Supermarine Sea Otter
June 10th 2009
Supermarine Sea Otter was a British designed biplane
amphibian intended to replace the once venerable Supermarine
Warlus in the Royal Air Force reconnaissance and search and
rescue missions. It had the distinction of being the last
biplane flying boat to achieve front line service in the
British armed forces.
The Otter was a result of an Air Ministry’s specification
request codenamed S.7-38 (Stingray). There was a
considerable effort placed on the development of Project
Stingray’s power plant. The original S.78-38 called for a
Bristol Perseus XI engine configuration with a two bladed
propeller arrangement. The Bristol Perseus configuration did
not give the platform the necessary thrust. A new
arrangement was developed with a four bladed propeller
mechanism set at an angle of 35 degrees. A major departure
from the frequently use 90 degree sets.
The first prototype, unit K8854, took to the air for its
maiden flight on the morning of September 23rd 1938.
Designed to take the place of the 1933-designed Walrus, the
Otter differed from its predecessor in many characteristics.
Most noticeable was its engine tractor configuration. The
Walrus utilized a pusher system. The new aircraft was also
faster, could fly farther and handled better in the water
that its predecessor.
was carried out by the front runner of British flying boats
designs, Saunders Roe who acted as the only subcontractors
to the Otter project. By the spring of 1939, the Royal Air
Force (RAF) and much of the British air industry was geared
up to produce badly needed fighters and bombers, so the
production of the Otter was delayed by almost three full
The first production Otter was delivered to the RAY on
January 1943. The original Air Ministry order was for 592
aircraft, but due to the tardiness of production and the end
of World War II, only 290 were ever built. Production ran
well into 1946 (July) before the order to stop arrived.
The first operational Sea Otters were assigned to the RAF
No. 277 Squadron. The Royal Navy (RN) also got into the act
and acquired a number of Otters for costal recon operations.
During WW II, Otters fielded nine RAF squadrons: No. 277,
278, 279, 281, 282, 292, No. 1350 Flight, 1351 and 1352.
Other countries also operated the Otter. The Royal
Australian Navy utilized the type to patrol the vastness of
the Coral Sea. The Royal Danish Air Force, the Dutch Naval
Aviation Services and the French Colonial Service in
Indochina; also employed the biplane.
After the Second World War was over, the RAF and RV promptly
retired the Otter from front line service. This did not mean
that the plane was useless. The RN Fleet Air Arm units
remained in service until the spring of 1952.
Two versions of the Otter were produced, the Mk I and II.
The amphibious Mk I carried bombs and depth charges while
the Mk II was employed only as an air rescue platform. Of
the 290 Otters built, only 40 were of the Mk II variety.
Today, only a nose section of a Royal Australian Navy Otter
remains. Currently the section sits on permanent display at
an Australian Naval Museum.
One Bristol Mercury 855hp XXX radial piston engine
Total wing area 56.67m square
Maximum Takeoff weight 4,912kg
Top Ceiling 4,877m
Operational Range 1,167m
Climb Rate 265m per minute