Short S.25 & 26 Sunderland

Access and servicing


Crew and others usually entered the aircraft through the bow compartment door on the left forward side of the aircraft.

Each of the compartments, from the front, were fitted with swash doors to maintain waterproof integrity of the compartment to about two ft (610 mm) above normal water level.

The doors could be opened for less agile passengers but they were otherwise normally kept closed.

There were five doors from the front to aft separating the bow from the gun room, the ward room, the galley, the bomb room and the after compartments.

There was another external door in the tail compartment on the right side.

This door was intended for boarding from a Braby (U-shaped) [Vous devez être inscrit et connecté pour voir ce lien] that was used where there was a full passenger
service mooring alongside a [Vous devez être inscrit et connecté pour voir ce lien] or similar.

This door could also be used to accept passengers or stretcher bound patients when the aircraft was in the open water where the engines had to be kept running to maintain the aircraft's position for the approaching vessel.

Because the aircraft was kept facing into wind it was not very difficult for ambulatory passengers to stand on the [Vous devez être inscrit et connecté pour voir ce lien] of their boat and step up into the doorway when the boat was alongside.

However, holding a small boat (such as a [Vous devez être inscrit et connecté pour voir ce lien] or [Vous devez être inscrit et connecté pour voir ce lien]) at right angles to the aircraft, so that a stretcher could be supported at the far end while it was being fed in through the doorway to a crew member inside, was fraught with difficulty, particularly if the stretcher and occupant was wider than the doorway!

Normally the stretcher occupant was most at risk, with the aircraft being the next most vulnerable from the bow of the boat.

Normal access to the external upper parts of the aircraft was through the astrodome hatch at the front of the front spar of the wing centre section, just at the rear of the navigator's station.

Bombs were loaded in through the "bomb doors" that formed the upper half walls of the bomb room on both sides.

The bomb racks were able to run in and out from the bomb room on tracks in the underside of the wing.

Weapons were hoisted up to the extended racks that were run inboard and then were either lowered to stowages
on the floor or prepared for use on the racks above.

The doors were sprung loaded to pop inwards from their frames and would fall under gravity so that the racks could run out through the space left in the top of the compartment.

The doors could be released locally or remotely from the pilot's position during a bomb run.

Normally the weapons were either bombs or depth charges and the racks were limited to a maximum of 1,000 lb
(450 kg) each.

After the first salvo was dropped it was a race for the crew to get the next eight loaded before the pilot had the aircraft positioned on the next bombing run.

The fixed nose guns (introduced by the Australians) were demounted when the aircraft was waterborne and stowed in the gun room just aft of the bow compartment.

The toilet was in the right half of this same compartment and stairs from the cockpit to the bow area divided the two.

Maintenance was performed on the engines by opening panels in the leading edge of the wing either side of the powerplant.

A plank could be fitted across the front of the engine on the extensions of the open panels.

A small manually started auxiliary petrol engine, which was fitted into the leading edge of the right wing, powered a
bilge and a fuel pump for clearing water and other fluids from the fuselage bilges and for refuelling.

Generally, the aircraft were reasonably water tight, and two people on a wobble pump could transfer fuel faster than the auxiliary pump.

In sheltered moorings or at sea, fuelling was accomplished by a powered or unpowered [Vous devez être inscrit et connecté pour voir ce lien] and with engine driven or hand powered pump(s).

At regular moorings there would be specially designed refuelling barges to do the job, normally manned by trained marine crew.

These vessels could refuel many aircraft during the course of the day.

Handling of the fuel nozzles and opening/closing the aircraft fuel tanks would normally be an aircraftman's task.

Where there were unreliable fuel supplies, usually at outlying moorings away from any fixed base, it might take a crew of four 3–4 hours to transfer 2,000 gallons (9,092 litres) of fuel into the aircraft.

If the barge had a capacity of only about 800 gallons (as was usual) it could take three times that.

Oil supplies and minor spares were carried in the aircraft at such outlying bases if the crew were operating
autonomously.

In serious cases, where refuelling from drums or when the supplies were otherwise in doubt, aircraft were refuelled through [Vous devez être inscrit et connecté pour voir ce lien] filters to separate the dirt, rust and water from the fuel.

Airframe repairs were either effected from the inside or waited until the aircraft was in a sheltered mooring, or beached.

One of the serious problems was that the heat treated rivets in the hull plates were susceptible to corrosion after a period in salt water (depending on the quality of the heat treatment process).

The heads would pop off, from stress corrosion, and leaks would start into the [Vous devez être inscrit et connecté pour voir ce lien].

The only resort was to haul the aircraft out onto the hard and replace them; usually at the cost of many additional
heads coming off because of the riveting vibrations.

Most maintenance and servicing personnel had tools modified to attach them to their person because dropping a tool normally meant it was gone forever.

Glooped, was the explanation for the loss, being the sound of the tool entering the water.

Beaching


The beaching gear was large and unwieldy.

The main legs had to be ballasted to sink, wheels down, so that the leg could be raised upright into its housing under the wing centre section, and then the lower part was pressed against the fuselage wall where it was pinned.

This usually meant that two people would get wet through.

The tail trolley was also ballasted to sink under the aft fuselage where the seagoing section of the hull ended.

The upper arms of the trolley were raised to locate in mating holes in the exterior skin of the hull where the main weight of the aircraft would ultimately keep it in place; but until then it was precariously unstable.

Meanwhile a rope from the shore to the header buoy at the nose of the aircraft was threaded through the pulley on the buoy and attached to the aircraft's bollard.

The shore end of this rope was managed by a person positioned at an electric [Vous devez être inscrit et connecté pour voir ce lien] that would control the release of the aircraft from the buoy.

A short rope connected the tail towing eye in the fuselage to another hauling device, most often a tractor, that was able to manoeuvre the aircraft on the slipway and on the hardstanding beyond.

When all was ready the bowman cast off from the buoy pendant.

The tail was pulled carefully to the slipway and the header buoy rope was paid out from the capstan off to the side.

The idea was that the tail trolley should be bought into contact with the submerged section of the slipway as gently as possible, ensuring that the aircraft remained securely in place on the trolley as it started rolling up the slip.

A sharp impact on the trolley wheels, located approximately five ft (1.6 m) below the keel, was enough to rotate the trolley around its fuselage attachment arms and dislodge it, allowing the aircraft's keel to strike the slip and thereby sustain damage.

When tidal flow or wind adversely affected the positioning of the aircraft, a situation could arise where the tail and attachments were running true, but the nose of the aircraft had now swung to one extreme of the slipway preventing the main wheels on one side from correctly contacting the slip.

Consequently it is not surprising that Sunderlands were not beached for any minor reason.

Once the tail trolley was well up the slipway a steering arm could be inserted into the lower part of the trolley and used to turn the wheels so that the assemblage could be guided to follow the tractor.

Movement in the opposite direction was effected by a bridle attached to the front of the lower part of the main legs.

On the slipway the tail towing eye was used to restrain the aircraft from running away down the slope.

Damage control


A large float mounted under each wing stopped the aircraft toppling over on the water.

With no wind, the float on the heavier side was always in the water; with some wind the aircraft could be held using the ailerons with both floats out of the water.

If a float was lost as the craft lost airspeed after landing, crew members would go out onto the opposite wing to keep the remaining float in the water until the aircraft could reach its mooring.

Aircraft with lower hull damage were patched or had the holes filled with any materials to hand before landing.

The aircraft would then be immediately put onto a slipway with its wheeled beaching gear or beached on a sandy shore before it could sink.

More than two fuselage compartments had to be full of water to sink the aircraft.

During the Second World War, a number of severely damaged aircraft were deliberately landed on grass airfields ashore.

In at least one case, an aircraft that made a grass landing was repaired to fly again

Marine growths on the hull were a problem; the drag caused could be enough that a fully loaded aircraft would be unable to gain enough speed to become airborne.

The aircraft could be taken to a freshwater mooring for sufficient time to kill off the fauna and flora growing on the bottom which would then be washed away during takeoff runs.

The alternative was to scrub it off, either in the water or on the hard.

The takeoff run of a flying boat was often only dependent on the length of water that was available.

The first problem was to gain sufficient speed for the craft to [Vous devez être inscrit et connecté pour voir ce lien], otherwise there would never be enough speed to become airborne.

Once planing, the next problem was to break free from the suction (from [Vous devez être inscrit et connecté pour voir ce lien]) of the water on the hull.

This was partly helped by the "step" in the hull just behind the craft's centre of buoyancy at planing speed.

The pilot could rock the ship about this point to try to break the downward pull of the water on the surface of the hull.

Somewhat rough water was a help in freeing the hull from the water, but on calm days it was often necessary to have a high speed [Vous devez être inscrit et connecté pour voir ce lien] cross in front of the aircraft to cause a break in the water flow under the aircraft.

It was a matter of judgement of the[Vous devez être inscrit et connecté pour voir ce lien] to get the crossing close enough but not too close.

Because it was expected that some takeoffs would be protracted affairs, often the crews were not very careful to keep within maximum all up weight limitations and getting airborne just took a little longer.

In such cases the flight engineer would ignore the climbing cylinder head temperatures and maintain the use of takeoff power for more than five minutes at a time.

On Mk V aircraft, fuel could be dumped from retractable pipes that extended from the hull and were attached the bomb room side of the galley aft [Vous devez être inscrit et connecté pour voir ce lien].

It was expected that dumping would be done while airborne, but it could also be done on the water, with care to
ensure that the floating fuel went downwind away from the aircraft.

Operational history


Second World War


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 [Vous devez être inscrit et connecté pour voir ce lien], two Sunderlands rescued the entire 34-man crew of the torpedoed merchantman Kensington
Court from the [Vous devez être inscrit et connecté pour voir ce lien].

As British anti-submarine measures improved the Sunderland began to show its claws as well.

A [Vous devez être inscrit et connecté pour voir ce lien] (RAAF) Sunderland (of [Vous devez être inscrit et connecté pour voir ce lien]) made the type's first unassisted kill of a [Vous devez être inscrit et connecté pour voir ce lien] on 17 July 1940.

As aircrew honed their combat skills, the Sunderland Mark I received various improvements.

The nose turret was upgraded to two .303 (7.7 mm) guns instead of one and 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 fair 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 [Vous devez être inscrit et connecté pour voir ce lien] medium bombers.

It shot one down, damaged another enough to send it off to a forced landing and drove off the rest.

The Germans are reported to have nicknamed the Sunderland the Fliegendes Stachelschwein ("Flying Porcupine") due to its defensive firepower and to the several prominent antennas protruding from it.