Tumansky M-90

The Tumansky M-90 was a prototype Soviet radial engine designed before World War II.

The M-90 began development in the spring of 1939 under the leadership of S. K. Tumansky as a coupled version of the 9-cylinder Gnome-Rhône 9K, which was built under license as the M-75.

Later, possibly after E. V. Urmin assumed leadership of the project, the cylinder-piston group of the Tumansky M-88 was adopted, although the cylinder ribbing area was increased.

They could not reach the engine's specified power output and suffered from broken crankshafts, pinion shafts and crankcase covers.

More prototypes were built between 1941 and 1943 and the engine began its state acceptance tests in December 1943.