A study of “Gyroplane” and its historical evolution, general characteristics, flight characteristics, various designs, potential applications and aerodynamics explaining its flight is attempted. “Gyroplane” is an official term designated by the Federal Aviation Administration (FAA) describing an aircraft that gets lift from a freely turning rotary wing, or rotor blades, and which derives its thrust from an engine-driven propeller. The focus is on highlighting the differences between a Gyroplane and a conventional helicopter, relative merits and demerits and to trace the development to helicopters from autogiros. What lies ahead in the future for gyroplanes is also discussed.
Cierva thought of designing a flying machine that remains stable, safe and controllable irrespective of its forward speed. He segregated the function of lift and forward propulsion, where the former was done by a freely rotating rotor (and not wings) and latter by a conventional pusher or tractor engine.The rotor of an Autogiro (term coined and patented by Cierva) always works in a state of autorotation and a small upward flow is sufficient to rotate the disk. Thus, as long as the machine has forward motion the rotor would produce sufficient lift to keep it afloat with the disk tilted slightly back. Increasing or decreasing the forward speed would cause the machine to ascend or descend accordingly. In case of engine failure, the rotor being in the auto-rotative state enables the autogiro to land safely to ground.The interest in autogiros was revived in 1950s with several prototypes being built in Britain and USA. They aimed at incorporating the hover capability of the helicopter in gyroplane and overcome the speed limitations of the conventional helicopters. Few companies even started commercial production but lack of general interest forced them to shut down. At this point the most active autogiro market is the homebuilt autogiros. People now fly autogiros as a flying experience or as a hobby. Some scientific study is also in progress so as to improve the capabilities of autogiros.Two US companies are taking active interest in autogiros namely Carter Aviation Technologies and Groen Brothers Aviation, Inc.Carter Aviation Technologies is a research and development company, pioneering new aviation concepts. Their primary focus is the slowed-rotor compound aircraft, a vertical takeoff and landing aircraft that uses the rotor for takeoff and landing, and a small, efficient wing for high speed flight, up to 500 mph, all with much less complexity than a tilt-rotor or other vectored thrust vehicle (Ref. 5).Groen Brothers Aviation, Inc has developed the first turbine powered autogiro (Ref. 6).
Autogiros were the first successful rotary wing aircraft and first heavier – than – air aircraft to fly successfully other than conventional airplane. Although they are not the main stay in modern aviation but it is unquestionable that the step by step and systematic way in which the designers and engineers approached and solved the problems led to development of both theoretical and technical knowledge in field of rotary wing flight that proved critical to development of Helicopters. The most significant was the development of articulated rotor hub. The success of autogiros paved the way for the helicopters and the modern aim of combining the advantages of autogiros with helicopters, if achieved, would make the modern Gyroplane to meet both military and civilian requirements.