Supermarine Seagull (1948)

The Supermarine Seagull was a British military flying boat, the last built by the Supermarine company. It was designed during the World War 2, but it didn't fly until three years after the end of the conflict and the project was cancelled without it being adopted for service.
The Seagull was made entirely out of metal with a two spar parasol mounted wing on a pylon connecting it to the fuselage. The single Rolls-Royce Griffon 29 V-12 liquid-cooled piston engine yielded 1815hp of power and drove contra-rotating propellers. Radiators were mounted below the engine in the pylon where an observer's position with two windows was placed too. An eye bolt was fitted on the wing to make it easier for the aircraft to be lifted by crane.
The wings were fitted with slotted flaps and full length leading edge slats and could be folded for compact ship-board stowage. It also had a variable angle of incidence, pivoting at the front spar and actuated by an electrically driven jackscrew attached to the rear spar in order to reduce stalling speed and increase lift, allowing the aircraft this way to use a smaller wing, as compactness was an important feature for a ship-borne aircraft.
Supermarine had already tested this arrangement in their previous Type 322 design, and its capability was demonstrated when test pilot Mike Lithgow flew a Seagull at just 35mph (56km/h). In July 1950 a Seagull piloted by Leslie R Colquhoun, achieved an air-speed record for an amphibian aircraft over a 100 Kilometre (62 milles) course by flying at an average speed of 249.1mph (389.3km/h).
The hull was a normal frame and longeron design with chines. The tailplane, which was carried on top of the fin, had a very large dihedral, with smaller fins mounted on its tips, perpendicular to its surface. A third fin was later added to the centre after discovering that, in the first prototype, instability in yaw. It was added to the second prototype while it was still under construction.
The undercarriage retracted into bays on either side of the fuselage and could be easily removed saving 180Kg (400lb) of weight when the aircraft operated as a pure flying-boat. It was also fitted with an arrestor hook for carrier operations, as well as JATO rockets just above the wheel wells.
The crew normally consisted of three, a pilot, a navigator and a medic. It could acommodate up to seven survivors.
In October 1940 the British Air Ministry issued the specification S.12/40 both to Supermarine and Fairey for a catapult-launched amphibian reconnaissance and spotter aircraft to replace both Supermarine Walrus and Supermarine Sea Otter. An order for three prototypes was placed on Supermarine in March 1943.
As Supermarine's design office at Woolston was bombed, there a was an interruption in design as the office had to be moved. Further delays were caused by the extensive wind tunnel testing that was needed and the switch from the Rolls-Royce Merlin to the more powerful Rolls-Royce Griffon. The design specification was also changed in 1944 to a new requirement, S.14/44 - the role of the aircraft changed from a ship-based reconnaissance and gunnery spotting to land-based Air-sea rescue, forcing the removal of a four-gun turret that initial designs featured.
The first prototype took off for the first time on 14th July 1948 from Southampton Water at the hands of test pilot Mike Lithgow. The second aircraft, flew in September 1949 and was used for carrier trials on HMS Ark Royal (R09), later in that year. During that testing it showed its passenger capacity of five passengers. Experiments with rocket-assisted take off were also carried out.
By early 1950s it was clear that the helicopters were the future on air-sea rescue, even if their range and endurance was too low and the project was discontinued leading to the two prototypes to be scrapped in 1952.

Sources:
1. https://en.wikipedia.org/wiki/Supermarine_Seagull_(1948)
2. http://aviadejavu.ru/Site/Crafts/Craft32244.htm