Coleopter
Encyclopedia
A coleopter is a type of Vertical Take-Off and Landing
aircraft design that uses a ducted fan
as the primary fuselage of the entire aircraft. Generally they appear to be a large barrel-like extension at the rear, with a small cockpit area suspended above it. Like most ducted fan designs, coleopters are generally arranged to take off and land on its tail
. The term is an anglicisation of the French coléoptère (beetle) after the first actual implementation of this design, the SNECMA Coléoptère
of the mid 1950s.
The first design of an aircraft clearly using the coleopter concept was developed during World War II
. From 1944 on the Luftwaffe
was suffering from almost continual daytime attacks on its airfields, and was finding it almost impossible to conduct large scale operations. Their preferred solution was to introduce some sort of VTOL interceptor that could be launched from any open location, and there were many proposals for such a system. Heinkel
conducted a series of design studies as part of their Wespe and Lerche
programs. The Wespe intended to use a Benz 2,000 hp turboprop engine, but these were not forthcoming and the Lerch used two Daimler-Benz DB 605
piston engines instead. Nothing ever came of either design.
In the immediate post-war era, most VTOL research centered on the helicopter. However, as the limitations of the simple rotary wing became clear, teams started looking for other solutions and many turned to using jet engines directly for vertical thrust. SNECMA
developed a series of such systems as part of their Atar Volant
series during the 1950s. To further improve the design, SNECMA had Nord Aviation
built an annular wing and adapted it to the last of the Volant series to produce the C.450 Coléoptère
. The Coléoptère first flew on 6 May 1959, but crashed on 25 July and no replacement was built. Even in this limited testing period, the design showed several serious problems related to the high angular momentum
of the engine, which made control tricky.
In the US, Hiller Helicopters had been working on a number of ducted fan flying platforms originally designed by Charles Zimmerman. After some early successes, the Army demanded a series of changes that continued to increase the size and weight of the platform, which introduced new stability problems. These generally required more size and power to correct, and no satisfactory design came from these efforts. Instead, Hiller approached the Navy with the idea of building a full coleopter design. This emerged as the Hiller VXT-8
which was significantly similar to the SNECMA design, although it used a propeller instead of a jet engine. However, the introduction of turbine-powered helicopters like the UH-1 Huey so significantly improved their performance over piston-powered designs that the Navy lost interest in the VXT-8 in spite of even better estimated performance. Only a mock-up was completed.
Convair
selected the coleopter layout for their Model 49 proposal, entered into the Advanced Aerial Fire Support System (AAFSS). AAFSS asked for a new high-speed helicopter design for the attack and escort roles, and gathered an impressive array of compound helicopters, dual-rotor designs and similar advances on conventional designs, but nothing was as unconventional as the Model 49. The Army "went conventional" however, and selected the AH-56 Cheyenne
and Sikorsky S-66 for further development.
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...
aircraft design that uses a ducted fan
Ducted fan
A ducted fan is a propulsion arrangement whereby a fan, which is a type of propeller, is mounted within a cylindrical shroud or duct. The duct reduces losses in thrust from the tip vortices of the fan, and varying the cross-section of the duct allows the designer to advantageously affect the...
as the primary fuselage of the entire aircraft. Generally they appear to be a large barrel-like extension at the rear, with a small cockpit area suspended above it. Like most ducted fan designs, coleopters are generally arranged to take off and land on its tail
Tailsitter
A tailsitter is a type of VTOL aircraft that launches and lands on its tail. One of the most famous examples of this type of aircraft is the Ryan X-13 Vertijet. Among the propeller-driven versions were the Lockheed XFV, and the Convair XFY Pogo. Studies and wind tunnel models were made of a...
. The term is an anglicisation of the French coléoptère (beetle) after the first actual implementation of this design, the SNECMA Coléoptère
SNECMA Coléoptère
The SNECMA Coléoptère was a VTO aircraft developed by the French in the 1950s. It was a single-person aircraft with an annular wing designed to land vertically, therefore requiring no runway and very little space to take-off. There were several prototypes developed and tested, however the design...
of the mid 1950s.
The first design of an aircraft clearly using the coleopter concept was developed during World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
. From 1944 on the Luftwaffe
Luftwaffe
Luftwaffe is a generic German term for an air force. It is also the official name for two of the four historic German air forces, the Wehrmacht air arm founded in 1935 and disbanded in 1946; and the current Bundeswehr air arm founded in 1956....
was suffering from almost continual daytime attacks on its airfields, and was finding it almost impossible to conduct large scale operations. Their preferred solution was to introduce some sort of VTOL interceptor that could be launched from any open location, and there were many proposals for such a system. Heinkel
Heinkel
Heinkel Flugzeugwerke was a German aircraft manufacturing company founded by and named after Ernst Heinkel. It is noted for producing bomber aircraft for the Luftwaffe in World War II and for important contributions to high-speed flight.-History:...
conducted a series of design studies as part of their Wespe and Lerche
Heinkel Lerche
-See also:-Notes & References:* Luftwaffe Secret Projects - Ground Attack & Special Purpose Aircraft, D. Herwig & H. Rode, ISBN 1-85780-150-4*...
programs. The Wespe intended to use a Benz 2,000 hp turboprop engine, but these were not forthcoming and the Lerch used two Daimler-Benz DB 605
Daimler-Benz DB 605
|-See also:-Bibliography:* Gunston, Bill. World Encyclopedia of Aero Engines. Cambridge, England. Patrick Stephens Limited, 1989. ISBN 1-85260-163-9* Jane's Fighting Aircraft of World War II. London. Studio Editions Ltd, 1989. ISBN 0-517-67964-7...
piston engines instead. Nothing ever came of either design.
In the immediate post-war era, most VTOL research centered on the helicopter. However, as the limitations of the simple rotary wing became clear, teams started looking for other solutions and many turned to using jet engines directly for vertical thrust. SNECMA
Snecma
Snecma is a major French manufacturer of engines for commercial and military aircraft, and for space vehicles. The name is an acronym for Société Nationale d'Étude et de Construction de Moteurs d'Aviation .In 2005, the Snecma group, which included Snecma ,...
developed a series of such systems as part of their Atar Volant
SNECMA Atar Volant
The original Atar Volant or C.400 P1 was a turbojet engine produced by SNECMA engineers, as part of their 'Atar' series....
series during the 1950s. To further improve the design, SNECMA had Nord Aviation
Nord Aviation
Nord-Aviation was a state-owned French aircraft manufacturer. It was created on October 1, 1954 upon the acquisition of SFECMAS by SNCAN...
built an annular wing and adapted it to the last of the Volant series to produce the C.450 Coléoptère
SNECMA Coléoptère
The SNECMA Coléoptère was a VTO aircraft developed by the French in the 1950s. It was a single-person aircraft with an annular wing designed to land vertically, therefore requiring no runway and very little space to take-off. There were several prototypes developed and tested, however the design...
. The Coléoptère first flew on 6 May 1959, but crashed on 25 July and no replacement was built. Even in this limited testing period, the design showed several serious problems related to the high angular momentum
Angular momentum
In physics, angular momentum, moment of momentum, or rotational momentum is a conserved vector quantity that can be used to describe the overall state of a physical system...
of the engine, which made control tricky.
In the US, Hiller Helicopters had been working on a number of ducted fan flying platforms originally designed by Charles Zimmerman. After some early successes, the Army demanded a series of changes that continued to increase the size and weight of the platform, which introduced new stability problems. These generally required more size and power to correct, and no satisfactory design came from these efforts. Instead, Hiller approached the Navy with the idea of building a full coleopter design. This emerged as the Hiller VXT-8
Hiller VXT-8
The Hiller VXT-8 Coleopter was a proposed annular wing VTOL aircraft designed in the United States in the late 1950s, inspired by the French SNECMA Coléoptère. The project did not progress beyond the mockup stage.-External links:*...
which was significantly similar to the SNECMA design, although it used a propeller instead of a jet engine. However, the introduction of turbine-powered helicopters like the UH-1 Huey so significantly improved their performance over piston-powered designs that the Navy lost interest in the VXT-8 in spite of even better estimated performance. Only a mock-up was completed.
Convair
Convair
Convair was an American aircraft manufacturing company which later expanded into rockets and spacecraft. The company was formed in 1943 by the merger of Vultee Aircraft and Consolidated Aircraft, and went on to produce a number of pioneering aircraft, such as the Convair B-36 bomber, and the F-102...
selected the coleopter layout for their Model 49 proposal, entered into the Advanced Aerial Fire Support System (AAFSS). AAFSS asked for a new high-speed helicopter design for the attack and escort roles, and gathered an impressive array of compound helicopters, dual-rotor designs and similar advances on conventional designs, but nothing was as unconventional as the Model 49. The Army "went conventional" however, and selected the AH-56 Cheyenne
AH-56 Cheyenne
The Lockheed AH-56 Cheyenne was a single-engine attack helicopter developed by Lockheed for the United States Army's Advanced Aerial Fire Support System program to produce the Army's first dedicated attack helicopter...
and Sikorsky S-66 for further development.
See also
- Focke-Wulf Fw TriebflügelFocke-Wulf Fw Triebflugel-External links:* * * *...
- TailsitterTailsitterA tailsitter is a type of VTOL aircraft that launches and lands on its tail. One of the most famous examples of this type of aircraft is the Ryan X-13 Vertijet. Among the propeller-driven versions were the Lockheed XFV, and the Convair XFY Pogo. Studies and wind tunnel models were made of a...
- TiltrotorTiltrotorA tiltrotor is an aircraft which uses a pair or more of powered rotors mounted on rotating shafts or nacelles at the end of a fixed wing for lift and propulsion, and combines the vertical lift capability of a helicopter with the speed and range of a conventional fixed-wing aircraft...
- TiltjetTiltjetA tiltjet aircraft is similar in concept to a tiltrotor design. Whereas a tiltrotor utilises rotors, the tiltjet employs jet engines with the entire propulsion system being rotated from the from axial to dorsal in order to achieve a transition from hover or vertical flight to horizontal. They are...
- TiltwingTiltwingA tiltwing aircraft features a wing that is horizontal for conventional forward flight and rotates up for vertical takeoff and landing. It is similar to the tiltrotor design where only the propeller and engine rotate. Tiltwing aircraft are typically fully capable of VTOL operations.The tiltwing...
- VTOLVTOLA 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...