The Kholshchevnikov VRDK (Vozdushno-Reaktivniy Dopolnitelniy Kompressor) (Russian: "Jet-Propelled Auxiliary Compressor”) was a motorjet developed in the Soviet Union during World War II.

[1] Design work on VRDK technology started in 1941 at the Central Aerohydrodynamic Institute with the goal of developing a motorjet where a piston engine would be combined with an axial flow compressor.

The VRDK was driven from a step-up gearbox and could be engaged/disengaged by the pilot via a clutch mechanism which connected it to the piston engine via a shaft.

[2] To protect the pilot and airframe, the VRDK was cooled during operation by water from a 78 L (20.6 US gal) tank mounted in the fuselage.

After the war interest in motorjets quickly declined as the Soviets acquired German and British turbojet engines.