Supermarine Sea Otter

The Supermarine Sea Otter was a British amphibian aircraft designed and built by Supermarine. It was a longer-range development of the Walrus and was the last biplane flying boat to be designed by Supermarine. It was also the last biplane to enter service with the Royal Navy and the RAF.

Design and development
The main difference between the Walrus and the Sea Otter was in the mounting of the power plant. The Walrus had a rear-facing engine with a pusher propeller. The Sea Otter's engine faced forward with a tractor propeller.

There was considerable development of the power plant/propeller combination during the design of the Sea Otter, which at its concept was called the "Stingray". The original test aircraft had a Bristol Perseus XI radial engine with a two-bladed propeller. This gave insufficient thrust so a two-position three blade was tried. This was changed again to a four-bladed type with the pairs of blades set at an angle of 35°, instead of the usual 90°. The first flight took place on 23 September 1938, but it was not until January 1942 that the Air Ministry placed a production order. Due to cooling troubles found with the Perseus, the power plant was changed for production aircraft to the Bristol Mercury XXX engine driving a three-bladed airscrew. The Sea Otter was used by both the RAF and the Royal Navy for air-sea rescue (ASR) and patrol roles.

Post-war, Sea Otters were converted for civilian use. The cabin was soundproofed and fitted with heating. Seating for four passengers, a chemical toilet and a stowage for baggage were provided. As they were intended for use as Bush airplanes in remote areas, versatility was important. To allow cargo to be carried, the cabin floor was strengthened and fitted with lashing points, and the passenger seats made easily removable.

Production
Of the 592 aircraft ordered, only 292 were built due to the end of the Second World War. Eight aircraft were bought for the Royal Danish Air Force, and another eight were supplied to the Dutch Naval Air Arm. The colonial service of France purchased six Sea Otters for use in French Indochina.

Variants

 * Sea Otter Mk I
 * Reconnaissance and communications amphibian aircraft.


 * Sea Otter Mk II
 * Air Sea Rescue amphibian aircraft.

Operators

 * Royal Australian Navy
 * No. 723 Squadron RAN
 * Royal Danish Air Force
 * 🇪🇬 Egypt
 * Royal Egyptian Air Force
 * Aeronavale
 * Troupes Coloniales operated six ex-RAF aircraft in Indochina between 1947 and 1952.
 * Royal Netherlands Navy
 * Dutch Naval Aviation Service including ASR duty aboard the light carrier Karel Doorman (R81)
 * Royal Air Force
 * No. 277 Squadron RAF
 * No. 278 Squadron RAF
 * No. 279 Squadron RAF
 * No. 281 Squadron RAF
 * No. 282 Squadron RAF
 * No. 292 Squadron RAF
 * No. 1350 Flight RAF
 * No. 1351 Flight RAF
 * No. 1352 Flight RAF
 * Marine Aircraft Experimental Establishment
 * Royal Navy
 * No. 1701 Squadron
 * No. 1702 Squadron
 * No. 1703 Squadron
 * Marine Aircraft Experimental Establishment
 * Royal Navy
 * No. 1701 Squadron
 * No. 1702 Squadron
 * No. 1703 Squadron

Survivors
No museum holds a complete aircraft. Australia's Museum of Flight has the nose section of JN200, a Sea Otter which served with the Royal Australian Navy.