Gyrodynes and Heliplanes
For the company, see Gyrodyne Company of America''For the Gyrodyne, as a patented concept, see
Gyrodyne TrademarkA
Gyrodyne is an intermediate form of heavier-than-air
aircraft having some of the characteristics of a
helicopter (where the rotor is propulsive) and some of the
autogyro (where the rotor autorotates freely). In recent years designs which combine more aeroplane characteristics with those of a gyrodyne have been promoted under the term
Heliplane.The term
compound helicopter is also used for aircraft like this although the term covers aircraft with and without wings as well as rotors.[
1]
Once the initial problems with rotary winged flight had been overcome, with the development of the
Cierva's
Autogiro, research began to focus on improving their range of abilities. Jump Take-Off gave autogyros a near-
VTOL capability, and work then addressed the possibilities of true VTOL, and hovering.
In Russia and Germany, engineers like
Anton Flettner moved the autogiro's propellor to its stub wings. This then provided the counter-torque that allowed the rotor to be permanently driven by the aircraft's engine. In forward flight, the aircraft would fly as autogyros or helicopters. One such aircraft was the
Flettner 184. Historically, these aircraft would properly be called
compound gyroplanes.
In Britain, Prof.
James Allan Jamieson Bennett (formerly the chief engineer of the Cierva Autogiro Company, but at that time with the Weir company in Glasgow) developed a third distinct type of rotorcraft. The concept was described in US Patent 2,317,340 granted to him and the "Autogiro company" (ie Cierva) in 1943 as,
In other words, in helicopters the air is pulled
downwards; in autogyros the air flows
upwards; in the Gyrodyne the air would flow neither up nor down but only
past the rotor.
Bennett's gyrodyne had a shaft-driven rotor with torque correction and propulsion for translational flight provided by a side-mounted propeller. Collective pitch of the rotor was a function of, and increased automatically with, shaft torque. During hover and low-speed flight, collective pitch of the propeller was controlled by the pilot with the yaw pedals. As airspeed increased, propeller drag also increased and in order to maintain constant rpm it drew increased power from the engine, which in turn reduced torque at the rotor hub. The latter condition caused an automatic reduction in rotor collective pitch. At cruise airspeed, the rotor operated at autorotative pitch with the tip-path plane parallel to the direction of flight; all propulsion was provided by the propeller. As airspeed was reduced, propeller torque demand decreased which resulted in increased torque at the rotor hub which in turn caused an increase in collective pitch.Classically, a gyrodyne had a rotor, and flew like an
autogyro or in some cases a
helicopter. It did not need a tail rotor, normally required in a helicopter to provide a torque to counterbalance the rotating effect of the engine that powers the main rotor, but in early models such as the
FB-1 Gyrodyne the countertorque was provided from the propellor(s) driving the craft forward. The subsequent
Jet Gyrodyne rotor was powered by jets at the tips of the rotor during vertical take-off, rather than taking it from an engine, and so there was no counter-torque required at all.Early autogyros often had stub wings which provided part of the lift for the aircraft in forward flight, but the main source of lift was the rotor. Many attempts were made to stop the rotor and use it as a fixed wing, but these proved to require complicated and heavy mechanisms which cancelled out the benefits of using an autogyro altogether.
|
The Fairey Rotodyne prototype XE521 |
Perhaps the most promising design of gyrodyne was the protoype
Fairey Rotodyne, which had short wings that carried the horizontal flight engines and up to 30% of the aircraft's weight in forward flight. The rotor was driven by tip mounted jets. It was a development from the company's Gyrodyne and Jet Gyrodyne experimental aircraft.
A "Heliplane" was built by
Kayaba in 1954, it was essentially a Cessna 170 with wings reduced to stubs sufficient to carry the undercarriage and a rotor powered by tip ram-jets. [
2]
The
McDonnell XV-1 also of the 1950s was a autogyro with tip jets to give vertical take off but improvements in helicopter performance led to project cancellation in 1957 Bennett's definition of "Gyrodyne" is no longer used in his original meaning. The
Federal Aviation Administration (FAA) gives the modern legal definition of a Gyrodyne in the USA as a rotor wing aircraft that powers its rotor for takeoff and landing, but en route, flies in autorotation, like a gyroplane, without power to the rotor. Forward thrust is provided by engine driven propellors. Being able to fly in autorotation gives the gyrodyne all of the advantages and simplicity of a gyroplane. Thus, the modern definition of
"Gyrodyne" actually describes the wider idea of a
"compound gyroplane".
The newer idea of a
Heliplane extends the gyrodyne concept. A heliplane does not fly like an autogyro but like a
fixed-wing aircraft with wings providing most of its lift at cruise. However, it can take off and land vertically like a gyrodyne or helicopter.
DARPA are funding a project under the name heliplane that uses a rotor together with sustantial wings[
3]
As with
"Gyrodyne", the term
"Heliplane" has been appropriated from what was originally a trademark, and given a wider meaning.
Since 2005,
Carter Aviation Technologies and
Groen Brothers Aviation have both begun research programmes directed at developing a heliplane concept. These are hoped to combine the large cargo capacity, fuel efficiency, and high cruise speed of an aeroplane with the VTOL capabilities and hovering ability of a gyrodyne.
Groen Brothers Aviation have concentrated their efforts on developing techniques for converting proven aeroplane designs into gyrodynes; the conversion intended to be a cheaper route than devleoping aircraft from scratch. Their concept designs have added rotors, trimmed wings though they are still major structires, and modified tailplanes.
Carter Aviation Technologies have focussed on developing technologies with the intention of selling and licensing intellectual property rights developed. Their patents include a high-inertia rotor that allows the aircraft to hover for a short time "while unpowered"; and the concept of slowing - but not stopping - the rotor at cruise speeds. The rotor is combined with wings that are optimised for high-speed flight only, providing a low-drag configuration.
Note also that the Gyrodyne Company of America has produced a number of coaxial helicopters under the US trademark 'Gyrodyne'.*
Flettner (Germany)
** The
Flettner 184 (1935) helicopter/autogyro [
4]
** "Avia" Helicopter Developments - the
Flettner 185 (1938)
*
Focke-Wulf**
Focke-Wulf Fw Triebflugel - a WW2 German design that used a jet powered rotor in place of wings.
*
Fairey Aviation (
UK)
**
Fairey Gyrodyne and
Jet Gyrodyne (1954)
**
Fairey Rotodyne (1957)
*
Lockheed**
XH-51**
AH-56 Cheyenne (1967)
*
Groen Brothers Aviation** Gyrodyne and Heliplane
concepts (2005)
*
CarterCopters (2005)
**
Demonstrator prototype**
Heliplane concept* U.S. Patent 2,317,340: Helicopter. J.A.J.Bennett. 27 April 1943
* "The Fairey Gyrodyne". J.A.J. Bennett. Journal of the Royal Aeronautical Society, 1949, Vol. 53
*
"Development of the Autogiro : A Technical Perspective" : J. Gordon Leishman : Hofstra University, New York (2003)
*
From Autogiro to Gyroplane : The Amazing Survival of an Aviation Technology : Bruce H. Charnov (2003)
* The Fairey Rotodyne: An Idea Whose Time Has Come â€" Again?
Detailed History*
The Royal Air Force Museum catalogue of Gyrodynes*
Gyrodyne Company of America (USA) - producers of
helicopters under the brand name "Gyrodyne"
**
Model 2C - Gyrodyne Co.'s contra-rotating rotor helicopter (1952)
*
Rotorfly Heliplane - RC Model
