The Short S.25 Sunderland was a British flying boat used as a patrol bomber by the Royal Air Force and the Commonwealths during and after World War II. First flying on 16 October 1937, it was designed according to specification R.2/33, which requested a more advanced four-engine seaplane to replace Britain's aging fleet of biplanes. Over 700 were built during its production cycle.
The Sunderland is a rare type of military aeroplane — one that was derived from a civil aircraft. Based upon the Short C Class “Empire” flying boats operated by Imperial Airways in the 1930s, the Short “Sunderland” became one of the Royal Air Force’s longest serving operational aircraft over the next two decades. One of the finest flying boats ever built, during World War ll the Sunderland played a decisive role in the defeat of German U—boats in the Battle of the Atlantic.
Although the first flight of the prototype Sunderland took place in October 1937, the Air Ministry was already familiar with the aircraft‘s successful civilian counterpart, and had placed an order in March the preceding year.
At the end of 1940 the Mk ll was introduced, with four Pegasus XVIII engines with two-stage superchargers, a twin-gun dorsal turret, an improved rear turret and ASV (air-to-surface-vessel) Mk ll radar. The most numerous version was the Mk III that first flew in December 1941. This variant had a modified hull for improved planing when taking off. This was followed by a larger and heavier version designated the Mk lV/Seaford. After evaluation by the RAF, the project of the flying boat was abandoned.
The Sunderland Mk V was the final version, and made its appearance at the end of 1943. It was powered by four 1200 hp Pratt & Whitney R-1830-90 Twin Wasp engines and carried ASV Mk VI radar. By the end of the final production run in 1945 a total of 739 Sunderlands had been built, and after World War ll, many continued to serve with the British, French, Australian, South African and New Zealand air forces. A total of 749 Sunderlands were built between 1937 and 1946.
In early June 1938 the first batch of production Sunderland Mk is were delivered to No.23O Squadron based in Singapore. The Sunderland replaced the RAF’s mixed fleet of biplane flying boats and represented a huge leap in capability.
By the outbreak of World War ll in September 1939, three Coastal Command squadrons had become operational and were ready to seek out and destroy German U—boats. The Sunderland also became a very welcome sight to the many seamen from sunken vessels and airmen who had had to ditch their aircraft. When the British merchant ship Kensington Court was torpedoed 113 km/70 miles off the Scillies on September 18, 1939, two patrolling Sunderlands had the entire crew of 34 back on dry land just an hour after the ship sank.
The Sunderland, with its crew of ten, was heavily armed and became known to the Luftwaffe as the Flying Porcupine. Many times during the war a lone Sunderland fought off or defeated a number of attacking aircraft.
Although Sunderlands did engage in many a “shoot-out” with German vessels, sometimes the sight of the large aircraft was enough to have an enemy crew scuttle their boat — such was the case on January 31, 1940, when the arrival of an aircraft from No.228 Squadron prompted the crew of U-Boat U-55 to do just that.
Post War Service
Post-war, RAF Sunderlands delivered nearly 5080 tonnes/5000 tons of supplies during the Berlin Airlift, and during the Korean War they were the only British aircraft to operate throughout the conflict. During the Malayan Emergency RAF Sunderlands carried out bombing raids on land against terrorists.
The Sunderland finally retired from the Royal Air Force on May 15, 1959, when No.205 Squadron flew the last sortie for the type from RAF Changl, Singapore, where the illustrious operational career of the Sunderland flying boat had begun 21 years earlier. However, the last air arm to retire the type from military service was the Royal New Zealand Air Force in March 1967.
- First Flight: October 16, 1937 (prototype)
- Power: Four Pratt & Whitney 1200 hp R-1830 Twin Wasp 14-cylinder air-cooled radials
- Armament: Eight 7.7 mm/0.303 in Browning machine guns in turrets, four fixed 7.7 mm/0.303 in Browning machine-guns in nose, two manually operated 12.7 mm/0.5 in machine-guns in beam positions; 2252 kg/4,960 lb of depth charges or bombs
- Size: Wingspan — 34.36 m/112 ft 9 in, Length — 26 m/85 ft 3 in, Height — 10.01 m/32 ft 11 in, Wing area — 138.14 m2/1,487 sq ft
- Weights: Empty - 16,798 kg/37,000 lb, Maximum take-off — 27,240 kg/60,000 lb
- Performance: Maximum speed — 343 kph/213 mph, Ceiling - 5456 m/17,900 ft, Range — 4795 km/2980 miles, Climb — 256 m/840 ft per minute
- Crosby, Francis. The World Encyclopedia of Bombers.
Anness Publishing Ltd. (2013) ISBN 1 78019 205 3 Pages 138 and 139
- Crosby, Francis. Page 139