The Sopwith Cobham was a British twin-engined triplane bomber aircraft designed and built by the Sopwith Aviation Company during the First World War. The only twin-engined aircraft built by Sopwith, the Cobham did not fly until after the end of the war, and was unsuccessful due to the failure of its engines, only three prototypes being built.
The Sopwith Cobham was designed to meet a June 1918 requirement for a twin-engined long-range medium bomber to equip the Royal Air Force (to meet RAF Type IV, VI and VII specifications). The design, by Herbert Smith was a twin-engined triplane with a wooden box-girder fuselage with fabric and plywood covering, while the wings, which were of equal span, each had two sprucespars and fabric covering. It was designed to be powered by two of the new ABC Dragonflyradial engines, which promised high power for low installed weight, and had been ordered in large numbers to equip most of the prospective types planned to equip the RAF.[1] It had a crew of three, with a pilot sitting in a cockpit just forward of the leading edge of the wings, while gunners sat in nose and dorsal positions, each armed with Lewis guns on Scarff rings.[2] Three 250 lb (114 kg) bombs could be carried vertically in the fuselage.[1]
Three prototypes were ordered,[2] the only twin-engined aircraft to be built by Sopwith.[3] The first prototype was completed in December 1918, but no Dragonfly engines were available, so it was fitted with 240 hp (179 kW) Siddeley Puma engines to allow flight testing, making its maiden flight in April 1919. It was later re-engined with more-powerful, high compression Pumas, rated at 290 hp (220 kW), being tested at RAF Martlesham Heath in March 1920.[1]
Flight-ready Dragonfly engines were delivered during 1919. As they were heavier than expected, the design had to be modified with the engines mounted further back and the stagger on the wings adjusted. The Dragonfly powered aircraft were also fitted with a larger rudder as a result of experience with the Puma powered aircraft. The two Dragonfly powered prototypes, designated Cobham Mk I (with the Puma-powered first prototype designated Cobham Mk II), flew in January and February 1920. The Dragonfly proved to be extremely unreliable, and development of the engine was stopped in September 1920, leading to the two Dragonfly powered prototypes being discarded. The first prototype did not last much longer, being last flown on 27 January 1921 at the Royal Aircraft Establishment, Farnborough.[1]
Variants
Cobham Mk I
Version powered by 360 hp (269 kW) Dragonfly IA engines. Two built.[1]
Cobham Mk II
First prototype, powered by Siddeley Puma engines. One built.[1]
Bruce, J.M. British Aeroplanes 1914-18. London:Putnam, 1957.
Lewis, Peter. The British Bomber Since 1914. London:Putnam, Third edition, 1980. ISBN0-370-30265-6.
Mason, Francis K. The British Bomber since 1914. London:Putnam, 1994. ISBN0-85177-861-5.
Robertson, Bruce. Sopwith-The Man and his Aircraft. Letchworth, UK:Air Review, 1970. ISBN0-900435-15-1.
External links
Retrieved: 26 September 2010
January 30, 2023
sopwith, cobham, british, twin, engined, triplane, bomber, aircraft, designed, built, sopwith, aviation, company, during, first, world, only, twin, engined, aircraft, built, sopwith, cobham, until, after, unsuccessful, failure, engines, only, three, prototypes. The Sopwith Cobham was a British twin engined triplane bomber aircraft designed and built by the Sopwith Aviation Company during the First World War The only twin engined aircraft built by Sopwith the Cobham did not fly until after the end of the war and was unsuccessful due to the failure of its engines only three prototypes being built CobhamRole Bomber aircraftNational origin United KingdomManufacturer Sopwith Aviation CompanyDesigner Herbert SmithFirst flight April 1919Number built 3 Contents 1 Design and development 2 Variants 3 Specifications Cobham II 4 See also 5 Notes 6 References 7 External linksDesign and development EditThe Sopwith Cobham was designed to meet a June 1918 requirement for a twin engined long range medium bomber to equip the Royal Air Force to meet RAF Type IV VI and VII specifications The design by Herbert Smith was a twin engined triplane with a wooden box girder fuselage with fabric and plywood covering while the wings which were of equal span each had two spruce spars and fabric covering It was designed to be powered by two of the new ABC Dragonfly radial engines which promised high power for low installed weight and had been ordered in large numbers to equip most of the prospective types planned to equip the RAF 1 It had a crew of three with a pilot sitting in a cockpit just forward of the leading edge of the wings while gunners sat in nose and dorsal positions each armed with Lewis guns on Scarff rings 2 Three 250 lb 114 kg bombs could be carried vertically in the fuselage 1 Three prototypes were ordered 2 the only twin engined aircraft to be built by Sopwith 3 The first prototype was completed in December 1918 but no Dragonfly engines were available so it was fitted with 240 hp 179 kW Siddeley Puma engines to allow flight testing making its maiden flight in April 1919 It was later re engined with more powerful high compression Pumas rated at 290 hp 220 kW being tested at RAF Martlesham Heath in March 1920 1 Flight ready Dragonfly engines were delivered during 1919 As they were heavier than expected the design had to be modified with the engines mounted further back and the stagger on the wings adjusted The Dragonfly powered aircraft were also fitted with a larger rudder as a result of experience with the Puma powered aircraft The two Dragonfly powered prototypes designated Cobham Mk I with the Puma powered first prototype designated Cobham Mk II flew in January and February 1920 The Dragonfly proved to be extremely unreliable and development of the engine was stopped in September 1920 leading to the two Dragonfly powered prototypes being discarded The first prototype did not last much longer being last flown on 27 January 1921 at the Royal Aircraft Establishment Farnborough 1 Variants EditCobham Mk I Version powered by 360 hp 269 kW Dragonfly IA engines Two built 1 Cobham Mk II First prototype powered by Siddeley Puma engines One built 1 Specifications Cobham II EditData from The British Bomber since 1914 1 General characteristicsCrew 3 Length 38 ft 12 m Wingspan 54 ft 16 m Height 13 ft 4 0 m Gross weight 6 300 lb 2 858 kg 4 Powerplant 2 Siddeley Puma water cooled six cylinder inline engine 290 hp 220 kW eachArmament Guns 2 303 in Lewis gun on Scarff ring in nose and dorsal cockpits Bombs 750 lb 340 kg bombs carried internallySee also EditAircraft of comparable role configuration and era de Havilland DH 11 Oxford Avro 533 Manchester Boulton Paul BourgesNotes Edit a b c d e f g Mason 1994 p 121 a b Lewis 1980 pp 110 111 Bruce 1957 pp 635 637 Robertson 1970 pp 236 237 References EditBruce J M British Aeroplanes 1914 18 London Putnam 1957 Lewis Peter The British Bomber Since 1914 London Putnam Third edition 1980 ISBN 0 370 30265 6 Mason Francis K The British Bomber since 1914 London Putnam 1994 ISBN 0 85177 861 5 Robertson Bruce Sopwith The Man and his Aircraft Letchworth UK Air Review 1970 ISBN 0 900435 15 1 External links EditHistoricAircraft org Retrieved 26 September 2010 Retrieved from https en wikipedia org w index php title Sopwith Cobham amp oldid 1013526689, wikipedia, wiki, book, books, library,
