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Supermarine Sea King

The Supermarine Sea King was a British single seat amphibious biplane fighter designed by Supermarine in 1919.

Developed from the Supermarine Baby and the Supermarine Sea Lion I, the Sea King was a single seat biplane powered by a pusher 160 horsepower (120 kW) Beardmore engine.

It first flew in early 1920 and was exhibited by Supermarine at the 1920 Olympia Show in London.

The company released drawings of the aircraft’s design prior to the show; what it exhibited was probably a modified Supermarine Baby.

The Sea King was redesigned by Supermarine’s new chief designer Reginald Mitchell in 1921, perhaps in order to meet the Air Ministry’s specifications for a fighter aircraft capable of operating both from an aircraft carrier and from the water.

Designated as the Sea King II, it was powered by a 300 horsepower (220 kW) Hispano-Suiza 8 engine.

It first flew in December 1921 and demonstrated excellent manoeuvrability and stability, but was not selected for production.

It was rebuilt by Mitchell and fitted with a Napier Lion engine; renamed as the Sea Lion II, it went on to win the Schneider Trophy race in 1922.

The Sea King I is thought to have first flown in early 1920 following its construction, although it may not ever have flown, as it was never registered.

The exact date and the name of the test pilot are unknown.

The aircraft was exhibited by Supermarine at the 1920 Olympia Show in London, where it was the sole example of a single-seat seaplane fighter at the show.

Supermarine released drawings of the Sea King’s design prior to the show; the aircraft exhibited was probably a modified N60 Baby. 

There is evidence that modifications to the wing structure had been undertaken before the aircraft appeared at Olympia, and that its performance improved when it was flown using a Siddeley Puma engine.

The Sea King II was registered as E-BAH in December 1921, when it was named as the Supermarine Amphibian Scout[ and first flew that month.

During trials it demonstrated excellent manoeuvrability and stability, without porpoising or bouncing when coming into contact with water.

It was not selected for production, and the Fairey Flycatcher and the Parnall Plover, both biplanes that could be converted between having conventional tailwheel undercarriage and floats, were ordered in small numbers for further evaluation.

The Flycatcher succeeded in being selected to equip the Royal Navy’s aircraft carriers.


Sea King I

Flying boat fighter.

Powered by 160 horsepower (120 kW) Beardmore or 240 horsepower (180 kW) Siddeley Puma engine.

One aircraft was built.

Sea King II

A revised Sea King I, converted in 1922.

Powered by 300 horsepower (220 kW) Hispano engine.


(Sea King II)




26 ft 9 in (8.15 m)


32 ft 0 in (9.75 m)


11 ft 7 in (3.53 m)

Wing area

352 sq ft (32.7 m2

Empty weight

2,115 lb (959 kg)

Gross weight

2,850 lb (1,293 kg)

Fuel capacity

50 gallons


1 × Hispano-Suiza 8F, 

V8 water cooled piston engine,

300 hp (220 kW)


4 bladed fixed pitch pusher propeller


Maximum speed

125 mph (201 km/h, 109 kn) at sea level


2 hours

Time to altitude

10,000 ft (3,048 m) in 12 minutes

Wing loading

8.1 lb/sq ft (40 kg/m2


8.4 lb/hp



1 × fixed forward firing 0.303 in (7.7 mm) Lewis Gun

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