Varga RMI-1 X/H

In the late 1930s Dr. György Jendrassik of Hungary had perfected the world's first turboprop jet engine, the Jendrassik Cs-1. In a period when turbojets, turbofans, gas-turbines, ramjets, therompropulsion units and ducted fans were being explored, the turboprop was yet another derivative. In the case of the turoprop the engine produces a jet thrust, as in the turbojet, but also turns a propellor either as a main- or auxiliary-power source. The Ganz factory near Budapest began testing and producing these engines from 1939-1942. However, in order to flight test the Cs-1 it was realized early on that an airframe would be needed, so Dr. László Varga consented to construct an aircraft that would utilize two of the engines.
It was agreed that the aircraft, although experimental, would be designed for reconnaissanse and as a "csatarepülogép" - destoyer (attack/bomber) with a crew of three. Designated RMI-1 for Repülo Muszaki Intézet (Aviation Technical Institute) X/H (experimental), construction was completed with delays in engine development. One airframe was re-engined with two German DB 605 piston-engines being redesignated RMI-2 X/G (trainer) for training purposes. This aircraft was later mistaken for the RMI-1 X/H aircraft in English language sources, however, the RMI-1 X/H aircraft was retained for the Cs-1 turboprop engines.
Testing of the Varga RMI-1 X/H with the Cs-1 engines began when construction was completed by 5 August 1943. The aircraft achieved a minor "hop" flight in September of 1943 which resulted in damage to one of the damper rings (used to control the pitch of the turboprop blades). This along with inclement weather put a pause to the flight testing which was then scheduled to resume in 1944. In early summer of 1944 both the Varga RMI-1 X/H and Varga RMI-2 X/G aircraft were destroyed in an American bombing raid. Thus the world's first designed turboprop aircraft was lost.
The Hungarian Air Force filled the gap by producing the German Messerschmitt Me-210Cs until the armistice with the Allies via the Soviet Union. The "Cs" designation was based on Hungarian production being done by Csepel Works of Manfred Weiss in Hungary
Dr. Varga's history is basically unknown once the Soviets entered Hungary. Dr. Jendrasik was forced to leave Hungary in 1947 partially for his anti-communist views. He emigrated to Argentina where he worked in aviation under General Peron after which he moved to the United Kingdom and worked with Metropolitan Vickers on gas-turbines. Later he started his own company and died in 1954.