|Type||Wright SGR-1820-G2 Cyclone||M-62IR|
|Wing area (m2)||35.07|
|Weights (kg) and loads|
|Loaded||4056||4280 to 5190|
|Wing Load (kg/m2)||116||122 to 148|
|Power load (kg/hp)||4.83||5.09 to 6.18|
|Turn time (sec)||?||?|
|Roll (m, [sec])|
|Gun Type||Browning 7.62mm|
|Position||4 in wing fairings|
The design of the Vultee V-11, an adaptation of the Vultee V-1A transport for the attack-bomber role, embodied the latest structural and aerodynamic techniques evolved in the USA and also featured a retractable undercarriage. Powered by a Wright Cyclone SR-1820-F53 radial engine driving a two-blade controllable-pitch metal propeller it was first flown in September 1935. It employed the same wing and undercarriage and essentially similar tail surfaces to the V-1A but had a new fuselage, a semi-monocoque stressed-skin structure of elliptical cross-section, incorporating an internal bomb-bay. A continuous four-section canopy ("greenhouse") joined the two cockpits and the stepped aft section of the canopy was pivoted at its base to permit deployment of an aft-firing machine gun. The fuselage structure included four strong longerones but no stringers and the metal skin was of 1.5-2.5mm thickness.
The wing centre section was built as an integral part of the fuselage and the stressed skin had corrugated reinforcements on the inside. The outer wing panels were tapering and had dihedral and the wingtips were rounded. The rudder and elevators were horn-balanced and the ailerons had trim tabs. Landing flaps were incorporated into the trailing edges of the wings. The main undercarriage legs were retracted electrically inwards into the wing centre section.
The V-11G was a two-seater but the V-11GB was fitted with three seats for a crew consisting of pilot, bomb-aimer and rear gunner. A window for bomb-aiming was inserted in the floor below the gunner's swiveling seat and aft of this window there was a hatch which permitted the bomb-aimer to fire a gun aft and downwards. Observation windows for the bomb-aimer were inserted in the rear fuselage sides. Armament comprised four fixed forward-firing machine guns mounted in the wings and two aft-firing, one dorsal and one ventral gun on flexible mounts. The internal bomb-bay could hold about 270kg of bombs and the alternative external load could comprise up to 550kg. A few V-11s were acquired for service tests by the USAAC as the A-19 and others were exported to Brazil (twenty-six), China (thirty) and Turkey (forty). A number of the V-12 derivative, which had a more powerful engine, was sold to China.
Soviet Amtorg representatives arrived at the Vultee plant in 1936 to discuss acquisition of the V-11GB. They obtained four as pattern aircraft and purchased a licence for series production in the Soviet Union. The first of the pattern aircraft, NR17328 (c/n 32), was flown on 31 January 1937, followed by NR17329 (c/n 33) on 26 February. Both were powered by 850hp Wright Cyclone GR-1820-G2 nine-cylinder air-cooled radial engines and had three-blade metal propellers, and one was converted to floatplane configuration in the USA for tests (c/n 33). Both aircraft were sold via Sam Carp, V.M.Molotov's brother-in-law, c/n 32 in March and c/n 33 in April, and shipped in April, the second on board the SS Lunacharsky. An export licence was granted for both aircraft on 20 April 1937. The remaining pair of V-11s (c/ns 34 and 35) were delivered unassembled and without engines.
All previous types in the light and heavy ground-attack (legkii/tyazhelyi shturmovik) categories during the late 1920s and early 1930s had been failures, including the Tupolev ANT-18 (TSh) and ANT-17 (TShB), the Grigorovich TsKB-6 (TSh-1), TsKB-21 (TSh-2) and TsKB-23 (ShON), and the Kocherigin- Gurevich TsKB-24 (TSh-3). The shturmovik units were equipped with light attack versions of the R-5 and R-Z reconnaissance aircraft and in the meantime types better suited for this role were sought abroad.
S.A.Kocherigin's design bureau was instructed to adapt the Vultee design to Soviet standards (metric system etc) and prepare the technical documentation needed for the licence production. The Vultee V-11GB was adopted by the VVS as the BSh-1 in the new armored assault aircraft category. Originally the V-11 had no armour protection for the crew, power plant or fuel tanks and it was relatively lightly armed. With the addition of light armour for the crew and a further increase in weight the performance suffered and finally became inadequate. The first aircraft powered by the 840...1,000hp M-62 air-cooled radial engine was completed in 1937 and a total of thirty-six were built, the first five allegedly from American components, before further production was cancelled at the end of 1938.
The BSh-1 did not pass the state acceptance trials because of poor performance, its maximum speed of 318km/h at sea level was only 42km/h higher than that of the Polikarpov R-Z, which it was to succeed, and its rate of climb was lower than that of the R-Z. In general the BSh-1 was much inferior to both the S.A.Kocherigin R-9 and the Neman R-10. Moreover, static tests revealed insufficient structural strength. As a stopgap a shturmovik version of the R-10 was developed but in the event this type did not enter VVS service either. The Vultee V-11 provided experience with modern American techniques in metal stressed-skin monocoque construction, however, and already during the negotiations in 1936 the Vultee representatives got the impression that the Soviets were more interested in the manufacturing techniques and structural design innovations than in the actual aircraft.
All aircraft and spare parts built were handed were handed over to Aeroflot in 1939 for conversion into mail planes and were redesignated PS-43. The first was completed and test-flown in April 1939. The thirty-one aircraft put into service were registered СССР-Л3000 to СССР-Л3030 (c/ns 500-531) and included one original Vultee-built machine with Wright Cyclone engine. Occasionally used also for passenger transport they could accommodate three passengers aft of the fuselage fuel tank. At the end of 1939 the first of twenty-four intended for airline service and three out of seven intended for use by the GVF training groups had been delivered from Zavod No. 1 in Moscow. At the beginning of April 1940 another thirteen were ready, of which one was assigned to the NII GVF, and by the end of the year all were in service. The PS-43s were used on the Moscow-Kiev and Moscow-Tashkent routes, carrying 3 passenger in redesigned fuselage.
In July 1941 five PS-43s were assigned to the 2nd Eskadril'ya of the AGON in Moscow and others were assigned to a Kiev-based AGON. Four of the PS-43s completed in 1941 were lost because of enemy action but the delivery of five additional aircraft to Aeroflot in August 1941 replaced some of those written off. The 'new' aircraft had probably been retained by the VVS until that time. СССР-Л3006 was used at the so-called Letnyi Tsentr (Flying Centre), which was operated by the GVF for military pilot training. Nineteen PS-43s remained in Aeroflot service at the beginning of 1942.
The V-11 impact on the Soviet Aircraft industry has two sides. No questions, some advanced technologies and skills were acquired. But the hypnosis of a multi-role aircraft concept (bomber, close troop support, reconnaissater) delayed development of the specialized ground attack aircraft for at least two years. As a result, during first stages of the Nazi invasion Soviet Army had no reliable air support aircraft for the front line troops. New Il-2's just began to arrive to the ground strike regiments.