The start of the Second World War was not exactly a surprise to the British government, but they still found themselves hopelessly underprepared for war in many aspects. New fighter and bomber aircraft emerging from design competitions promised a very powerful Royal Air Force in the near future. But in 1939 the RAF consisted of a mix of obsolescent airframes and a smattering of new, modern concepts like monoplane fighters and multi-engine bombers. Only in maritime patrol aircraft did the British forces start the war with an up-to-date and powerful patrol platform, in the shape of the Short Sunderland.
The Sunderland was a derivative of the beautiful and elegant S.23 Empire flying boat, which had provided luxurious and comfortable long-distance travel for the well-heeled British public before the outbreak of the war.
The S.25 Sunderland was also known for the amenities provided for its personnel and may have been one of the most comfortable platforms for aircrews during the conflict, with bunks, galleys and even toilets.
However, the Sunderland was no powder-puff airframe, and as one of the most heavily armed maritime patrol aircraft of the Second World War gained a deserved reputation for being a formidable adversary for enemy ships, submarines and combat aircraft.
Along with the Catalina and Liberator patrol aircraft, the Sunderland did much to help win the Battle of the Atlantic, thereby ensuring the Allies emerged as the victors over the combined forces of Germany and Italy.
In November 1933 the Air Ministry issued Specification R.2/33, calling for a multi-engine maritime patrol aircraft. The program languished until a revised Specification R.22/36 was released in March 1936, and the Short Brothers’ proposal for a flying boat was authorised to manufacture a prototype in 1934, which was deemed to be worthy of further development.
This concept was based on the S.23 Empire clipper, and the resultant S.25 design leaned heavily on the earlier aircraft, except for having a deeper hull.
The first flight of the prototype took place on October 1937, and was relatively trouble-free, which led the RAF to order 21 examples of the Sunderland for pre-production analysis.
The initial production model was the Sunderland I, of which 75 examples were produced, and the platform formally entered service with the RAF in June 1938. This version introduced a powered rear turret (a first for the RAF) and revised nose armament, and introduced a more powerful engine than fitted in the prototypes.
The next major variant was the Sunderland II, which introduced engines with two-speed superchargers giving a boost in performance. The Mark II had a revised armament, and late production models introduced a dorsal turret for self-defence. Only 43 units of this version were manufactured before production shifted to the Sunderland III.
This new model introduced a powered nose turret, an increase in offensive weaponry, a slight re-design to the hull and upgraded the surface-search radar to help deal with German radar-warning equipment such as the Metox passive receiver that warned of airborne radar. This version of the Sunderland was the definitive model, with 461 units manufactured.
The Sunderland IV was a major effort to deal with the few deficiencies of earlier models, showcasing a new design with strengthened wings, more powerful engines and a host of other improvements.
All these changes were so pronounced that the Air Ministry decided to rename this variant under a new specification, and the aircraft became known as the Short Seaford. Intended for use in the Pacific theatre, this version never got beyond the testing of the 8 airframes produced and was not accepted for service.
The last major variant of the Sunderland was the Mark V, which was introduced in 1944. Fitted with American Double-wasp engines, this version fixed the problem with earlier power plants wearing out too quickly from prolonged hard use on long patrols.
These new engines were fitted with new Hamilton propellers giving a boost in performance and also mounted a new model surface-search radar. 155 examples were made, and 33 Mark IIIs were converted to this specification.
With the end of the war in 1945, large contracts to build Sunderland Vs were abruptly cancelled, and the last Sunderland rolled off the assembly line in June 1946. The type was rapidly retired from front-line service, and the final production total was 749 examples of all models. The last Sunderland in military service was retired from the Royal New Zealand Air Force (RNZAF) in 1967.
All specifications given are for the Sunderland III. The Sunderland had a crew of 11 members; two pilots, a radio operator, a navigator, a flight engineer, a bomb aimer and 3-5 dedicated air gunners.
The Sunderland had the following dimensions; a height of 32 feet 10 inches (10 metres), a length of 85 feet 4 inches (26 metres) and a wingspan of 112 feet 9 inches (34.4 metres). Empty, the aircraft weighed in at 34,500 lbs (15,700 kg) and at full load, the gross mass of the Sunderland was 58,000 lbs (26,300 kg).
The Sunderland III was equipped with four radial Bristol Pegasus XVIII engines, each rated at 1,070 horsepower. This enabled the Sunderland to have a top speed of 210 mph (340 km/h) and a best economical cruise speed of 178 mph (286 km/h).
The service ceiling of the aircraft was 17,200 feet (5,200 metres) and it had an operating range of 1,780 miles (2,860 kilometres). The Sunderland had an endurance of 13 hours of continual operation.
The later Sunderland III was armed with 12-14 7.7 mm Browning machine guns in three powered turrets and fitted to the fuselage in a fixed, forward-firing position, (see service record) and also had two M2 .50 calibre 12.7 mm heavy machine guns mounted in the fuselage to cover the beam areas.
Up to 2,000 lbs of bombs, mines or depth charges (or a combination of all three) can be carried in a ‘bomb room’ in the fuselage, with the racks of weapons sliding out onto the wings for employment, an ingenious design that reduced drag on the airframe for long-endurance patrols.
A surface-search radar set was fitted for anti-shipping/submarine work, but the Sunderland was never fitted with the Leigh Light, relying on flares for nighttime illumination.
The Sunderland had a distinguished service history, with 40 examples of RAF strength at the outbreak of the war. While not initially a success in prosecuting U-boat contacts, the type performed useful service in rescuing the crews of sunken merchant ships in these early days.
As anti-submarine tactics and equipment evolved the Sunderland began to take a toll on German submarines; the first un-assisted U-boat kill was made by a Sunderland from 10 Sqn RAAF on July 1940.
By virtue of its sturdy construction and heavy gun armament, the Sunderland was a handful for any enemy aircraft that attempted to attack it. Indeed the Germans nicknamed the aircraft the ‘Porcupine’ as a tribute to its tenacity in air combat.
Two examples, in particular, stand out: on the 13th of April 1940, a Sunderland operating off the coast of Norway was attacked by six Ju-88C heavy fighters – the Sunderland shot down one JU-88, damaged another so seriously it had to quit the fight, and drove the rest away.
A 1943 encounter with JU-88 was even more savage when a Sunderland from 461 Sqn RAAF was attacked by eight JU-88C long-range fighters. Despite the Sunderland being heavily damaged with most of the crew wounded, the Sunderland downed three attackers, damaged and drove off the rest and made the 560-kilometre return journey to Britain where the heavily damaged aircraft was beached at Cornwall.
The pilot received the Distinguished Service Order, and several other crew members were decorated as well.
The Sunderland also served with distinction in the Mediterranean theatre, with a Sunderland actually performing a dangerous reconnaissance mission that led to the famous Taranto attack in November 1940 by the Fleet Air Arm that sunk or damaged a number of Italian capital ships.
A number of Sunderlands also performed transport duty when the Allied forces were evacuating from the island of Crete after the Germans invaded the island.
New model surface-search radars enabled the Sunderland to take an increasing toll of U-boats from 1943 onwards – in a clever move a British POW told the Germans that their radar-detecting equipment was giving away positions of U-boats at sea, and the Kriegsmarine mistakenly ordered U-boat captains to switch this equipment off, which immediately led to higher operational losses for the fleet.
Australian crews field-modified the Sunderland by fitting four Browning machine guns to fire from fixed positions on the frontal fuselage. This was done to increase firing power when the Sunderland was stooping into an attack on a U-boat, as some U-boats were fitted with increased gun armament in an attempt to fend off or destroy maritime patrol aircraft attacking the submarine.
The platform also served in the 1948-9 Berlin Airlift, with the Sunderland specially tasked to carry large quantities of salt, as the fuselage was already protected from salt-water corrosion. The Sunderland also served during the Korean War with the RAF, providing UN-mandated patrols until 1954. The type served with the Far East Command at Singapore until 1960, as runways for conventional aircraft were underdeveloped, crowded and over-utilised.
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The British were extremely fortunate to have such a high-quality airframe for maritime patrol from the early days of the Second World War, and along with the Catalina and VLR Liberator maritime patrol aircraft the Sunderland can be said to be a war-winning weapon by way of its sterling service during the Battle of the Atlantic.
The Sunderland was much appreciated by her crews, who enjoyed the comforts available for long-endurance patrols, and the sturdy construction and heavy armament that ensures many a Sunderland crew safely made it home, despite serious attention from the Luftwaffe and Kriegsmarine. Perhaps we should finish with a short poem written by a Sunderland crewman, which clearly states the affection the aircrews had for the Sunderland:
‘Reconnaissance sounds inoffensive,
Like a gull sailing high o’er the sea.
But the Sunderland’s prickly defensive
Makes patrolling a porcupine’s spree’.
- Crew: 9–11 (two pilots, radio operator, navigator, engineer, bomb-aimer, three to five gunners)
- Length: 85 ft 4 in (26.01 m)
- Wingspan: 112 ft 9.5 in (34.379 m)
- Height: 32 ft 10.5 in (10.020 m)
- Empty weight: 34,500 lb (15,649 kg)
- Gross weight: 58,000 lb (26,308 kg)
- Powerplant: 4 × Bristol Pegasus XVIII 9-cylinder air-cooled radial piston engines, 1,065 hp (794 kW) each
- Maximum speed: 210 mph (340 km/h, 180 kn) at 6,500 ft (2,000 m)
- Range: 1,780 mi (2,860 km, 1,550 nmi)
- Service ceiling: 17,200 ft (5,200 m)
- Rate of climb: 720 ft/min (3.7 m/s)