 The rear seat was replaced with tanks holding kerosene and nitric acid, and the OR-2 rocket motor was installed in the fuselage.The resulting craft was referred to as the RP-318.The RP-318 was tested numerous times with the engine installed, and was deemed ready for test flights in April 1938, but the plane's development halted when Joseph Stalin performed a purge of RN II, executing the director and chief engineer, and imprisoning Korolev to the Kolyma gold mines for 10 years.