Gyrodyne Trademark
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Gyrodyne as a US trademark was granted to Gyrodyne Company Of America, Inc. in 1950.
The term gyrodyne was defined by a US Patent 2,317,340, issued in 1943 itself based on a 1939 UK Patent assigned to the Cierva Autogiro Company, Ltd., in which gyrodyne is "a rotary wing aircraft intermediate in type, hereinafter referred to as gyrodyne, between a rotaplane (with the rotor free for autorotation and an upward total axial flow through the rotor disc), on the one hand, and a pure helicopter (with the rotor driven, and a downward total axial flow through the rotor disc), on the other hand, that is with a mean axial flow through the rotor disc substantially zero at high forward speed".
The gyrodyne, invented by Cierva Autogiro Company engineer James Allan Jamieson Bennett, is a third distinct type of rotorcraft, the category of aircraft that includes the gyroplane and helicopter. A gyrodyne has a shaft-driven rotor with torque correction and propulsion for translational flight provided by a side-mounted propeller. Collective pitch of the rotor is a function of, and increases automatically with, shaft torque. During hover and low-speed flight, collective pitch of the propeller is controlled by the pilot with the yaw pedals. As airspeed increases, propeller drag also increases and in order to maintain constant rpm it draws increased power from the engine, which in turn reduces torque at the rotor hub. The latter condition causes an automatic reduction in rotor collective pitch. At cruise airspeed, the rotor operates at autorotative pitch with the tip-path plane parallel to the direction of flight; all propulsion is provided by the propeller. As airspeed is reduced, propeller torque demand decreases which results in increased torque at the rotor hub which in turn causes an increase in collective pitch.
Other features included in the definition of gyrodyne include:
1. Low rotor disc loading.
2. Ease of piloting.
3. Compact fuselage.
4. Use of a powered rotor which operates in autorotative pitch in cruise flight.
The USA Federal Aviation Administration (FAA) in Federal Aviation Regulations, Part 1: Definitions and Abbreviations, defines a gyrodyne as a rotary-wing aircraft that powers its rotor for takeoff, landing and low speed flight, and in cruise flight flies with the rotor in autorotation. Forward thrust is provided by one or more engine driven propellers. This definition of gyrodyne is incorrect; it instead defines a "compound gyroplane."
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[edit] Heliplanes
The term heliplane was proposed by Don Farrington as an alternative to gyroplane in an attempt to market the Air and Space 18A gyroplane. An application for a U.S. trademark by the Air & Space America Corporation was abandoned in 1994. This term has been adopted as an alternate term for compound gyroplane, often incorrectly defined as gyrodyne in which by definition the rotor is always powered in flight.
The Fairey Gyrodyne is the only example of a gyrodyne to have been constructed. The second prototype gyrodyne was converted to a compound gyroplane to develop the tip-jet rotor drive system employed on the Fairey Rotodyne "compound gyroplane."
[edit] Examples
[edit] External Links
- Jet Gyrodyne (1954)
[edit] References
- Autogyro
- U.S. Patent 2,317,340: "Helicopter" by J.A.J. Bennett, 27 April 1943
- "The Fairey Gyrodyne" by J.A.J. Bennett. Journal of the Royal Aeronautical Society, 1949, Vol. 53
