William Kuhnle

IN THE thirties the autogiro was one of the marvels of the modern world but, alas, today it is usually mistaken for a helicopter. The helicopter, using rotor technology developed for the autogiro, almost pushed the autogiro into oblivion. Now it appears that model helicopters may rekindle interest in model autogiros. A demonstration, at the Richardson R/C Club, of a model helicopter initiated a chain of events that lead to my building an autogiro. The 50-inch diameter rotor has three blades, each of which has a "flapping hinge" and a "lag (or drag) hinge." The rotor hub, containing two ball bearings, turns on a stationary 1/4-in. diameter shaft. The rotor hub parts are machined from aluminum bar. The major portion of the machining was done on a small metal turning lathe, the holes drilled on a drill press, and the remainder done the hard way-with saw and file.