The Supermarine Sea Otter was designed as the replacement for the Walrus, but although the first aircraft made its maiden flight in September 1938 Supermarine was busy with the far more important Spitfire programme, and only a small number of Sea Otters saw active service late in the Second World War.
Work on the Sea Otter began in February 1936. The Air Ministry wanted a more powerful aircraft, with longer range, the ability to operate from aircraft carriers, and the ability to act as a dive bomber, all in an aircraft with a wingspan of 46ft. The new aircraft had to be roughly the same size as the Walrus so that it could operate in the cramped hangers available on the Navy’s cruisers.
The resulting aircraft was very similar in appearance to the Walrus. It had a cleaner airframe, reducing drag, but very similar folding wings. The Perseus engine was used in a tractor configuration, reverting to the layout used on the earlier Supermarine Seagull.
The prototype Sea Otter made its maiden flight on 29 September 1938. Early in 1939 it was sent to Felixstowe for tests with HMS Pegasus, after which the bow was altered. Its catapult launching capability was tested on land in May 1939 and at sea in July, and then in September it was tested for seaworthiness. Despite the pressures imposed by the outbreak of the Second World War in the same month, the tests were completed satisfactorily, and in January 1940 the Sea Otter was ordered into production.
The first production aircraft did not make its maiden flight until January 1943. This was partly because Supermarine’s design team was constantly working on improving the Spitfire, and partly because it was difficult to find an aircraft manufacturer with the spare capacity to produce the Sea Otter. Supermarine was swamped with Spitfire production. The contract was then offered to Blackburn, but they were also too busy. Finally, in January 1942, Saunders-Roe was given the production contract.
The first Saro-built Sea Otter made its maiden flight in early January 1943. The first few aircraft were built as reconnaissance aircraft, and were armed withthree machine gun, but from the eighth aircraft onwards the Sea Otter was built as the ASR Mk II, with all guns removed. The Sea Otter’s longer range and greater load carrying capability made it a better air-sea rescue aircraft than the Walrus, and it carried out valuable work in this role.
A total of 592 Sea Otters were ordered. Of these 292 were built during the war, and the remainder were cancelled. Most (241) went to the RAF, where they equipped six squadrons, starting with No.277 Squadron from November 1943. The Fleet Air Arm Sea Otters entered service one year later, joining No.1700 Squadron in November 1944. They saw service in home waters, the Far East and in Australia and the Admiralty Islands. A small number remained in service with air-sea rescue units throughout the 1940s, and more were exported to Denmark and Holland.
Engine: Bristol Mercury XX
Wing span: 46ft 0in
Length: 39ft 5in
Height: 16ft 2in
Maximum speed: 163mph
Service ceiling: 17,000ft
Maximum range: 690 miles
Armament: up to three 0.303in machine guns