After basic design work was completed on the
Tu-4 bomber,
Tupolev decided to design a passenger variant with a pressurized fuselage, given the internal designation of Tu-70. It was intended to use as many Tu-4 components as possible to reduce cost and save development time. It was a low-wing, cantilever monoplane with tricycle landing gear, powered by four
Shvetsov ASh-73TK radial engines. Design work on a mockup began in February 1946 and the
Council of Ministers confirmed an order for a single prototype the following month. A production decision for the Tu-12, as it was to be known, would be made after testing. The Tu-70 was completed in October 1946, but did not make its first flight until 27 November. It began manufacturer's trials in October, but an engine fire on the fourth flight caused it to make a crash-landing. This was traced to a design defect in the American-built
supercharger-control system, but identifying the problem and fixing it prolonged the manufacturer's trials through October 1947. It was redesignated as the Tu-70 when it went through the State acceptance trials which ended on 14 December. It met all the design goals, but was not accepted for production as all the factories were already committed to building aircraft with a higher priority and Aeroflot had no requirement for the type, being fully satisfied with its existing
Ilyushin Il-12 airliners. It was sent to the NII VVS ( – Scientific-Research Institute of the Air Forces) for evaluation as a military transport aircraft in December 1951. It was used afterwards for a variety of tests before being scrapped in 1954. Its design was modified to a military transport as the
Tupolev Tu-75, but this was also not placed into production. ==Specifications ==