Sopwith Hippo

{{short description|British WW1 biplane fighter aircraft}} {{Use dmy dates|date=December 2016}} {{Use British English|date=December 2016}}  {{Infobox aircraft | name = Hippo | logo = | logo_size = | image = | alt = | caption = | long_caption = | other_names = | aircraft_type = Two-seat [[fighter aircraft]] | aim = | outcome = | related = | national_origin = [[United Kingdom]] | manufacturer = [[Sopwith Aviation Company]] | design_group = | designer = | builder = | issuer = | status = Prototype | owners = | primary_user = | more_users = | service = | major_applications = | proposals = | prototypes = | number_built = 2 | construction_number = | civil_registration = | military_serial = | radio_code = | requirement = | aircraft_carried = | flights = | total_hours = | total_distance = | construction_date = | introduction = | retired = | first_flight = 13 September 1917 | initiated = | in_service = | last_flight = | expected = | developed_from = | variants = | developed_into = | preservation = | fate = | predecessors = | successors = | concluded = }} The '''Sopwith 3F.2 Hippo''' was a prototype [[United Kingdom|British]] two-seat [[fighter aircraft]] of the [[First World War]]. It was a single-engined [[biplane]] with considerable negative [[Stagger (aviation)|stagger]]. It was not successful, the [[Bristol F.2 Fighter]] (already in production) being preferred by the [[Royal Flying Corps]].

==Development and design== In the summer of 1917, the [[Sopwith Aviation Company]] designed a two-seat fighter aircraft, the 3F.2 Hippo, possibly to replace the [[Sopwith 1½ Strutter]] in [[History of the Armée de l'Air (1909–1942)|French service]].<ref name=robertson228>Robertson 1970, p. 228.</ref> While the British [[Air Ministry#The Air Board|Air Board]] did not place an order for the Hippo, it did grant Sopwith a licence to allow it to build prototypes as a private venture. The Hippo was designed to give the best possible view to the pilot and gunner, which dictated the aircraft's shape. Its [[interplane strut|two-bay]] wings had heavy (2 ft 3 in (0.69 m)<ref>Robertson 1970, p. 236.</ref>) negative [[Stagger (aviation)|stagger]], with the pilot sitting ahead of the upper wing and the gunner sitting behind the rear spar of the upper wing. The fuselage filled the gap between the wings, with the crew's heads level with the upper wing and cutouts in the wing's forward and trailing edges for the pilot and gunner.<ref>Bruce 1969, pp. 4–5.</ref> The pilot was armed with two [[synchronization gear|synchronised]] [[Vickers machine gun]]s, while the observer was provided with two [[Lewis gun]]s on a rocking pillar mount. It was powered by a [[Clerget 11]] eleven-cylinder [[rotary engine]], chosen as it was not heavily used.<ref name=mason123>Mason 1992, p. 123.</ref>

The first prototype Hippo flew on 13 September 1917.<ref name=gs538>Green and Swanborough 1994, p. 538.</ref> When tested, it was found to have sluggish controls and poorer performance than the [[Bristol F.2 Fighter]] which was already in service.<ref>Bruce 1969, p. 5.</ref> Despite these results, which meant that there was little chance of it being built for the [[Royal Flying Corps]], Sopwith rebuilt the Hippo, with increased [[Dihedral (aircraft)|dihedral]] on the upper wing, reduced wing stagger and an enlarged tailfin. The crude rocking pillar mount for the gunner's Lewis guns was replaced by a more conventional [[Scarff ring]] mounting a single Lewis gun.<ref>Bruce 1969, pp. 5–6.</ref> The rebuilt prototype flew in April 1918, with a second prototype following in June. No further production followed.<ref name=gs538/>{{ref label|Note1|a|a}}

==Specifications== {{Aircraft specs |ref=British Aeroplanes 1914–18<ref>Bruce 1957, p. 621.</ref> |prime units?=imp  |genhide=

|crew=Two |capacity= |length m= |length ft=24 |length in=6 |span m= |span ft=38 |span in=9 |height m= |height ft=9 |height in=4 |wing area sqm= |wing area sqft=340 |wing area note= |aspect ratio= |airfoil= |empty weight kg= |empty weight lb=1481 |empty weight note= |gross weight kg= |gross weight lb=2590 |gross weight note= |fuel capacity={{convert|40.5|impgal|USgal L|abbr=on}} |more general=  |eng1 number=1 |eng1 name=[[Clerget 11Eb]] |eng1 type=11-cylinder [[rotary engine]] |eng1 kw= |eng1 hp=200 |more power=

|perfhide=

|max speed kmh= |max speed mph=115.5 |max speed kts= |max speed note=at {{convert|10000|ft|m|abbr=on}} |cruise speed kmh= |cruise speed mph= |cruise speed kts= |range km= |range miles= |range nmi= |combat range km= |combat range miles= |combat range nmi= |endurance= |ceiling m= |ceiling ft=17000 |climb rate ms= |climb rate ftmin=1000 |time to altitude=13 min 25 s to {{convert|10000|ft|m|abbr=on}} |more performance=  |guns=<br /> **2× forward firing [[.303 British|.303 in]] [[Vickers gun]]s **1× .303 in [[Lewis gun]] on [[Scarff ring]] in rear cockpit |bombs= |rockets= |missiles= |hardpoints= |hardpoint capacity= |hardpoint rockets= |hardpoint missiles= |hardpoint bombs= |hardpoint other=

|avionics= }}

==See also== {{aircontent  |see also= |related= |similar aircraft=*[[Bristol F.2 Fighter]] *[[Sopwith Bulldog]] |lists= }}

==Notes== {{note label|Note1|a|a}} Some sources suggest that, rather than a rebuilt first prototype, that the Hippo with reduced stagger was a new aircraft.<ref name=robertson228/><ref name=mason123/> {{reflist}}

==References== {{refbegin}} *Bruce, J. M. ''British Aeroplanes 1914–18''. London: Putnam, 1957. *Bruce, J. M. ''War Planes of the First World War: Volume Three Fighters''. London: Macdonald, 1969. {{ISBN|0-356-01490-8}}. *Green, William, and Swanborough, Gordon. ''The Complete Book of Fighters''. New York: Smithmark, 1994. {{ISBN|0-8317-3939-8}}. *Mason, Francis K. ''The British Fighter since 1912''. Annapolis, USA: Naval Institute Press, 1992. {{ISBN|1-55750-082-7}}. *Robertson, Bruce. ''Sopwith-The Man and his Aircraft''. Letchworth, UK: Air Review, 1970. {{ISBN|0-900435-15-1}}. {{refend}}

[[Category:1910s British fighter aircraft]] [[Category:Sopwith aircraft|Hippo]] [[Category:Aircraft first flown in 1917]] [[Category:Rotary-engined aircraft]] [[Category:Biplanes with negative stagger]]