Austrian engineer (1916-2000) who developed the first jet-propelled helicopter while working for Wiener Neustaedter Flugzeugwerke during World War 2. Scarce TLS signed “F. L. Doblhoff,” three pages, 8.25 x 10.5, personal letterhead, March 22, 1979. Letter to Randall Sutherland, in part: "I had been intrigued by the possibilities of vertical take-off ever since my highschool days. At first, I did not like the concept of whirling blades and toyed with a number of schemes to deflect the slipstream of propellers…While attending college in Vienna I studied various approaches to the helicopter…[and] a system which would pump air by the centrific action of the rotor blades, burn it at the tip and exhaust it tangentially…When the war started in 1939, I had just finished college and was working in an aircraft factory near Vienna. In 1940 I convinced my company (Wiener Neustaedter Flugzeugwerke) that we should attempt the development of a jet-powered helicopter…The project went ahead and after 1941 it was funded by the German Ministry of Defense as a research project. In September 1943 we had the first model (V1) flying…The day following the first flight (which consisted of an 8-min. hover) the hangar in which the helicopter was stored collapsed in an air raid and destroyed the aircraft. I then moved my development group to another location which was less vulnerable and we started building he V2 and then the V3 models…The V3 was transported to Wright Patterson Air Force Base where it made one captive flight with myself at the controls before being delivered to General Electric as a study object for the XH-17 helicopter…I then joined McDonnell and pursued the same thoughts which eventually led to the development of the Army-funded XV-1 Convertiplane which, for the first time, demonstrated the principle to its full advantage. The XV-1 flew for about 300 hours and was officially evaluated by the U.S. Air Force and the U.S. Navy…To answer your question about Hitler: I never met him. Goering toured the Wiener Neustaedter Flugzeugwerke once and was shown a run-up of the V1 before it made its first flight." In fine condition.
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