The Tupolev Tu-70 (Russian: Туполев Ту-70; NATO reporting name: Cart) was a Soviet passenger variant of the Tu-4 bomber, an unlicensed, reverse engineered copy of the Boeing B-29 Superfortress.
[1] Designed immediately after the end of World War II, it used a number of components from Boeing B-29s that had made emergency landings in the Soviet Union after bombing Japan.
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 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.
[5] It was sent to the NII VVS (Russian: Научно-Исследовательский Институт Военно-Воздушных Сил – Scientific-Research Institute of the Air Forces) for evaluation as a military transport aircraft in December 1951.