StraitTales2

 

           Sunderlands of the Cinderella Service.

 

 

Perhaps one of the most extraordinary aircraft ever to grace our shores was the Short S.25 Sunderland flying boat, used by Coastal Command during World War 2. The RAF requirement was based on the airframe of the Short S.23 Empire flying boat but completed to their military spec… and what an aircraft they produced. The capability to land virtually anywhere around the globe from Lake Windermere to Sydney Harbour made it possibly the most versatile aircraft of the age. Coupled with long range and enormous payload the original requirement for a maritime patrol aircraft soon expanded into a multitude of roles.

Originally commissioned for coastal surveillance, the Sunderland’s most famous role was as U-Boat killers, but they also served in transporting personnel and rescuing survivors from sinking ships; they would often carry the entire crew from a torpedoed merchantman.

This was a large aircraft; measuring 85 ft 3” long and 32 ft 2” high with a wingspan of 112 feet 9 inches. The aircraft was of metal construction, except for most of the control surfaces, which were metal framed and covered by fabric. As with the S.23, the Sunderland's fuselage contained two decks but in a re-designed and deeper hull. Unlike the Empire boats, this was functional rather than luxurious; but six bunks and a galley with a twin-burner paraffin pressure stove, as well as a yacht style porcelain toilet, made long ocean patrols more comfortable and provided the crew of seven with quarters when operating from remote locations; there was even a small machine shop for in-flight repairs. The seven to nine man crews would eventually be increased to eleven in later versions.

           


          

                                                   Rescued sailors being fed in a Sunderland Mess

The wings carried four Pegasus XXII air cooled radial engines of 1010HP (753Kw) each and accommodated six drum fuel tanks with a total capacity of 2,023 gallons (9,200 litres). Four more fuel tanks would later be added behind the rear wing spar to give a total fuel capacity of 2,552 gallons (11,602 litres). This pushed the Sunderland’s range up to 2,500 miles and was sufficient to allow eight to fourteen hour patrols. Offensive armament load was 2,000 pounds (900 kilograms) of bombs, mines, or eventually depth charges. Ordnance was carried inside the aircraft and winched out under the wings through doors on each side of the fuselage.

           

The Sunderland was provided with a nose turret mounting a single 7.7mm machine gun and the whole assembly could be winched back into the hull to leave a ‘pulpit’ from which mooring or anchoring operations were conducted via a forward hatch. The Fraser-Nash power-assisted tail turret mounted 4x 7.7mm machine guns and on each side of the fuselage a single 7.7mm gun, mounted above and behind the wing, fired from an oval port with a sliding shutter.

 

        

 

To facilitate bringing the aircraft on shore, (it was not an amphibian) two-wheeled struts could be fitted to each side of the fuselage and a small two-wheeled trolley with a tow bar could be attached under the rear of the hull. Despite their empty weight of 13 and a half tons, many a Sunderland was frequently hauled on shore by hand… usually many hands.

So how did these remarkable aircraft come to be operating from Gibraltar? Well it’s a long story that started with the formation of Coastal Command, as the RAF’s maritime arm, in 1936. During the inter-war period, naval aviation had been sadly neglected with virtually no investment in men or machines. Because the Air Ministry concentrated on Fighter Command and Bomber Command, Coastal Command was often referred to as the ‘Cinderella Service’ a phrase first used by the then First Lord of the Admiralty AV Alexander. This continued until the outbreak of the Second World War, during which Sunderlands came to prominence.

Initially Coastal Command was supplied with the AVRO Anson, which lacked sufficient range for deep ocean reconnaissance, alongside Vickers Vildebeests and SARO Londons; both of which were obsolescent. Fortunately, they had three squadrons with suitable aircraft, Sunderlands and Lockheed Hudsons, which could operate effectively in the required roles. The RAF had received its first Sunderland Mk1 in June 1938, with the second production aircraft flown out to Singapore. By the outbreak of war in September 1939, Coastal Command was operating forty Sunderlands.

Throughout the war the Short Sunderland would play a decisive role in the defeat of German U-boats in the Battle of the Atlantic. The first confirmed U-Boat kill by an aircraft was achieved on January 30, 1940 when British destroyer HMS Whitshed, British sloop HMS Fowey, French destroyers Valmy and Guépard, and a British 228 Squadron S.25 Sunderland aircraft sank German submarine U-55 by depth charges. The large Sunderland was also much in demand for convoy escort work, due not only to its striking power but its ability to land on the water for immediate rescue. The Sunderland was a very welcome sight to the many seamen from sunken vessels and airmen who were forced to ditch; when the British Merchant ship Kensington Court was torpedoed, 70 miles off the Scillies on September 18, 1939 two patrolling Sunderlands had the entire crew of thirty-four personnel back on dry land within an hour of the vessel sinking. In this, and during many subsequent desperate evacuation operations early in the war, Sunderlands were regularly found carrying a large number of personnel in an almost continuous stream without ever needing the use of a land airfield.

However, British anti-submarine efforts were somewhat disorganised at the beginning of the war; some early anti-submarine bombs were found to bounce up and hit their launch aircraft. As A/S measures improved, an RAAF Sunderland performed the first unassisted kill of a U-boat on 17^th July 1940. This was the start of their reputation as U-Boat killers.

 

  

          

First we might look at how U-boats operated during the first years of war. The normal procedure for U-boats attacking convoys at this time seems to have been as follows: The U-boat gained contact with the convoy during the day, either as a result of reports from long-range German reconnaissance aircraft, reports from other U-boats, or by sighting smoke, and they then shadowed the convoy at visibility distance on the bow or beam. When darkness had fallen, the U-boat trimmed down on the surface, closed the convoy, and endeavoured to reach a position broad on its bow. She kept very careful watch for the escorts and attempted to pass astern of those stationed on the bow of the convoy. The attack was pressed home as close as the U-boat captain dared, and it is possible that, in some cases, a firing range of about 600 yards was achieved. Having reached a firing position on the beam of the convoy, most U-boats increased to full speed, fired a salvo of four torpedoes, turned away still at full speed, firing stern tubes if possible, and retired as rapidly as possible on the surface in the direction considered safest. If their retreat was unseen, they might reload their torpedo tubes on the surface and attack again in the same manner later in the night.

Here is a typical attack launched against HG53 whose 21 ships departed Gibraltar on 6 February 1941 bound for Liverpool and escorted by the destroyer HMS Velox and the Grimsby class sloop HMS Deptford. The convoy commodore was Rear Admiral Sir OH Dawson aboard SS Dagmar. Whilst southbound in African waters, at o435 on the morning of 9th February, the German U-37 sighted the convoy southwest of Cape St Vincent and torpedoed the British freighters Courland and Estellano.

Co-operation between U-boats, aircraft and surface vessels is well illustrated by this attack: U-37 reported the convoy to Bordeaux-Merignac Air Base and commenced shadowing the convoy providing beacon signals for an airborne bomber unit (Kampfgesschwader 40). Five Focke-Wulf Condor bombers took off at dawn and found the convoy at noon 400 miles southwest of Lisbon. They bombed from an altitude of 150 feet because they lacked bombsights. Each flight mechanic fired at their target ship with a ventral machine gun during the approach to discourage anti-aircraft gunners; but one of the bombers was hit in a wing fuel tank and crash-landed in Moura, Portugal, when his fuel became exhausted on the return trip. Six of the twenty bombs dropped hit ships, sinking the convoy commodore's freighter Dagmar, the Norwegian freighter Tejo, and British freighters Britannic, Jura, and Varna. U-37 sank the British freighter Brandenburg after dark and continued to send beacon signals for the German cruiser Admiral Hipper which found and sank the straggling British freighter Iceland on 11 February.  The U-boat continued to shadow the convoy and again attacked on the 10th, sinking one ship. After this, she maintained touch with the convoy, reporting its position. Her reports were evidently intended for the Admiral Hipper. While closing HG 53, the cruiser came upon the unescorted slow portion of SL 64 and directed her attack against this easy target, sinking seven ships.

                                                                          Focke-Wulf Condor

For an air patrol to be able to locate submarines, on or near the surface, the crew’s prime asset was the same as that of their foe; the Mk 1 eyeball. But they were assisted by air-to-surface-vessel radar (ASV) which would detect a submarine on the surface. Introduced to operations in January 1940, it could detect a submarine at about 4 to 5 miles, in good conditions.

  

    

 Sterba curtain mounted on the hull ahead of the tail gave the ‘horizontal’ direction before switching to   the highly directional yagi arrays beneath the wings to zoom in on the target.      

Experiments proved that this relatively poor performance was caused by low gain antennae, so developers installed a Sterba, or curtain array, which had about 2.5x the gain of the original. This boosted performance to 10-15 miles. Whilst useful, it also led the enemy to introduce a radar detection system so that they knew when they were being painted by radar.

 There were spin-offs from the ASV too. It was very useful for keeping track of the convoys they were covering, particularly at night, and the signals reflecting from cliffs, etc. were very handy for navigation in poor weather. It led to the deployment of the first IFF (identification friend or foe system) as a homing beacon, when Squadron Leader Sidney Lugg mounted a transponder at a base, tuned to ASV frequency (176 MHz) which sent a short burst of radio signal whenever it heard a pulse from an ASV. Since it was a powerful signal it could be picked up 50-60 miles away and many a crew were very grateful. In fact the crews christened it ‘mother’.

At night however, whilst radar brought them to the target, they had to be able to see it. The available aircraft lighting was inadequate and all they could do was drop flares to illuminate the target. As returning crews explained, whilst able to locate submarines they often failed to destroy them in the darkness. One of those listening was Squadron Leader Humphrey de Verd Leigh, who proposed what eventually became the Leigh Light. This was a 22-million candlepower, 24 inch diameter searchlight, which in Sunderlands, was mounted below the wing. It was effective enough to change the U-boat procedure of surfacing at night to recharge their batteries, to daytime surfacing where at least they could see the aircraft approach. Clearly, it increased their vulnerability.

         

 

To achieve any sort of success in the Atlantic and the western approaches patrols were regularly flown from Pembroke Dock, Mountbatten (Devon)  Castle Archdale (N.I.), Stranraer (Galloway) Bowmore (Argyll and Bute) Bathurst (at the mouth of the Gambia River) Jui creek in SierraLeone and of course Gibraltar.

Gibraltar was host to 202 Squadron, operating off North Front, until 1944 when they were withdrawn to Castle Archdale. The war against the U-boats was pretty well won by the end of 1943. Although a flying boat can land or take off on any reasonably calm stretch of water, it still needs the same infrastructure and engineering support as any other aircraft. The installation at Gibraltar was significant as it had to cope with Sunderlands, SAROs and Catalinas, as well as land based aircraft. In fact our slipways, workshops and flying boat hangars only disappeared relatively recently. It also had to deal with accidents… The most serious Sunderland accident here was W4029 returning from patrol on August 22^nd 1941, following a convoy mission. During a night approach, at 0429 local time, the aircraft hit the water, exploded and disintegrated about 1000 yards off shore. The Observer, Pilot Officer Kenneth Gordon Gray, survived though seriously injured and the remaining 11 other occupants were killed.  It remains unclear whether the thin metal skin of the Sunderland ruptured as it hit the water or if perhaps the depth charges on board were triggered by the impact.

There were other hazards to flying from the Rock; the wind conditions, which we all know about, the swells, then the rough seas generated by equinoctial gales, but there were other unexpected hazards as one pilot found:

“Our patrol on 5 November 1943 was an absolute nightmare. Everything went wrong. First, within a short time I noticed that my Second Pilot appeared to be asleep but I could not rouse him. Then, I could not raise my Navigator on the intercom and it was not long before I realised that all of my crew were comatose. It later turned out that all but me, had sandwiches before take-off, which must have been poisoned. Although I was able to rouse them, eventually, that was just the start of my problems. The radar was not functioning properly then we found that the radio, too, wasn’t working. Having decided to continue with the patrol regardless, we had complete engine failure, which was later attributed to mishandling of our fuel supply when the aircraft was prepared for the patrol. As we prepared to ditch, frantic efforts were made to hand-pump fuel to the engines, which alternately sprang back into life such that we were able to climb to about two thousand feet. Without radar, I had no choice but to head in an easterly direction where I was confident of being able to find the entrance to the Med.”

                            The difficulty of refuelling afloat at some distant locations.

Frequently overshadowed by more glamorous aircraft, the Sunderland served throughout the war, and would later deliver nearly 5,000 tons of essential supplies during the Berlin airlift. It was also the only RAF aircraft to be used from the beginning to the end of the Korean War. The last Sunderland was finally retired from RAF service on the 20th May 1959, after an extensive and notable career.

                                        

 

 

First published at Gibraltar History Society 2020, revisited 2025.         Paul Hodkinson.