Supermarine Seagull (1948)

Supermarine Seagull

Company type	Military aircraft
Industry	Aerospace
Founded	1940 (design commenced)
Headquarters	Southampton , United Kingdom
Products	Amphibious military flying boats

Not to be confused with the Supermarine Seagull (1921), predecessor to the Supermarine Walrus.

The Supermarine Seagull was a British amphibious military flying boat and marked the final such aircraft developed by the Supermarine firm. Although its design commenced during the Second World War, it did not achieve its maiden flight until three years post-war, and ultimately the programme was discontinued without entering operational service.

Development

In October 1940, the British Air Ministry issued Specification S.12/40 to both Supermarine and Fairey, calling for a catapult-launched amphibian aircraft intended for reconnaissance and spotting duties to succeed the Supermarine Walrus and Supermarine Sea Otter. By March 1943, Supermarine had received an order for three prototypes of their design.

Design progress was interrupted due to the relocation of Supermarine’s design office following bombing damage at their Woolston facility. Additional postponements arose from comprehensive wind tunnel evaluations and a transition from using the Rolls-Royce Merlin engine to the more powerful Rolls-Royce Griffon. In 1944, the specification was revised to S.14/44 (later S.14/44/2), which altered the aircraft’s intended role from shipborne reconnaissance and gunnery spotting to land-based Air-sea rescue. This revision led to removal of the four-gun turret initially incorporated in the design.

The prototype Seagull with serial number PA143 achieved its first flight on 14 July 1948 over Southampton Water, piloted by test pilot Mike Lithgow. The second prototype, PA147, took to the air in September 1949 and participated in carrier trials aboard HMS Ark Royal later that year, demonstrating capacity for five passengers. Trials also included tests of rocket-assisted takeoff capabilities.

By the early 1950s, helicopters increasingly assumed responsibility for air-sea rescue missions. Consequently, in 1952, both completed prototypes along with an unfinished third aircraft, PA152, were dismantled.

Design

The Seagull featured an all-metal framework with a parasol wing supported by two spars, attached to the fuselage via a pylon. Power was provided by a single Rolls-Royce Griffon engine that turned contra-rotating propellers; radiators were positioned beneath the engine within the pylon structure. Behind the engine, the rear section of the pylon housed an observer's compartment equipped with two windows. An eye bolt was installed on the wing just aft of the engine to facilitate crane lifting from the water.

Equipped with slotted flaps and full-span leading edge slats, the wings could be folded for efficient shipboard storage. They also incorporated a variable angle of incidence, pivoting around the front spar and adjusted via an electrically powered jackscrew connected to the rear spar. This design lowered stall speed and enhanced lift, enabling a smaller wing size—a crucial attribute for naval aircraft requiring compactness.

Supermarine had previously experimented with this mechanism on the Type 322, and its effectiveness was proven when test pilot Mike Lithgow managed to fly a Seagull at just 35 miles per hour (56 km/h). In July 1950, pilot Les Colquhoun participated in the Air League Cup Race flying a Seagull that set a new airspeed record for amphibious aircraft over a 100-kilometre (62 mi) course, averaging 241.9 miles per hour (389.3 km/h).

The hull utilized a conventional frame and longeron construction with distinct chine lines. The tailplane, mounted atop the fin, featured a pronounced dihedral angle, with smaller vertical fins affixed at its tips, oriented perpendicular to its surface. Following stability tests on the initial prototype that revealed yaw instability, a central third fin was added to the second prototype during its assembly.

The retractable undercarriage folded into compartments located on either side of the fuselage and could be removed easily, reducing weight by approximately 180 kilograms (400 lb) when operating solely as a flying boat. Additionally, the Seagull was equipped with an arrestor hook for carrier landings, and mounting points for JATO rockets were situated just above the wheel wells.

Typically, the aircraft's crew comprised three members. During air-sea rescue missions, it could carry a pilot, navigator, medic, plus up to seven rescued individuals.

Operators

Template:UK

• Royal Navy

Specifications (Seagull ASR.1)

(estimated performance based on production models equipped with Griffon 57 / RG30SM) Template:Aircraft specs

Bibliography

• Andrews, C.F. and Morgan, E.B. Supermarine Aircraft Since 1914. London: Putnam Books Ltd., 2nd revised edition 2003. ISBN 0-85177-800-3.
• Burnett, Charles and Eric B. Morgan. "Dumbo and Seagull: Two Pairs of Variable Incidence Prototypes". Air International, November 1982, Vol. 23 No. 5. ISSN 0306-5634. pp. 237–243, 251.
• Gunston, Bill. "Last of the Seagulls". Aeroplane Monthly, December 1976, Vol. 4, No. 12. pp. 620–625.
• Kightly, James and Wallsgrove, Roger. Supermarine Walrus & Stranraer. Sandomierz, Poland / Redbourn, UK: Mushroom Model Publications, 2004. ISBN 83-917178-9-5.
• London, Peter. British Flying Boats. Sutton Publishers Ltd., 2003. ISBN 0-7509-2695-3

External links

• Colour photograph of the Seagull prototype
• 1948 Flight feature on High-Performance Amphibian