"Dual Rotor Powered Autogyro (design)

Anton Flettner again reappears, now the founder of his own company in New York after the war. The Fl 201 Heligyro, evolving out of his earlier work on the Fl 185, was a 30 - 40 passenger twin-rotor helicopter designed to takeoff and land as a helicopter but fly as an autogyro. Under United States Navy sponsorship the Fl 201 Heligyro was tested at New York Naval Air Station, Floyd Bennett Field the model never advanced beyond the testing phase."

"After the war, Mr Flettner approached US Army with a new helicopter idea. Helicopters need no airfields and are theoretically ideal for short-haul transport of troops, but a big trouble with them has been that the life of the central nerve, the gear box for the rotor, is not nearly so long as military leaders would like. Rotor gears require major overhauls every few hundred flying hours.

In 1954, Mr. Flettner thought that he had the answer. He decided that if the gear life was the main problem, the rotor gears should be used less. He designed a helicopter with a forty troops capacity in which two conventional propellers would assume the burden of forward flight, with the intermeshing overhead rotors, drawing 20 per cent or less of the engine power and simply providing lift. The result, he said, would be gear life 10 times what it is when the rotor does the whole job. The Army financed the design with the idea that it might eventually invest in production.

Mr Flettner was an honorary member of the American Helicopter Society and of the Convertible Aircraft Pioneers."