# Sopwith Hippo

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British WW1 biplane fighter aircraft

Hippo General information Type Two-seat fighter aircraft National origin United Kingdom Manufacturer Sopwith Aviation Company Status Prototype Number built 2 History First flight 13 September 1917

The **Sopwith 3F.2 Hippo** was a prototype [British](/source/United_Kingdom) two-seat [fighter aircraft](/source/Fighter_aircraft) of the [First World War](/source/First_World_War). It was a single-engined [biplane](/source/Biplane) with considerable negative [stagger](/source/Stagger_(aviation)). It was not successful, the [Bristol F.2 Fighter](/source/Bristol_F.2_Fighter) (already in production) being preferred by the [Royal Flying Corps](/source/Royal_Flying_Corps).

## Development and design

In the summer of 1917, the [Sopwith Aviation Company](/source/Sopwith_Aviation_Company) designed a two-seat fighter aircraft, the 3F.2 Hippo, possibly to replace the [Sopwith 1½ Strutter](/source/Sopwith_1%C2%BD_Strutter) in [French service](/source/History_of_the_Arm%C3%A9e_de_l'Air_(1909%E2%80%931942)).[1] While the British [Air Board](/source/Air_Ministry#The_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 [two-bay](/source/Interplane_strut) wings had heavy (2 ft 3 in (0.69 m)[2]) negative [stagger](/source/Stagger_(aviation)), 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.[3] The pilot was armed with two [synchronised](/source/Synchronization_gear) [Vickers machine guns](/source/Vickers_machine_gun), while the observer was provided with two [Lewis guns](/source/Lewis_gun) on a rocking pillar mount. It was powered by a [Clerget 11](/source/Clerget_11) eleven-cylinder [rotary engine](/source/Rotary_engine), chosen as it was not heavily used.[4]

The first prototype Hippo flew on 13 September 1917.[5] When tested, it was found to have sluggish controls and poorer performance than the [Bristol F.2 Fighter](/source/Bristol_F.2_Fighter) which was already in service.[6] Despite these results, which meant that there was little chance of it being built for the [Royal Flying Corps](/source/Royal_Flying_Corps), Sopwith rebuilt the Hippo, with increased [dihedral](/source/Dihedral_(aircraft)) 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](/source/Scarff_ring) mounting a single Lewis gun.[7] The rebuilt prototype flew in April 1918, with a second prototype following in June. No further production followed.[5][\[a\]](#endnote_Note1a)

## Specifications

*Data from* British Aeroplanes 1914–18[8]

**General characteristics**

- **Crew:** Two

- **Length:** 24 ft 6 in (7.47 m)

- **Wingspan:** 38 ft 9 in (11.81 m)

- **Height:** 9 ft 4 in (2.84 m)

- **Wing area:** 340 sq ft (32 m2)

- **Empty weight:** 1,481 lb (672 kg)

- **Gross weight:** 2,590 lb (1,175 kg)

- **Fuel capacity:** 40.5 imp gal (48.6 US gal; 184 L)

- **Powerplant:** 1 × [Clerget 11Eb](/source/Clerget_11Eb) 11-cylinder [rotary engine](/source/Rotary_engine), 200 hp (150 kW)

**Performance**

- **Maximum speed:** 115.5 mph (185.9 km/h, 100.4 kn) at 10,000 ft (3,000 m)

- **Service ceiling:** 17,000 ft (5,200 m)

- **Rate of climb:** 1,000 ft/min (5.1 m/s)

- **Time to altitude:** 13 min 25 s to 10,000 ft (3,000 m)

**Armament**

- **Guns:** - 2× forward firing [.303 in](/source/.303_British) [Vickers guns](/source/Vickers_gun) - 1× .303 in [Lewis gun](/source/Lewis_gun) on [Scarff ring](/source/Scarff_ring) in rear cockpit

## See also

**Aircraft of comparable role, configuration, and era**

- [Bristol F.2 Fighter](/source/Bristol_F.2_Fighter)

- [Sopwith Bulldog](/source/Sopwith_Bulldog)

## Notes

[**a**](#ref_Note1a) Some sources suggest that, rather than a rebuilt first prototype, that the Hippo with reduced stagger was a new aircraft.[1][4]

1. ^ [***a***](#cite_ref-robertson228_1-0) [***b***](#cite_ref-robertson228_1-1) Robertson 1970, p. 228.

1. **[^](#cite_ref-2)** Robertson 1970, p. 236.

1. **[^](#cite_ref-3)** Bruce 1969, pp. 4–5.

1. ^ [***a***](#cite_ref-mason123_4-0) [***b***](#cite_ref-mason123_4-1) Mason 1992, p. 123.

1. ^ [***a***](#cite_ref-gs538_5-0) [***b***](#cite_ref-gs538_5-1) Green and Swanborough 1994, p. 538.

1. **[^](#cite_ref-6)** Bruce 1969, p. 5.

1. **[^](#cite_ref-7)** Bruce 1969, pp. 5–6.

1. **[^](#cite_ref-8)** Bruce 1957, p. 621.

## References

- 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](/source/ISBN_(identifier)) [0-356-01490-8](https://en.wikipedia.org/wiki/Special:BookSources/0-356-01490-8).

- Green, William, and Swanborough, Gordon. *The Complete Book of Fighters*. New York: Smithmark, 1994. [ISBN](/source/ISBN_(identifier)) [0-8317-3939-8](https://en.wikipedia.org/wiki/Special:BookSources/0-8317-3939-8).

- Mason, Francis K. *The British Fighter since 1912*. Annapolis, USA: Naval Institute Press, 1992. [ISBN](/source/ISBN_(identifier)) [1-55750-082-7](https://en.wikipedia.org/wiki/Special:BookSources/1-55750-082-7).

- Robertson, Bruce. *Sopwith-The Man and his Aircraft*. Letchworth, UK: Air Review, 1970. [ISBN](/source/ISBN_(identifier)) [0-900435-15-1](https://en.wikipedia.org/wiki/Special:BookSources/0-900435-15-1).

v t e Sopwith aircraft By role Fighters Buffalo Bulldog Camel Dolphin Dragon Gunbus Hippo Hispano-Suiza Triplane L.R.T.Tr. Pup Snail Snapper Snark Snipe Swallow Triplane Bombers B.1 Cobham Rhino Torpedo bomber Cuckoo Scouts/bombers Baby Sparrow 1½ Strutter Tabloid Two-Seat Scout Seaplanes Bat-Boat Circuit of Britain floatplane Sopwith Pusher Seaplane/S PG N Admiralty Type 137 Admiralty Type 138 Admiralty Type C Special torpedo seaplane Type C Type 807 Type 860 Schneider (1914) Baby Schneider (1919) Ground attack Salamander Sports tourer Gnu By designation B.1 B.2 2B.2 F.1 2F.1 4F.1 5F.1 7F.1 8F.1 3F.2 (I) 3F.2 (II) FR.2 2FR.2 FS.1 T.1 TF.1 TF.2 By name Antelope Atlantic Baby Bat-Boat Bee Buffalo Bulldog Circuit of Britain floatplane Camel Cobham Cuckoo Dolphin Dove Dragon Gnu Grasshopper Gunbus Hippo Hispano-Suiza Triplane L.R.T.Tr. Pup Rainbow Rhino Salamander Scooter Snail Snapper Snark Snipe Sparrow Sociable Swallow 1½ Strutter Tabloid Tadpole Three-seater Triplane Special torpedo seaplane Type C Wallaby Designers Herbert Smith Thomas Sopwith

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Adapted from the Wikipedia article [Sopwith Hippo](https://en.wikipedia.org/wiki/Sopwith_Hippo) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Sopwith_Hippo?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.