The Supermarine Stranraer was the last of a series of large biplane flying boats designed by Reginald Mitchell, and was essentially a larger version of the Supermarine Scapa, itself an improved version of the earlier Southampton.
Like the Saro London the Stranraer was designed to satisfy Air Ministry Specification R.24/31, for a twin engined general-purpose coastal reconnaissance flying boat. The Stranraer was known as the Southampton V while it was under development, but was renamed in August 1935, soon after the prototype made its maiden flight.
The Stranraer had a slightly longer hull than the Scapa, partly to make room for a new tail gunner’s position. The upper wing was made 10ft longer than on the Scapa, and the wings were swept back slightly. Empty weight increased by just over 1,000lb. The prototype was powered by Bristol Pegasus IIIM radial engines, while production aircraft were given 920hp Pegasus Xs, powering three-blade metal propellers. The extra power gave the Stranraer a top speed of 165mph, 24mph faster than the Scapa and 70mph faster than the Southampton.
Like the Scapa the Stranraer carried three 0.303in machine guns, but while the earlier aircraft had carried one in the nose and two in dorsal positions, the Stranraer carried one in the nose, one in the dorsal position and one in the tail. This required the addition of a sixth crewman to man the tail gun.
Seventeen production aircraft were built in Britain, serving with Nos. 201, 209, 228 and 240 squadrons in home waters. The Stranraer remained in service with Coastal Command until mid-1940, when the last aircraft were replaced by Short Sunderlands and the short-lived Saro Lerwick. The remaining Stranraers were used during 1941 by No.117 Squadron, before going to No.13 Operational Training Squadron.
Another forty Stranraers were built under license by Canadian Vickers, for use by the RCAF. These aircraft were produced between 1938 and 1941, and were used to carry out anti-submarine patrols off the east and west coasts of Canada. They remained in service until April 1944, when No.9 Squadron, RCAF, received Consolidated Cansos (the Canadian designation for the PBY Catalina).
Engine: Two Bristol Pegasus X
Power: 920hp each
Wing span: 85ft
Length: 54ft 10in
Height: 19ft 9in
Empty weight: 11,250lb
Loaded weight: 19,000lb
Top speed: 165mph
Range: 1,350 miles
Service ceiling: 18,500ft
Armament: Three 0.303in Lewis guns
Bomb load: 1,000lb