T U P O L E V A N T - 2 9 , DIP
Tupolev ANT-29, DIP Purpose: A heavy fighter with large-calibre recoilless guns. Design Bureau: KOSOS-CAHI (department of experimental aeroplane construction, central aero-hydrodynamics institute), Chief Constructor A N Tupolev.
ANT-29, DIP
This large fighter was a natural successor to the ANT-21 MI-3 (MI = multi-seat fighter) ordered in January 1932 and flown in May 1933. Whereas that aircraft had had conventional armament, the ANT-29 or DIP (Dvukhmestnyi Istrebitel' Pushechnyi, two-seat cannon [armed] fighter) was designed around two of the largest available calibre of APK recoilless guns (see preceding story). Funds for a single prototype were made available by the WS in September 1932. Tupolev entrusted the design to his first deputy P O Sukhoi. Normally the aircraft would have flown in about a year, but priority was given to the ANT-40 fast bomber (which flew in 1934 as the SB), and the ANT-29 was not completed until February 1935. Flight testing was started by S A Korzinshchikov, who reported that the flight controls, especially the ailerons and rudder, were unacceptably ineffective. This prototype was returned to CAHI's ZOK (factory for prototype construction) for rectification, the main task being to re-skin the control surfaces. Testing resumed in late 1935, but by this time the ANT-46 (DI-8) was flying. The ANT-29 belonged to the previous generation, and it was abandoned in March 1936. Like its predecessor, the ANT-21, the ANT29 was an aerodynamically clean monoplane powered by two liquid-cooled engines. The wings were aerodynamically similar but totally different structurally, and the engines likewise were quite new. They were two of the first 760hp Hispano-Suiza 12Ybrs 12-cylinder engines to be imported into the Soviet Union. Later this engine was developed by VYaKlimov into the VK-103 and VK-105, of which over 129,000 were constructed. In this aircraft they drove imported French Chauviere three-blade variable-pitch propellers of 3.5m (138in) diameter. Carburettor air entered through a small inlet under the wing leading edge, and the radiator was in a shutter-controlled duct directly under the engine. The wing had a modern structure with two plate spars, made as a 3m (9ft 1 0in) horizontal centre section and 5.9m (19ft 4in) outer panels with taper and dihedral. Like the rest of the airframe the outer wing skins were smooth. In this Sukhoi broke new ground, previous 'ANT' aircraft having had corrugated metal skins showing that they originated in Junkers technology of the early 1920s. The short fuselage was of tall oval section and 195