Su-5 is a Soviet experimental fighter-interceptor with a combined power plant, which consisted of a VK-107A piston engine with a four-blade propeller and an additional compressor jet engine (VRDC), which served as an accelerator. In this case, the compressor of the jet engine was driven by the piston.
The first stage of factory flight tests took place in April - June 1945. According to calculations, the inclusion of the VFDK was supposed to increase the speed of the aircraft at the ground by 90 km/h, and at an altitude - by 110 km/h. During tests at an altitude of 4350 m, a speed of 793 km / h was reached against the calculated speed of 768 km / h. The maximum design speed at an altitude of 7800 m with the inclusion of the VRDK should have been 810 km / h.
Testing was interrupted due to engine failure. Further work on the aircraft was stopped, since by this time it became clear that combined installations with power take-off to the compressor from a piston engine were unpromising.