Austro-Hungarian Empire (1916)
Triplane Bomber Prototype – 1 built
Front view of the Luftkreuzer colorized by Michael Jucan
The Lloyd 40.08 was a prototype triplane bomber built for Austria-Hungary under an order for a new bomber by the Luftfahrtruppen (LFT, Aviation Troops) in 1915. The 40.08 “Luftkreuzer” (Air Cruiser) was a twin boom design that would have carried 200 kg of bombs into battle. The aircraft had frequent problems with its design, such as being front-heavy and the center of gravity being too high. Attempts to fix the issues were minimal and it would never fly. The aircraft was sent to a scrapyard in the end, but it was an interesting venture of a now-defunct empire.
History
World War I showcased the first widespread use of combat airplanes and the subsequent specialization of aircraft to fit certain roles. Bombers proved their effectiveness and most countries involved developed some sort of bomber for their early air forces. One shining example is the Gotha series of bombers, which were able to bomb London and eventually replace Zeppelin raids entirely. The Austro-Hungarian Empire was no exception to building their own bombers. At the time, in 1915, Austria-Hungary was fighting on several fronts, with the ongoing Russian front dragging on and by May, Italy had joined and had begun fighting its neighbor. A new bomber would be a helpful addition to Austria-Hungary’s military.
Direct frontal view of the Luftkreuzer [armedconflict.com]In 1915, the Luftfahrtruppen sent out an order for a 3-engine bomber design. The exact date the order was given in 1915 is unknown, but it is very likely the order was a reaction to Italy joining the war, as similarly, Austria-Hungary attempted to buy Hansa-Brandenburg G.1 bombers to bolster their aircraft complement. The requirement specified that two engines would be mounted inside fuselages and the main engine in a central hull. The bomb payload would be 440 Ibs (200 kg) and defenses would be six machine guns mounted around the aircraft. Expected flying time was up to 6 hours. Given the long flying time, strategic bombing might have been in mind but the bomb load is much smaller compared to other bombers in the role. Tactical bombing would be more practical in the long run for the aircraft. Three companies would submit their designs and would be awarded funding: Oeffag, Phönix, and Lloyd.
Lloyd was one of several aircraft manufacturers in Austria-Hungary. Most of their aircraft that entered production were reconnaissance planes, but they had designed and built several experimental designs as well, some of which had unique and unorthodox designs, such as their FJ 40.05 Reconnaissance/Fighter hybrid. Their bomber design would also verge on to the strange. This would be the only bomber the company would produce. Lloyd came forward with two designs in January of 1916, the Luftkreuzer I and the Luftkreuzer II. The first would eventually be redesignated the 40.08 and the second would be redesignated the 40.10. A complete 40.08 was constructed by June 20th, 1916 and was ready for testing. Given there is no further evidence of work on production examples of the 40.10, it can be assumed the 40.08 was chosen over this design.
Engine testing would shortly begin with the 40.08 at the Aszod Airport. Early testing showed the design was severely flawed. The center of gravity was too high and the aircraft was too front heavy. During ground testing, this problem became clear with the aircraft tipping forward, resulting in damage to the front. A frontal wheel was added to fix this problem, as well as other minor changes. With the modifications completed in Aspern (a section of Vienna), the aircraft was slated to finally take off, with a pilot being assigned to the aircraft. The aircraft would attemp a take off in October of 1916, with Oberleutnant Antal Lányi-Lanczendorfer at the controls. Attempts at flight proved the aircraft was too heavy as well and it would never get truly airborne. A solution came with reducing the bomb load to decrease the takeoff-weight, but at the cost of ordnance.
Little work was done on the aircraft between October and November. In December, large rails were fixed to the bottom of the aircraft, replacing the tailings on the aircraft in February of 1917. With the number of problems the Luftkreuzer faced, it was obvious it would not be possible to improve the plane fast enough for it to have any value on the battlefields of Europe. In March of 1917, all work had stopped on the Luftkreuzer after an attempt to revise the aircraft was denied. The sole Luftkreuzer was sent to storage where it would remain for almost a year. In January of 1918, what was left of the aircraft was taken to an aircraft boneyard and destroyed in Cheb (located in soon to be Czechoslovakia). Thus concludes the story of Austria-Hungary’s attempted triplane bomber.
Austria-Hungary itself wouldn’t survive by the end of the year and would dissolve into Austria and Hungary and new national states such as Czechoslovakia. This wouldn’t be the only bomber built nor used in Austria-Hungary. Several other companies had designed large bombers, but none of these would enter production either. The only bombers that would be operated by the Luftfahrtruppen and see combat would be German and license-built Hansa-Brandenburg G.1s. These were bought in 1916 and would go on a single sortie before being sent to training duty, as they were found to be heavily outdated by the time they arrived on the battlefield. In the end, Austria-Hungary wouldn’t see itself using a mass-produced bomber.
Design
Side view of the Luftkreuzer, notice the absence of a frontal wheel and the side window of the cockpit. [armedconflict.com]The Luftkreuzer was a large triplane, twin-boom design. On the end of each boom, an Austro-Daimler 6-cylinder engine was mounted in tractor configuration (engine faced forward) and ended with a wooden propeller. These propellers did not counter rotate. Each boom itself was a reused fuselage taken from the Lloyd C.II aircraft. Each wing on the aircraft was actually a different length; with the top wing having a 76.3 ft (23.26 m) wingspan, the middle wing with a 73.42 ft (22.38 m) wingspan and the lower wing being 55.2 ft (16.84 m) wingspan. The central wing would be connected to the main fuselage and booms while the upper and lower wings would be connected via struts.
The main hull was rather tall and was one of the causes for why the aircraft was so front heavy and had such a high center of gravity. The cockpit was located beneath the upper wing and had several windows on both sides. The lower extended area was where the bombardier would sit, and was between the middle and lower wings. The central hull also contained the main engine, an Austro-Daimler 12-cylinder water-cooled engine in a pusher configuration. This engine was linked to a wooden two-bladed propeller. The hull was designed in a way so that the gunners would have a clear field of vision. Despite its prototype status, the aircraft was fully marked with the Luftfahrtruppen’s insignia, including one very large symbol painted directly in the front of this aircraft. The Luftkreuzer originally only had two main landing gear legs, with 4 wheels being mounted to each leg. When it was realized the aircraft was front heavy, a 3rd landing gear leg was directly in front of the central hull. No photos exist that show this third landing gear leg.
The armament would consist of 4 machine guns and 440 Ibs (200 kg) of bombs. The bombs would be mounted in the main central hull. The machine guns would most likely be Schwarzloses. These guns would be placed around the airframe, with two being in the central hull and the other two being located in the side hulls. Certain gunner stations would be equipped with a searchlight to aid in night missions. The aircraft was never fully armed before being scrapped, but it is likely it was loaded with bombs or ballast, given that the aircraft had weight issues before taking off and the solution given was to lower the bomb load.
Variants
Lloyd 40.08 – The only version of the aircraft built. Never truly flew.
Operators
Austro-Hungarian Empire– The Lloyd 40.08 was built in and for the Austro-Hungarian Empire’s Lufthahrtruppen, but did not see action.
*Given that the aircraft never truly flew, speed and similar flight statistics were never found.
Lloyd 40.08 Specifications
Wingspan
76 ft 3 in / 23.26 m
Length
31 ft 3 in / 9.6 m
Height
16ft 5 in / 5 m
Wing Area
110.0 ft² / 10.2 m²
Engine
1 × Pusher Austro-Daimler 12-cylinder water cooled engine 300 hp (224 kW)
2 × Tractor Austro-Daimler 6-cylinder inline water-cooled engines 160 hp (120 kW)
Weight
10,670 Ibs / 4840 kg
Endurance
Maximum 6 hours of flight
Crew
4-5
Armament
440 Ibs (200kg) of bombs
4 × 0.315 in (8 mm) Schwarzlose machine guns
Gallery
Lloyd-40.08 Side Profile View by Ed JacksonFrontal shot [dieselpunks.com]
Nazi Germany (1945)
Rocket Interceptor Trainer – 1 Built
A rear 3/4 view of the Soviet captured “White 94” Me 163S. Colorization by Michael Jucan [Yefim Gordon]The Messerschmitt Me 163S (Schulflugzeug / Training Aircraft) Habicht (Hawk) was an unarmed two-seat training glider based off of the famous Messerschmitt Me 163 Komet. Originally designed for the purpose of training novice pilots for landing, the Habicht ultimately never saw active service with the Germans and only a single example was produced through the conversion of a serial Me 163B-1. With the sole example captured by the Russians after the war, the Habicht underwent extensive testing by the Soviet Air Force which helped them understand the flying characteristics of the Komet and prepared Soviet pilots for flying the powered Komets. The Habicht undoubtedly played a part in helping Soviet engineers understand the Komet and thus played a part in the future development of Soviet rocket aircraft.
History
A closeup view of the Me 163S showing the right wing. [Yefim Gordon]The Messerschmitt Me 163 Komet was one of Nazi Germany’s most famous aircraft produced during the Second World War. Although bearing the title of the world’s first mass-produced rocket-powered interceptor, the Komet did have its fair share of flaws, such as the volatile and sometimes dangerous Walter HWK 109-509 rocket engine, which prevented it from becoming an effective weapon against the Allies.
As the Komet was designed to have a limited amount of fuel to engage Allied bombers, pilots were expected to glide the Komet back to friendly airfields once they disengaged from combat. With gliding landings as a potential problem for the less experienced pilots, one of the ideas proposed by Messerschmitt designers in 1944 was to introduce a dedicated trainer variant of the Komet which would have a student pilot accompanied by an instructor pilot. Designated as the Messerschmitt Me 163S (Schulflugzeug / Training Aircraft) Habicht, the trainer glider differed from the production model with the addition of an instructor’s cockpit behind the forward cockpit. This addition was accompanied by the removal of the Walter HWK 109-509 rocket engine and the Habicht would have to be towed by another aircraft in order to get airborne. Another interesting addition to the Habicht was a second liquid tank behind the instructor’s cockpit for counterbalancing. All the liquid tanks would be filled with water for weight simulation and ballast. A total of twelve examples were planned for production, but only one was produced due to wartime production constraints.
The sole example of the Habicht was built by converting an earlier Me 163B-1 production model. Due to the scarcity of information regarding the Me 163S, it is unknown exactly when the Habicht was produced and what sort of testing it may have undergone during German possession. However, it is known that the Soviet Union was able to capture the only example during the final stages of the World War II’s Eastern Front. The sole Habicht was sent to the Soviet Union along with three Me 163B Komets during the Summer of 1945 for thorough inspection and testing. In historian Yefim Gordon’s book “Soviet Rocket Fighters – Red Star Volume 30”, he claims that in addition to the three Komets, seven Habicht trainer models were also captured. This, however, remains quite dubious as there is no evidence that more than one Habicht existed, and all current photographic material, research materials, and books all suggest that only a single example was produced.
The Me 163S in simulated flight configuration aided by struts. [Yefim Gordon]As the Soviets were particularly interested in rocket propulsion aircraft, the State Defence Committee issued a resolution which called for the thorough examination of the Walter 109-509 jet engine and the Me 163 Komet along with captured German documents on rocket propulsion. The three Me 163B Komets, of which only one was airworthy, and the Me 163S Habicht were sent to the Flight Research Institute (LII), the Valeriy P. Chkalov Soviet Air Force State Research Institute (GK NII VSS), and the Central Aerohydrodynamic Institute (TsAGI). The Habicht and Komets saw extensive testing in Soviet hands, undergoing several structural, static and wind tunnel tests. During the initial flight testing period, the Komet only flew as a glider as Soviet pilots and engineers were unsure of whether or not the Walter rocket engine was ready for use since bench tests were not completed. Securing the T-Stoff and C-Stoff propellants for the rocket engine was also a problem. In order to understand the handling characteristics of the Komet, the Habicht was flown numerous times at different altitudes, as was the unpowered Komet. A Tupolev Tu-2 bomber was responsible for towing the Habicht to these altitudes. Under Soviet ownership, the Habicht was given the nickname of “Карась” (Karas / Crucian Carp) due to the glider’s distinct silhouette. The test pilot responsible for flying the Habicht was Mark Lazarevich Gallaj. In general, the Habicht was considered relatively easy to handle by the Soviet test pilots. It is unknown how many test flights the Habicht underwent, but the aircraft certainly aided Soviet pilots in understanding the handling characteristics of the Komet. The Habicht’s service came to an end once the Soviet state trials of the Komet concluded. The sole example was scrapped sometime in 1946, along with seemingly all the other Komets.
If the Me 163S was able to be mass produced and flown with the Luftwaffe, the aircraft would have been a valuable tool to train German pilots. Landing the Komet was a problem for some pilots and in some cases resulted in fatalities but, with the use of the Habicht, the number of accidents would have certainly decreased.
Design
The Me 163S hung upside down in an unspecified TsAGI workshop for static testing. [Yefim Gordon]The Messerschmitt Me 163S Habicht was a semi-monocoque aluminum based two-seat training glider developed off the standard tailless Messerschmitt Me 163B-1 Komet. The sole example was converted from a production Komet, which meant dramatic modifications had to be made to the aircraft. The Walther HWK 109-509 rocket engine was removed and in its place was a cockpit for an instructor. The fuel tanks in the airframe were all filled with water to simulate fuel weight while another water tank was added behind the instructor’s cockpit for ballast purposes. There was no armament fitted to the glider. There was a small transparent section between the student pilot’s cockpit and the instructor pilot’s cockpit, presumably for the purpose of communication. As there are no known German documents on the Habicht and Russian documents are scarce, not much is known on the other differences the Habicht may have had. Detailed specifications of the Habicht are unknown, but theoretically it should have been identical to the standard Me 163B-1 Komet except for possibly weight, air drag and center of gravity.
Operators
Nazi Germany – The intended operator and producer of the Me 163S Habicht.
Soviet Union – The main operator of the Me 163S Habicht. A single Habicht was captured and tested by the Soviets after the war. The Habicht was scrapped in 1946.
*Editor’s note: As noted above, the exact specifications of the Me 163S Habicht are unknown. However they are presumed to be similar to that of the Me 163B-1 Komet.
Me 163S Habicht “White 94” in Russian Service [Haryo Panji]Me 163S Habicht in German Service [Haryo Panji]
Now known as the “White 94”, the Me 163S sits idly by. [Yefim Gordon]A closeup view of the Me 163S showing the transparent section between the two cockpits. [Yefim Gordon]The Me 163S in simulated flight configuration aided by struts. [Yefim Gordon]A top down view of the “White 94” Me 163S. [Yefim Gordon]A photo of the “White 94” Me 163S in flight being towed by a presumed Tupolev Tu-2. The pilot in the photo is likely Mark L. Gallaj. [Yefim Gordon]The Me 163S inside TsAGI’s T-101 wind tunnel for testing. The struts support the Habicht and simulate its flight configuration. [Yefim Gordon]An alternate closeup view of the Me 163S during static tests. [Yefim Gordon]
Yet another inverted static test, but this time the tail wheel strut and tire were removed from the Me 163S. [Yefim Gordon]
Nazi Germany (1942)
Experimental Aircraft – 1 Prototype Built
Three-quarters view of the B9, note the large glazed cockpit. Colorized by Michael Jucan [airwar.ru]The Akaflieg Berlin B9 was a German experimental twin engine aircraft designed with the pilot placed in the prone position. It was designed to withstand extremely high g-forces. One prototype was built and tested by a glider production workshop in 1943 but it would not be adopted for mass production. The author would like to especially thank Carsten Karge from the Archiv Akaflieg Berlin for providing information on this generally unknown aircraft.
Why prone position?
During sharp up and down turns while flying an aircraft, strong g-forces appear that act on the pilot, potentially leading to loss of consciousness. Under normal flying conditions, the g-forces that appear are relatively harmless. The first effect of the g-force which the pilot notices is the difficulty of moving his body normally, as normal movements feel much heavier. Another effect of strong g-forces, which is much more dangerous, is the loss of oxygen flow to the brain. In some cases, the flow of oxygen and blood to the human brain can be greatly diminished, which can lead to the pilot losing consciousness momentarily. This effect lasts a short time, but it is enough for the pilot to lose control of the plane with a potentially fatal outcome.
While today, devices such as advanced anti-g suits help the pilot withstand strong g-forces, during the World War Two, other solutions had to be found. The Germans had noticed that, especially during sharp dive bombing actions, the pilots often lost consciousness. One way to tackle this was to put the pilot into a prone position, which in essence means to fly the plane while lying on the belly. In this position, the pilot has both his heart and his brain at the same level, which means that blood is no longer stopped from travelling to the brain during high-g maneuvers. Thus, this flying position allows the pilot to endure much greater g-forces than he would normally be able to if he would be in an ordinary sitting position. Other advantages of the prone position are the reduced aircraft size, smaller fuselage, less drag due to the smaller cockpit, and it would be easier for the pilot to operate the plane when conducting bomb sighting and ground attack, among other advantages.
During the war, the Germans would test several such aircraft designs, sush as the Henschel Hs 132 or B9, mostly for the ground attack role. Beside a few prototypes built, none were ever used operationally.
History
The SF 17 prone glider was the forerunner of the B9 powered aircraft [Akaflieg Stuttgart]In order to test the idea of an aircraft with the pilot in the prone-position, the Aero-Technical Group (Flugtechnische Fachgruppe/FFG) of Stuttgart designed and later built the FS 17 all-wood test glider. It was especially designed to withstand forces up to 14 G. It made its first test flight on 21st March, 1938. In the spring of 1939, FFG Stuttgart made the first design drawings and calculations for a prone-piloted aircraft. This aircraft was to be powered by two Hirth HM 50 engines with an estimated speed of 250 mph (400 km/h).
FFG Stuttgart never completed this project as it was forced, for unknown but likely politicaly reasons, to hand over the project to Akaflieg (Akademische Fliegergruppe/Academic Aviator Group) Berlin. It is possible the order came from the German Experimental Department for Aerospace (Deutsche Versuchanstalt für Luftfahrt e.V. Berlin-Aldershof) DVL or even from the Ministry of Aviation (RLM – Reichsluftfahrtministerium), but precise information is lacking. Akaflieg Berlin, founded in 1920, was one of the oldest gliding clubs in Germany and it still exists today.
The RLM designation for this aircraft was “8-341” but Akaflieg used the simpler B9 designation. The technical characteristics that the new plane was supposed to have were a good field-of-view for the pilot in the prone position, a high degree of safety for the pilot, a high speed during diving, good general flying characteristics and being able to withstand forces of up to 25 G, or 22 G depending on the sources.
Akaflieg Berlin had a small number of engineers and workers and an adequately equipped workshop to complete the task given. For this purpose, a design team was formed with Theodor Goedicke, Leo Schmidt and Martin G. Winter, which was responsible for the creation of this new aircraft design. The first prototype was to be ready by August 1942 but this was never achieved, and the prototype was only completed in early 1943. It made its first test flight on the 10th April, 1943 at the Schönefeld airfield, near Berlin.
The Design
Front view of the B9 [airwar]The B9 was a single-seat, low wing, mixed construction aircraft with the pilot in prone position. It consisted of a metal airframe, made of steel ribs, covered with wood and canvas. The main fuselage’s cross-section was trapezoidal shaped. As the B9 was specifically designed to withstand forces of up to 25 G, it had to have a strong fuselage.
The wings were made of wood covered with duralumin sheets. In order for the wooden wings to withstand the strong torsional forces which occur during high acceleration maneuvers, the spaces between the spars were heavily reinforced. The middle part of the wings viewed from above have a square shape and then narrow towards the wing tips. The wings were held in place by four bolts on each side. The rear tail design was a simple one, with standard rudder and elevators.
The B9 had a standard retractable landing gear copied from the Me-108, which consisted of two larger wheels and one smaller non-retractable wheel at the back. The landing gear was lowered and raised manually. The front wheels retracted into the engine nacelles, but they were not fully enclosed.
The B9 had a large 4.9 ft (1.5 m) long glazed cockpit with good all-around view. But, as the pilot was in a prone position, the above and the rear views were limited by the human body’s inability to turn the head in these directions. The glazed cockpit was made of two parts, the front windshield and the rear larger canopy that opened to the right side. The cockpit interior had to be especially designed for a pilot lying in the prone position. The usual flight controls were almost useless in this situation and, thus, certain changes were necessary. It was important to divide the controls on both sides of the cockpit, in order to avoid the pilot crossing hands, which could lead to complications in flight. On the right side were the controls for ailerons and elevation. The pilot would use his right hand to gain access to the harness and the canopy release mechanism. For controlling the rudders and brakes, the pilot would use his feet. Using his left hand, he would operate the remaining instruments, the throttles, flaps, ignition switches, emergency pump, fire warning, undercarriage control and others. Additional engine and flight instruments were located behind the pilot. These included, among others, the distance indicator, climb indicator, compass, oil and fuel pressure gauges and airspeed indicator. For the pilot to be able to see them, a small mirror was provided. There were also inclined and horizontal line markers on the inner windshield to help the pilot with orientation. For flying at high altitude, an oxygen supply system with a mask was provided to the pilot.
The aircraft was powered by two Hirt HM 500 air-cooled engines, with 105 hp each. The maximum speed was around 140 mph (225 km/h) but, according to some sources, it was as high as 155 mph (250 km/h). The four fuel tanks, with a total capacity of 25 gallons (95 l), were located between the spars on both engine sides. The B9’s effective operational range was 250 mi (400 km). Originally, the B9 was meant to be equipped with two variable-pitch propellers, but it was instead fitted with ordinary wooden fixed pitch propellers made by the Schäfer company.
As the B9 could be used as a ground attack aircraft, a bomb rack was meant to be installed, but it is not clear if this was ever implemented.
Operational Testing
The B9 in flight [airwar]The operational prototype was ready by the summer of 1943. The first test flights were carried out by Ing. L. Schmidt and Dipl.-lng. E. G. Friedrichs. On one flight, L. Schmidt had an accident, the details of which are not known, but the plane probably suffered only minor damage.
The B9 was meant to make a series of test flights in order to ascertain if the prone position design had any merit and to test the general flying and overall structural performance. If these proved to be successful, the B9 would serve as base for future development and be put into active service. The B9 aircraft received the ”D-ECAY” marking, which was painted on both sides of the fuselage.
The tests were carried out from July to October 1943, during which time around thirty pilots had the opportunity to fly it. The test flights were conducted without any major problems and only one accident was recorded. This accident was caused not by any mechanical problems, but by a pilot mistake during takeoff. The B9 was damaged, but it was repaired and put back into service in only a few weeks.
The pilots did not have many objections to flying in the new prone position. They described it as comfortable and that it was relatively easy to adapt to the new commands. There were some issues, like fatigue and tiredness of the neck and shoulder muscles because of the constant moving of the upper arms. There were also some complaints about the chin supporter, which was deemed as unpleasant during flight but it was essential during high g-force maneuvers. During these test flights, the control panel and the controls did receive some changes in design. The large and fully glazed cockpit provided the pilot with good front and below fields of view, while the rear and upward view was somewhat problematic due to the prone position.
These tests showed that this type of aircraft was well suited for bomber, ground attack, high speed reconnaissance and possibly even in a high-speed fighter role. But it was also noticed that, due to the somewhat restricted view, the use of low speed prone pilot aircraft without air support was not recommended. Despite being designed to withstand forces of up to 25 G, the maximum achieved was only 8.5 G. One of the reasons for this was the use of low rotational speed propellers.
For 1944 and 1945 unfortunately, there is no information about the B9’s operational use. The B9 was found abandoned at the Johannisthal airfield near Berlin after the war. In what condition it was by the time of capture is not known. What is unusual is that the B9 was captured by the Americans and not the Soviets (according to author Hans J.W.). What the Americans did with the plane is unknown to this day, but it was most likely scrapped.
Only one B9 plane prototype was ever built. By 1943 and 44, a large amount of resources were invested in the production of fighters for the defense of the Reich and there were neither the time nor the resources needed to develop and test such an aircraft.
United Kingdom (1915 & 1917)
Anti-Airship Fighter – 1 Each Built
Supermarine PB.31E Nighthawk
In 1915, Germany began bombing Great Britain by Zeppelin. For the first time, Britain itself was under threat by enemy aircraft. Early attempts to counter the Zeppelins were ineffective. The Royal Air Corps needed an aircraft to be able to endure long, nighttime missions to chase the Zeppelins. The Pemberton-Billing aircraft company designed the PB.29E quadruplane for this task. The aircraft didn’t perform as hoped, but before a final conclusion could be made it was lost in a crash. Years later in 1917, with the company under new management and renamed Supermarine, the program would rise again as the PB.31E. The PB.31E was dubbed the Nighthawk, and like its predecessor, proved to be ineffective in the role. The fighter is significant for its unusually large quadruplane layout and the first aircraft to be built by Supermarine.
History
The arrival of the Zeppelin in 1915 as a new type of weapon was an unwelcome one. It offered a new way of strategic bombing, as Zeppelins were faster and able to ascend higher than aircraft at the time. Zeppelins also served as a weapon of terror, as the civilians of England had never been faced with anything like it before, especially since the Zeppelins attacked mainly at night. Early attempts to counter Zeppelin raids proved ineffective, as anti-aircraft guns had a hard time spotting and aiming at the Zeppelins. Early forms of countermeasures involved aircraft dropping flares to illuminate the Zeppelins for gunners to see. None of these aircraft were used to actually intercept the airships. The Royal Air Corps needed an aircraft that would be able to reach and pursue Zeppelins on the homefront and on the battlefield. A potential solution came from a man named Noel Pemberton Billing.
Noel Pemberton Billing (1881-1948)
Noel Pemberton Billing was a man of many talents. He was an inventor, aviator, and at one point a member of Parliament. At the time, he was invested in many forms of new technology and aircraft was one of them. Having formed his own aircraft company in 1913, he built several aircraft types for the Royal Naval Air Arm (RNAA), such as the PB.25. He had taken a short break from designing planes for the RNAA and wanted to pursue aircraft to help in the war effort. The task of taking on Zeppelins got him interested in designing a plane to fill the role.
His answer was the PB.29E, a quadruplane aircraft. Information regarding the PB.29E is sparse and no specifications can be found for it. To get the aircraft to the altitudes at which Zeppelins usually lurked, Pemberton Billing applied triplane principles in making the aircraft, except taking it a step further and adding an extra wing. Having more wings, in theory, would assist with lift, a necessary factor when trying to chase the high-flying Zeppelins. Work began in late 1915, with the aircraft being finished before winter. The PB.29E was intended to fly for very long missions and needed to operate at night. To assist in spotting the behemoths, a small searchlight was to be mounted in the nose of the aircraft. The sole PB.29E crashed in early 1916. From test flights, the aircraft proved to be cumbersome and would not have been able to pursue Zeppelins. The two Austro-Daimler engines did not prove to be sufficient for the intended role, and performance suffered from it.
German Navy – R Class Zeppelin L 31
On September 20th, 1916, Noel Pemberton Billing sold his company to Hubert Scott Paine so he could become a member of Parliament. His career in Parliament was full of slander and conspiracy, and ultimately negatively affected the war effort. Soon after being acquired, Paine renamed the company as the soon to be famous Supermarine Aviation Works, in honor of the firm’s telegraph address. Work continued on a Zeppelin interceptor, which would eventually become the PB.31E. The PB.31E was technically the first aircraft built by Supermarine and it resembled a larger and more advanced version of the PB.29E. It retained many aspects from its predecessor: the quadruplane layout, the mounted searchlight, and endurance for long nighttime missions. The armament was expanded with a second Lewis gun mounted in the rear cockpit as well as a Davis gun mounted on top of the cockpit above the wings. To make the crew more comfortable, the cockpit was fully enclosed, heated, and had a bunk for crewmembers. The Austro-Daimler engines were replaced by 100hp Anzani radial engines. Expected speed was 75 mph (121 km/h) and it was to operate up to 18 hours.
The design team poses in front of the newly completed Nighthawk, fourth from the left is R.J Mitchell.
The aircraft was constructed in February of 1917, with a second in the works. On board the project was R.J Mitchell, the future designer of the Supermarine Spitfire. He began as a drafstman for the company and several designs concerning the fuselage and gun mounts of the PB.31E are labeled with his name. To the engineers, the aircraft was dubbed the Supermarine Nighthawk, however, this name was never official. Early flights were conducted at the Eastchurch airfield by test pilot Clifford B. Prodger. Tests showed that, like its predecessor, the engines weren’t capable of propelling the aircraft to its desired level of performance. To reach altitudes most Zeppelins were found at took an hour. Not to mention, newer Zeppelins could go even higher. Its expected 75 mph (121 km/h) top speed was never reached, with the aircraft only going 60 mph (96 km/h). However, it had a safe 35 mph (56 km/h) landing speed, which would have given the aircraft easy landing capability. With the performance lacking, the RAC deemed the project to be a dead end.
With the introduction of new incendiary rounds which easily ignited Zeppelins, Britain could defend itself with the improved AA guns. Along with the new rounds, the RAC started using the Royal Aircraft Factory B.E.2 to intercept Zeppelins at night. Originally intended for dogfighting, the B.E.2 proved to be ineffective and slow against fighters, but Zeppelins were easier, and much larger targets. With the Nighthawk now not needed, Supermarine ended up scrapping the first and incomplete second prototypes in 1917. Although the Nighthawk would never have been successful had it entered production, it still represents major innovations in aircraft design. It was one of the first true night-fighting aircraft to be designed, a concept later heavily utilized in the Second World War. The honor of being the first aircraft built by Supermarine under their name also goes to the Nighthawk.
Design
Overhead and side schematic views of the PB.29E
The PB.29E was a quadruplane designed to chase and intercept Zeppelins. Its fuselage was mounted between the lower two wings, with a gunner port being mounted in the upper two wings, leaving an opening in the middle between the two. Two crewmembers occupied the central fuselage with a single gunner gunner position in a seperate section above. The cockpit was open to the elements, as well as the gunner port. For armament, a single Lewis gun was mounted for attacking Zeppelins. For engines, the PB.29E had two Austro-Daimler six-cylinder engines in a pusher configuration. The tail itself was doubled.
Schematics for the Nighthawk with R.J Mitchell’s initials.
The PB.31E was a quadruplane like the PB.29E, but it was larger utilized a different fuselage design. Instead of having the fuselage between the lower two wings, the PB.31E positioned its body between the middle two wings. The body itself was of all wooden construction. To reduce splinters if the aircraft was fired upon or in the event of a crash, the fuselage was taped and covered in heavy fabric. To make the long missions more comfortable the cockpit was heated and completely enclosed by glass. A bunk was added for one crew member to rest during the flights as well, as the expected flights could last up to 18 hours. A searchlight mounted protruding from the center of the nose for use in patrols at night. The searchlight was movable to allow pointing it at different targets. It was powered by an onboard dynamo hooked up to a 5hp A.B.C petrol engine. For fuel storage, the PB.31E had 9 individual petrol tanks located around the cockpit area. The tanks were built to be interchanged if they were damaged or empty. In the front of the aircraft were several slits behind the searchlight that would assist in cooling. The wings of the PB.31E had significant cord to them. The tailplane was doubled like on the PB.29E, and the tail itself was lower to allow the rear mounted Lewis gun more range
The newly completed PB.29E, the gunner position between the two topmost wings is easily visible
of fire. For engines, the PB.31E had two Anzani radial engines in tractor configuration. These engines gave the PB.31E its slow speed of 60 mph (96 km/h), and its hour-long ascent to 10,000 ft (3000 m). The fluid lines, controls and other parts connected to the engines were placed outside the fuselage in armored casings. For armament, the PB.31E carried a frontal Lewis gun, a top mounted Davis recoilless gun and a rear Lewis gun. The Davis gun was built on a mount that allowed an easy range of motion in most directions. Lewis gun ammo was stored in six double cartridges and 10 Davis gun rounds were stored onboard as well. Also on board were an unknown amount of incendiary flares to be dropped should a Zeppelin be directly below the craft.
Variants
29E– First aircraft built for the Anti-Zeppelin role. Armed with a single Lewis gun. Crashed during testing.
31E– Second aircraft. One prototype and one unfinished plane. Resembled a larger version of the PB.29E. Carried a Davis gun and two Lewis guns. Scrapped once the design was deemed unworthy.
Operators
Great Britain – The two prototypes were built and tested in England.
Pemberton-Billing PB.29ESupermarine PB.31 NighthawkThe PB.29E under construction in WoolstonA frontal view of the PB.29E, note the searchlightThe newly constructed Nighthawk sits in a hangar at WoolstonThe Nighthawk on the runway, notice the weapons and spotlight are absent
Yugoslavia (1939)
Prototype Advanced Trainer – 1 Built
The MM-2 prototype had an unusual color scheme with a combination of red and polished aluminum.
With the emergence of new fighter planes in the years leading up to the Second World War, it became necessary to replace the older biplane trainer aircraft, which were too slow, in order to efficiently train new pilots to fly the newest fighters. Thus, it was logical that more modern advanced trainer aircraft would be needed. The MM-2 was an experimental Yugoslavian solution to this problem.
First Steps
At the end of the thirties, the Yugoslav Air Force was equipped with modern planes, such as the German Me-109, the indigenous IK-3, and the British Hurricane, highlighting the need for an updated trainer. There were several older aircraft in use for the role, like the FP-2 and the Rogožarski PVT, with a maximum speed of around 140 mph (230 km/h) but there was a need for a much faster and modern aircraft trainer.
The designer of the MM-2 trainer, Captain Dragutin Milošević.
To fill this gap, Air Force engineer and pilot Captain 1st Class Dragutin Milošević, on his own initiative, began to work on a new advanced trainer in 1936. The first aerodynamic calculations, choice of engine, structure, and the design were done by 1937. This new plane was conceived as a two-seater with seats one behind the other, with an enclosed cockpit and dual controls. It had a low wing, mixed construction, with a single engine and retractable landing gear. The engine would have been the Renault 6Q-02, giving 162 kW (220 hp). Milošević never gave a designation for this plane, but was later simply named the M-1.
Captain Dragutin Milošević submitted this project to the Yugoslav Department of Aviation in 1937. The Department analyzed this proposal and, while on paper it would have had great flying performance, a decision was made to reject it because the parts necessary for its construction had to be imported from abroad.
This decision did not discourage Captain Milošević, and he made attempts to improve his design. He proposed replacing the Renault with the license-built Gnome-Rhone K-7 309 kW (420 hp) air-cooled 7-cylinder engine. By adding this engine, the length of the plane would be reduced from 23 ft 7 in to 20 ft 4 in (7.2 m to 6.7 m) but the total weight increased to 2,160 lbs (980 kg). To improve the landing characteristics of the aircraft, it would have been necessary to increase the distance between two front landing wheels from 6 ft 2 in to 7 ft 10 in (1.9 m to 2.39 m). All aerodynamic and statistical calculations were finished by 1939. The second version was named M-2 and it was, in essence, the basis of the future MM-2 aircraft.
One wooden model (1:10 scale) was built by the Albatros factory in Sremska Mitrovica. This model would be used to test the aerodynamic properties and accuracy of earlier calculations. Aerodynamic properties were tested in the Paris wind tunnels on the 17th and 18th of July 1939. After these trials, the fuselage length reverted to the original 23 ft 7 in (7.2 m).
Later, Captain Milošević did new calculations that showed that certain changes to the design of the aircraft were necessary. Adding weapons and increasing fuel capacity would lead to an increase of the mass of the M-2 by 242 lbs (110 kg), some 60 lbs (30 kg) in fuel and 176 lbs (80 kg) in armament. After all the other modifications, the total mass reached 2,782 lbs (1,262 kg) compared to the initial 2,160 lb (980 kg). The wing area had to be increased from 129 to 146 sq ft (12 to 13.6 m²) and the wingspan from 27 ft 10 in to 30 ft 3 in (8.5 to 9,23 m).
Adoption of a Prototype
Captain Milošević submitted a letter, together with documents, plans and calculations, to the supreme headquarters of the Yugoslavian Air Force, notifying them of the test results of the proposed M-2 aircraft. Since he did not receive any kind of response, he asked Major Đorđe Manojlović, also an aviation engineer, for help. Although Đorđe Manojlović did not have a direct impact on the design of the M-2, his great influence and connections in the Supreme Air Force Command lead to the continuation of the project. The cooperation of these two men lead to the final approval for construction of the M-2 aircraft project.
The only MM-2 prototype during its construction by Ikarus.
When the Air Force Headquarters of the Army of the Kingdom of Yugoslavia accepted the M-2, construction of this project was given to the Ikarus factory. The contract was signed on the 25th March 1940. It was planned to build one prototype aircraft for testing in order to ascertain if the M-2 was fit to be accepted for serial production. The project was monitored by a team composed of engineer Sava Petrović, Air Force Major Vojislav Popović and the technician Stefan Lazić. The prototype was ready by the first half of November 1940.
Origin of the Name
In the Kingdom of Yugoslavia, there was a custom of using the initials of the names of the designers as the official designation for most of new types of aircraft in service (like the IK-2/3), and MM-2 was no exception. MM comes from the initials of the surnames of Captain Dragutin Milošević and the constructor and engineer Major Đorđe Manojlović. There is sometimes confusion about the exact name of this aircraft. It is sometimes also called MiMa-2. In some documents found after the war, it is also called M.M. 2. In this article, the MM-2 name will be used, as it is the most common.
Technical Characteristics
Captain Dragutin Milošević’s first drawing of the MM-2. Note that the engine nose design appears to be for an inline engine, different from the actual prototype.
The MM-2 was designed as an advanced two-seater trainer, with seats one behind the other, with dual controls and a fully enclosed cockpit. It was a low wing, mixed construction, a combination of wood and metal, single engine aircraft with retractable landing gear.
The wings had a trapezoidal shape with a rounded top. They were constructed by using two racks which were made of steel tubes welded together. The racks were welded to the plane’s hull and the wooden ribs were connected to them by rivets. The wings were covered with canvas, except for the central parts, which were made of aluminum sheet. This was done so that the technicians and repair crews could have easy access to the inside of the wing. The ends of the wings were made of wood that were held in place by steel fittings. The flaps were covered in canvas and operated either manually or hydraulically.
The MM-2 hull was of mixed construction. The main body was made by using welded pipes. The front part was covered with aluminum sheet and the rear with canvas. The tail was made mostly of wood and covered with canvas.
The main engine was the Gnome-Rhone K-7, which supplied 310 kW (420 hp). It was domestically built under license from Franch aircraft manufacturer Rakovica. It was hoped to use a two-bladed metal propeller but, due to the lack of resources, wood was used. The maximum estimated speed (never achieved) was around 250 mph (400 km/h), with an effective range of 475 mi (764 km) with some 40 gallons (150 l) of fuel capacity. Climbing to 6,500 ft (2,000 m) could be achieved in 3 minutes and 9 seconds, but the maximum service ceiling was never adequately tested.
The landing gear was supposed to be of the ‘Nardi’ type imported from Italy, but it was planned to domestically build the landing gears for the production version, to avoid being dependent on foreign countries. On the prototype, no radio was installed but it was hoped to equip all future production aircraft with the FuG VII radios.
The main armament consisted of two wing-mounted 7.7 mm Darn-type machine guns with 175 rounds of ammunition for each gun. The total bomb load consisted of four 10 kg bombs carried under the wings. It must be noted that the armament was never installed on the prototype, as testing was interrupted by the beginning of the war.
First Test Flights
MM-2 Side View
The first test flights were made by the beginning of the 1941 at the Zemun airport. The pilot for these flights was Vasilije Stojanović, the test pilot of the Ikarus factory. By the end of March 1941, some 45 flights had been made with a total of 20 flying hours. The pilot assessed the flying performance of this plane as excellent. The results of these tests indicated that this aircraft had good flight performance. The controls were adequate, both instructor and the students cockpits had enough room with a good field of view and, during flights, the aircraft did not present any tendencies for sudden unpredictable movements. Due to its good air brakes and flaps, take-offs and landings were quite easy. There were no major objections from the test pilot about the MM-2.
The MM-2 could very easily reach speeds of up to 217 mph (350 km/h). The design maximum speed was never tested, but calculations suggested that it could be as high as 250 mph (400 km/h). This was never confirmed due to the outbreak of the war. The MM-2 prototype had an unusual color scheme with a combination of red on most of the rear fuselage and wings, and polished aluminum on the majority of the fuselage and the engine section, with a small Yugoslav flag painted on both sides of the tail.
On the 25th of March 1941, a contract was signed between Ikarus and the Air Force. According to this contract, Ikarus was to prepare for production of MM-2 trainer planes in the near future. Before the production would begin, a last series of tests was to be conducted by a test group at an airfield near city of Kraljevo. An order was given to Stojanović to fly the MM-2 from Zemun to the Kraljevo airfield. Once there, it was planned to do some more flight performance trials in order to examine the limit of the flying characteristics of the MM-2 aircraft. Stojanović completed the flight on the 4th April. Final production was never achieved due to the German invasion of Yugoslavia that started only a few days later.
Operational Service
The MM-2 did not see any active service in the Royal Yugoslav Army because of the beginning of the April war, the German attack on Yugoslavia in April 1941. After the defeat of the Yugoslav army, the Independent State of Croatia, or NDH, was created. In order to form the new NDH military air force, it was necessary to find and obtain planes to equip these new units. Like many other former Yugoslav planes, the MM-2 was also pressed into NDH service in a very limited role.
It seems that the MM-2 had some engine problems (possibly sabotaged) when it was captured by the Germans at airfield near Kraljevo. It is possible that it was in a bad condition since the Germans did not even bother to repair it and put it into operational use.
The MM-2, together with other Yugoslav captured aircraft, was collected and handed over to the NDH. After a while, the MM-2 was repaired under code name No. 6301, and returned to active service. Additional flight tests were conducted by Georgije Jankovski, a test pilot for Dornier-Werke. In September 1941, the plane was transferred to the Zemun airport and handed over to Croatian Major Ivan Pupis for future use. Major Pupis was the leader of the group responsible for the repair, reception and later transfer of all Yugoslavian aircraft captured during the April war. When the MM-2 was repaired and ready for active service, Pupis to keep it for his personal use rather than handing it over to the military.
On the May 13 1942 pilot Vid Saić, he lost control of the aircraft and crashed due to inexperience. The MM-2 was deemed too complicated and expensive to repair.
The MM-2 was ‘owned’ by Pupis until March 23rd, 1942, when he received a direct order from the Croatian Aviation Command to transfer the MM-2 to the ‘Rajlovac’ airfield near the city of Sarajevo in Bosnia. The aircraft arrived at the beginning of April 1942. The MM-2 was given to the 17th Squadron (Jato) which was part of the 6th group (Skupina) under the Command of the Major Romeo Adum. The MM-2 was used mostly for limited test flights. On May 13, 1942 while piloted by Vid Saić (from the 18th Squadron), the plane crashed. The pilot survived the crash with no injuries. A commission was formed to investigate the causes of the crash and found several irregularities: The pilot did not ask for permission and had no orders to fly on the MM-2 that day, and he also did not know anything about the flying characteristics or the condition of the plane. The conclusion was that the pilot was guilty for the accident and, as punishment, Vid Saić lost his Pilot rank. The damage to the MM-2 was estimated to be around 90%. There was no point to try to rebuild it from scratch and the remaining parts were destroyed. There is no information whether it was equipped with any armament in Croatian military service.
Production
Due to the outbreak of war on April 6th, 1941, except for the prototype, no other specimen of this aircraft was ever built. In some documents and letters found after the Second World War, it was discovered that the Ministry of Aviation planned to order around 50 copies of the MM-2 aircraft. Along with this, the Yugoslav military negotiated with Germany for the purchase of Arado Ar 96 training planes, but nothing came of this.
After the war, the new communist Ministry of Aviation and the Ikarus factory representatives were also interested in restarting the production of this aircraft but, as the chief designer had died in one of the many German prison camps and the necessary machines and tools were lost during the war, this was too difficult and was abandoned.
Operators
Kingdom of Yugoslavia – Built and tested the single prototype.
Independent State of Croatia NDH – Used the MM-2 captured during the April war, but it was lost in an accident.
MM-2 Specifications
Wingspan
30 ft 6 in / 9.23 m
Length
23 ft 7 in / 7.20 m
Height
9 ft 6 in / 2.89 m
Wing Area
14.6 ft² / 13.60 m²
Engine
One Gnome-Rhone K-7, 309 kW (420 hp) air-cooled 7-cylinder engine
United States of America (1944)
Prototype Ground Attack Aircraft – 1 Built
XA-41 in flight
The Vultee XA-41 was a single-engine aircraft that began life as a dive bomber. Months later, its role was changed to a low-level attack aircraft. The XA-41 performed admirably in flight tests, but the United States Army Air Corps (USAAC) eventually decided that the fighter aircraft then in service were already performing well enough in the attack role. Despite its job being erased, the XA-41 continued development as a testbed, showing off the powerful XR-4360 engine it mounted and how much it could carry. The aircraft itself would have been deadly had it been produced in large numbers, as it boasted four 37mm cannons. As the war went on, the XA-41 was still being tested. Throughout the trials, the aircraft had extremely good performance, even being able to outturn a P-51, but its speed wasn’t quite enough for its role. At one point, it was given to the Navy for testing and eventually it would wind up at Pratt & Whitney (PR). At PR, it served as a testbed through the war and was eventually scrapped in 1950.
History
Cutaway Concept for the XA-41
The XA-41 began as part of a United States Army Air Corps (USAAC) requirement in October 1941 for a new single-seat attack aircraft. The Douglas A-20 Havoc (and soon to be produced North American A-36 Apache) was performing well at the time, but the USAAC wanted something new. The aircraft requested had to be able to reach at least 300mph (482.8kph) at sea level, have a service ceiling of at least 30,000ft (9,144m), and a range of 1,200 miles (1,932km). For the attack role, the aircraft was to have either 37mm, 20mm, or 50. cal guns mounted in the wings. Given this imposing armament, it is likely the aircraft would have attacked soft targets or even been used for tank-busting.
The USAAC commissioned Vultee Aircraft Corporation, Kaiser Fleetwings, and Curtiss to design a new aircraft for the role. Kaiser Fleetwings developed the XA-39, which would have mounted the R-2800-27 engine. Their aircraft didn’t progress beyond the mockup stage. Curtiss reused their naval XTBC-1 prototype for their part, renaming it the XA-40. This also didn’t go beyond the mockup stage. Vultee’s answer was the V-90, a ground attack aircraft mounting the fairly new and powerful R-4360 engine. Interestingly, the XA-41 started off as a dive bomber, despite it being commissioned as an attack aircraft. It isn’t often stated, but the Army had been interested in dive bombers since 1940, going as far as purchasing several Navy designs. The Army bought several SB2D-1 Helldivers in December of 1940 and renamed them the A-25 Shrike. They also had a troubled history with one of Vultee’s own aircraft, the A-35 Vengeance, which they tried numerous times, but to no avail. The XA-41 was most likely a chance for the Army to have a successful dive bomber or attack aircraft. The Army was satisfied with Vultee’s V-90 design and awarded a contract for two prototypes on November 10, 1942. Shortly after a mockup inspection, the Army interestingly switched the role from a dive bomber to a dedicated attack aircraft. The switch was rather abrupt and caused a delay in the development.
XA-41 Prototype
On April 30th, a new contract was signed which included a static mockup. Vultee continued construction on the project until the prototype was halfway completed, at which point the Army decided that the most current aircraft, the Republic P-47 Thunderbolt and North American P-51 Mustang, were already quite capable in the attack role. But this wouldn’t be the end of the XA-41. Maj.Gen Oliver P. Echols, Chief of the Material Division, opted not to cancel the program and instead complete it in order to show the true potential of a new attack aircraft with the new R-4360 engine. This decision went through on November 20th, with the prototype ¾ the way through completion. The 2nd prototype was cut at this point and only one would be built (Serial No. 43-35124/5).
On February 11th, 1944, the XA-41 flew for the first time from Vultee Field, California, with test pilot Frank Davis at the controls, and landed at March Field, California. Several flights after this were conducted at the nearby army base. The aircraft was flown by both Vultee and Army pilots, and both agreed it handled well. There were some problems here and there, which Vultee quickly fixed with some additions to the airframe. On June 25, the Army accepted the XA-41. On July 16th, on its 60th flight, the aircraft was ferried to Eglin Field, Florida. Testing proved the XA-41 was an exceptional aircraft, with many great features. The craft had an excellent turn rate, being able to outturn the P-51. For its size, it carried an impressive arsenal of weapons. But the Army wanted an attack aircraft that could also defend itself if the need would arise, and the 350mph (563.2 km/h) of the XA-41 wasn’t that impressive compared to other aircraft in service. The United States Navy became interested in the XA-41 at some point and the prototype was given to them for testing at Patuxent River, Maryland. The Navy wanted to see if the aircraft could be flown from aircraft carriers. After the Navy briefly tested it, the XA-41 was given to Pratt & Whitney (PR) on August 22, 1944. It was obvious at this point that the XA-41 would never see combat, but would remain in the US as a testbed aircraft. Serving with PR, it was used as a flying testbed for their R-4360 engine, as well as having a supercharger mounted. As testing continued, the aircraft was purchased by PR on October 9 and re-registered as NX6037N. There are few documents that reference the XA-41 post-war. The only thing mentioned is that the sole XA-41 was finally scrapped in 1950, having served for many years at PR.
Design
The XA-41 was a conventional single-engine aircraft. It had a slight gull wing and a tail sitter configuration. The landing gear in the wings would retract inboard and was placed widely to allow better landing performance. During development, the tail wheel had doors installed to completely cover it in-flight. The cockpit was placed far forward and raised to allow the pilot to see over the engine, giving him better visibility when attacking ground targets. The ventral tail had an extension that spanned most of the length of the aircraft. This was added during development. A spinner was also added at some point. The XA-41 mounted the PR XR-4360 Wasp Major engine, which was the main reason the Army and PR were so interested in the project.
For armament, the XA-41 had four M2 Browning .50 cal machine-guns mounted in the wings. For the attack role, it was meant to mount four more 37mm cannons (sources don’t mention what particular kind of gun) in the wings. All armament in the wings was placed outside of the propeller’s range. For bombing, the XA-41 had a bomb bay that could carry four 500Ibs bombs, a torpedo, additional fuel, or two 1,600Ibs weapons. In total, it had up to 6,500Ibs of ordnance. Documents mention that up to 1,100Ibs of additional bombs could be mounted to the wings. The aforementioned competing XA-39 only sported the four Brownings, two 37mms, as well as a predicted carrying capacity of six 500Ibs bombs.
Variants
XA-41 – [The sole prototype built, used as a testbed for the XR-4360 engine.]
Operators
United States of America – The United States Army Air Corps would have operated it had it entered production. After serving as a testbed for the Army, the Navy and Pratt & Whitney also did tests with the aircraft.
Vultee-XA-41 Original Prototype ColorsVultee XA-41 with possible service markings (artist interpretation)XA-41 at Patuxent RiverXA-41 on the runwayXA-41 in a slight climbXA-41 parked on the ramp
The Douglas XTB2D-1 “Skypirate” was a large, single-engine torpedo bomber built for use on the Midway class carriers during World War 2. At the time, it was the largest aircraft to be used aboard a carrier, dwarfing even two-engine designs. Unfortunately for the Skypirate, engine troubles, little support from the US Navy (USN), and numerous setbacks with the construction of Midway-class carriers nearly doomed it from the start. By the time it was airworthy, it was trying to fill an obsolete role which other aircraft, such as the TBF/TBM Avenger, already filled adequately. Work continued after the war, with several attempts to revive the program but it proved to be too costly and the Skypirate program was finally cancelled in 1947, with the two prototypes being scrapped in 1948.
History
With engagements such as the Battle of the Coral Sea and the hunt for the Bismarck, the effectiveness of torpedo bombers, such as the TBF/TBM Avenger and Fairey Swordfish, was clear. With the announcement of the large Midway-class carriers, the possibility of a new torpedo-bomber/scout bomber came about. In February 1942, a competition was put forward by the Navy for this role. The Douglas Aircraft Company, based in Southern California, proposed the Skypirate. The single-engine Skypirate was picked from eight different designs, most of which were two-engined. The Bureau of Aeronautics (BuAer) wasn’t expecting a single engine design to be submitted, assuming the specified massive carrying capacity would require a two-engine design. The program was being headed by Ed Heinemann as lead designer and Bob Donovan as the chief engineer, who would be on the project until the end.
An impressive look at the massive Skypirate from the front.
In November of 1942, Douglas was given permission to begin production of two prototypes and a mockup of the XTB2D-1 (then called the Devastator II, before being changed to Skypirate). Delays in the development of the Midway class would continue to hamper the Skypirate throughout its life. The finished product was a formidable aircraft, capable of carrying four torpedoes from land or two torpedoes from a carrier, the former being four times the carrying capacity of the TBM Avenger. In March and May of 1943, the mockup was inspected and an order for 23 production aircraft was put in. This was enough for a single squadron to operate from a Midway carrier. Problems began about this time, with the delivery of engines and propellers being delayed. By 1944, the Skypirate was still not airborne and it was obvious it wouldn’t be operational anytime soon. With earlier torpedo bombers performing adequately, a lack of support from the Navy, most of the Japanese fleet in shambles and continued delays with the Midway class (which would eventually sail after the war), the 23 production planes were cancelled. On February 18th, 1945, the first Skypirate was rolled out of the production facility, being completed on March 13th and finally going airborne on May 8th. Neither of the prototypes had any defensive armaments, but they were tested with torpedoes and drop tanks. Although no production was to ever start, the Skypirates would continue flying until the end of the war. During one such flight in June of 1945, a Skypirate was damaged mid-flight, but the craft was brought down safely. Engine problems were a frequent issue with the Skypirate and propeller problems would ground it in August of 1945, not flying again until after the war.
Perhaps the most well known photo of the aircraft, the Skypirate prepares to land.
Postwar, the aircraft industry changed with the introduction of jet aircraft, thus eliminating the need for many prototypes being developed during the war. The Skypirate was no exception. With the torpedo bomber role now fading, the Douglas firm looked at other options to revive their Skypirate. Some ideas included using the Skypirate for an electronic warfare role or even as an anti-submarine aircraft (a role overtaken by another piston engine aircraft, the Grumman AF Guardian), but none of these propositions ever managed to become reality. As the Cold War was just beginning, the Skypirate program ended in 1947 and the 2 prototypes were scrapped in 1948.
Design
The Skypirate is most likely the largest single-engine aircraft to ever be designed for carrier operations. In comparison, the twin-engined B-25 Mitchell medium bomber measured around the same in length and width.
The 2nd prototype in flight, notice how the tail is shorter in comparison to the first prototype.
The initial Skypirate design had an internal bomb bay, which the prototypes dropped in favor of four external Mark 51 Mod 7 bomb hardpoints. These hardpoints could carry a range of weapons including 500Ib-2000Ib bombs, torpedoes, depth charges, mines or even incendiary bombs. The use of up to 4 Mk.13 Torpedoes (from land) were planned had it entered production. The Skypirate could alternatively carry up to 8,400Ibs of bombs. For offensive armament, the Skypirate had 4 M2 Browning machine guns in the wings. For defense, it had a Firestone model 250CH-3 remote turret behind the cockpit which carried 2 M2 Brownings and a turret in the back of the lower fuselage which carried a single M2 Browning. The lower turret was remotely fired through electronic control and powered hydraulically. Drawings indicate that Mark 2 Gun Containers could be added for extra forward firepower but none were ever attached during testing. 300 gallon drop tanks were also fitted during testing and could have been used had the craft been operational.
The sole mockup made alongside the 2 prototypes.
Along with such an impressive weapons payload, the Skypirate was full of advancements which would have improved its performance. To get such a large aircraft off the ground, the Skypirate was powered by a single Pratt & Whitney XR-4360-8, the largest radial engine ever built up to that time. The engine had a unique exhaust style that combined the exhausts in alternating rows to lower the effects of backpressure. Being a carrier-based aircraft, the Skypirate had folding wings as well as a catapult hook. The inclusion of a tricycle landing gear was also interesting, as it helped with bomb loading and carrier space. Most single engine aircraft of the time preferred using a tailwheel. The Skypirate had large flaps that extended the length of wingspan. The outer flaps served as ailerons while the midsection flaps were used as dive flaps. The dive flaps could also be lowered to help the aircraft cruise or assist in turning to help ease the stress off the aircraft when fully loaded. To assist with bombing or flight in general, a Type 3 Sperry vacuum-controlled, hydraulic autopilot was also to be added. A de-icing system was also added that pumped hot air over the wings and tail section.
The planned modifications of the prototypes are interesting to note. The 2nd prototype (Bu.36934) differed from the first, having a shorter tail of 8.6 ft, compared to the regular 10.5 ft tail of the original design. This was done most likely to conserve valuable space when inside a carrier. Along with these differences, plans to fit a jet engine in the fuselage of the 2nd prototype were made, but nothing ever came to fruition. The first prototype (Bu.36933) had a larger tail and was planned to be converted for the scout bomber role. These plans included adding cameras onboard. As with the jet engine designs, these also never came to be.
Variants
XTB2D-1 Bu.36933 – Prototype version, lacked any armament
XTB2D-1 Bu.36934 – The 2nd prototype. The tail was shortened to 8.6 ft. Also lacked any armament.
TB2D-1 – Proposed production version, 23 were ordered and planned production was to be 100 built every month. These versions were to be fitted with four .50 caliber machine guns in the wings, two in a Firestone power turret and one remotely controlled in the ventral hull. Eventually, the production versions were cancelled in favor of higher priority projects.
Operators
United States of America – Slated to be used aboard the Navy’s Midway-class carriers, with the end of the war and other setbacks, the XTB2D-1 was never used operationally.
The design team poses with the first Skypirate on rollout day.
TB2D-1 Specifications
Wingspan
70 ft / 21.3 m
Length
46 ft / 14 m
Height
22 ft 6 in / 6.9 m
Wing Area
605 ft² / 184.4 m²
Engine
1x 3,000 hp ( 2240 kW ) XR-4360-8
Propeller
1x 8 bladed Hamilton Standard contra-rotating propeller
Fuel Capacity
501 US gal / 1896 L
Oil Capacity
28 US gal / 106 L
Empty Weight
18,405 lbs / 8350 kg
Gross Weight
28,545 lbs / 12950 kg
Maximum Weight
34,760 lbs / 15765 kg
Rate of Climb at Sea Level
1,390 ft / 425 m per minute
Time to 10,000 ft / 3048 m
8.2 minutes (Normal) 10.2 minutes (Military)
Time to 20,000 ft / 6096 m
22.3 minutes (Normal) 26.5 minutes (Military)
Maximum Speed
340 mph / 550 km/h at 15,600 ft / 4755 m
Cruising Speed
168 mph / 270 km/h
312 mph / 500 km/h (with torpedoes)
Range
1,250 mi / 2010 km (Torpedoes)
2,880 mi / 4635 km (Maximum)
Maximum Service Ceiling
24,500 ft / 7470 m
Crew
1 pilot
2 gunners
Armament
4 Browning M2 machine guns mounted in the wings (1600rds)
Douglas XTB2D Skypirate Side ViewDouglas TB2D Skypirate Side View – With the Defensive Gun Pod
The last known photos of the Skypirates before being scrapped.One of the prototypes with mounted Mk-13 torpedoes.A back view of one of the prototypesFirst prototype of the Skypirate on the runway.An impressive look at the massive Skypirate from the front.Perhaps the most well known photo of the aircraft, the Skypirate prepares to land.The 2nd prototype in flight, notice how the tail is shorter in comparison to the first prototype.The sole mockup made alongside the 2 prototypes.The design team poses with the first Skypirate on rollout day.
The VL Pyörremyrsky prototype parked on a ramp [Colorized by Michael J.]The VL Pyörremyrsky (translates as Hurricane) was a prototype Finnish fighter plane designed to keep up with its contemporaries. It was to be domestically produced, using wood, but using the same engine as the Bf 109 G. Due to limitations brought about due to the war, only one prototype was produced and it wasn’t ready until the end of 1945.
Development and History
As Finland found itself still at war with the Soviet Union in 1942, with no end in sight, it turned to ways to bolster its military force. In order to become as self sufficient as possible, it was engaged in various projects for domestically designed and produced weapons systems. The VL Myrsky project was severely behind schedule and the air force realised that it would be outclassed by the newer Soviet aircraft by the time it reached production. With this in mind, it placed order number 2012/42 on 26th November 1942 for a new aircraft design, under the name Pyörremyrsky.
The State Aircraft Factory (Valtion Lentokonetehdas) was tasked with producing the new fighter and Captain of Engineering Torsti Verkkola was assigned chief designer of the team. The main premise was that the aircraft was to be made out of wood, as much as was possible, and that it was to be comparable with the German Messerschmitt Bf 109G. Verkkola used the Bf 109 as the base for his design, making modifications to allow it to be produced with local skills and materials. However, as the war dragged on, and the Finnish Air Force required more proven aircraft, as well as repairs to the planes already in service, the Pyörremyrsky found itself given a lower priority.
Profile of the Pyörremyrsky. Source: Warthunder forums
Upon the cessation of hostilities between Finland and the Soviet Union in September 1944, the Pyörremyrsky project had only a partially completed prototype and the Ministry of Defence (puolustusministeriö) cancelled the advance order of 40 aircraft, as well as the second prototype on the 29th September, but they did allow the first prototype to be completed. In Autumn 1945 the prototype, now christened PM-1 (which led to the nickname Puu-Mersu or Wooden Messerschmitt), was ready for pilot tests. On the 21st of November 1945, Luutnantti (Lieutenant) Esko Halme took off in PM-1 from Tampere-Härmälän airfield. The flight only lasted 25 minutes as part of the engines’ exhaust system came loose, forcing an emergency landing as Lt. Halme was unable to see through the exhaust blowing into his cockpit. Despite the incident, Halme reported good flying controls and characteristics. PM-1 would do 2 more test flights at Härmälän airfield before moving to Kuorevesi for Air Force testing. In total 31 test flights were performed, amounting to 27 hours of flight time. All 8 pilots reported the same, smooth and controlled flying characteristics, good speed and turning ability, however it was not quite up to the same performance of the Bf 109 G but close enough. The last flight of PM-1 was on the 22nd of July 1947, when Kapteeni (Captain) Osmo Kauppinen took off for a 20 minute general test flight. After this it was put into storage until it was officially removed from the Air Force’s rolls on the 1st April 1953. This was mainly due to the lack of ability to source new engine parts as part of the armistice Finland signed with the Allies forbade them from receiving military goods from Germany, as well as the decline of the piston aircraft as a fighter.
The Air Force didn’t want such a unique piece of Finnish aviation history to be scrapped however and ordered it to be preserved. It was sent to the State Aircraft Factory’s depot and was refurbished in the early 1970’s and sent to the Finnish Air Force Museum, where it is still on display.
The experiences learnt with the Pyörremyrsky were not totally in vain or wasted as the basic design was used in the development of the VL Vihuri fighter trainer.
Design
Access panels open revealing the engine. Source: Suomen Hävittäjät
Captain Verkkola used the Bf 109’s low-wing cantilever monoplane configuration as his base for the Pyörremyrsky. The Germans were also willing to supply the Daimler-Benz DB 605A-1 liquid cooled V12 engines and VDM 9-12087 three-bladed light-alloy propellers that were used on the Bf 109 series. It was also installed with a German produced Telefunken FuG 7a model of compact airborne receiver/transmitter.
The main body of the aircraft was built using the vast amounts of wood available to the Finns, with metal being used where absolutely necessary, like the cockpit and engine housing. While many believe the design is similar, if not copied from the Bf 109, there are many differences outside of just the materials used. The rear portion of the fuselage is of wooden monocoque design, with the horizontal stabilizers mounted at the near end, as opposed to the Bf 109’s which are mounted on the vertical stabilizer. The wings were of negative transverse V shape and covered in plywood panelling.
PM-1 at the Tampere trial airfield in the Summer of 1945. Source: Suomen Hävittäjät
Unlike the wing fuel tanks found in the Bf 109, the Pyörremyrsky had a single tank behind the cockpit, protected by a 10mm thick armoured plate. The landing gear was copied from the Bf 109 but the Finns made some changes to eliminate the narrow and problematic system that plagued the Germans. The tailwheel was also retractable, thus helping it with aerodynamics.
Due to wartime shortages, Finland was forced to rely on substandard replacement products. The use of Lukko glue was one of the main reasons for the failings in the VL Myrsky and so it has been suspected that the Pyörremyrsky would have suffered similar issues to its sister aircraft had it been pushed into service or flown for longer periods of time.
Armament was not fitted to the PM-1 but it was designed to be installed with a Motorkanone mounted 20 mm (.78 in) MG 151/20 cannon and two nose mounted synchronized 12.7 mm LKK-42 machine guns. It was also proposed that the wings would have provisions for two 100kg bombs each for fighter bomber duties, but it is not clear if the proposal was ever considered seriously.
Operators
Finland – The VL Pyörremyrsky was intended to be used by the Finnish Air Force.
VL Pyörremyrsky Sideart by EscodrionPM-1 in the Finnish Air Force Museum, next to a BF-109G. Source: WikimediaClose up of the undercarriage. Notice how they are copies of the BF-109 but close inwards. Source: WikimediaThe PM-1 cockpit. Taken at the Tampere trial airfield in the Summer of 1945. Source: Suomen HävittäjätProfile of the Pyörremyrsky. Source: Warthunder forums
Sources
Suomen Ilmavoimien Historia 14 Suomen Hävittäjät, Kalevi Keskinen, Vammalan Kirjapino Oy 1990, Suomen Ilmavoimien Historia 17 LeR2, Kalevi Keskinen, Edita OYJ 2001, www.ilmailumuseot.fi, Valtion Lentokonetehtaan historia – Osa 2: Tampereella ja sodissa 1933–1944. Jukka Raunio, 2007, Images: Side Profile Views by Escodrion – https://escodrion.deviantart.com, Colorized Images by Michael J.
The PZL P.50 Jastrząb (Hawk) entered development in 1937 as a replacement for the outdated PZL P.11 and PZL P.24 fighters. Very little was known about the aircraft until relatively recently, with only a few photographs and documents about this aircraft surviving World War II. Most of what is known at the time of writing is based on accounts and sketches from PZL engineers years after the war and mostly based on memory, which is not the most reliable form of historiographic evidence. Ultimately, the project was cancelled in March of 1939 due to dissatisfaction with its underpowered radial engine, despite an attempt being made to fit an inline vee engine to the aircraft in the form of the PZL P.56 Kania (Kite).
History
In the latter half of 1936, plans to replace all of Poland’s PZL P.11 single-engine fighters with the twin-engined PZL P.39 heavy fighter were abandoned, and the need for a maneuverable single-engine interceptor was recognized. Briefly, the PZL P.24 was considered in order to fulfill this role, but as it did not offer much of an improvement over the P.11, it was ultimately decided that an entirely new design was needed.
Wsiewlod Jakimiuk, the head of PZL’s fighter team, submitted a proposal in autumn 1936 featuring “an advanced low-wing monoplane which offered improved all-around performance and great scope for future development” (Cynk, p. 259). The aircraft resembled the American Seversky/Republic fighter designs. One of the things that Jakimiuk focused on in the design of this aircraft was to allow upgrading to larger and more powerful engines to be a simple task to accomplish at any later time.
Ultimately, after a heavily-protracted design process plagued by numerous issues, the aircraft never saw combat and only 32 airframes had been built before Poland was invaded by Germany and the USSR in September 1939, but 30 of these were not completed.
Design
This image shows Count Ciano of Italy inspecting the P.50/I. Note the cowling’s radial engine cooling system.
In the fall of 1937, the design, now called the PZL P.50 Jastrząb and powered by a British 840-horsepower Bristol Mercury VIII radial engine, was approved and two prototypes were soon built. The first prototype, called the P.50/I, was designed to take engines up to 1,200-horsepower while the second prototype, the P.50/II, was designed for engines of up to 1,600-horsepower. Both versions were to be armed with four 7.7-millimeter machine-guns in the wings although, confusingly, the few images of the P.50/I show two of these guns in the forward fuselage instead. The P.50A production version of the P.50/I was envisioned to have a top speed of 310 miles per hour (500 kilometers per hour) at 14,100 feet (4,300 meters).
The Polish Aviation Command almost immediately ordered 300 aircraft and paid for the first 100 in advance, with the first 50 expected to be delivered by September 1939. In order to speed up development The Dowty Company of Britain was contracted to build the landing gear for the prototype, while PZL and the Czech Avia company would design the production aircraft’s landing gear. Dowty delivered the landing gear over four months late, and the P.50/I Jastrząb prototype, still utilizing the Mercury engine, did not even fly until February 1939.
During the P.50/I’s initial flight trials, it was discovered that the desired performance parameters were far out of reach. The top speed at full load was only 274 mph (442 kph). It also handled low-speed turns very poorly and had a tendency to wobble at top speed. Curiously, it was discovered that the engine was unable to produce full power under any circumstances. It was not until May that it was realized that the carburettor air intake was too small. After enlarging the intake and improving the tail and wing surfaces, the aircraft’s performance was improved. In August, the aircraft finally reached its desired speed but, by the time the war began in September, the aircraft was still a long way from being ready for service. The only known photos of the P.50/I come from a visit in February 1939 by the Italian Foreign Minister, Count Galeazzo Ciano.
Developed alongside the P.50/I was the P.50/II, which had been completed in the spring of 1939 and was still waiting for an engine by the time of the invasion in September. The P.50/II differed greatly from the P.50/I, so much so that it is believed to have received a new designation just before the war began. The canopy was an all-round-vision hood, somewhat similar to the Soviet Yak-1b. The P.50/II also included provision for additional fuel tanks and a 660-pound (300kg) bomb, and two 20mm cannons were added to the wings. The two machine-guns which were in the fuselage of the P.50/I were also moved to the wings. The powerplant was supposed to be the PZL Waran radial engine, capable of up to 1,400hp, with the intended top speed of the P.50/II being 350mph (560kph). However, development of the engine was far behind schedule and it was estimated that it would not be ready before the middle of 1940. In a desperate search for a suitable engine, several different options were considered. These included the 1,375hp Bristol Hercules and the 1,400hp Gnome-Rhone 14N, again both radial engines. In the end, the Hercules appears to have been chosen, and it was around this time that the P.50/II received its new designation.
This angle of the same visit by Count Ciano shows off the two machine-guns in the forward fuselage.
There was one more derivative of the P.50, beginning in late 1938. Political upheaval was ongoing in the Polish Air Force high command, and General Ludomil Rayski, who favored radial engines, was coming under heavy criticism and was nearing replacement by General Jozef Zajac, who favored vee engines. This replacement would eventually take place in March 1939. Jakimiuk, the designer of the P.50, anticipated this shift and proposed a Jastrząb adapted to take an inline engine. The aircraft was given the designation P.56 Kania (Kite) and was to be powered by the 1,200hp Hispano-Suiza 12Y, and later by the improved 1,600hp Hispano-Suiza 12Z. However, another PZL designer, Jerzy Dabrowski, submitted a competing design bearing the designation P.62, and this design was preferred over the P.56. The P.56 was ultimately cancelled in the summer of 1939.
When General Rayski was ousted from the command of the Polish Air Force in March 1939, the P.50/I was still having severe problems. His replacement, General Zajac, canceled all production of the P.50 almost immediately. 30 P.50A airframes had begun construction at the W.P.1 plant in Okecie and, after the P.50/I began to show improvement, construction was permitted to continue on these aircraft only. Because of the unsatisfactory results of the Mercury engine, plans were made to power the very first of these production aircraft with the 870hp Gnome-Rhone 14Kirs, and this aircraft was very close to being ready in September 1939. This was to be a sort of test aircraft for an improved version of the P.50A, the P.50B Jastrząb B. There were also plans to mount the 1,100hp Gnome-Rhone 14K or the 1,000hp Pratt & Whitney R-1830 Twin Wasp, although these never came to fruition.
“The Hawk Which Would Never Prey”
On September 5th, 1939, the PZL factory in Warsaw was evacuated. Test pilot Jerzy Widawski attempted to escape with the P.50/I prototype, but was accidentally shot down by Polish anti-aircraft guns. Five pre-production P.50A airframes and the P.50/II prototype, including the aircraft intended to be equipped with the 870hp engine mentioned earlier, were moved out of the Okecie plant on September 3rd. These were captured by the Germans and scrapped in 1940, bringing a final end to the P.50 Jastrząb project.
Variants
PZL P.50/I Jastrząb – Initial prototype of the PZL P.50 series. Powered by an 840hp Mercury VIII engine, the top speed was intended to be 310 mph, but it only ever reached 275 mph. Armament was four 7.7mm machine-guns, with two in the forward fuselage and two in the wings. One produced, first flew in February 1939.
PZL P.50A Jastrząb A – Planned production version of the PZL P.50/I. 300 were ordered, but only 30 built, all incomplete by the time of Polish capitulation. Fuselage was changed to a razorback rear, akin to the American P-47. It is unclear whether the fuselage machine-guns were moved to the wing, as documents imply they were but sketches of the aircraft still show them in the fuselage. Top speed had been improved to 310 mph (500kph).
PZL P.50B Jastrząb B – Planned development of the P.50A with a more powerful radial engine. One P.50A was planned to fit an 870hp Gnome-Rhone 14Kirs engine as a sort of testbed for the P.50B, but that is all that is known about this variant.
PZL P.50/II Jastrząb II – Second prototype developed alongside the P.50/I prototype as an all-around upgraded version. The canopy was changed. A 660 lbs (300 kg) bomb was added, along with two 20mm cannon to the wings. The engine was upgraded to the 1,400hp PZL Waran engine, giving a projected top speed of 350 mph (560 kph) . Only one was produced, without the engine, and never flew.
PZL P.56 Kania – Planned development of the P.50A Jastrząb A using either a 1,200hp Hispano-Suiza 12Y or 1,600hp Hispano-Suiza 12Z inline Vee engine. None produced.
Operators
Poland – 300 copies of the P.50A type were ordered, with only 30 incomplete airframes + 1 P.50/I prototype produced. Did not see service. A single P.50/II prototype also existed, but the type was never ordered.
PZL P.50A Jastrząb A Specifications
Wingspan
31 ft 9.875 in / 9.7 m
Length
25 ft 3.125 in / 7.7 m
Height
8 ft 10.25 in / 2.7 m
Wing Area
208.83 ft² / 19.4 m²
Engine
One 840hp (648.8kW) Bristol Mercury VIII nine-cylinder radial engine
Empty Weight
3,748 lbs / 1,700 kg
Maximum Takeoff Weight
5,511 lbs / 2,500 kg
Maximum Speed
310.6 mph / 500 kmh
Range
466 mi / 750 km
Maximum Service Ceiling
14,107 ft / 4,300 m
Crew
1 pilot
Armament
Four 7.7mm KM Wz 36 machine-guns mounted in the wings OR two in the fuselage and two in the wings
Provision for an unknown weight of bombs, possibly 220.5lbs (100kg), to replace two wing machine-guns
Gallery
Side view of the P.50/I illustrated by Ed JacksonSide view of the P.50 as it would have appeared in service by EscodrionThis blueprint of the P.50/I was drawn was based off of a PZL engineer’s sketch of the blueprints after the planes had been captured or destroyed.A period illustration of the P.50This photo shows one of the 30 incomplete P.50A’s, captured by the Germans after the invasion of Poland in 1939. They would later be scrapped.A small image with the Count Ciano of Italy inspecting the P.50/I. Note the cowling’s radial engine cooling system.This angle of the same visit by Count Ciano shows off the two machine-guns in the forward fuselage.Italian Foreign Minister Count Galeazzo Ciano inspects the P.50/I prototype in Warsaw, February 1939.
Polish aircraft historian Zabytki Nieva discusses the PZL P.50. Audio is in Polish with English subtitles available.
Video made by the author specifically to accompany this article.
The VL Myrsky (translates as Storm) is a Finnish domestically produced fighter. 51 were manufactured between 1941 and 1945 and it was one of the fastest aircraft in the Finnish inventory at the time. Despite having good performance on paper, it was plagued with issues and uncertainty. It would be withdrawn from service in 1947 having served in numerous roles such as interceptor, fighter-bomber and reconnaissance.
Development
Finland, being a small and newly independent nation, suffered from severe financial limitations and this included funds allocated towards its air force. However, the situation in 1930s Europe was not looking promising and in 1937 major funds were allocated to the defence budget for modernisation and expansion of Finland’s armed forces. By 1938, Finland had bought 7 Fokker D.XXI fighters, as well as the manufacturing license to produce more. However, Head of the Defence Council, Marshal Mannerheim, highlighted the need to produce a local fighter in order to lessen reliance upon foreigners in case of war. Major General Jarl Lundqvist, commander of the Finnish Air Force, replied that alternatives were being sought out but that high prices of specialised machinery, as well as many nations gearing up for war themselves, needed to produce such aircraft put limitations in place.
In early 1939, the Air Force made a survey of various aircraft designs and, upon completion in April, invited the State Aircraft Factory (Valtion lentokonetehdas) to ‘negotiations in Tampere on the construction of a prototype of a fighter machine in Finland’. On 4th May 1939, VL presented 5 different designs using the Bristol Taurus engine to the Ministry of Defence (puolustusministeriö) .
The Ministry of Defence placed contract 1094/39 with the State Aircraft Factory on 8th June 1939, which called for 33 aircraft to equip a fourth squadron. The design chosen was to be powered by the Bristol Taurus III 14-cylinder two-row radial aircraft engine, have semi-elliptical 19 square meter wings and retractable landing gear with allowances for ski pods. Its initial appearance was similar to the VL Pyry trainer which was undergoing prototype trials at the time.
Myrsky conducting patrols over ice floes
However, when the United Kingdom declared war upon Germany in September 1939 due to its invasion of Poland, the possibility of acquiring the Bristol Taurus disappeared and a solution was needed. The design team thought the best replacement was the Pratt & Whitney R-1830-S3C3-G Twin Wasp and an order was placed. Due to the inevitable delays and mounting pressure in Europe, the Air Force placed an order for 35 Fiat G.50s to equip the fourth squadron. On 30th November 1939, Soviet forces attacked Finland in the opening moves of what would become known as the Winter War. This action put paid to many of Finland’s rearmament plans, including the Myrsky development, with an official order of termination being issued by the Ministry of Defence on 8th December (which seems to have not been fully complied with due to archival material showing dates during the Winter War).
After the conclusion of the Winter War on 13th March 1940, Finland saw itself in a critical situation which was further enhanced by the actions of Germany in Denmark and Norway. In April, the Finnish domestic programme was restarted with an emphasis upon speed, which led to more delays on the design. Finland reached out to both the US and Germany for more powerful engines, like the American Pratt & Whitney R-2800 Double Wasp and German BMW 801. However, the US put an export ban on war material in July and Germany was unwilling to sell any materials except captured ones like the Curtis 75A Hawk and Morane Saulnier MS 406. This then led to the placement of the programme in suspension until the winter of 1940.
On 20th December 1940, contract 1621/40 was issued ordering a prototype. About 60,000 hours went into the design phase, with 77,000 manhours going into the manufacture of the prototype. The original goal was for a working prototype to be completed in early July 1941 but, with the outbreak of the Continuation War, the project saw delays again. The prototype was finally completed in December and made its maiden flight on the 23rd December 1941 by Lieutenant (Luutnantti) Erkki Itävuori. A few redesigns were made during this second stage of development, the most notable being the copying of the tailplane of the Brewster Buffalo F2A. Given the serial MY-1, the prototype suffered from engine difficulties, as well as displaying a tendency to yaw. Also, it had a high wing loading (194 kg/m2) which meant that its rate of climb and maneuverability were compromised.
Myrsky in flight above the runway
The MY-1 was redesigned and modified in order to fix the issues highlighted in the small scale test flights. The yaw was resolved by redesigning the whole rudder with an enlarged area and removing the supports from the horizontal stabilizers. Weight was reduced by changing the fuel tank, changing the engine gills and a few other minor changes, freeing up 317 kg and decreasing the wing loading to 175 kg/m2. The Hamilton Standard propeller was replaced by a locally designed VLS 8002 adjustable propeller and the exhaust pipes were modified to attain better thrust. Overall the MY-1 prototype went through four major modification stages and attained a final maximum speed of 519 km/h at 3250 meters altitude and a climb to 5000 metres in 6.5 minutes. While not perfect, the aircraft was seen as satisfactory. MY-1 took its last flight on 26th November 1943 with Captain (Kapteeni) Kokko, ending with a total logged time of 142 hours and 20 minutes in 162 flights.
Pre-Series Production
Prototype Mockup Myrsky
Before the prototype’s test flights had all finished the Air Force placed an order for a pre-series of three aircraft to be produced on 30th May 1942. The idea was for these three aircraft to help test concepts and make mass production faster when the time came. These craft were serialled MY-2 to MY-4 respectively. MY-2 was completed in April 1943, it had thinner wings, Hamilton Standard metal propeller, pneumatic brakes and was the lightest Myrsky at 2150kg empty. It was destroyed on 6th ofMay 1943 when its engine failed from lack of fuel, Captain P.E. Sovelius was injured during the crash landing. MY-4 was finished 5th June, it boasted a thicker wing, easier removable engine, better cowlings, hydraulic brakes and the VLS 8002 adjustable propeller. It weighed in at 90 kg more than the MY-2, or 2 240 kg. MY-3 was completed on the 11th July, it weighed in at weighed 2 210 kg but was similar to the MY-2 except for slight modifications. This series was known officially as the I Series (I Sarja).
MY-3 made a belly landing on 5th August 1943 as the landing gear malfunctioned. During the repairs, they patched up the fuselage with plywood, adding another 10 kgs. Splines were added to the propeller spinner to help reduce overheating and these were carried over to the production models. After repairs the MY-3 was cleared for more flights, on 19th November 1943, during a test dive, aeroelastic flutter broke off the wings and then the tail, plunging the aircraft into the ground at 855 km / h. Warrant Officer (Vääpeli) Aarre Siltavuori was killed. Investigation after the event concluded that the wings needed to be reinforced and that dive speeds should not exceed 600 km/h.
MY-4 was continually used for testing and its armament layout was the one used in the production series. In February 1944 it was issued to No. 26 Fighter Squadron (Hävittäjälentolaivue 26) to assess its viability as a combat aircraft, it immediately caused problems as the 20 pilots who took turns to fly it noticed issues with its flying characteristics in comparison to their Fiat G.50s. On the 17th March, during a diving test the plane was attempting to spin to the right and lieutenant Jaakko Marttila struggled with the aircraft, under such stress the right wing finally broke at two metres from the tip, causing the plane to enter into an uncontrollable spinning dive that killed the pilot.
Production Series and the Continuation War
Crew posing with their Myrsky
On the 18th August 1942, contract 1952/42 was issued that specified a production of 50 Myrskys, split into two batches. A three aircraft pre-series, as covered above, and a production series, to be called the II series, of 47 aircraft to be serialized as MY-5 to MY-51. MY-5 was completed in December 1943 and MY-51 was finished in December 1944.
The Myrsky continued to show problems during dives, MY-6 crashing due to the left elevator breaking loose when it reached 640 km/h in June 1944. This caused an order to reinforce all elevators, both on completed models and those going through production. Due to the numerous delays, the now adequate performance, as well as the many Bf 109’s supplied by Germany, the Fighter squadrons were not interested in the Myrsky. Indeed, only No. 26 Squadron were equipped with Myrskys to replace their aging Fiat G.50s but these were soon replaced by Brewster F2A Buffalo s. Orders from Air Force command saw the Myrsky banned from crossing the front lines due to their poor performance against contemporary Soviet fighters. Instead the reconnaissance squadrons (Tiedustelulentolaivue) gratefully received these speedy and modern aircraft, by comparison to their previous machines. No. 12 Reconnaissance Squadron became the first Myrsky reconnaissance unit in July 1944, there first mission was on the 9th August with a patrol flight in the Suistamo area where they attempted to intercept a flight of Yak-7 fighters with no results. The 22nd August saw the Myrskys baptism of fire when a 6 plane reconnaissance mission came across 3 Yak-9s at Mantsi. Lieutenant Linden scored confirmed hits upon one Yak but failed to bring it down, during the return flight Captain Virkkunen scored hits upon a La-5 but still not confirmed kills (after the war it was confirmed the Yak made an emergency landing at its home base and the La-5 suffered from damaged pressure systems).
During the later design phase, it was decided that the planes should be able to mount two 100 kg bombs. Pilots at the Tampere testing facility practiced the concept using weight concrete bricks but due to the planes relegation to reconnaissance, it was believed that the racks would not be used. However on the 3rd September, Captain Oiva Tylli led a six plane formation to bomb the Soviet 7th Army Corps headquarters at Orusjärvi (this saw the lifting of the crossing frontlines orders, as the HQ was some 35-40km behind the Soviet lines). 11 of the 12 bombs detached from their racks and damaged the lightly defended headquarters and the planes flew out of there before they could be intercepted. Later that same day the last combat mission of the Mysrky during the Continuation War took place, a four Myrsky flight was sent on a patrol at Sortavalan-Lahdenpohja but returned empty handed.
On the 4th September 1944 a ceasefire came into effect as a result of negotiations between the Finnish and Soviet Governments. No. 12 Reconnaissance Squadron was ordered to fly to Joroinen and await further orders. At the closing of hostilities, 44 of the 47 II series aircraft were completed. One squadron, No.12, was fully equipped, and another squadron, No.16, was partially equipped with six.
Lapland War and Peace
One of the stipulations of the ceasefire was the cessation of diplomatic relations with Nazi Germany and the expelling of Wehrmacht forces from Finnish territory by the 15th September 1944. With over 200,000 troops residing in Finland, as well as the essential nickel mines in Lapland, the Germans were both incapable and unwilling to withdraw in such a quick manner. This led to the outbreak of what became termed ‘The Lapland War’ (Lapin Sota).
A Finnish force of some 75,000 (4 Divisions as well as some attached elements) was assigned to the task of pushing the Germans from their land. A special air detachment was formed, Lentoryhmä Sarko, with the mission to support ground operations. 2nd flight of No. 12 Reconnaissance Squadron was subordinated to No. 26 Fighter Squadron at Kemi. Soon Myrskys were performing reconnaissance missions over Lapland but the severe weather soon put paid to any more flights by the Myrskys and on the 23rd November the last flight in combat conditions by a Myrsky was completed.
After the formalisation of the Moscow Armistice in September 1944, the Air Force was put in to peacetime strength in December. This saw a major reduction and restructuring of the Air Force as a whole. No.12 Reconnaissance Squadron became No.11 Fighter Squadron, and No.16 Reconnaissance Squadron became No.13 Fighter Squadron, these squadrons were amalgamations of other units and so were also equipped with BF-109G-2s and Curtiss Hawk 75As. The Myrskys continued to serve in these fighter units but were still subject to accidents, especially from stalling, which saw a suggestion to modified the wings with slots. MY-50, which was never issued to the air force but remained at the factory’s hanger, was modified with slotted wings but nothing went further. On 9th May 1947, Captain Kauko Ikonen, took MY-28 out for a training flight when it suddenly entered into a dive and broke up in the air. The plane plunged into the soft clay and was not recovered, No.11’s commander ordered a grounding of the entire Mysky fleet, which was confirmed by the Wing’s headquarters later that day.
The last flight of the Myrsky took place on 10th February 1948, when MY-50, was allowed to fly from its test hanger to Tampere for storage but as it came into land, it overshot the runway and landed on its belly.
Today there is a restoration project to bring back MY-14 to a fully reconditions state for display at the Finnish Aviation Museum. The project has reach a stage where it could be unveiled to the public for Finnish Air Force 100th anniversary air show in June 2018.
Design
When the original order went out for the design, Arvo Ylinen (head of the design-bureau), Martti Vainio (aerodynamics), and Torsti Verkkola (structural design), were assigned the task of designing the new plane.
They decided to combined the learning they had from the Pyry trainer with the experience of licensed building of modern aircraft like the Fokker D.XXI. This allowed for not only cheaper design and production but also allowed for the design to be tweaked to Finnish desires. Due to the limitations upon Finnish industry (both due to its economic and geographical locations), it was decided that the design would be a combination of wood and metal.
The fuselage used a metal wire frame which was then covered with fabric and plywood, while the wings made from plywood and covered in a birch veneer (called Kolupuu).This did allow for cheaper production and lighter construction but contributed to the breaking of the wings upon reaching certain speeds. Because of the rarity of duraluminium, it was decided that the Myrsky should have none of it in its construction (but because of problems finding a suitable replacement, it was used in certain aspects of the machine like the flaps), instead aluminum (which had been bought from Norway and Sweden before the war) would be used sparingly and combined with specialised wooden parts.
The generalised design was the conventional piston aircraft, with a low wing attached just forward of center. The cockpit suffered from the same issues that many of its contemporaries did, in that the long nose limited its forward vision, but it is have excellent side visibility. The armament was four VKT 12,70 mm LKk/42 machine guns, mounted two per side of the engine, these were synchronised to fire through the propeller. It was also decided to add a hard point under each wing which would allow for an additional fuel tank or a 100kg bomb to be used.
Due to wartime shortages, Finland was forced to rely on substandard, replacement products. The use of Lukko glue was one of the main reasons for the failings in the Myrsky. It was not of the same quality as pre-war glue and did not stand up to rain, frost and humidity (a common occurrence in Finland), and would require more man hours to keep the aircraft in a flyable condition.
Losses
During its lifespan, the Myrsky was involved in 48 separate incidents, 10 of these resulted in the complete loss of the aircraft and 4 pilots died as a result.
MY-2 was destroyed on 6th May 1943 when its engine failed from lack of fuel, Captain P.E. Sovelius was injured during the crash landing.
MY-3 was destroyed on 19th November 1943 when aeroelastic flutter broke the wings of the aircraft. The Pilot, Warrant Officer Aarre Siltavuori was killed
MY-4 was lost on 17th March 1944 during a training flight. The plane entered into a dive which then broke one of the wings. Lieutenant Jaakko Marttila died in the crash.
MY-29 was destroyed on 4th September 1944 during a transfer flight. Lieutenant Aulis Kurje lost control of his aircraft when the engine overheated and cut out. The plane crashed into the wood, causing the seat to break free, killing the pilot.
MY-25 was destroyed on 13th November, 1944. During a reconnaissance flight near Kemi, MY-25s engine cut out forcing Lieutenant Berndt Schultze to perform a crash landing, he sustained minor injuries.
MY-27 was destroyed on 26th January 1945. After a crash landing on the 23rd January 1945, it was decided to fly the aircraft down to Pori, during the flight the fuel ran out. Warrant Officer N. Satomaa crashed the plane into a forest near Veteli. He was badly wounded but survived.
The MY-26 was destroyed 25th December, 1945. Due to malfunction, Staff Sergeant (Ylikersantti) E. Tähtö was forced to crash land in Pori. He walked away with minor injuries.
MY-24 was destroyed on 11th December 1945. Sergeant (Kersantti) Onni Kuuluvainen lost control of his craft when performing a speed correction. After several attempts to recover the plane he parachuted to safety. The plane crashed into a farmer’s field in the Pori area.
MY-5 was destroyed on November 20th, 1946. Lance corporal (Korpraali) Erkki Jaakkola was forced to make a crash landing in a field after his plane suffered from a fuel feeding problem after climbing to 7,000 metres.
MY-28 was destroyed on 9th May, 1947. During a training session, Captain Kauko Ikonen lost control of his plane, which then broke into pieces and smashed into the ground at Nakkila. This caused the entire Myrsky fleet to be grounded.
Variants
VL Myrsky – Myrsky prototype. Serialled MY-1. It differed from the later versions in being armed with two fuselage mounted 12,7mm mgs and four wing mounted 7,7mm mgs in the wings. It also had the Pratt & Whitney R-1830-S3C3-G Twin Wasp engine. The altitude stabilizers were originally supported but removed during the stage III modifications. Its undercarriage is also 15cm longer, giving it a more angled appearance when on a flat surface. Only 1 produced
VL Myrsky I – The pre-series production. Used to test ideas from the prototype, and to help gain experience in production. Each one was slightly different with various modifications. These were powered with the Pratt & Whitney R-1830-SC3-G Twin Wasp engine. They had more fabric pieces than their production counterparts. 3 produced.
VL Myrsky II – The production series. Taking the experience gained in the prototype and pre-series phases and putting it into practice. Using the R-1830-SC3-G Twin Wasp engine, it was modified with different gears to produce 1,155 horsepower on take-off. 47 were built.
VL Myrsky III – In March 1944 an order for 10 improved Myrsky versions was given to the State Aircraft Factory. This order was cancelled on 30th September 1944 and the whole series was cancelled on 30th May 1945.
Conclusion
The VL Myrsky was the embodiment of Finnish thinking, small and quick, hard hitting but light. The domestic fighter programme would not only bring more jobs to the locals but would be a point of pride that Finland could stand its own if it needs be. Also, as it was the only domestic fighter to see service during the war, it became a symbol of pride of Finnish independence.
Because of the many delays in its production, by the time it arrived on the front lines, the war had stabilized into what is termed ‘asemasota kausi,’ or The Trench War period. This meant that the war was much quieter in comparison to the other fronts that the Soviets were fighting on. The fighter pilots reports upon its mediocre performance in terms of speed and maneuverability in comparison to the Yaks and Las they were facing but the reconnaissance pilots reported positively upon these characteristics. It occupied the second fastest serving aircraft in the Finnish Air Force (only the BF-109 being faster) and its cockpit ergonomics were favorable and the pilots enjoyed its ground handling properties, thanks to the wide undercarriage.
It was far from the perfect aircraft, at low speeds it had a tendency to stall to the left. Its batteries tended to drain quickly if not pulled from the aircraft when not in use and the metal parts were prone to rusting. The inferior quality of the glue used during the war meant that more maintenance was required to keep the airframe flight worthy, reports of seams on the wing surfaces, rudder and elevators opening were a common occurrence. Pilots, both fighter and reconnaissance, reported upon the armament being too weak to take on the modern Soviet fighters and that due to the engine being governed, the plane was ‘too slow’ for what it should have been.
Operators
Finland – The VL Myrsky was only used by the Finnish Air Force
VL Myrsky II
Wingspan
36.08 ft / 11.00 m
Length
27.39 ft / 8.35 m
Height
9.84 ft / 3.00 m
Wing Area
193.75 ft² / 18.00 m²
Engine
1x Pratt & Whitney R-1830-SC3-G Twin Wasp modified (1,155 hp)
Maximum Weight
7,083 lbs / 3,213 kg
Empty Weight
5,152 lbs / 2,337 kg
Climb Rate
49.21 ft/s / 15.00 m/s
Maximum Speed
292.04 mph / 470 km/h at Sea Level
332.43 mph / 535 km/h at 10830 ft / 3,300 m
Maximum Service Ceiling
31,170 ft / 9,500 m
Crew
1x Pilot
Armament
4x 12.7mm VKT 12,70 Lkk/42 (960 Rounds Total)
Ordinance
2x 220.5 lb /100 kg Bombs or
2x 39.62 Gal / 150 L Drop Tank
The Hakaristi (Finnish Swastika)
It is important to note the use of the ‘Swastika’ on Finnish military equipment due to the confusion of its application.
Finland first adopted the Swastika (known as Hakaristi, broken cross, in Finnish) on the 18th March 1918, thanks to a donated aircraft that arrived earlier that month from Swedish Count Eric von Rosen (who used a blue swastika as his personal symbol). The Hakaristi became a national symbol from that moment, being used on everything from the Medal of the War of Liberation, the Mannerheim Cross, tanks, aircraft, to even a Women’s auxiliary organisation.
It became part of the official Air Force insignia, being used as an identification symbol as well as on certain badges and awards, from its inception in 1918 and today is still maintained upon certain symbols like the Standards of Commands.
Due to this early adoption, it has no association with the Nazi regime and the usage of such a symbol by both parties is only a coincidence.
Gallery
VL Myrsky – MY-50 by Brendan MatsuyamaVL Myrsky MY-5 by Brendan MatsuyamaPrototype Mockup MyrskyMyrsky in flight above the runwayCrew posing with their MyrskyMyrsky conducting patrols over ice floesMyrskys hangared for maintenance
Austro-Hungarian Empire (1916)
Nazi Germany (1945)
United Kingdom (1915 & 1917)
Yugoslavia (1939)
United States of America (1944)
USA (1945)
Finland (1945)
Poland (1939)
