Short Sunderland

At the onset of World War Two, RAF Coastal Command was changing over from the Short Singapore to the new Short Sunderland for its maritime patrols. The aircraft was a direct derivative of the civil Short Empire seaplanes of Imperial Airways. They were large aircraft which were to play an important role in combat against for instance the German U-boats. The Sunderlands were a formidable gun platform of which the defensive capabilities were gradually increased during the war to such an extent that it really brought fear to U-boat commanders as well as to attacking German aircrews. The latter called respectfully called it Das fliegende Stachelschwein or the flying porcupine.

Short Sunderland Mk I, L2163, DA-G, No. 210 Squadron. Source: Imperial War Museum CH 795

The Sunderland was a direct descendant of the Short Empire C class seaplanes of the 30s. A flying boat was developed under factory designation S.25 which could, based on the experience with the Empire aircrat, count on an immediate order of 21 units in March 1936. In 1933, the Air Ministry had issued specification R.2//33, inviting Short and Saunders Roe to construct two prototypes. Short was the only company which managed to complete a prototype on time.^[1]

Short Empire vliegboot Caledonia. Source: Imperial War Museum ATP 8906B.

The design was directly derived from the Short Empire. Naturally, for military purposes, a number of adaptations had to be made. Nose and tail construction were adapted in order to accommodate an automatic gun turret. This meant the cockpit had to be moved further to the back. The hull was adapted to the altered construction and in order to compensate for the weight of the tail turret, the wings were slightly V-shaped. The hull had been split in two decks with the bomb bay situated on the upper deck. In order to enable the bombs to be dropped, rails were fitted on both sides of the fuselage beneath the wings. Bombs, depth charges or mines were shoved out on these rails and then dropped.^[2]

For its defense, a twin-gun Frazer-Nash turret was fitted in the nose, the tail turret contained four machineguns and there was a position for a hand-held machinegun on each side of the upper hull.

The first prototype - K 4774 - made its maiden flight on October 16, 1937 and was not an outright success. The engines used were the Bristol Pegasus X, an older model than had been intended in the design. After modification, the prototype was propelled by four Bristol Pegasus XXII engines of 1,010 hp each. This aircraft turned out to be a magnificent performer.^[3]

prototype K 4774. Source: Imperial War Museum ATP 9278C.

Overview of types:

The Sunderland Mk I was propelled by the same engines as the prototype. The first aircraft were delivered to the RAF in the summer of 1938, replacing the Short Singapores of No. 230 Squadron in Singapore and No. 210 Squadron at Pembroke, England. At the outbreak of the war in September 1939, another two squadrons had switched to the Sunderland, followed by another three during the first months of the war.

Short Sunderland Mk I, L2163, DA-G, No. 210 Squadron. Source: Imperial War Museum CH 805.

The Australian air force ordered nine planes but they designated them A18. On September 11, 1939, No. 10 RAAF Squadron stationed in England received its first plane and No. 461 RAAF Squadron, also stationed in England, a short time later.

The first task of the Sunderland weren't the famous anti U-boat patrols however but mainly rescuing crews of torpedoed vessels. On July 17, 1940, the first U-boat fell victim to an Australian Sunderland. In the course of time, a second machinegun was installed in the nose turret in order to enhance its defensive capability.

Technical data

Some modification to the wings enabled stronger Bristol Pegasus XVIII engines to be installed. This Mk II differed from the Mk I on several points. The hand-held machineguns on the flanks were gradually replaced by a twin-gun dorsal turret.

Short Sunderland Mk II, RB-S, No. 10 Squadron, R.A.A.F. Source: Imperial War Museum CH 7504.

The first Mk II was offered in May and delivered to the RAF in August 1940. Another novelty fitted to the Mk II in the course of time was an ASV Mk II air-surface radar. To this end, a number of characteristic aerials was fitted to the top of the fuselage and the flanks.

Technical data

The Sunderland Mk III followed in 1942 and was able to carry a larger fuel load, considerably increasing its range. Its maiden flight was made in June 1942. This would be the most important production version. When early 1943 it became clear that U-boats protected themselves better against aerial attacks by installing AA guns, the Mk III were adapted accordingly. At the front of the fuselage, two additional fixed, forward firing machineguns were fitted on both sides. These were operated by the pilot so the deck of the U-boat could be 'wiped clean' after which the vessel could be attacked by bombs or depth charges.

Short Sunderland Mk III, W6013 '2-B', No. 423 Squadron RCAF. Source: Imperial War Museum HU 91910.

The Canadian squadrons Nos. 422 and 423 operated from England, Scotland and Ireland with 74 Mk II and III aircraft in total. In addition, Australian squadrons Nos 10 and 461 flew both versions as well.

Gun emplacements from various Mk III aircraft were removed to convert them to unarmed transport aircraft. These were operated by BOAC (today British Airways) to carry mail and other goods. These aircraft performed magnificently and it was therefore decided to construct an additional version of the Sunderland, based on the airframe of the Mk III. This became the Short S.25/V Sandringham. Whereas the adapted Mk III aircraft could carry only 6 passengers, the interior of the Sandringham had been adapted to such an extent, it actually had been converted to a passenger aircraft carrying 24 persons by day and - equipped with beds - 16 on night flights.

Technical data

The planned Sunderland Mk IV was constructed with so many adaptations, it actually turned into a brand new design. Therefore the aircraft was given a new designation: Short S.45 Seaford. The plane was specifically designed for operations in the Far East^[4]

The airplane had become considerably larger, heavier and stronger than the original design. For propulsion, four Bristol Hercules XIX engines of 1,720hp each were selected and the defensive armament was drastically expanded. However, the aircraft came too late to enter service during the war. Only a few planes were built and because of the end of the war, supplementary orders were cancelled. The six planes that actually had been completed were converted after the war to transport aircraft for BOAC and renamed Short Solent.

Short Seaford. Source: Imperial War Museum ATP 14556B.

Technical data

The Sunderland Mk V was the last production model of the Sunderland family. The aircraft was equipped with the stronger and more reliable Pratt & Whitney Twin Wasp engines. The armament was strengthened as well by installing two 12,7 Browning machineguns next to the standard weapons on either side. The Mk V was delivered from March 1944 onwards.

Sunderland GR Mark V, ML778,NS-Z, No. 201 Squadron. Source: Imperial War Museum CH 18020

Technical data Mk V

Notes

1. Klaauw, 1977, p. 50
2. Klaauw, 1977, pag. 50
3. Klaauw, 1977, p 50
4. Klaauw, 1977, pag. 52