A coleopter is a type of VTOL 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. Coleopters are generally designed as tail-sitters. 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.
French Snecma Coléoptère, which gave its name to the coleopter category
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 Heinkel Wespe and Heinkel Lerche programs. The Wespe intended to use a Benz 2,000 hp turboprop engine, but these were not forthcoming and the Lerche used two Daimler-Benz DB 605 piston engines instead. Nothing ever came of either design.
In the immediate post-war era, most VTOL research involved helicopters. 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 (now Safran Aircraft Engines) developed a series of such systems as part of the SNECMA Atar Volant series during the 1950s. To further improve the design, SNECMA had Nord Aviation build an annular wing and adapted it to the last of the Volant series to produce the SNECMA 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 Aircraft 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 Bell UH-1 Iroquois 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.
AAFSS asked for a new high-speed helicopter design for the attack and escort roles. Submissions included gyrodynes, dual-rotor designs and similar advances on conventional designs, but nothing was as unconventional as the Model 49.
The Model 49 was based on a twin-turbine design featuring counter-rotating propellers within a shroud. Exposed areas were armored to withstand 12.7mm fire. The two-man crew was located in an articulated capsule which could either point forward of the shroud when horizontal or at right-angles to it when vertical, and pilot controls were limited to engine speed, blade angle and directional control. The design was believed by its manufacturers to be inherently more reliable than that of conventional helicopters.[1]
As a "tail-sitter" design, and like its forebear the Convair XFY-1 POGO, the Model 49 was intended to take off from a vertical orientation before transitioning to horizontal orientation for flight. Once at its destination it could transition back to horizontal mode to hover and provide fire support.[2]
The design was intended to be capable of carrying multiple armament configurations, with all weapons being remotely controlled by the gunner from the crew capsule.[2] Its hardpoints consisted of two side turrets, a center turret, and two hardpoints each for two of the nacelles. All of the weapons could be used in either horizontal or vertical configuration, as well as while grounded. The turrets were mechanically prevented from firing "up" at the crew capsule while in vertical configuration. The side turrets could feature either 7.62 mm machine guns with 12,000 rounds of ammunition each, or 40mm grenade launchers with 500 rounds each. The center turret carried an XM-140 30mm cannon with 1000 rounds, with the option for a second 30mm cannon, or 500 WASP rockets. Any of the four hardpoints could carry three BGM-71 TOW missiles, or three Shillelagh missiles; alternatively, up to one hardpoint on each of the nacelles could carry an M40A1C 106mm recoilless rifle with 18 rounds. As an alternative, the hardpoints could mount up to 1200 gallons of additional fuel in tanks.[1]
Deemed overly complicated, The Army instead selected the Lockheed AH-56 Cheyenne and Sikorsky S-66 for further development. In the end only scale models of the model 49 were ever built.[2]
^ ab"Convair Model 49 helicopter - development history, photos, technical data". www.aviastar.org.
^ abc"Convair Model 49 | Strange Vehicles | Diseno-Art". www.diseno-art.com.
ReferencesEdit
Spenser, Jay (1998). Vertical Challenge: The Hiller Aircraft Story. University of Washington Press.
Landis, Tony; Jenkins, Dennis (2000). Lockheed AH-56A Cheyenne. Specialty Press Publishers and Wholesalers.
Bradley, Robert (2013). Convair advanced designs. II, Secret fighters, attack aircraft, and unique concepts 1929-1973. Crecy Publishing. ISBN9780859791700.
External linksEdit
A Coleopter patent
Footage of the scale model of the Convair Model 49
October 20, 2023
coleopter, insect, order, beetle, this, article, multiple, issues, please, help, improve, discuss, these, issues, talk, page, learn, when, remove, these, template, messages, this, article, includes, list, references, related, reading, external, links, sources,. For the insect order see beetle This article has multiple issues Please help improve it or discuss these issues on the talk page Learn how and when to remove these template messages This article includes a list of references related reading or external links but its sources remain unclear because it lacks inline citations Please help to improve this article by introducing more precise citations August 2021 Learn how and when to remove this template message This article needs additional citations for verification Please help improve this article by adding citations to reliable sources Unsourced material may be challenged and removed Find sources Coleopter news newspapers books scholar JSTOR December 2022 Learn how and when to remove this template message Learn how and when to remove this template message A coleopter is a type of VTOL 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 Coleopters are generally designed as tail sitters The term is an anglicisation of the French coleoptere beetle after the first actual implementation of this design the SNECMA Coleoptere of the mid 1950s French Snecma Coleoptere which gave its name to the coleopter category Contents 1 Early experiments 2 Convair Model 49 3 See also 4 Notes 5 References 6 External linksEarly experiments Edit nbsp Hiller VXT 8 mockup on display at the Hiller Aviation MuseumThe 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 Heinkel Wespe and Heinkel Lerche programs The Wespe intended to use a Benz 2 000 hp turboprop engine but these were not forthcoming and the Lerche used two Daimler Benz DB 605 piston engines instead Nothing ever came of either design In the immediate post war era most VTOL research involved helicopters 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 now Safran Aircraft Engines developed a series of such systems as part of the SNECMA Atar Volant series during the 1950s To further improve the design SNECMA had Nord Aviation build an annular wing and adapted it to the last of the Volant series to produce the SNECMA Coleoptere The Coleoptere 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 Aircraft 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 Bell UH 1 Iroquois 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 Model 49 EditConvair 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 Submissions included gyrodynes dual rotor designs and similar advances on conventional designs but nothing was as unconventional as the Model 49 The Model 49 was based on a twin turbine design featuring counter rotating propellers within a shroud Exposed areas were armored to withstand 12 7mm fire The two man crew was located in an articulated capsule which could either point forward of the shroud when horizontal or at right angles to it when vertical and pilot controls were limited to engine speed blade angle and directional control The design was believed by its manufacturers to be inherently more reliable than that of conventional helicopters 1 As a tail sitter design and like its forebear the Convair XFY 1 POGO the Model 49 was intended to take off from a vertical orientation before transitioning to horizontal orientation for flight Once at its destination it could transition back to horizontal mode to hover and provide fire support 2 The design was intended to be capable of carrying multiple armament configurations with all weapons being remotely controlled by the gunner from the crew capsule 2 Its hardpoints consisted of two side turrets a center turret and two hardpoints each for two of the nacelles All of the weapons could be used in either horizontal or vertical configuration as well as while grounded The turrets were mechanically prevented from firing up at the crew capsule while in vertical configuration The side turrets could feature either 7 62 mm machine guns with 12 000 rounds of ammunition each or 40mm grenade launchers with 500 rounds each The center turret carried an XM 140 30mm cannon with 1000 rounds with the option for a second 30mm cannon or 500 WASP rockets Any of the four hardpoints could carry three BGM 71 TOW missiles or three Shillelagh missiles alternatively up to one hardpoint on each of the nacelles could carry an M40A1C 106mm recoilless rifle with 18 rounds As an alternative the hardpoints could mount up to 1200 gallons of additional fuel in tanks 1 Deemed overly complicated The Army instead selected the Lockheed AH 56 Cheyenne and Sikorsky S 66 for further development In the end only scale models of the model 49 were ever built 2 See also EditFocke Wulf TriebflugelNotes Edit a b Convair Model 49 helicopter development history photos technical data www aviastar org a b c Convair Model 49 Strange Vehicles Diseno Art www diseno art com References EditSpenser Jay 1998 Vertical Challenge The Hiller Aircraft Story University of Washington Press Landis Tony Jenkins Dennis 2000 Lockheed AH 56A Cheyenne Specialty Press Publishers and Wholesalers Bradley Robert 2013 Convair advanced designs II Secret fighters attack aircraft and unique concepts 1929 1973 Crecy Publishing ISBN 9780859791700 External links EditA Coleopter patent Description of and plans for building a model coleopter Footage of the scale model of the Convair Model 49 Retrieved from https en wikipedia org w index php title Coleopter amp oldid 1172814098, wikipedia, wiki, book, books, library,
