Gyrodyne

A Gyrodyne is a rotorcraft with a rotor system that is normally driven by its engine for takeoff and landing—hovering like a helicopter and has either one or two propellers mounted on wingtips, for propulsion and for torque correction. In response to a Royal Navy request for a helicopter, Dr. James Allan Jamieson Bennett designed the gyrodyne whilst serving as the chief engineer of the Cierva Autogiro Company. The gyrodyne was envisioned an intermediate type of rotorcraft, its rotor operating parallel to the flightpath to minimize axial flow with one or more propellers providing propulsion.

There is controversy over the correct usage of the term gyrodyne stemming from the difference between the description in Bennett's patent, the use of the term as a trademark by the Gyrodyne Company of America, the Federal Aviation Administration (FAA) classification of rotorcraft, and the terms compound helicopter and compound gyroplane frequently used to describe similar aircraft. In recent years, a related concept has been promoted under the name heliplane. Originally used to market gyroplanes built by two different companies, the term has been adopted to describe a Defense Advanced Research Projects Agency (DARPA) program to develop advances in rotorcraft technology with the goal of overcoming the current limitations of helicopters in both speed and payload.

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