09/30/2007. Dr. Friedrich von Doblhoff invented the helicopter with a rotor powered by ramjets mounted at the rotor tips. With the help of Dr. August Stepan and Theodor Laufer a series of helicopters was build at the Wiener Neustädter Flugzeugwerke (also known as WNF) in Vienna, Austria. The four different prototype helicopters were designated WNF-342 V1 to V4.
The pictured fourth prototype used the ramjets at the rotor tips for
take-off, hovering and landing only. An 140hp Siemens & Halske Sh.14A
radial engine drove a conventional pusher propeller for forward
flight while the rotor blades 'free-wheeled' in autorotation pitch.
The side-by-side two-seater was first flown early in 1945 and
captured by US forces in April of the same year. It was transferred
to the USA for testing, where Dr. von Doblhoff provided assistance.