Avia B.71
The Avia B.71 was the Czechoslovak licence version of the Soviet Tupolev SB (ANT-40) fast bomber. Under a 1937 agreement Czechoslovakia received 61 Soviet-built aircraft fitted with Avia-built Hispano-Suiza engines and Czech armament, and Avia, Aero and Letov were to build 161 more under licence. None was completed before the German occupation of March 1939: the delivered aircraft were seized, and licence production ran under the Protectorate from July 1939 to April 1941, when Avia and Aero completed 111 aircraft, used by the Luftwaffe mainly for training and target towing, with part sold to Bulgaria.
Why It Mattered
The Avia B-71 was the Czechoslovak licence version of the Tupolev SB, the Soviet fast bomber that had proved itself in Spain and could outpace many fighters of its day. Under a 1937 agreement, Czechoslovakia received 61 Soviet-built aircraft, adapted with Avia-built engines and Czech guns, while Avia, Aero and Letov were to build a further 161 under licence. No licence-built aircraft was finished before Germany occupied the Czech lands in March 1939, so the production run was completed for the Luftwaffe instead. The B-71's career was therefore spent in other hands than the ones that ordered it: German training units, a Bulgarian purchase, and one Slovak aircraft flown to Turkey by its defecting crew.
Design Notes
B-71 was the licence designation of the Tupolev ANT-40, developed in the Tupolev bureau under Alexander Arkhangelsky and built in the Soviet Union as the SB-2 from 1936. The aircraft was an all-metal mid-wing monoplane with two engines, a crew of three and a bomb load of up to 600 kg. In Soviet service its engines were licence copies of the French Hispano-Suiza 12Y. The Czechoslovak standard replaced them with the Avia-built HS 12Ydrs of 860 hp and swapped the Soviet ShKAS guns for Czech vz. 30 machine guns, with a single gun in the nose instead of the original twin mounting. With the Avia engines fitted, maximum speed was 430 km/h.
Operational History
The 1937 agreement traded the bombers and their production licence against Czechoslovak artillery technology, including the rights to the Škoda 75 mm Model 1936 mountain gun. During 1937 and 1938 the Czechoslovak Air Force took delivery of 61 Soviet-built machines, already fitted with Czechoslovak engines, guns and radios. Licence production was prepared from 1938, but events overtook it: not one Czech-built aircraft was completed before 15 March 1939, and the delivered machines were seized by Germany. Production then ran under the Protectorate, and between July 1939 and April 1941 the Avia and Aero works completed 111 licence-built aircraft, 66 from Avia and 45 from Aero. The occupiers used them for crew training, and several were converted as B-71B target tugs, towing gunnery sleeves for fighter and anti-aircraft gunnery practice. Part of the Avia production was bought by Bulgaria, which operated the aircraft successfully for years; VHÚ puts the number sold at between 24 and 32. The one delivered aircraft left on Slovak territory served the Slovak Air Force until April 1943, when Anton Vanko and four fellow airmen defected with it to Turkey.
Afterlife
Of the B-71 itself, only fragments survive in Prague. A rudder and four fuselage frames, believed to be leftovers of the unfinished series production, were kept by the National Technical Museum. In 1974 the parts were transferred to the collections of the Military History Institute in Prague. The institute also preserves the photographic record of the seizure, including a photograph taken just after 15 March 1939 of a German soldier standing by a captured B-71. The Bulgarian aircraft, by contrast, remained in service for years after their purchase, operated long and successfully in VHÚ's account.