The Short S.25 Sunderland was a British flying boat patrol bomber developed for the RAF by Short Brothers. It took its service name from the town (latterly, city) and port of Sunderland in northeast England.
Based in part upon the S.23 Empire flying boat, the flagship of Imperial Airways, the S.25 was extensively re-engineered for military service. It was one of the most powerful and widely used flying boats throughout the Second World War, and was involved in countering the threat posed by German U-boats in the Battle of the Atlantic. RAF Sunderlands also saw service throughout the Korean War and continued in service until 1959. It also took part in the Berlin airlift. Sunderlands remained in service with the Royal New Zealand Air Force (RNZAF) until 1967.
Sunderlands converted for civil use, known as Short Sandringhams, continued in airline operation until 1974. A single airworthy example remains on display in Florida at Fantasy of Flight.
The early 1930s saw intense competition in developing long-range intercontinental passenger service between the United Kingdom, the United States, France and Germany, but the United Kingdom had no equivalent to the new American Sikorsky S-42 flying boats or the German Dornier Do X. However, in 1934, the British Postmaster General declared that all first-class Royal Mail sent overseas was to travel by air, establishing a subsidy for the development of intercontinental air transport in a fashion similar to the U.S. domestic programme a decade earlier. In response, Imperial Airways announced a competition to design and produce 28 flying boats, each weighing 18 long tons (18 t) and having a range of 700 mi (1,100 km) with a capacity for 24 passengers.
The contract went to Short Brothers of Rochester and while the first example of the new type, the S.23 Empire was under development, the British Air Ministry was taking actions that would result in a military version. The 1933 Air Ministry Specification R.2/33 called for a next-generation flying boat for ocean reconnaissance. The new aircraft had to have four engines but could be either a monoplane or biplane design.
Specification R.2/33 was released roughly in parallel with the Imperial Airways requirement, and while Short continued to develop the S.23, it also worked on a response to R.2/33 at a lower priority. Chief Designer Arthur Gouge originally intended that a 37 mm COW gun be mounted in the bow with a single Lewis gun in the tail. As with the S.23, he tried to make the drag as low as possible, while the nose was much longer than that of the S.23. The military flying boat variant was designated S.25 and the design was submitted to the Air Ministry in 1934. Saunders-Roe also designed a flying boat, the Saro A.33, in response to the R.2/33 competition, and prototypes of both the S.25 and A.33 were ordered by the Ministry for evaluation. The initial S.25 prototype first took flight in October 1937.
The S.25 shared much in common with the S.23 but it had a deeper hull profile. As construction proceeded the armament was changed to a single 0.303 Vickers K machine gun in the nose turret and four 0.303 Browning machine guns in the tail. Then there was a change in the tail turret to a powered version and Gouge had to devise a solution for the resulting movement aft of the aircraft’s centre of gravity. The unarmed prototype (K4774) first flew, on 16 October 1937. Following some flight trials it was modified with a wing sweepback of 4° 15′ by adding a spacer into the front spar attachments. This moved the centre of lift enough to compensate for the changed centre of gravity. The modified K4774 flew on 7 March 1938 with Bristol Pegasus XXII engines of 1,010 hp (750 kW).
As with the S.23, the Sunderland’s fuselage contained two decks with six bunks on the lower one, a galley with a twin kerosene pressure stove, a yacht-style porcelain flush toilet, an anchoring winch, and a small machine shop for in-flight repairs. The crew was originally intended to be seven but increased in later versions to 11 crew members or more.
It was of all-metal, mainly flush-riveted construction except for the control surfaces, which were of fabric-covered metal frame construction. The flaps were Gouge-patented devices that slid backwards along curved tracks, moving rearwards and down, increasing the wing area and adding 30% more lift for landing.
The thick wings carried the four nacelle-mounted Pegasus engines and accommodated six drum fuel tanks with a total capacity of 9,200 litres (2,025 Imperial gallons, 2,430 U.S. gallons). Four smaller fuel tanks were added later behind the rear wing spar to give a total fuel capacity of 11,602 litres (2,550 Imperial gallons, 3,037 U.S. gallons), enough for eight- to 14-hour patrols.
The specification had called for an offensive armament of a 37 mm gun and up to 2,000 lb (910 kg) of bombs, mines or (eventually) depth charges. The ordnance was stored inside the fuselage in a bomb room and was winched up to racks, under the wing centre section, that could be traversed out through doors on each side of the fuselage above the waterline to the release position. Defensive armament included a Nash & Thomson FN-13 powered turret with four .303 British Browning machine guns in the extreme tail and a manually operated .303 on either side of the fuselage, firing from ports just below and behind the wings. These were later upgraded to 0.5-inch calibre Brownings. There were two different nose turret weapons, the most common, later, being two Browning machine guns. The nose weapons were later augmented by four fixed guns, two each side, in the forward fuselage that were fired by the pilot. Much later a twin-gun turret was to be dorsal-mounted on the upper fuselage, about level with the wing trailing edge, bringing the total defensive armament up to 16 machine guns.
Portable beaching gear could be attached by ground crew so that the aircraft could be pulled up on land. The gear consisted of a pair of two-wheeled struts that could be attached to either side of the fuselage, below the wing, with a two- or four-wheel trolley and tow bar attached under the rear of the hull.
During the Second World War, although British anti-submarine efforts were disorganized and ineffectual at first, Sunderlands quickly proved useful in the rescue of the crews from torpedoed ships. On 21 September 1939, two Sunderlands rescued the entire 34-man crew of the torpedoed merchantman Kensington Court from the North Sea. As British anti-submarine measures improved, the Sunderland began to inflict losses as well. A Royal Australian Air Force (RAAF) Sunderland (of No. 10 Squadron) made the type’s first unassisted kill of a U-boat on 17 July 1940.
During its service the Sunderland Mark I received various improvements. The nose turret was upgraded with a second .303 (7.7 mm) gun. New propellers together with pneumatic rubber wing de-icing boots were also fitted.
Although the .303 guns lacked range and hitting power, the Sunderland had a considerable number of them and it was a well-built machine that was hard to destroy. On 3 April 1940, a Sunderland operating off Norway was attacked by six German Junkers Ju 88C fighters. It shot one down, damaged another enough to send it off to a forced landing and drove off the rest. The Germans are reputed to have nicknamed the Sunderland the Fliegendes Stachelschwein (“Flying Porcupine”) due to its defensive firepower.
Sunderlands also proved themselves in the Mediterranean theatre. They flew many evacuation missions during the German seizure of Crete, carrying a surprising number of passengers. One flew the reconnaissance mission to observe the Italian fleet at anchor in Taranto before the famous Royal Navy Fleet Air Arm’s torpedo attack on 11 November 1940.
New weapons made the flying boats more deadly in combat. In 1939 during an accidental fratricidal attack, one 100 lb anti-submarine bomb hit the British submarine Snapper doing no more damage than breaking its light bulbs; other bombs had reportedly bounced up and hit their launch aircraft. In early 1943, these ineffective weapons were replaced by Torpex-filled depth charges that would sink to a determined depth and then explode. This eliminated the problem of bounce-back, and the shock wave propagating through the water augmented the explosive effect.
While the bright Leigh searchlight was rarely fitted to Sunderlands, ASV Mark II radar enabled the flying boats to attack U-boats on the surface. In response, the German submarines began to carry a radar warning system known as “Metox”, also known informally as the “Cross of Biscay” due to the appearance of its receiving antenna, which was tuned to the ASV frequency and gave the submarines early warning that an aircraft was in the area. Kills fell off drastically until ASV Mark III radar was introduced in early 1943, which operated in the centimetric band and used antennas mounted in blisters under the wings outboard of the floats, instead of the cluttered stickleback aerials. Sunderland Mark IIIs fitted with ASV Mark III were called Sunderland Mark IIIAs. Centimetric radar was invisible to Metox and baffled the Germans at first. Admiral Karl Dönitz, commander of the German U-boat force, suspected that the British were being informed of submarine movements by spies. In August 1943, a captured RAF airman misled the Germans by telling them that the aircraft were homing in on the signals radiated by the Metox, and consequently U-boat commanders were instructed to turn them off.
The Germans responded to Sunderland attacks by fitting U-boats with one or two 37 mm and twin quad 20 mm flak guns to fire back at their attackers. While Sunderlands could suppress flak to an extent with their nose turret guns, the U-boats guns had superior range, hitting power and accuracy. Attempting to shoot down Allied aircraft did, however, prolong the U-boat’s presence on the surface, which made the sinking the vessel easier. Nonetheless, the fitting of substantial arrays of anti-aircraft guns temporarily decreased U-boat losses while both Allied aircraft and shipping losses rose. As a countermeasure to the increased defensive armament of the U-boats, the Australians fitted their aircraft in the field with an additional four .303s in fixed mounts in the nose, allowing the pilot to add fire while diving on the submarine before bomb release. Most aircraft were similarly modified. The addition of single .50 inch (12.7 mm) flexibly mounted M2 Browning machine guns in the beam hatches behind and above the wing trailing edge also became common.
The rifle calibre .303 guns lacked hitting power but the Sunderland’s defensive armament was nonetheless formidable.
The aircraft’s capacity to defend itself was demonstrated in an air battle between eight Junkers Ju 88C long range heavy fighters and a single Sunderland Mark III of No. 461 Squadron RAAF on 2 June 1943. This was one of several stories of the type’s operations related by author Ivan Southall, who flew in Sunderlands during the war. There were 11 crewmen on board the Sunderland: nine Australians and two British. The aircraft was on an anti-submarine patrol and also searching for remains of BOAC Flight 777, an airliner that had left Lisbon the day before and had subsequently been shot down over the Bay of Biscay, killing 17, among them, the actor Leslie Howard. In the late afternoon, one of the crew spotted the eight Ju 88s. Bombs and depth charges were dumped and the engines brought to maximum power. Two Ju 88s made passes at the flying boat, one from each side, scoring hits and disabling one engine while the Sunderland went through wild “corkscrew” evasive manoeuvres.
On the third pass, the dorsal turret gunner shot down a Ju 88. Another Ju 88 disabled the tail turret, but the next one that made a pass was hit by both the dorsal and nose turrets and shot down. Another destroyed the Sunderland’s radio gear, wounding most of the crew to varying degrees and mortally wounding one of the side gunners. A Ju 88 tried to attack from the rear, but the tail turret gunner had regained some control over the turret and shot it down. The surviving Ju 88s continued to attack, but the nose gunner damaged one of these, setting its engines on fire. Two more of the attackers were also hit and the final pair disengaged and departed, the only two to make it back to base. The Sunderland had been heavily damaged.
The crew threw everything they could overboard and nursed the aircraft back to the Cornish coast, where pilot Colin Walker managed to land and beach the aircraft at Praa Sands. The crew waded ashore, carrying their dead comrade, while the surf broke the Sunderland up. Walker received the Distinguished Service Order and several of the other crew members also received medals. With the exception of Walker, the crew returned to Sunderlands – they disappeared without trace over the Bay of Biscay two months later after reporting that they were under attack by six Ju 88s.
On 2 June 2013, a memorial was opened on the green at Praa Sands.
In late 1942, the British Overseas Airways Corporation (BOAC) obtained six Sunderland Mark IIIs, which had been de-militarised on the production line, for service as mail carriers to Nigeria and India, with accommodation for either 22 passengers with 2 tons of freight or 16 passengers with 3 tons of freight. Armament was removed, the gun positions being faired over, and simple seating fitted in place of the bunks. As such they were operated by BOAC and the RAF jointly from Poole to Lagos and Calcutta. Six more Sunderland IIIs were obtained in 1943. Minor modifications to the engine angles and flight angle resulted in a significant increase in the cruise speed, which was a relatively unimportant issue for the combat Sunderlands. In late 1944, the RNZAF acquired four new Sunderland Mk IIIs already configured for transport duties. In the immediate postwar period, these were used by New Zealand’s National Airways Corporation to link South Pacific Islands in the “Coral Route” before TEAL Short Sandringhams took over after 1947.
BOAC obtained more Mark IIIs and gradually came up with better accommodation for 24 passengers, including sleeping berths for 16. These conversions were given the name Hythe and BOAC operated 29 of them by the end of the war. In February 1946, the first of these, G-AGJM, made a 35,313 mile route survey from Poole to Australia, New Zealand, Hong Kong, Shanghai and Tokyo in 206 flying hours. It was the first British civil flying boat to visit China and Japan.
A more refined civilian conversion of the Sunderland was completed by the manufacturer as the postwar Short Sandringham. The Sandringham Mk. I used Pegasus engines while the Mk. II used Twin Wasp engines.
At the end of the Second World War, a number of new Sunderlands built at Belfast were simply taken out to sea and scuttled as there was nothing else to do with them. In Europe it was removed from service relatively quickly but in the Far East, where well developed runways were less common and large land based maritime patrol aircraft like the new Avro Shackleton could not be used so easily, there was still a need for it, and it remained in service with the RAF Far East Air Force at Singapore until 1959, and with the Royal New Zealand Air Force’s No. 5 Squadron RNZAF until 1967.
During the Berlin Airlift (June 1948 – August 1949) 10 Sunderlands and two transport variants (known as Hythes) were used to transport goods from Finkenwerder on the Elbe near Hamburg to the isolated city, landing on the Havel river beside RAF Gatow until it iced over. The Sunderlands were particularly used for transporting salt, as their airframes were already protected against corrosion from seawater. Transporting salt in standard aircraft risked rapid and severe structural corrosion in the event of a spillage. When the Havelsee did freeze over the Sunderland’s role was taken by freight-converted Handley Page Halifaxes with salt being carried in panniers fitted under the fuselage to avoid the corrosion problem.
From mid-1950, RAF Sunderlands also saw service during the Korean War initially with No. 88 Squadron but shortly followed by Nos. 205 and 209 Squadrons. The three squadrons shared the operational task equally with rotational detachments of three or four aircraft and crews based at Iwakuni, Japan. Missions lasting 10 to 13 hours were flown daily throughout the war, and also during the Armistice period that followed, until September 1954. The Sunderland also saw service with the RNZAF until 1967.
The French Navy Escadrille 7FE, which received Sunderlands when it was formed in 1943 as No. 343 Squadron RAF, continued to operate them until December 1960, the last unit to operate Sunderlands in the Northern Hemisphere.
AA27502 Corgi Aviation Archive Short Sunderland Mk.III ML788/2-S, No.422 Squadron RCAF, Pembroke Dock
New from the forthcoming Corgi Aviation Archive 2016 second half catalogue is the AA27502 Corgi Aviation Archive Short Sunderland Mk.III ML788/2-S, No.422 Squadron RCAF, Pembroke Dock.
Although the new Corgi Catalogue has not yet been released (end of the month) Corgi have previewed this model as a “taster” on what is to come. It has been ordered in good numbers already with many model collectors stating a preference of this version over the first release. It is due for release in October and is available to pre-order from Flying Tigers now. Simply click on the image or links to go straight to the model page.
Lockheed F-22 Raptor and F-35 Lightning II at RIAT
Well the Royal International Air Tattoo is nearly upon us… not long to wait now ! If the weather is kind to us it really should be a fantastic show, and without doubt the stars of the show promise to be the United States participants F-22 Raptor and F-35 Lightnings. I will be there camera in hand at the Sunday show. I will report back afterwards all being well.
I have noticed a steady build up of orders for models of these aircraft over the last few weeks or so, in anticipation of the display causing an increase in demand. A few of the variants I had are now unfortunately Sold Out, but I have been able to get further supplies of the following models. If you still don’t have an example of these in your collection, now is a good time to get one before the Airshow has taken place. Please click on any of the images or links below to go straight to the model of your choice.
Offers of the Week
I have added the following models to “Offers of the Week”. There are limited stocks on these , so first come, first served. Please click on the model of your choice or CLICK HERE to see them all.
Latest Arrivals at Flying Tigers this week.
The following models have arrived at Flying Tigers this week. All pre-orders are being dispatched in the next few days. Please click on the model of your choice below to go straight to the model page.
Well that’s it for another week. Corgi seem to be catching up with their model deliveries now so keep your eyes peeled for more arrivals in the next couple of weeks.
Thank you for taking time to read this week’s Newsletter.
Richard.
Flying Tigers.