Tupolev ANT-21
In January 1932, the Soviet Air Forces ordered the TsAGI design bureau led by Andrei Tupolev to design a twin-engined multi-seat fighter to replace the KR-6 escort fighter version of the Tupolev ANT-7 twin-engined multi-purpose aircraft.The oval-section fuselage was a new design, being a partially flush riveted semi-monocoque structure made of duralumin, a first for Tupolev aircraft, and it was fitted with a twin tail.[1][2] The first prototype, officially designated MI-3 and nicknamed Mitrich made its maiden flight in August 1933.[1][2] As a result of this accident, Arkhangelsky redesigned the aircraft, retaining the wings, but providing a new fuselage and tail, with a single vertical fin.It was officially tested during July–December 1934, but was not accepted for service by the Soviet Air Force, as it now wanted fighters armed with heavy recoilless rifles, and interest switched to the Tupolev ANT-29 derivative.