However, after speaking with him, Skorzeny managed to mislead him by claiming that Hitler himself was quite interested in the project’s realisation, even though Hitler actually knew nothing about it.

This claim, combined with Skorzeny’s reputation, allowed him to secure approval after presenting the concept to a commission of aviation engineers that was to be formed the following day. Eventually, Skorzeny received permission and assembled a small team of engineers to design and build such an aircraft. After ten days of fifteen-hour shifts, the three prototypes were fully completed and ready for testing.

What is the truth? 

So, is the whole account correct? Skorzeny does not mention the involvement of the DFS and instead claims personal credit for the construction of the first prototypes, alongside a small team of workers and engineers. Which of these two versions is true, we will likely never know, as either could be accurate—or entirely wrong.

 

Regardless of who actually built the first prototype, they were quicklydelivered and used for testing. This particular example is fitted with a dummy warhead. Source; A. L. Kay MonogramClose-Up 4 Buzz Bom

Designation

Given that it was based on the V-1 project, the manned flying bomb was considered an extended variant of the V-1 and was designated Fi 103A-1/Re 4. The Re was short for Reichenberg and the number ‘4’ indicates that it was the fourth variant of the V-1.  The 1 indicates a variant with an extended range of the original flying bomb, and 2 for a towed variant. The two-seat training variant was known as Fi 103A-1/Re 3. This information is according to by A. L. Kay (MonogramClose-Up 4 Buzz Bomb).

According to S. J. Zaloga (V-1 Flying Bomb 1942–1945), the designation system appears slightly different. He states that the experimental models were designated Fi-103 Re.1. The Re.2 designation was applied to an unpowered trainer version, while Re.3 referred to the powered variant of that trainer. Finally, Re.4 was intended to be the production version.

Another author, A-1, mentioned the following designations: Reichenberg 1, referring to a single-seat glider variant without an engine; Reichenberg 2, a dual-cockpit trainer version again without an engine; Reichenberg 3, a single-seat training variant equipped with a working engine; and finally Reichenberg 4, essentially the production variant.

For the sake of simplicity, we will refer to both collectively as the Fi 103R.

Initial Testing

The precise history of the testing phase and its chronological order remain unclear, depending largely on the sources used. According to Skorzeny’s account, these tests began in September 1944 at the Rechlin test center. The trials were conducted by launching the Fi 103R from a He 111 carrier aircraft. In contrast to the V-1, which was mostly launched from ground-based, specially designed ramps, the Fi 103R man-piloted bomb was intended to be launched exclusively from carrier aircraft. An He 111 could carry up to two such aircraft.

Problems appeared almost immediately. During the first flight test, the pilot was severely injured when the Fi 103R landed at high speed and lacked any form of landing gear beyond a simple skid. The next test also ended in a crash, again leaving the pilot badly hurt. This temporarily halted further flights until the design could be refined.

At this point, Hanna Reitsch, Willy Fiedler, and Heinz Kensche were requested to serve as test pilots. Skorzeny initially opposed this, as Reitsch was a well-known public figure in Germany, and her injury (or worse, her death) in an accident could have had serious consequences for everyone involved.

The second series of test flights was carried out in early November. These also caused further problems; during one flight, a stabilizing fin broke off. The test pilot, however, managed to bail out and land safely.

On the other side of the story, Reitsch claimed that she was initially rejected from flying the Fi 103R, being told that it was “a man’s job.” During the first test flight, the pilot mistakenly disengaged the Fi 103R from the He 111 too early, lost control, and crash-landed, surviving the landing but sustaining multiple injuries. In a second flight, the pilot made a miscalculation during landing and was severely injured. These setbacks may have caused delays or even cancellations of certain tests, prompting Reitsch to try flying the aircraft herself. She later reported that the controls were too sensitive and that the Fi 103 was difficult to land, as it possessed extremely poor low-speed handling and a high landing speed of 190 km/h. Of the six test pilots who flew the Fi 103R with Reitsch, two would die, and four were injured,

Production 

While the initial tests were concluded, they did not provide perfect test results. Despite this, production was scheduled to begin as soon as possible. The production, or more accurately, the conversion of existing V-1s was carried out at two small Luftwaffe ammunition depots located in a concealed wooded area near the town of Dannenberg, and at a second site known as Pulverhof. The exact number of reproduced units is unclear, but it is known that when the Allies captured Dannenberg in April 1945, they found around 175 Fi 103Rs. With additional units produced at Pulverhof, it is estimated that more than 200 were built in total.

Training Variant

Despite the extremely low chance of survival, there were allegedly thousands of volunteers for these missions. These men were referred to as Selbstopfermänner (Eng. self-sacrifice men). From this large number, an initial group of only 70 was selected. They were intended to form the core training cadre for future pilots. A darker part of this history is that Heinrich Himmler went so far as to suggest that the pilots used in such attacks were recruited from people the Nazi officials considered “undesirable,” such as politically apathetic citizens, prisoners, and others deemed expendable.

To effectively train pilots to fly these missions, a special two-seat variant was developed, designated Fi 103 A-1/Re3. This training version consisted of two stations for the pilot and the instructor.  The original pilot cockpit position was retained. The space for the warhead had been, an elongated nose section was installed contained the second cockpit.

In addition, because it was used for training, it needed to land after each flight. Since no landing gear could be installed, the Germans decided to use a simple landing skid instead. It was powered by an Argus 109-014 pulsejet, which provided approximately 350 kg of thrust.

 

These two training variants were captured by the Allies in April 1945 near Dannenberg. Interestingly, their canopies had been destroyed by German personnel to prevent them from being of any use to the Allies. Source: A. L. Kay MonogramClose-Up 4 Buzz Bomb

Combat Use and Fate

Once the training process was completed and the produced Fi 103t were cleared for use, the next step was to pursue the designated targets. Being besieged on all sides, the Germans had plenty of options to choose from. However, even before any real operation could be launched, the project was constantly delayed. Shortages of resources and fuel prevented any deployment in combat. In addition, the idea of using the already obsolete He 111 bombers as a host aircraft was considered too dangerous, as the Allies had almost complete control of the skies. Even German-held territory was no longer safe from their air superiority.

The expected order for the first combat missions kept being delayed. Although some training was carried out, nearly half of the initial group of 70 volunteer pilots never even had the chance to fly the aircraft. As the months passed, the Fi 103 continued to be used in various experimental test flights. During one such flight in March 1945, both of the new shortened wings fell off an Fi 103R.

While the concept of a piloted Fi 103 was appealing to some of the officers involved, it failed to gain lasting support among higher-ranking officials, many of whom tried to shut the project down. The accident in March 1945 proved to be the final straw for KG 200’s new commander, Oberstleutnant Werner Baumbach. He went directly to Minister of Armaments Albert Speer in an effort to have the project cancelled for good. Both Speer and Baumbach later spoke to Hitler about it, and based on his earlier reluctance toward the idea, they managed to convince him to forbid any combat use of the Fi 103R. As a result, the roughly 200 completed aircraft were left scattered around the factories where they had been assembled.

By April 1945, Allied forces captured the production facilities at Dannenberg. There they found between 125 to 175 Fi 103A-1/Re 4 aircraft. In addition, an unknown number of two-seat versions were also captured. The U.S. Army was particularly eager to examine anything related to the V-1 program, including the manned flying bomb. At least one Fi 103 was shipped to the United States for testing. Although the U.S. spent some time evaluating the V-1, the idea of using this type of manned, suicide-style flying bomb held no interest and was not pursued by the Allies after the war.

 

All produced Fi 103 were seized by the Allies. While some were examined to analyze their overall design, the Allies, for obvious reasons, did not attempt to reuse or replicate a similar design of their own based on the Fi 103. Source: wikipedia

Technical characteristics

The intended Fi 103R-4 was developed primarily based on the V-1 flying bomb; however, it differed in several significant ways. The overall fuselage shape was largely retained, but changes were introduced, most notably the replacement of the V-1’s front section with a new truncated, cone-shaped nose. At the nose, an 850 kg warhead consisting of a mixture of Amatol high explosive, connected to an impact fuse, was installed.

Here, it is important to note that, despite around 200 Fi 103s being completed, the precise shape of the cone-shaped nose is not entirely clear. Nearly all surviving photographs of it show little of its dimensions. Additionally, those Fi 103s assembled by the Allies after the war for examination often had their frontal sections taken from V-1s and fitted directly onto the Fi 103R airframes. It is also worth considering that although up to 200 Fi 103s were built, it is possible that their original warheads were removed and reused for the V-1, and therefore were not present when they were captured.

The V-1’s wings were modified to include ailerons so that a pilot could control the Fi 103 during flight. The rear tail section with its rudder and elevator remained mostly unchanged.

Given its specific role, the Fi 103R was not provided with a landing gear. Instead, the training variants were equipped with simple landing skids. Its design was fairly basic and simple, held in place by three rubber cushions. Early tests showed that it was sufficient for training purposes, but it was not suitable for operational use. It was only possible to land the aircraft when the fuel tanks were completely empty and at very low speed.

In addition, given the lack of landing gear, the Fi 103R could be brought into the air only by being carried by larger aircraft such as the He 111. While a special launch ramp with a steam catapult for the V-1 did exist, it could not be used for the training variant, as it generated too much G-force for a human pilot to survive.

A close-up view of the Fi 103R fuselage showing the forward nose section without the explosive payload. Soyuce: A. L. Kay MonogramClose-Up 4 Buzz Bomb
This example, being examined by the Allies, lacked a dedicated front explosive charge section and was fitted with a demonstration nose section.Source: wikipedia
This one, captured by the Allies and exhibited after the war, had a nose section taken from the V-1. Source: reddit

It was powered by an Argus 109-014 pulsejet, which provided approximately 310 to 350 kg of thrust. With it, its maximum speed was around 644 km/h.  However, the estimated maximum speed during a dive attack was expected to reach up to 850 km/h when released from an altitude of 2,740 m. The fuel load provided an endurance of 30 minutes, giving the aircraft a range of approximately 330 km.

Since the proposed manned version did not require many of the V-1’s internal components, several were removed, including the two spheres containing pressurized gas for its pneumatic controls, and the autopilot system. This created enough free space to accommodate a very cramped cockpit for the pilot. Additionally, a small air container for fuel-tank pressurization was installed.

The cockpit itself was quite crude and equipped only with basic controls: rudder, aileron, and elevator controls, a warhead-arming switch, an altimeter, a speed indicator, a clock, and other essential instruments. To allow communication between the He 111 carrier crew and the Fi 103R pilot, headphones and a microphone were provided. Because of the pulsejet’s position, the pilot’s canopy had to open on the starboard side. It was a straightforward design, intended to break away once it reached a 45° opening angle.

Here we can see a release mechanism on a He 111 that carries an original V-1 bomb. The release mechanism for the Fi 103R would have been the same. Source: thoughtco

The canopy was held in place by curved prongs hinged to the right side of the cockpit. The left side was secured by two eyelets and sliding pins. To open it, the pilot needed only to activate a lever that disconnected the sliding pins from the eyelets. The last noticeable feature of the canopy was a set of painted lines intended to help the pilot estimate the angle of attack.

The close-up look at the Fi 103 cockpit with its basic command instrument table. Source: landmarkscout

The pilot was then expected to jump out of the cramped cockpit at high speed. During this procedure, there was a significant risk that he or his parachute could be struck, damaged, or entangled by the pulsejet. In practice, escaping quickly enough from the cockpit was only theoretically possible. Proposals to equip the aircraft with an ejection seat were rejected. While an ejection seat would have offered a better chance of survival, there was no room to install one, nor were any suitable designs available. German engineers also calculated that such a mechanism might deflect the bomb from its intended course

Japanese counterpart

While conceptually similar, the Japanese developed their own variant of a man-operated flying bomb. It was designated the Yokosuka MXY-7 Ohka. The weapon was carried close to its intended target by a large bomber before being released. The pilot of the flying bomb would then activate a rocket propulsion system and guide the Ohka into the target.

The Japanese developed this weapon completely independently from the Germans, intending it specifically for attacks against Allied ships in the Pacific. Its effectiveness was limited, however, because the bomber aircraft carrying it were usually shot down before they could launch the weapon.

In contrast to the German designs, the Japanese made no effort to provide the pilot with any chance of survival, as the Ohka was deliberately built as a one-way weapon.

 

Despite not knowing about the German effort, the Japanese built their own piloted flying bomb. In contrast to the Germans, the Japanese did not care much about survivability, as they intentionally designed these weapons to be used only once. Source: fandom

Surviving aircraft

While they were never used in combat, a few of them actually survived to this day. One can be found in the Swiss Military Museum in the Canton of Aargau. Another example is located at the Dutch National Military Museum (NMM). Several more can be seen at the La Coupole V-2 Museum in Helfaut-Wizernes, France. The last one was actually gifted to the city of Antwerp after the war by General Clare Hibbs Armstrong, who was the commanding officer of the 50th Anti-Aircraft Artillery Brigade. This unit provided anti-aircraft protection against the German V-1. Although it was stored for many years, in 1998 it was loaned to the French museum.

The Swiss Military Museum in the Canton of Aargau has both the original V-1 and the piloted variant Fi 103 on exhibit. Source: wikipedia
This one is exhibited at the Dutch National Military Museum. Source: .landmarkscout
And the one seen in La Coupole V-2 Museum in Helfaut-Wizernes. Source: landmarkscout

Conclusion

The Fi 103R manned missile was a fundamentally flawed concept from the very beginning. While the idea of using a cheap flying machine capable of carrying a heavy payload which could be accurately aimed may have seemed appealing, the drawbacks were simply too great. It remains unclear whether those involved in its development ever seriously considered how this aircraft’s launch platform was supposed to bypass Allied protective air cover and overwhelming air superiority.

Although the Fi 103 could achieve high speeds, its carrier aircraft (the He 111) was an aging and slow design, an easy target for enemy fighters. Once released, there was no guarantee that the Fi 103R would be able to navigate toward its target effectively, let alone hit it accurately. As for the pilot, survival was essentially nonexistent. Even in the unlikely event that a pilot managed to endure the entire ordeal, they would almost certainly be captured behind enemy lines. In every respect, it was a one-way mission.

Despite growing desperation as the war drew to a close, Germany never embraced the level of fanaticism that characterized the Japanese kamikaze attacks. Even Hitler, who initially approved the concept, never fully supported it, and canceled it when its technical failings were brought to his attention. While some effort was invested in the project, it appears that many within the Luftwaffe and the organizations responsible for its production quietly worked to delay its implementation, allowing the project to fade away—a fortunate outcome for the pilots who would have been forced to fly it.

  Fi 103A-1/Re 4 Specifications

Wingspans 5.72 m / 18  ft 9 in
Length 8.8 m / 27  ft 2 in
Height 1.4 m / 4 ft 8 in
Engine Argus 109-014 pulsejet
Empty Weight kg / 3,483 lbs
Maximum Takeoff Weight kg / 4,310 lbs
Maximum Speed 850 km/h /  528 mph
Cruising speed 644 km/h / 400 mph
Range 330 km/ 205 miles
Crew 1 pilot
Armament
  • 850 kg explosive

Illustration

Credits

Source:

  • R. O’Neill (2001) Suicide Squads, Salamander Books
  • S. J. Zaloga (2008) V-1 Flying Bomb 1942-1945, Osprey Publishing
  • A. L. Kay (1977) MonogramClose-Up 4 Buzz Bomb, Tien Wah Press
  • Specijalna Misija Oto Skorceni (2007) Serbian translation by Ivan Jovanović, Algoritam
  • Duško N. (2008)  Naoružanje Drugog Svetsko Rata-Nemacka. Beograd.
  • D. Monday (2006) The Hamlyn Concise Guide To Axis Aircraft OF World War II, Bounty Books
  • D. Myhra (2001) Fieseler Fi 103R, Schiffer Military History

 

PZL.23 in Romanian Service

Romania (1939-1946)

Light Bomber/Reconnaissance Aircraft : 21 Aircraft Operated

During the 1930s, the Polish Air Force sought to modernize by introducing several new aircraft into its inventory. One of these was the PZL.23, a single-engine reconnaissance/bomber aircraft. More than 200 were built and entered service before the outbreak of war, several of which they obtained through unorthodox channels. When Germany invaded in September 1939, the Polish Army was defeated after a month of heavy fighting, and a substantial portion of its forces managed to escape into neighboring countries. A large number of aircraft of various types were flown to Romania, among them 21 PZL.23s. After being inspected, 19 of these were incorporated into the Royal Romanian Air Force. Although outdated by 1941, the PZL.23s were a welcome addition. They saw extensive service on the Eastern Front and remained in use until 1943.

One of the 19 PZL.23 in Romanian service. Source: https://tvd.im/aviation/1666-pzl-p-23-karas.html

A Brief History of the PZL.23

In the early 1930s, the Polish Air Force began modernizing its outdated fleet. One of its top priorities was to acquire a new class of aircraft capable of both reconnaissance and light bombing, intended to support ground forces. The requirements called for a modern all-metal, low-wing monoplane design, a significant step forward compared to earlier models.

After reviewing several proposals, the winning design came from a young engineer, Stanisław Prauss, working at Państwowe Zakłady Lotnicze (PZL, or State Aviation Works). By early 1932, a full-scale wooden mock-up of the fuselage had been completed. Both the drawings and the mock-up were presented to the Polish Aviation Department in the spring of that year. Following a detailed analysis, the department approved the project and ordered three prototypes for testing. The first prototype was finished in 1934. After nearly a year of refining the design, the Polish Air Force placed an order for 200 aircraft at the end of 1935, designating the model as PZL.23. However, production was delayed for almost two years due to a shortage of suitable engines.

 

The Polish Bomber/reconnaissance plane PZL.23 Source: https://en.wikipedia.org/wiki/PZL.23_Kara%C5%9B

Of the first batch, 40 were built as the PZL.23A, while the remaining 160 were completed in the improved PZL.23B variant. The latter featured a more powerful engine and a reinforced fuselage.

The initial order of 200 aircraft was completed by September 1937. Due to continued demand, the Polish Air Force allocated additional funding for 50 more aircraft, which were delivered by February 1939.

In New Hands

While the Polish Army attempted to secure export sales of the PZL.23, their efforts were largely unsuccessful. The only country to purchase the aircraft was Bulgaria, which acquired 50 modified versions fitted with new engines, designated as the PZL.43. The next operators of the PZL.23, however, were not buyers at all but rather countries that came into possession of the aircraft following the collapse of Poland’s armed forces in September 1939.

After a period of rising political tensions between Germany and Poland over the status of the Free City of Danzig, relations between the two nations rapidly deteriorated. On 1 September 1939, Germany invaded Poland, marking the beginning of the Second World War. Contrary to the common misconception that the Polish Air Force was destroyed within the first days of the conflict, this was not the case. Although it suffered heavy losses, the Polish Air Force, despite being outnumbered and equipped with largely outdated machines, continued to resist.

The PZL.23, originally intended as a light bomber, was primarily employed in reconnaissance missions, with occasional bombing sorties. By the time Poland surrendered in early October 1939, most of the PZL.23s had been lost in combat. Yet this was not the end of the aircraft’s story. Both Germany and, later, the Soviet Union, after their invasion from the east, managed to capture several examples. However, neither power showed significant interest in putting them to extensive use.

An Unexpected Gift

With their nation collapsing, many Polish soldiers tried to escape to neighboring countries, hoping to continue the fight on the Allied side, or at least find safety in a neutral country. Through this exodus, Romania came into possession of nearly 300 Polish aircraft of various types, both military and civilian.

On the 17th September, a formation of 21 PZL.23 (mostly the B variant) crossed the border into Romania, with the Polish crews required to surrender their planes for their internment. For the Romanian Air Force, this was an unforeseen opportunity to acquire relatively modern aircraft. At that time Romania had only a modest air force, so the new arrivals were viewed as an unexpected but welcome addition. However, the sudden influx of aircraft also created serious logistical challenges. It was therefore unsurprising that many of them were either never accepted into active service or saw only brief use.

The 21 bombers were quickly taken over by the Romanian Air Force and carefully inspected to assess their mechanical condition. Having been used in combat, most required extensive overhauls. Of the 21 that reached Romania, 19 were deemed suitable for service. Still, the lack of spare parts soon became a major problem. With the factories in Poland out of operation and Germany unwilling to produce replacement components, the only way to keep the aircraft operational was to cannibalize some to support the others. Those not selected for service were dismantled for parts.

In Romanian service, the aircraft did not receive any special designation and continued to be referred to simply as Karaś (Eng.  Crucian carp – a fish native to central Europe).

Markings

On their new PZL.23 aircraft, the Romanians painted large yellow Michael’s Crosses on both the fuselage sides and the wings. This marking was introduced on all Romanian aircraft after May 1941. In addition, the tail assembly carried the nickname Karaś and the aircraft’s identification number (ranging from 1 to 19), both painted in white. Lastly, the 73rd Bomber Flight, which primarily operated these aircraft, added its own unit insignia just behind the rear gunner’s position, a depiction of three horses pulling a cart.

After May 1941, the Romanians applied the large yellow Michael’s Cross to their newly acquired aircraft. This particular plane carried the number 12, with the nickname Karaś painted above it. Source: https://forum.il2sturmovik.com/topic/73926-romanian-pzl23-carasi/
When it entered service with the 73rd Bomber Flight, the aircraft received its own unit insignia, painted just behind the rear gunner’s position, a depiction of three horses pulling a cart Source: C.Craciunoiu and J. L. Roba, Romanian Aeronautics In The Second World War

In Service

Once accepted for service, the 12 PZL.23B aircraft were formed into the 1st Bomber Flotilla, based in Brașov. Alongside them, seven older variants of the type were issued for training duties and as potential replacement aircraft.

At the beginning of 1941, the reorganization of the Romanian Air Force saw the PZL.23s reassigned to the 73rd Bomber Flight. For the next several months, the unit was employed mainly in training activities.Things changed drastically in July 1941, when Romania joined the German invasion of the Soviet Union. The offensive was supported by the 6th Bomber Group, which included both the 73rd Bomber Flight and the 18th Bomber Flight.

Most of the combat-ready PZL.23B aircraft were initially used by the 1st Bomber Flotilla, based in Brașov. Alongside them, seven older variants of the type were issued for training duties and as potential replacement aircraft. Source: T. J. Kopanski PZL.23 Karaś

The PZL.23 was not used in the initial offensive operations. Its first combat action took place on 5th August 1941 near Kishinev. The mission was not a bombing run but rather a reconnaissance flight over Soviet positions along the Dniester River. The following day, eight PZL.23s took off, this time equipped with bombs. They attacked Soviet positions near Karargi-Buzinovo. While the mission succeeded in striking the enemy, one aircraft was heavily damaged by Soviet anti-aircraft fire. The pilot managed to bring it back to Romanian-held territory but was forced to crash-land. The aircraft was written off.

In the following months, additional bombing missions were carried out. PZL.23s also took part in the Romanian offensive that led to the capture of Odessa. On 20th October, the 73rd Bomber Flight was withdrawn from the front line for rest and to undergo a major overhaul of its aircraft.By this time, the Romanian Air Force had achieved remarkable results: about 7,857 fighter sorties were flown, bringing down an estimated 266 Soviet aircraft at the cost of 40 losses. The bomber units, meanwhile, flew 463 combat missions and dropped 2,287 tonnes of bombs. They were credited with destroying around 170 Soviet aircraft on the ground, while losing 29 bombers of various types, including one PZL.23.

For the remainder of 1941 and most of 1942, the PZL.23s were stationed in Romania. However, the heavy fighting around Stalingrad in late 1942 forced the recall of the 73rd Bomber Flight to the front. They remained in action against Soviet forces until January 1943, when they were once again withdrawn. By then, the aircraft were considered obsolete, and the unit was reequipped with newly acquired German Ju 87s, marking the end of the PZL.23’s frontline service.

 

Although dated, these aircraft remained in front-line service until the beginning of 1943. Photographs show them operating near the infamous city of Stalingrad. Source: https://forum.il2sturmovik.com/topic/73926-romanian-pzl23-carasi/

By that point, 12 aircraft had been assigned to a unit simply designated as PZL Flight. The unit remained relatively inactive throughout most of 1943 and the early months of 1944. In April, it was recalled to the front lines to conduct night harassment raids. For this role, the aircraft were to be equipped with bomb carriers designed to hold 1 kg shrapnel bombs. However, it is unclear whether they were ever actually used in this capacity, as no records from that period have survived.

By late August 1944, only five aircraft remained operational, with another five unserviceable. Despite their extensive use, very few survived, and the last examples were finally withdrawn from service and scrapped in 1946.

Technical characteristics

The Romanians did not make any major changes to the PZL.23 original design and it remains practically the same throughout its service. The PZL.23 was a single-engine, low-wing aircraft intended for both bombing and reconnaissance missions. The fuselage featured an oval-shaped 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 smoothly covered with duralumin sheeting.

An excellent illustration of the PZL.23’s 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 an inner panel with two spar assemblies that were joined to the fuselage. In addition to serving as the attachment point for the rest of the wing structure, this central section also housed the mounting points for the two landing gear units. 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 outer panel, and wing tips. 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

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. Finally, at the rear of the aircraft was the gunner’s position

The first variant was powered by a 670 hp Bristol Pegasus II M2 V-12 engine. Later production aircraft were equipped with the more powerful 710 hp Bristol Pegasus VIII radial. 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, each enclosed in aerodynamic spats. 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.

For self-defense, 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.

Conclusion

The Romanian PZL.23, despite being obsolete in almost every respect (speed, maneuverability, and overall performance), nevertheless saw extensive operational service. Initially, it was deployed on the Eastern Front in a reconnaissance role before being reassigned to ground-attack missions. Over time, their numbers gradually declined due to combat losses and frequent mechanical breakdowns. Some aircraft, however, continued to serve in secondary roles until 1944, when they had become hopelessly outdated. By that stage, their only occasional use was for night attack operations.

PZL.23B  Specifications

Wingspans 13.95 m /  45 ft 9 in
Length 9.82 m / 31 ft  9 in
Height 3.3  m /  10 ft 10 in
Wing Area 26.8 m² /  288 ft²
Engine 710 hp Bristol Pegasus VIII
Empty Weight 1,980 kg / 4.251 lbs
Maximum Takeoff Weight 2,893 kg / 6,378 lbs
Maximum Speed 319. km/h /200 mph
Cruising speed 270 km/h / 168 mph
Range 1.260 km/ 782 miles
Maximum Service Ceiling 7.300 m / 23.949 ft
Crew 1 pilot, observer, rear gunner
Armament
  • One forward-mounted machine gun
  • Two more at the rear
  • 700 kg bombs

Credits

Source:

  • B. Belcarz and R. Peczkowski (2001) White Eagle:s The Aircraft, Men and Operation of the Polish Air Force 1938-1939, Hikoki
  • C.Craciunoiu and J. L. Roba,(2003) Romanian Aeronautics In The Second World War
  • D. Bernad (2000) Romanian Air Force: The Prime Decade 1938-1947, Squadron Publication
  • T. J.  Kopanski (2004) PZL.23 Karaś, Stratus
  • J. B. Cynk (1966) The P.Z.L.23 Karaś, Profile Publication
  • J. B. Cynk (1971) Polish Aircraft 1893-1939, Putham

 

 

Belyayev DB-LK

USSR flag 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.

Close-up view of the pilot cockpit. Source: forum.warthunder.com

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
Empty Weight 6,000 kg / 13,230 lbs
Maximum Takeoff Weight 10,670 kg / 23,530 lbs
Fuel Capacity 3.444 l
Maximum Speed 490 km/h / 300 mph
Cruising Speed 395  km/h / 245 mph
Range 1.270 km / 790 mi
Maximum Service Ceiling 8,500 m / 27,890 ft
Climb speed Climb to 5,000 m in  13.6 minutes
Crew Pilot, navigator, and two gunners
Armament
  • Six 7.62 mm ShKAS machine guns
  • Two 1,000 kg bombs or four 500 kg bombs

Illustration

Credits

Source:

  • Y. Gordon and B. Gunston (2000), Soviet X-Planes, Midland Publishing
  • D. Nešić (2008), Naoružanje Drugog Svetskog Rata SSSR, Beograd
  • Y. Gordon and D. Khazanov (1999), Soviet Combat Aircraft Of The Second World War, Midland Publishing
  • B. Gunston (1996),  The Osprey Encyclopedia Of Russian Aircraft 1875-1995, Osprey Aerospace
  • W. Kopenhagen (1989) Sowjetische Bombenfluhzeuge , Transprees

 

 

Fw 190 Höhenjäger 2

Nazi Germany (1942)

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.

 

Credits

Written By Henry H.

Edited By Henry H.

Illustration by Oussama Mohamed “Godzilla”

 

Sources:

Primary:

Pilot Training Manual for the P-47 Thunderbolt. AAF Office of Flying Safety. March 1945.

Motorhandbuch zum Mercedes-Benz-Flugmotor DB 603A Baureihe 0,1 und 2. Daimer-Benz A.-G. 1942.

Fw 190A-5/A-6 Flugzeug-Hanbuch Tiel 1: Rumpfwerk. Der Reichsminister der Luftfahrt und Oberbefehlshaber der Luftwaffe. 1943.

Fw 190A-5/A-6 Flugzeug-Hanbuch Tiel 3: Leitwerk. Der Reichsminister der Luftfahrt und Oberbefehlshaber der Luftwaffe. 1943.

Fw 190 A-2 bis A-6 Flugzeug-Handbuch Tiel 1 Rumpfwerk. Der Reichsminister der Luftfahrt und Oberbefehlshaber der Luftwaffe. 1943.

Fw 190 A-2 bis A-6 Flugzeug-Handbuch Tiel 2 Fahrwerk. Der Reichsminister der Luftfahrt und Oberbefehlshaber der Luftwaffe. 1943.

Horizontalgeschwindigkeit über der Flughöhe, Normaljäger Fw 190 A-5. 20.10.1943

Flugzeug Flugleistungen Me 109G-Baureihen. Messerschmitt AG Augsburg. August 1943.

Secondary

Cooper, M. The German Air Force, 1933-1945: An Anatomy of Failure. Jane’s Pub, 1981.

Douglas, Calum E. Secret Horsepower Race: Second World War Fighter Aircraft Engine Development on the Western Front. TEMPEST, 2020.

Smith, J. & Creek, Eddie. Focke-Wulf Fw 190, Vol. 2: 1938-1943. Specialty Pr Pub & Wholesalers. 2015.

Smith, J. & Creek, Eddie. Focke-Wulf Fw 190, Vol. 1: 1944-1945. Specialty Pr Pub & Wholesalers. 2015.

Brown, Eric Melrose. Wings of the Luftwaffe. Hikoki, 2010.

The Focke Wulf 190 A Famous German Fighter. Heinz J Nowarra. Harleyford Publications. 1973.

 

Hafner Rotabuggy

UK Union Jack 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.

The experimental Hafner Rotabuggy. Source: www.macsmotorcitygarage.com

An Airborne Dilemma

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.uk
The 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.ru
The 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.

Hafner Rotabuggy  Specifications

Length 2.9 m / 9  ft 6 in
Height 2.06 m / 6  ft 9 in
Main rotor Area 15.9 m² /  173 ft²
Engine None / ( 60 hp in Jeep)
Empty Weight (for Jeep only) 964 kg / 2,125lbs
Maximum Takeoff Weight 1,411 kg / 3,110 lbs
Maximum estimated speed 241 km/h / 150 mph
Cruising estimated speed 130 km/h / 80 mph
Crew Two – The pilot and the driver
Armament
  • none

Illustration

 

Credits

 Source:

   

Fw 189C 

Nazi flag Nazi Germany (1939)

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 Unsuccessful Ground Attack Variant of the Fw 189. (Source: planehistoria.com)

A Modern Reconnaissance Aircraft

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.

The first Fw 189V1 prototype. (Source: wikipedia)

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.

Fw 189C (Estimated) Specifications

Wingspans 18.4 m / 60 ft 4 in
Length 12 m / 39 ft 5 in
Height 3.1 m / 10 ft 2 in
Wing Area 38m² / 410 ft²
Engine Two 465 hp Argus As 410A-1 engines
Crew pilot, rear gunner
Armament
  • Two 2 cm MG 151.20
  • Four 7.92 mm MG 17
  • And two 7.92 mm MG 81

Illustration

Credits

Source:

  • D. Donald (1996) German Aircraft of World War II, Orbis Publishing
  • D. Nesic  (2008)  Naoružanje Drugog Svetsko Rata-Nemacka
  • D. Monday (2006) The Hamlyn Concise Guide To Axis Aircraft OF World War II, Bounty Books
  • J. R. Smith and A. L. Kay (1972) German Aircraft of the WW2, Putnam
  • G. Punka (1993) Focke-Wulf Fw 189 in Action, Signal Publication
  • Captain E. ‘Winkle’ Brown (2010) Wings of the Luftwaffe, Hikoki Publication
  • https://vintageaviationnews.com/warbirds-news/unique-focke-wulf-fw-189-offered-for-sale.html

 

 

Me 261

Nazi flag Nazi Germany (1938)

Type: High endurance experimental, reconnaissance aircraft

Number built: Three prototypes

Before the outbreak of the Second World War, the Luftwaffe (Eng. German Air Force) was undergoing a massive expansion. Numerous new aircraft designs were either being introduced into service or undergoing testing, with many being integrated into the military for various roles. A number of newly developed aircraft were also primarily used for evaluation and experimentation, and, there were also several designs created specifically to set records. One such aircraft, the Me 261, was built specifically at the request of Adolf Hitler to set long-range records. Due to its specialized role, and the fact that it was not initially ordered by the Luftwaffe, only three prototypes of the Me 261 were built.

The rather obscure Me 261 long-range transport and recconaissance aircraft. Source: alternathistory.ru

History

With the rise of Nazis in Germany, substantial financial resources were allocated to military projects. The Luftwaffe was founded, and saw massive expansion and the introduction of new aircraft designs. However, not all these designs were intended for pure military service. Some projects were mainly aimed at experimentation, and among these were aircraft designed solely to showcase technological advancements and break world records. This trend was quite common in the years leading up to the outbreak of the Second World War in Europe. For example, the Messerschmitt Me 209 was created to set a world speed record, with little to no concerns made over a possible military application.

Speed was not the only record to be pursued, there were others, such as long-range flight. This particular challenge fascinated Hitler, who in 1937, initiated the development of a long-range monoplane. Aside from the many things that might be learned from the experiment, Hitler envisioned this aircraft undertaking the long-range flight from Berlin to Tokyo for the 1940 Olympic Games, carrying the Olympic Torch from Germany over Asia. To meet this requirement, the initial requirements specified that the aircraft needed to have an operational range of over 13,000 km.

The Reichsluftfahrtministerium (RLM), or German Air Ministry, selected the Messerschmitt company for this task. Despite being a relatively small enterprise at the time, Messerschmitt had achieved great success with the Bf 109, one of the best fighters of its era. The official contract was signed on the 18th March, 1938. Under the designation P.1064, Messerschmitt presented a proposal to Hitler for a new aircraft. This aircraft was to be operated by a crew of five within a rather cramped, and elongated fuselage. Due to the aircraft’s specific role, the fuel load was prioritized over crew comfort. Hitler approved the proposal and ordered the construction of three prototypes. The project was subsequently renamed Me 261. Due to Hitler’s keen interest, the aircraft was nicknamed Adolfine by its crew.

In 1939, work began on the three Me 261 prototypes. Despite Hitler’s ambitions, the Me 261 was given low priority, and construction proceeded slowly, and anticipating a war with Poland, work on these aircraft was halted. However, recognizing its potential for long-range reconnaissance and the valuable information it could provide, work resumed in 1940.

The first prototype, Me 261 V1 (BJ-CP or BC-CP, depending on the sources), was flight-tested by Karl Baur in December 1940. The following year, the second prototype, Me 261 V2 (BJ-CQ), was tested. The V2 featured a glazed observation dome on the dorsal fuselage, replacing the rear dome used on the V1. The construction of the third prototype, Me 261 V3 (BJ-CR), faced delays and only completed its test flight in 1943. This version was distinct from the earlier prototypes, featuring a larger crew capacity of seven and being powered by two 2,950 hp DB 610 engines. On the 16th April, 1943, Karl Baur conducted a ten-hour test flight with the V3.

 

The last of the Me 261 was the V3 prototype, which was powered by stronger engines. Source: airpages.ru

Technical characteristics

Unfortunately, since the Me 161 did not progress beyond the prototype stage. It was designed as an all-metal, long-range transport and later as a reconnaissance aircraft. The fuselage was slim but cramped, made of metal, and covered in duralumin.

The wings of the Me 261 were constructed using a metal frame with a single spar. They were then covered with flush-riveted, stressed-skin metal panels. Notably, the section of the wing closest to the fuselage had a thick profile, which tapered to the wingtips. This design was intentional, as it allowed for a large fuel storage area. The aircraft also featured a twin-rudder tail at the rear.

For its long-range flight operations, the Me 261 had a crew of five: a pilot, co-pilot, radio operator, navigator, and flight engineer. The pilot and copilot sat side-by-side in the cockpit with the radio operator in a central compartment, and the flight engineer and navigator seated in the rearmost compartment, where the aircraft’s bunks were also located.

The first two prototypes were powered by twin 2,700 hp DB 606A/B twenty-four-cylinder engines. These engines were essentially two twelve-cylinder DB 601 engines coupled together to drive a single shaft, requiring two separate radiators and oil coolers. Each DB 606A/B engine was housed within a large nacelle and used four-blade propellers with a diameter of 4.6 meters.

The Me 261 DB 606A/B twenty-four-cylinder engine consisted of two coupled twelve-cylinder DB 601 engines. They worked well on the He 261 and no major issue was reported with it. Source: oldmachinepress.com

Despite frequent mentions of the aircraft being overburdened, sources do not specify a consistent maximum takeoff weight. Additionally, the total fuel capacity is also unspecified. Depending on the sources, the operational range varies from 11,000 to 13,200 km.

To accommodate the aircraft’s weight, it required large-diameter landing wheels that could retract up to 90 degrees into the wings. In addition to these, it had a fully retractable tail wheel retracted towards the front of the aircraft.

The Me 261 was designed as an all-metal, long-range transport and later as a reconnaissance aircraft source: Wikipedia
The first two prototypes were powered by twin 2,700 hp DB 606A/B twenty-four-cylinder engines. To cope with their weight, it was provided with two large-diameter landing wheels. Source: planehistoria.com
Side view of the second prototype. Source:  alternathistory.ru

Fate

Despite demonstrating some potential for long-range reconnaissance, the Me 261 was ultimately rejected from service due to the additional equipment requirements that would have further strained its already overburdened airframe, thereby compromising its flight performance. Despite its cancellation, the V3 prototype (and possibly the other two prototypes) saw operational use as reconnaissance aircraft during the war. In July or April of 1943, the V3 suffered an accident during landing that heavily damaged its landing gear. Although repaired and returned to service, the V3 was eventually scrapped by order of the RLM.

The V1 aircraft was lost during an Allied bombing raid on the Rechlin test center in September 1944, while the V2 was captured by the Allies at the same location in April 1945. Neither prototype survived the war; the captured V2 was scrapped a few weeks after its capture.

The V3 aircraft was damaged during a landing accident but was repaired and put back into service. Source: www.destinationsjourney.com
The V2 was captured by the Allies and was eventually scraped. Source: planehistoria.com

Conclusion 

The Me 261 was an aircraft that was not ordered by the Luftwaffe as a military aircraft and thus received low priority. Despite its initial potential for use as a reconnaissance aircraft, it quickly became evident that it would not be feasible for adoption in this role due to its considerable weight. Ultimately, only three were built, and none of them survived the war.

Me 261 V3 Specifications

Wingspans 26.9 m / 88 ft 1 in
Length 16.7 m / 54  ft 9 in
Height 4.72 m /  15 ft  5 in
Wing Area 76 m² /  817.8 ft²
Engine Two 2,950 hp DB 610 engines
Endurance 24 hours and 36 minutes
Maximum Speed 620 km/h / 385mph
Cruising speed 400 km/h / 248 mph
Range 11,000 km / 6,831 miles
Maximum Service Ceiling 8,250 m  / 27,060 ft
Crew 1 pilot
Armament
  • None

Illustration

Credits

  • Article written by Marko P.
  • Edited by  Henry H.
  • Illustration by Oussama Mohamed “Godzilla”

Source:

  • D. Herwig and H. Rode (2000) Luftwaffe Secret Projects Strategic Bombers 1935 to 1945, Midland Publishing
  • D. Nesić  (2008)  Naoružanje Drugog Svetsko Rata-Nemačka. Beograd
  • D. Monday (2006) The Hamlyn Concise Guide To Axis Aircraft OF World War II, Bounty Books.
  • J. R. Smith and A. L. Kay (1972) German Aircraft of the WW2, Putnam

 

ANT-2

USSR flag USSR (1923)
All-metal passenger aircraft – five built

Following his successful first attempt to develop an aircraft, Andrei Nikolayevich Tupolev felt confident in his ability to attempt the design an all-metal aircraft. Although some European nations had already tested or built such aircraft during the First World War, this concept was still novel in the burgeoning Soviet Union of the early 1920s. With the advent of duralumin production in the Soviet Union, and the experimentation with various construction methods, Tupolev began work on the aircraft known as the ANT-2 in 1922. After a period of testing and evaluation, five aircraft of this type were constructed.

Tupolev ANT-2 was the Soviet first operational all-metal aircraft. Source: P. Duffy and A. Kandalov Tupolev The Man and His Aircraft

History

The success of the ANT-1 (standing for the initials of Andrei Nikolayevich Tupovlev) test aircraft prompted Tupolev to advocate for the development of fully metal-constructed aircraft. The harsh weather conditions in many parts of the Soviet Union caused wooden materials to decay quickly. Metal alloys, on the other hand, offered numerous advantages over wood: they were stronger, more durable, and allowed for overall more resilient aircraft designs. Tupolev saw the use of wood in modern aviation as an obsolete construction material.

His view was shared by others in the burgeoning Soviet aviation industry. In 1922, a commission at the Central Aero/Hydrodynamics Institute (TsAGI) was formed under the leadership of Andrei Nikolaevich. Its purpose was to spearhead the development of factories and facilities capable of producing duralumin. One such production center was already operating in Kolchuginsk, near Moscow, where the production of duralumin, nicknamed “Kolchugaluminium”, began in September 1922. This development enabled Tupolev to start working on an all-metal aircraft.

Tupolev established his design bureau with 15 supporting members. However, the initial phase was challenging, as the new technology required skilled workers who needed training in this new field. Additionally, many components used in all-metal aircraft construction had to undergo extensive testing. Tupolev, being a cautious man, did not want to risk any pilot’s life before he was certain that the new all-metal aircraft would perform as intended. Consequently, he spent considerable time refining various designs, mostly using speedboats and gliders. In 1921, Tupolev spent some time testing his ideas and designs using speedboats from his base of operations in Crimea. The experience he gained there greatly helped him in his further work.

Work On the ANT-2

As soon as Tupolev was sure that all crucial components were sufficiently tested, the work on the new all-metal aircraft, designated ANT-2, began in 1923. The design was largely driven by the requirements of the Soviet UVVS-RKKA (Directorate of the Air Fleet of the Workers and Peasants). This was the first official request for a new military aircraft, one capable of transporting two passengers, armed with two machine guns, and would most importantly, be inexpensive to build. Tupolev and his team established a small workshop in Kolchuginsk.

Initially, there were problems as the Kolchuginsk factory was only known for producing duralumin, not for shaping it into the various forms needed for aircraft construction. Time was needed to train the workers to effectively shape duralumin into the necessary parts.

During this period, while working on various proposed designs, Tupolev had the opportunity to inspect a Junkers K16 transport aircraft. The German company Junkers, wanting to avoid the sanctions on arms and aviation development imposed by the Allies, sought cooperation with the Soviets. They even managed to set up a small production plant in the Soviet Union.  The Soviets, in turn, were eager to acquire new technologies. The Junkers K16 featured a high wing and an open cockpit, design characteristics that Tupolev incorporated into his ANT-2 project.

The Junkers K16 served as inspiration for the ANT-2 Source: Wiki
The ANT-2, when compared to the K16, exhibits many similarities in overall shape. While Tupolev drew inspiration from the K16, he did not merely replicate it. Instead, he used it as a foundation to experiment with many of his own design elements, particularly in its wings. Source: en.topwar.ru

The prototype was completed in 1924 and underwent its first flight test in late May of that year, piloted by Nikolai Petrov. To simulate the weight of two passengers, two sandbags were used, as Tupolev did not want to risk any lives at the prototype stage. Further flight tests were conducted on May 28 by a Soviet military delegation. Starting from June 11, the ANT-2 was tested with two, and occasionally three, passengers inside its fuselage. Overall, the performance was deemed sufficient, though a significant modification was required for the rear tail assembly. The rudder and stabilizer size had to be increased, subsequently improving the aircraft’s performance. To conduct further tests, four more aircraft were built. By 1930, at least one of these aircraft was equipped with a more powerful 200 hp Wright Whirlwind engine.

Fate

A total of five ANT-2 aircraft were produced. While these were used for various tests, their specific operational roles are not well documented. The anticipated military variant, which was to feature a new cockpit positioned behind the wings and be armed with one or two machine guns, was never built. The first aircraft has been preserved and can be seen at the Aviation Museum in Monino, near Moscow. The fate of the remaining aircraft is unclear, but they were likely scrapped at some point.

The only surviving ANT-2 can be seen at the Aviation Museum Monino near Moscow. Source: Wiki
In recognition of its significant role in Soviet aviation history, the ANT-2 was featured on a Soviet postage stamp. Source: stock.adobe.com

Specification

The ANT-2 was designed as a high-wing, all-metal monoplane. Tupolev chose a triangular shape for the fuselage, with the sides sloping inward from top to bottom. This triangular design provided excellent structural integrity, reducing the need for additional fuselage struts. The fuselage was divided into three sections: the front section housed the engine, the open cockpit, followed by a small passenger compartment. The compartment could accommodate two passengers seated opposite each other. Although the aircraft was intended for three occupants, this was generally avoided due to weight limitations. Passengers entered the aircraft through a door on the left side of the fuselage.

The wing was located just behind the cockpit. It was constructed with two spars connected by 13 ribs on each side and covered with duralumin. Tupolev designed the wing with a curved, concave underside. The entire wing assembly was then attached to the top of the fuselage using four bolts. To accommodate the cockpit, part of the central section of the wing was cut off. Additionally, two handles were added to the ends of the wings on both sides, allowing the ground crew to maneuver the aircraft on the ground. The rear tail assembly consisted of a metal frame covered with duralumin.

The landing gear featured two fixed road wheels mounted on vertical struts, equipped with shock absorbers to ensure smoother landings. At least one aircraft was instead fitted with skis. A pivoting tail skid was used at the rear.

It was powered by a Bristol Lucifer three-cylinder engine producing 100 horsepower. With it a maximum speed of 170 km/h could be achieved. This engine, however, had some difficulties due to its significant torque, which could occasionally damage the engine mounts. Topolev, aware of this issue, designed a strong mount to counteract this problem. To allow access for repairs, the engine cover was secured with a few bolts. The engine drove a wooden two-blade propeller with a diameter of 2.2 meters. Fuel was stored in two 36 kg tanks located in the wings.

The cockpit was open, and to enter, the pilot used a small footrest on the left side of the fuselage. The cockpit was equipped with the basic and necessary controls and indicators, such as fuel level, RPM counter, and oil pressure gauge.

The ANT-2 was powered by a Bristol Lucifer three-cylinder engine producing 100 hp with a wooden two-blade propeller with a diameter of 2.2 meters. Source: Wiki
At least one aircraft was fitted with skis. Source: en.topwar.ru
The wings were constructed using two spars connected by 13 ribs on each side and covered with duralumin. Source:  en.topwar.ru
A good view of the real tail assembly. Source: www.valka.cz
The small passenger compartment was located inside the fuselage. Source: Wiki
Top view of the pilot’s open cockpit. Source:  en.topwar.ru

Conclusion

While the ANT-2 did not enter mass production, this was less important as it showed that the concept of using metal for the construction of a fully functional aircraft was feasible. It was the first stepping stone of the new, and slowly rising, Soviet aviation industry. It was the first such aircraft to be successfully tested by the Soviets, and paved the way for further Tupolev’s research and work, which enabled him to develop, in time,  more advanced designs. In addition, it was the first aircraft that was officially ordered by the Soviets for limited production.

ANT-2 Specifications

Wingspans 10.45 m / 34 ft 3 in
Length 7.6 m / 24 ft 11 in
Height 2.12 m / 6 ft 11 in
Wing Area 17.9 m²  / 193 ft²
Engine One
Empty Weight 523 kg / 1,153 lb
Maximum Takeoff Weight 837 kg / 1,846 lb
Maximum Speed 170 km/h / 106 mph
Range 750 km/ 466 miles
Maximum Service Ceiling 3,300 m / 10,926 ft
Crew 1 pilot
Armament
  • None

Illustration

 

Credits

  • Article written by Marko P.
  • Edited by  Henry H.
  • Illustrations by Oussama Mohamed “Godzilla”

Sources:

  • Duško N. (2008)  Naoružanje Drugog Svetsko Rata-SSSR. Beograd.
  • Y. Gordon and V. Rigmant (2005) OKB Tupolev, Midland
  • P. Duffy and A. Kandalov (1996) Tupolev The Man and His Aircraft, SAE International
  • B. Gunston () Tupolev Aircraft Since 1922, Naval Institute press

 

Me 309Zw (Me 609)

Nazi Germany (1944)

Proposed Fighter Design

During the war, Messerschmitt endeavored to find potential successors to their existing aircraft models. This quest yielded several aircraft proposals, one of which was the Me 309, which they sought to replace their older Me 109 fighter with. Despite Messerschmitt’s hopes for its success, the Me 309 proved to be unreliable and mechanically flawed, leading to its rejection for adoption. Undeterred by this setback, Messerschmitt persisted with the project, eventually turning their attention to a new twin-fuselage fighter, often referred to in various sources as the Me 609.

Artistic 3d model of the “Me 609” . Source: www.3dcadbrowser.com

A Brief History of Germany Twin-Fighter Program History

In the early stages of the war, the Messerschmitt Me 109 emerged as an exceptional fighter, arguably one of the world’s best at the time. However, despite its prowess, there remained ample room for improvement in its design. By the early 1940s, engineers at Messerschmitt began exploring avenues to enhance its overall flight performance. Among the considerations was the idea that while one engine delivered outstanding results, pairing two engines might yield even greater capabilities, bringing an increase in operational range and top speed. This notion laid the groundwork for a bold project: combining two Me 109s into a single aircraft, designated as the Me 109Z, with the ‘Z’ representing the German word “Zwilling”, meaning twin. The concept aimed to harness the power of dual fuselages and engines to significantly enhance both performance and firepower, envisioning the aircraft as either a formidable destroyer or a fighter bomber.

In theory, the design was relatively straightforward: merging two fuselages along with a central wing. The cockpit would be positioned within one of the fuselages, along with modifications to the landing gear. Despite the unconventional approach, a functional prototype utilizing two Me 109Fs was successfully constructed in 1942. However, the evaluation and test flight process extended until 1943, during which the prototype was either lost or severely damaged in one of the numerous Allied bombing raids.

Amidst the pressing demands of concurrent projects, such as the development of the Me 262, the Me 109Z initiative was ultimately abandoned, reflecting the shifting priorities and challenges faced by German engineers during the Second World War .

An Me 109Z drawing. Source: www.luft46.com

A Second Option 

Another Messerschmitt project aimed at enhancing the performance of the Me 109 was the Me 309. This new endeavor sought substantial improvements, integrating several new features such as enhanced armament, a pressurized cockpit, a tricycle undercarriage, and retractable radiators. Initiated by Messerschmitt in 1940, the project faced reluctance from the German Aviation Ministry (RLM), leading to significant delays. It wasn’t until the end of 1941 that actual work on the project began. Despite these challenges, the first Me 309 V-1 prototype was completed in June 1942, followed by a few more test models. However, the project encountered various mechanical issues that remained unresolved, including engine overheating, the problematic landing gear which caused the aircraft to crash onto its nose should the nose gear fail, and flight instability, among other issues. As a result, the RLM showed little enthusiasm for the Me 309, prioritizing increased production of the Me 109 instead. Introducing another fighter design would also inevitably lead to production delays. Moreover, refining the Me 309 design would likely necessitate additional time, possibly extending into months or even years. Consequently, a decision was made to abandon the development of the Me 309 entirely.

The Me 309 was an attempt to develop a completely new fighter to replace the Me 109. Given its many mechanical flaws, it did not go beyond the prototype stage. Source: /www.luftwaffephotos.com

However, Messerschmitt hoped that proposing a new variant of the twin-fuselage fighter based on the Me 309 might renew interest from the RLM. Unfortunately, this strategy didn’t yield the desired results. Despite some initial drawings, the aircraft designated as the Me 609 was abandoned at the beginning of 1944 in favor of the Me 262.

A drawing of the proposed “Me 609” aircraft. Source: D.Sharp Luftwaffe: Secret Designs of the Third Reich

Technical characteristics

Given that it was a paper proposal, and no working prototype was built, its overall technical specifications are rather obscure. In essence, the Me 609 consisted of paired Me 309 fuselages which were joined together by a central wing section. Given this fact, in theory, most of the components for this aircraft would be available and reused from the Me 309. The Me 309 was conceived as a single-seat fighter, featuring an all-metal construction with a low-wing design. So we can assume that the new Me 609 would also follow a similar construction.

The two fuselages were connected with the new inner wing section. Besides this, it also served to house the two main landing gear units. The nose wheel was located under the engine, and retracted to the rear. The pilot’s pressurized cockpit was located on the left fuselage, while; the right-sided fuselage had its cockpit covered.

The Me 309 used an unusual, at least for the Germans, tricycle landing gear unit. Source: www.luftwaffephotos.com

Depending on the source it was either powered by a  Daimler Benz 603 or 605 or a  2,000hp Jumo 213E june engine. In the case of the latter, the estimated maximum speed was to be 760 km/h. All of which were inverted V-12 engines.

The main armament was to consist of two 3 cm MK 108 and Two MK 103 cannons. Including either two 250 kg or one 500 kg bomb. Two more cannons could be mounted under the center wing section.

The Truth of it

The information as previously mentioned, however, may not be entirely accurate. According to various sources such as D. Herwing and H. Rode (Luftwaffe: Secret Projects Ground Attack and Special Purpose Aircraft), as well as several internet sources, it is asserted that the twin-fuselage Me 309 variant was designated as the Me 609. Contrary to this, D. Sharp (Luftwaffe: Secret Designs of the Third Reich) argues that this designation was incorrectly assigned to the project. The actual designation for it was Me 309 Zw (Zw standing for Zwilling, meaning twins). Claiming, the Me 609 was unrelated to this project. Sharp supports this assertion by citing surviving Messerschmitt documentation salvaged after the war, in which the projects are referred to as 309 Zw. Thus, the twin-fuselage fast bomber/destroyer based on the Me 309 existed only as a proposal, albeit under a different name.

Now, what about the aircraft bearing the Me 609 designation? Simply put, it did not exist. In reality, it was a designation that Messerschmitt applied to describe the Me 262 twin-engine fighter. Why this designation was used remains unknown, but it may have been employed to deceive the intelligence offices of the Western Allies

The evidence for the claim of the wrong designation lies in the old Messerschmitt documentation salvaged after the war. Here we can see the Me 262 which was for an unknown reason referred to as Me 609. Source: D. Sharp Luftwaffe: Secret Designs of the Third Reich

Conclusion 

The Me 309Zw project was an intriguing endeavor aimed at enhancing the overall performance of German fighters by integrating two fuselages. However, it failed to progress beyond the prototype stage, leaving us unable to determine its feasibility.

Me 309Zw Estimated Specifications

Wingspans 16 m / 52  ft 6  in
Length 9.52 m / 31 ft 2 in
Height 3.24 m / 10 ft  7 in
Wing Area 26.755 m² /  288 ft²
Engine Two 2,000hp Jumo 213E
Empty Weight 5,247 5kg / 11,660 lbs
Maximum Takeoff Weight 6,534kg / 14,520 lbs
Maximum Speed 760 km/h / 472mph
Crew 1 pilot
Armament
  • Two MK 108 and Two MK 103
  • Bomb load two 250 kg or one 500 kg

Illustration

 

Credits

  • Written by Marko P.
  • Edited by Henry H.
  • Illustrations by Oussama Mohamed “Godzilla”

Source:

  • D. Nesić  (2008)  Naoružanje Drugog Svetsko Rata-Nemačka. Beograd.
  • D. Monday (2006) The Hamlyn Concise Guide To Axis Aircraft OF World War II, Bounty Books.
  • J. R. Smith and A. L. Kay (1972) German Aircraft of the WW2, Putnam
  • D. Myhra (2000) Messerschmitt Me 209V1, Schiffer Military History
  • M. Griehl () X-planes German Luftwaffe prototypes 1930-1940, Frontline Book
  • D.Herwing and H. Rode (2002) Luftwaffe: Secret Projects Ground Attack and Special Purpose Aircraft, Midland
  •  D.Sharp (2018) Luftwaffe: Secret Designs of the Third Reich, Mortons

 

Me 309

Nazi Germany (1943)

Fighter: Four prototypes Built

The Messerschmitt Me 109, although an outstanding aircraft, still had room for improvement. Its most noticeable shortcomings included a rather small operational radius, significantly reducing its combat potential in prolonged engagements. To address this, Messerschmitt initiated the development of a successor model designated as the Me 309. However, from the outset, this new fighter was plagued with numerous mechanical faults that could not be resolved in the foreseeable future. Consequently, only four prototypes were built before the project was ultimately canceled.

The Me 309 first prototype. Source: https://www.luftwaffephotos.com/lme2091.htm

History

At the onset of the Second World War, Germany relied heavily on the Me 109 as its primary fighter aircraft. Renowned for its exceptional performance and cost-effectiveness, the Me 109 outmatched most of the enemy fighters it encountered over Europe. Following the fall of France in June 1940, Germany launched a significant bombing campaign against the UK. This prolonged engagement highlighted a critical issue: the Me 109’s limited operational range prevented it from carrying out long-range fighter sweeps, or being usable as a bomber escort.

Recognizing the urgent need for enhancements, Messerschmitt began experiments on improving the performance, and range, of the Me 109. Initial assessments underscored the necessity for substantial improvements, including an 85% increase in operational range and a minimum 25% boost in maximum speed. Additionally, there were aspirations to augment its firepower, introduce a pressurized cockpit, implement a tricycle undercarriage, and incorporate retractable radiators. Before commencing work on a completely new fighter, Messerschmitt opted to experiment with these features by modifying an existing Me 109F

Some of the changes such as the tricycle undercarriage were first tested on one Me 109. Source: https://militarymatters.online/forgotten-aircraft/the-messerschmitt-me-309-redundant-beauty/

The new fighter project was initiated by Messerschmitt in 1940. However, the German Aviation Ministry (RLM) was not enthusiastic about it, after significant delays. Actual work on the project didn’t commence until the end of 1941. The project, designated Me 309, was led by Woldemar Voigt and Richard Bauer. It’s worth noting that Messerschmitt’s previous attempt to develop a fighter, based on the record-breaking Me 209, failed because its airframe wasn’t suitable for military purposes. Despite the RLM’s initial skepticism towards the Me 309, they eventually ordered nine prototypes.

The side view of the Me 209V1 prototype. While initially used as a speed record-breaker, Messerschmitt tried to adopt it for the military role but ultimately failed in this. Source: ww2fighters.e-monsite.com

The first Me 309 V-1 (GE-CU) prototype was completed in June 1942, and immediately underwent ground trials at the end of that month. However, almost from the outset, a major issue became apparent, the new landing wheel configuration proved difficult to control on the ground. Subsequent flight tests revealed additional challenges, including strong vibrations at high speeds. In July 1942, after a series of modifications, the prototype underwent flight testing once more, only to encounter new problems with the landing gear. The hydraulic retraction system was found to be inadequate, and issues with engine overheating and aerodynamic instability persisted. On one occasion, test pilot Karl Baur was forced to abort the flight after just seven minutes in the air.

Addressing these issues required further modifications, including redesigning the tailplane and improving the hydraulic system for the landing gear. Despite these efforts, subsequent test flights did not yield significant improvements in the overall flight performance of the Me 309. Messerschmitt’s test pilot, Fritz Wendel, expressed dissatisfaction with the aircraft, noting that its flight characteristics were not markedly superior to those of the Me 109. He criticized the high landing speed and the poor design of the control surfaces.

Not ready to abandon the Me 309 prematurely, the first prototype underwent evaluation at the Rechlin test center for further assessment. On the 20th of November 1942, a report was issued deeming the overall performance of the Me 309 unpromising, even inferior to the new Me 109G. Consequently, the RLM reduced the initial production order from nine prototypes to just four. Initially, the RLM had little enthusiasm for the Me 309, and still preferred instead to prioritize increased production of the Me 109. Introducing another fighter design would inevitably cause production delays. Compounding the industrial challenges, perfecting the Me 309 design would likely require additional time,  months if not years of work.

Despite these setbacks, the development of the Me 309 continued at a sluggish pace. The first prototype was initially equipped with a 1,750 hp DB603A-1 engine. It would later be replaced by a 1,450 hp DB 605B engine instead during the testing phase. During one landing, the front landing gear collapsed, causing the aircraft to nose down. Fortunately, the damage sustained was minor. However, the same couldn’t be said for the second prototype (GE-CV), which underwent flight testing on November 28, 1942. Upon landing during its maiden flight, the front landing gear failed, resulting in a hard impact on the ground. The force of the impact nearly split the aircraft into two parts, rendering it extensively damaged and subsequently written off. Despite this setback, two more prototypes were constructed during 1943.

The Me 309 had a troublesome landing gear and a tendency to flip over the nose. In one such accident, the second prototype was lost. Source: https://militarymatters.online/forgotten-aircraft/the-messerschmitt-me-309-redundant-beauty/

Technical characteristics

The Me 309 was conceived as a single-seat fighter, featuring an all-metal construction with a low-wing design. There is limited information available regarding its overall construction. The fuselage was of an oval shape, while the wings were characterized by a dihedral angle with rounded tips, accompanied by automatic leading-edge slots for better maneuverability at low speed. Notably, the wings also incorporated large flaps extending from the wing roots to the ailerons’ end. The canopy was fully glazed, affording excellent visibility of the surroundings.

There is some disagreement among available sources regarding the precise engine used in this aircraft. According to J.R. Smith and A.L. Kay in (German Aircraft of WWII) it was initially powered by a 1,750 hp DB 603A-1 engine, which enabled the Me 309 to achieve a maximum speed of 733 km/h at an altitude of 8,500 meters. This claim is supported by B.C. Wheeler in (Aviation Archive: German Fighters of WWII)  although Wheeler does not specify which DB 603 engine was used. On the other hand, Jean-Denis G.G. Lepage, in (Aircraft of the Luftwaffe) mentions that the Daimler-Benz DB 603G engine model was used, with the same maximum speed being achieved. The DB 603G is the likely most correct engine used on the Me 309, considering it was an experimental high-altitude model that never entered mass use.

The later prototypes were powered by a smaller 1,450 hp DB 605B engine. Even the first prototype was eventually reequipped with this engine. As a result, the overall performance dropped significantly to 575 km/h, according to D. Nesić (Naoružanje Drugog Svetsko Rata-Nemačka).

With a fuel capacity of 880 liters, its operational range extended to 1,400 km. Equipped with a retractable ventral radiator positioned under the fuselage, the aircraft’s landing gear retracted inward into the wings. A notable departure from convention was the absence of the standard tailwheel; instead, it featured a nosewheel, retracting rearward into the fuselage’s front section.

The Me 309 was initially tested with the DB 603A-1 engine with which it achieved a maximum speed of 733 km/.h. Source: http://www.luftwaffephotos.com/lme2091.htm
Rear view of the Me 309. Source: http://www.luftwaffephotos.com/lme2091.htm
The Me 309 incorporated some new features such as the new landing gear and a retracting radiator both of which can be seen here. Source: airpages.ru

Fate

Despite the considerable investment of time and resources into the Me 309 project, its overall flight performance fell short, ultimately leading to the project’s demise. By the beginning of 1943, the RLM had lost interest in the aircraft, prompting the cancellation of the project after the completion of four prototypes. Despite the cancellation, Messerschmitt proceeded to develop two additional prototypes.

One of these, the Me 309V-3 (CA-NK or CA-CW), was intended as a replacement for the lost V-2 prototype. Its maiden flight took place in March or April of 1943. The fourth prototype marked a significant milestone as it was the first to be equipped with offensive armament, including four 13 mm MG 131 (300 rounds), two 20 mm MG 151 (150 rounds), and two 30 mm MK 108 (65 rounds) cannons. Alternatively, it could be outfitted with two 15 mm MG 151 cannons and three 13 mm MG 131s. Although these armaments were primarily experimental and not used operationally, they were essential for various testing purposes.

Unfortunately, the fate of the last two prototypes remains unclear, with records suggesting they were lost during Allied bombing raids in 1944.

Despite the Messerschmitt hope the Me 309 would not be adopted for service, and the few built prototypes would be mainly used for various testing and evaluation. Source: http://www.luftwaffephotos.com/lme2091.htm

Even before the official cancellation, Messerschmitt officials were hopeful for a larger production order. To this end, they presented several variant proposals for the Me 309. The Me 309A was designed as a fighter variant, equipped with one MG 151 cannon and two MG 131 machine guns. The Me 309B was intended to serve as a fighter-bomber variant, armed with two 250 kg (550 lbs) bombs. As for the Me 309C, it was designed as a destroyer, featuring three MG 151 cannons and up to four MG 131s. An intriguing proposal was the Me 309 Zwilling (Eng. Twins), which involved two aircraft joined together in a configuration reminiscent of the post-war US F-82, but ultimately, this concept did not materialize.

A drawing of the proposed Me 309zw aircraft. Source: D.Sharp Luftwaffe: Secret Designs of the Third Reich

 

Interestingly in 1944 Japan expressed interest in its design and asked for plans and drawings of the Me309V-3 aircraft. But nothing came of this in the end.

Prototypes

  • Me 309V-1 – First prototype powered by a  1,750 hp DB 603A-1 engine
  • Me 309V-2 –  Second prototype lost during the first test flight
  • Me 309V-3 – This prototype was built in early 1943 as a replacement for the second prototype
  • Me 309V-4 – First prototype to be armed.

Proposed Variants

  • Me 309A – Proposed fighter variant
  • Me 309B – Proposed  fighter-bomber variant
  • Me 309C –Proposed destroyer variant
  • Me 309zw- Proposed twi-aircraft configuration

Conclusion 

The Me 309, despite the investment and the hope that it would be an adequate successor to the Me 109, proved to be a troubled design and pulled down by wartime pragmatism. From the start, it was plagued by various mechanical problems that were never resolved. The fact that RLM was never interested that much in such a project did not help either. As it would take considerable time to fully remediate all the noted issues, the project was abandoned in favor of the latter Me 262.

Me 309V-1 Specifications

Wingspans 11.04 m / 36  ft 2  in
Length 9.46 m / 31 ft 1 in
Height 3.4 m /  ft
Wing Area 16.55 m² /  178.08 ft²
Engine One 1,750 hp DB 603A-1
Empty Weight 3,530 5kg / 7,784 lbs
Maximum Takeoff Weight 4,250 kg / 9,371 lbs
Maximum Speed 733 km/h / 455 mph
Cruising speed 665 km/h / 413 mph
Range 1,400 km / 870 miles
Maximum Service Ceiling 12,000 m  / 39,360 ft
Climb to 8 km In 10 minutes
Crew 1 pilot
Armament

Illustration

Credits

  • Written by Marko P.
  • Edited by Henry H.
  • Illustrations by Oussama Mohamed “Godzilla”

Source:

  • D. Nesić  (2008)  Naoružanje Drugog Svetsko Rata-Nemačka. Beograd.
  • D. Monday (2006) The Hamlyn Concise Guide To Axis Aircraft OF World War II, Bounty Books.
  • J. R. Smith and A. L. Kay (1972) German Aircraft of the WW2, Putnam
  • D. Myhra (2000) Messerschmitt Me 209V1, Schiffer Military History
  • M. Griehl () X-planes German Luftwaffe prototypes 1930-1940, Frontline Book
  •  D.Sharp (2018) Luftwaffe: Secret Designs of the Third Reich, Mortons
  • Jean-Denis G.G. Lepage (2009) Aircraft Of The Luftwaffe, McFarland & Company, Inc
  • B. C. Wheeler (2014) Aviation Archive German Fighters of WWII, Kelsey Publishing Group