Channel wing
Encyclopedia
The channel wing is an aircraft wing
principle developed by Willard Ray Custer
in the 1920s. The most important part of the wing consists of a half-tube with an engine placed in the middle, driving a propeller
placed at the rear end of the channel formed by the half-tube.
(Custer Channel Wing 1) airplane was flying for the first time. Custer built additional experimental aircraft; the last one was CCW-5, of which a few were manufactured in 1964.
A wing functions because the air over the wing has a lower pressure
than the air under it. The conventional aircraft must reach a significant minimum speed before this pressure differential become large enough that it generates sufficient lift to become airborne.
In Custer's channel wing the rotating propeller will direct a stable stream of air backwards through the channel. A propeller will at the low pressure side normally be supplied by air from all directions. Since the half-tube prevents air from being drawn from below, the air will be sucked through the channel instead. This creates a strong low pressure area in the channel, which again generates a lift.
were capable of full vertical takeoff
, but instead were characterized as STOL
(short takeoff and landing). The required runway for takeoff was very short, however, 200 feet (61 m) for the CCW-1, 66 feet (20.1 m) for the CCW-2, with a take off speed of as low as 20 mi/h. Full vertical takeoff is theoretically feasible, but would require additional modifications and means of control.
Custer investigated both aircraft with pure channel wings as well as aircraft with additional conventional wings located outside of the channels. The construction functions very well at relatively low speeds. At higher speeds, at high propeller RPM, oscillations would occur in the areas around the propeller, causing increased noise as well as creating long term destructive vibrations in the structure.
The twin engine layout featuring two channel wing features, was the most tested configuration. The twin layout had a higher risk of loss of control during a single engine failure situation, and required very high nose up attitude for STOL flight compaired to conventional twin engine aircraft.
Two of Custer's CCW aircraft survive. The CCW-1 is located at the Smithsonian´s National Air & Space Museum
in Suitland, Maryland. The CCW-5, which was based on the Baumann Brigadier
executive aircraft, is exhibited at the Mid-Atlantic Air Museum
in Pennsylvania
.
Later, research performed by NASA
concluded that the advantage in lift and field length performance achieved did not offset the layout's many deficiencies in climb and high speed ability, and problems meeting certification requirements for general aviation
. The main issue is that the semi-circular beam wing configuration incurs increased profile drag and weight penalties over a conventional wing of the same lifting planform, and a common straight wing could provide almost the equivalent lift enhancement when exposed to the same slipstream induced increased dynamic pressure.
. Performance of the wing was increased, and angle of attack was lowered, reducing some of the drawbacks of the design. The resultant design has been patented.
Wing
A wing is an appendage with a surface that produces lift for flight or propulsion through the atmosphere, or through another gaseous or liquid fluid...
principle developed by Willard Ray Custer
Willard Ray Custer
Willard Ray Custer was an American engineer and aircraft visionary, inventor of the channel wing concept...
in the 1920s. The most important part of the wing consists of a half-tube with an engine placed in the middle, driving a propeller
Propeller (aircraft)
Aircraft propellers or airscrews convert rotary motion from piston engines or turboprops to provide propulsive force. They may be fixed or variable pitch. Early aircraft propellers were carved by hand from solid or laminated wood with later propellers being constructed from metal...
placed at the rear end of the channel formed by the half-tube.
Development
In 1925, Willard Custer had himself observed how very strong winds had managed to lift the roof of a barn. Custer realized it was the high velocity of the wind that created this suction, even when the barn itself was obviously not moving. He started studies into this phenomenon, and by 1928 he had made the first models of a wing with a half-tube-formed section instead of the usual wing profile. This was patented in 1929. Development of the half-tube channel wing was then refined further, and on November 12, 1942, the CCW-1Custer Channel Wing
-External links:**...
(Custer Channel Wing 1) airplane was flying for the first time. Custer built additional experimental aircraft; the last one was CCW-5, of which a few were manufactured in 1964.
Functional principle
Custer's summary of his invention was that the key to the lift created by a wing is the velocity of the stream of air passing over the wing, not the velocity of the airplane itself: It's the speed of air, not the airspeed!.A wing functions because the air over the wing has a lower pressure
Pressure
Pressure is the force per unit area applied in a direction perpendicular to the surface of an object. Gauge pressure is the pressure relative to the local atmospheric or ambient pressure.- Definition :...
than the air under it. The conventional aircraft must reach a significant minimum speed before this pressure differential become large enough that it generates sufficient lift to become airborne.
In Custer's channel wing the rotating propeller will direct a stable stream of air backwards through the channel. A propeller will at the low pressure side normally be supplied by air from all directions. Since the half-tube prevents air from being drawn from below, the air will be sucked through the channel instead. This creates a strong low pressure area in the channel, which again generates a lift.
Applications and limitations
The layout was for a long time not successfully proven in an aircraft, even though Custer showed theoretically and experimentally that the principle was capable of vertical flight. Since they were built with conventional rudders needing some minimum airspeed to be functional, none of the aircraft designed by CusterCuster Channel Wing
-External links:**...
were capable of full vertical takeoff
VTOL
A vertical take-off and landing aircraft is one that can hover, take off and land vertically. This classification includes fixed-wing aircraft as well as helicopters and other aircraft with powered rotors, such as cyclogyros/cyclocopters and tiltrotors...
, but instead were characterized as STOL
STOL
STOL is an acronym for short take-off and landing, a term used to describe aircraft with very short runway requirements.-Definitions:There is no one accepted definition of STOL and many different definitions have been used by different authorities and nations at various times and for a myriad of...
(short takeoff and landing). The required runway for takeoff was very short, however, 200 feet (61 m) for the CCW-1, 66 feet (20.1 m) for the CCW-2, with a take off speed of as low as 20 mi/h. Full vertical takeoff is theoretically feasible, but would require additional modifications and means of control.
Custer investigated both aircraft with pure channel wings as well as aircraft with additional conventional wings located outside of the channels. The construction functions very well at relatively low speeds. At higher speeds, at high propeller RPM, oscillations would occur in the areas around the propeller, causing increased noise as well as creating long term destructive vibrations in the structure.
The twin engine layout featuring two channel wing features, was the most tested configuration. The twin layout had a higher risk of loss of control during a single engine failure situation, and required very high nose up attitude for STOL flight compaired to conventional twin engine aircraft.
Two of Custer's CCW aircraft survive. The CCW-1 is located at the Smithsonian´s National Air & Space Museum
National Air and Space Museum
The National Air and Space Museum of the Smithsonian Institution holds the largest collection of historic aircraft and spacecraft in the world. It was established in 1976. Located in Washington, D.C., United States, it is a center for research into the history and science of aviation and...
in Suitland, Maryland. The CCW-5, which was based on the Baumann Brigadier
Baumann Brigadier
-References:*Bridgman, Leonard. Jane's All The World's Aircraft 1953-54. London:Sampson Low, Marston & Company, 1953.*Mondey, David. The Illustrated Encyclopedia of Aircraft. London:Hamlyn Publishing, 1978. ISBN 0 600 303780.-External links:...
executive aircraft, is exhibited at the Mid-Atlantic Air Museum
Mid-Atlantic Air Museum
The Mid-Atlantic Air Museum is membership supported museum and aircraft restoration facility located at the Carl A. Spaatz Field, the regional airport serving Reading, Pennsylvania. The museum, founded by Russ Strine, the current President, collects and actively restores historic war planes and...
in Pennsylvania
Pennsylvania
The Commonwealth of Pennsylvania is a U.S. state that is located in the Northeastern and Mid-Atlantic regions of the United States. The state borders Delaware and Maryland to the south, West Virginia to the southwest, Ohio to the west, New York and Ontario, Canada, to the north, and New Jersey to...
.
Later, research performed by NASA
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...
concluded that the advantage in lift and field length performance achieved did not offset the layout's many deficiencies in climb and high speed ability, and problems meeting certification requirements for general aviation
General aviation
General aviation is one of the two categories of civil aviation. It refers to all flights other than military and scheduled airline and regular cargo flights, both private and commercial. General aviation flights range from gliders and powered parachutes to large, non-scheduled cargo jet flights...
. The main issue is that the semi-circular beam wing configuration incurs increased profile drag and weight penalties over a conventional wing of the same lifting planform, and a common straight wing could provide almost the equivalent lift enhancement when exposed to the same slipstream induced increased dynamic pressure.
Hybrid Channel Wing
From 1999-2004 A joint research project lead by Georgia Institute of the Technolgy Research Institute in Atlanta was funded by Langley Research Center. Aircraft were tested using channel wing principle layouts with circulation control devices that leveraged the Coandă effectCoanda effect
The Coandă effect is the tendency of a fluid jet to be attracted to a nearby surface. The principle was named after Romanian aerodynamics pioneer Henri Coandă, who was the first to recognize the practical application of the phenomenon in aircraft development....
. Performance of the wing was increased, and angle of attack was lowered, reducing some of the drawbacks of the design. The resultant design has been patented.
Channel wing principle aircraft examples
| Model | Designer | Company | approximate year |
|---|---|---|---|
| CCW-1 | Willard Ray Custer | Custer Channel Wing Corporation | 1942 |
| CCW-2 | Willard Ray Custer | Custer Channel Wing Corporation | 1948 |
| CCW-5 | Willard Ray Custer | Custer Channel Wing Corporation | 1953-64 |
| RFV-1 Rhein-Flugzeugbau RF-1 |-See also:... |
Hanno Fischer | Rhein-Flugzeugbau, Mönchengladbach | 1960 |
| P-20 Raider | Product Development Group | 1985 | |
| P-50 Devastator | Product Development Group | 1986 | |
| Modified V-22 Osprey V-22 Osprey The Bell Boeing V-22 Osprey is an American multi-mission, military, tiltrotor aircraft with both a vertical takeoff and landing , and short takeoff and landing capability... |
not finished | Product Development Group | 1988 |
| Izdelie 181 | Oleg K. Antonov | Antonov | 1990 |
External links
- Custer-Channelwing Website
- Another Custer Channel Wing Website
- Video of Custer explaining his theories and actual flight footage
- Pictures of the Custer CCW-1 National Air and Space MuseumNational Air and Space MuseumThe National Air and Space Museum of the Smithsonian Institution holds the largest collection of historic aircraft and spacecraft in the world. It was established in 1976. Located in Washington, D.C., United States, it is a center for research into the history and science of aviation and...
- Pictures of the Custer CCW-5 Mid-Atlantic Air Museum, Reading, PennsylvaniaReading, PennsylvaniaReading is a city in southeastern Pennsylvania, USA, and seat of Berks County. Reading is the principal city of the Greater Reading Area and had a population of 88,082 as of the 2010 census, making it the fifth most populated city in the state after Philadelphia, Pittsburgh, Allentown and Erie,...
- Modern channelwing aircraft design Stavatti designed channelwing transport for the 2000s