Sopwith Hippo

Hippo

National origin: United Kingdom
Manufacturer: Sopwith Aviation Company
First flight: 1917
Status: Prototype
Number built: 2

The Sopwith 3F.2 Hippo was a prototype British two-seat fighter aircraft of the First World War. It was a single-engined biplane with considerable negative stagger. It was not successful, the already in production Bristol F.2 Fighter 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 French service. While the British 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 both the pilot and gunner, which dictated the aircraft's configuration. Its two-bay wings had heavy (2 ft 3 in (0.69 m)) negative 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 crews heads level with the upper wing, and cut-outs in the wing's forward and trailing edge for the pilot and gunner respectively. The pilot was armed with two synchronised Vickers machine guns, while the observer was provided with two Lewis guns on a rocking pillar mount. It was powered by a Clerget 11 eleven-cylinder rotary engine, chosen as it was not heavily used.

The first prototype Hippo flew on 13 September 1917. When tested, it was found to have poorer performance than the Bristol F.2 Fighter that was already in service, and had sluggish controls. 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 on the upper wing, reduced wing stagger and an enlarged fin. The crude rocking pillar mount for the gunners Lewis guns was replaced by a more normal Scarff ring mounting a single Lewis gun. The rebuilt prototype flew in April 1918, with a second prototype following in June. No further production followed.

Specifications

Data from British Aeroplanes 1914-18

General characteristics

Crew: 2
Length: 24 ft 6 in (7.46 m)
Wingspan: 38 ft 9 in (11.81 m)
Height: 9 ft 4 in (2.85 m)
Wing area: 340 sq ft (31.6)
Empty weight: 1,481 lb (673 kg)
Loaded weight: 2,590 lb (1,177 kg)
Powerplant: 1x— Clerget 11Eb 11-cylinder rotary engine, 200 hp (149 kW)

Performance

Maximum speed: 115 mph (100 knots, 185 km/h) at 10,000 ft (3,050 m)
Service ceiling: 17,000 ft (5,200 m)
Rate of climb: 1,000 ft/min (5.1 m/s)
Climb to 10,000 ft (3,050 m): 13 minutes 25 sec

Armament

Guns:
2x— forward firing .303 in Vickers guns
1x— .303 in Lewis gun on Scarff ring in rear cockpit

Comparable aircraft

Bristol F.2 Fighter
Sopwith Bulldog

Some sources suggest that, rather than a rebuilt first prototype, that the Hippo with reduced stagger was a new aircraft.

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 0356 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 0 900 435 15 1.

Sopwith Hippo Pictures and Sopwith Hippo for Sale.

Living Warbirds: The best warbirds DVD series.

Source: WikiPedia