Fw 190A-4 at the Soviet AF SRI
D.A. Sobolev, D.B. Khazanov
In autumn 1942, Fw 190 fighters began to be widely employed on the Soviet-German front. Back during their visit to Germany in 1940, Soviet delegation members made an attempt to see that aircraft. The Germans refused to demonstrate the prototype at that time. In mid-August 1941, Red Army soldiers from the 30th Army captured a detailed description of the Focke-Wulf fighter during combat near the settlement of Pochinok. About a month later, intelligence departments of operational units were informed of the German innovation. The expectation was that Red Army Air Forces aviators could face this aircraft at any time. But, its power plant was not yet developed properly (in particular, the BMW 801 engine cooling system) and Germans were not ready to equip their squadrons on the Eastern Front with this Focke-Wulf aircraft.
On 23 June 1942, Ober-Lieutnant A. Faber flying Fw 190A-3 Werk Nr 0313 from III/JG2 became disoriented and landed in South Wales. The British considered the airplane the most valuable trophy of the air war and tested K. Tank's innovation in detail. They published the materials on the Fw 190 and shared information with their Soviet ally. Even prior to the appearance of these aircraft en masse against the Red Army Air Forces, it became known that the "short forward fuselage, tapered wings with square tips, and V-dihedral at the wing roots" could help to identify the aircraft in the air. The English also stated that the Focke-Wulf was demonstrating its highest combat effectiveness at altitudes of 5000-7000 meters.
Detailed examination of a BMW 801 engine in the Soviet Union taken from a Do 217K-1 aircraft that had made a force landing helped in learning more about the Focke-Wulf fighter. A TsIAM team of engineers that B. A. Terekhov and Kh. M. Kuzyakhmetov led performed special tests on model A-2 engine Nr 30871 under laboratory conditions. The conclusions were as follows: the engine took the form of a carefully developed standard power plant for fighters and bombers. The main idea of the construction was to reduce drag to a minimum. For this, the German engineers made the piston stroke equal to the cylinder diameter, used a short connecting rod, and did away with external intake pipes. Supercharger air was taken from beneath the oil coolant situated inside the cowling.
During testing, attention was devoted to the direct injection of fuel into the combustion chamber (as on DB 601-605 engines) and forced air-cooling of the cylinder heads from a fan, the drive of which was installed in the reduction gear head. The engine was fuel-efficient and could run on low-octane gasoline.
TsIAM chief V. I. Polikovskiy deemed it necessary to point out the reliable work of the ceramic spark plugs that showed no signs of overheating. He recommended that German know-how be used in selecting the plugs for domestic M-82F engines. At the time, our specialists did not know that, beginning in 1941, Focke-Wulf fighters were fitted with the more powerful BMW 801D engine.
The British determined that, with a takeoff weight of 3890 kilograms, the Fw 190A-3 reached a speed of 603 km/h at an altitude of 5500 meters and reached a speed of 627 km/h at 6000 meters when a 1-minute reheat was used. But, we needed to verify the Focke-Wulf tactical flight characteristics for ourselves. This opportunity arose on 16 January 1943, thanks to a synchronizer failure. Warrant Officer Helmut Brandt of I/JG54 shot off his propeller blades with a cannon round and he was unable to get his aircraft to his side of the front line. His airplane landed on the ice of Lake Ladoga and he tried to escape on skis, but was caught by Russian patrols. The captured fighter aircraft was urgently evacuated to the rear and then handed over to Engineer-Captain P. S. Onopriyenko, a lead engineer, for testing at the Air Forces Scientific Research Institute.
Fw 190A-4 Werk Nr 2310 was examined for a longer period of time and more carefully than any other captured aircraft. In June of 1943 Major Yu. A. Antipov flew 37 sorties that made it possible to define not only basic flight data, but also maneuverability and acceleration at different altitudes and the how reliably various components operated. Not only Major Antipov, but test pilots Major Golofastov and Engineer-Lieutenant Colonel Kochetkov, gave its speed and rate of climb low marks and thought domestic Yak-9 and La-5F were better at altitudes up to 6000 meters.
They also noted the obvious Focke-Wulf advantages: excellent all-round view without object distortion, good horizontal handling in all speed ranges, and automatic supercharger gear switchover during combat. The Fw 190 was very heavily armed. It had four 20mm cannon and a pair of synchronized standard-caliber machine guns. The aircraft was stable while diving, accelerated rapidly, transitioned from bank to bank easily, and rolled vigorously but, nevertheless, the pilots felt that the German fighter was more difficult to handle than domestic Yakovlevs and Lavochkins.
Many special design features drew the attention of Soviet specialists. For example, a single master central made handling easier, providing untroubled and efficient engine adjustment. The cowling layout with armored forward ring where the oil radiator and oil tank were placed, pumping oil from the engine directly to the oil tank, and engine forced air-cooling all were of great interest. Soviet designers and above all S. A. Lavochkin, who specialized in fighters powered by air-cooled engines, had an opportunity to evaluate these ideas and use them in part in their latest aircraft modifications.
By early 1944, having analyzed how the canopy mechanisms on different types of fighters operated, experts from the TsAGI New Equipment Bureau concluded that one of the best ways to solve the problem was a model the K. Tank team developed.51 This canopy jettison mechanism driven by an explosive charge compared favorably with widely used springs and cushions applied, for example, on Bf 109F and American P-40 aircraft. Due to the German influence, the canopy jettison mechanism appeared on Soviet fighters for the first time on Soviet Yak-3 prototypes in September 1943.
In late 1942-early 1943, Soviet designers reduced the rear fuselage fairing and introduced bubble-shaped canopies on fighters. This provided pilots flying Lavochkin and Yakovlev aircraft all-around visibility. But, their windshields were still stained with oil, although not as badly as was the case early in the war. La-5 cockpit ventilation was unsatisfactory and pilots suffered from heat and stuffiness. Distorted images of objects seen through the Plexiglas canopy panes hindered the Yakovlev pilots. At the same time, the Fw 190 canopy was made from a sheet of high-quality Plexiglas and was elevated above the fuselage, providing an all-round view. Its efficient cockpit ventilation kept the pilot comfortable both in summer and winter.
It might be said that the Fw 190A-4 No. 2362 was possibly evaluated too harshly. Pilot M. L Gallay thought that the most unpleasant special feature in handling the aircraft was the great dependency of its longitudinal stability upon speed and engine operating mode. His colleague A. N. Grinchik noted insufficient longitudinal stability at nominal speed and considered the lateral stability as excessive. In general, domestic fighters were more pleasant to fly. All test pilots thought that the Focke-Wulf cockpit was too confining and a long sortie tired the pilot. At the same time, the fighter was easy to land and allowed a high flare despite its high landing speed and considerable wing loading.
An automatic tail wheel lock mechanism connected with the elevator controls had aroused the interest of Soviet specialists before the war when the aircraft bought in Germany were examined. It substantially increased the aircraft's ground maneuverability. When the airfield soil was soggy, this was a very valuable advantage. A demand was made for Soviet engineers to develop a similar design as soon as possible. Already working on a Yak-1M prototype built in late winter 1943, A. S. Yakovlev introduced a semi-automatic tail wheel lock connected with the control stick. When the stick was moved forward from neutral, the tail wheel became an unlocked castor. Test pilots, and then line pilots, appreciated this device installed in prototypes and series-produced Yak-3 fighters.
The E-67 two-speed engine automatic gear-changing device developed at TsIAM following examination of a similar unit on the German BMW 801 engine proved rather useful for domestic aircraft. Previously it had been established that they sometimes "lost" up to 25 km/h in speed due to difficulties in observing the recommended gear-change altitude during combat, especially when the battle was underway close to critical altitude. This fact defined the tactical value of the E-67 for Soviet aircraft, especially fighters. The device underwent extensive testing on M-105PF and M-82FN engines and confirmed its reliability and its operational, tactical, and technical value.
The VG system of combined throttle and propeller pitch control, also created at TsIAM after study of the German Daimler-Benz and BMW engines, made possible selection of the most efficient engine rpm for each flight mode. The design of the main unit—a differential gear mechanism with two degrees of freedom — did not differ much from the one the German engineers designed. In 1943-1944, the VG system was successfully tested on Yak-1, Yak-7B, La-5FN, Il-2, and Pe-2 aircraft and produced good results. For one, the Yaks consumed 20 percent less fuel, Pe-2 technical range increased 10 percent, and there was no engine overspeed when diving and recovering from a dive. In addition, domestic aircraft handling became significantly less complicated since pilots no longer were distracted by the requirement to monitor propeller pitch.
- "The German Imprint on the History of Russian Aviation " /D.A. Sobolev, D.B. Khazanov/