Short Sunderland

https://en.wikipedia.org/wiki/Short_Sunderland

The Short S.25 Sunderland was a British flying boat patrol bomber, developed and
constructed by Short Brothers for the Royal Air Force (RAF). The aircraft took
its service name from the town (latterly, city) and port of Sunderland in North
East England.

Developed in parallel with the civilian S.23 Empire flying boat, the flagship of
Imperial Airways, the Sunderland was developed specifically to conform to the
requirements of British Air Ministry Specification R.2/33 for a long-range
patrol/reconnaissance flying boat to serve with the Royal Air Force (RAF). As
designed, it served as a successor to the earlier Short Sarafand flying boat.
Sharing several similarities with the S.23, it featured a more advanced
aerodynamic hull and was outfitted with various offensive and defensive
armaments, including machine gun turrets, bombs, aerial mines, and depth
charges. The Sunderland was powered by four Bristol Pegasus XVIII radial engines
and was outfitted with various detection equipment to aid combat operations,
including the Leigh searchlight, the ASV Mark II and ASV Mark III radar units,
and an astrodome.

The Sunderland was one of the most powerful and widely used flying boats
throughout the Second World War. In addition to the RAF, the type was operated
by other Allied military air wings, including the Royal Australian Air Force
(RAAF), Royal Canadian Air Force (RCAF), South African Air Force (SAAF), Royal
New Zealand Air Force (RNZAF), French Navy, Norwegian Air Force, and the
Portuguese Navy. During the conflict, the type was heavily involved in Allied
efforts to counter the threat posed by German U-boats in the Battle of the
Atlantic. On 17 July 1940, a RAAF Sunderland (of No. 10 Squadron) performed the
type's first unassisted U-boat kill. Sunderlands also played a major role in the
Mediterranean theatre, performing maritime reconnaissance flights and logistical
support missions. During the evacuation of Crete, shortly after the German
invasion of the island, several aircraft were used to transport troops. Numerous
unarmed Sunderlands were also flown by civil operator British Overseas Airways
Corporation (BOAC), traversing routes as far afield as the Pacific Ocean.

During the post-war era, use of the Sunderland throughout Europe rapidly
declined, while greater numbers remained in service in the Far East, where large
developed runways were less prevalent. Between mid-1950 and September 1954,
several squadrons of RAF Sunderlands saw combat action during the Korean War.
Around a dozen aircraft had also participated in the Berlin airlift, delivering
supplies to the blockaded German city. The RAF continued to use the Sunderland
in a military capacity up to 1959. In December 1960, the French Navy retired
their aircraft, which were the last remaining examples in military use within
the Northern Hemisphere. The type also remained in service with the RNZAF up to
1967, when they were replaced by the land-based Lockheed P-3 Orion. A number of
Sunderlands were converted for use within the civil sector, where they were
known as the Short Sandringham; in this configuration, the type continued in
airline operation until 1974. Several examples were preserved, including a
single airworthy Sunderland which has been placed on display in Florida at
Fantasy of Flight.

Overview

The Short S.25 Sunderland was a large four-engined flying boat developed for
military use. The design of the S.25 shared much in common with the
civil-orientated S.23, principally differing in its use of a deeper hull
profile. As with the S.23, the interior of the Sunderland's fuselage contained
two individual decks; the lower deck contained a total of six bunks, along with
a galley outfitted with a twin kerosene pressure stove, a yacht-style porcelain
flush toilet, an anchoring winch, and a small machine shop for performing
inflight repairs. The crew was originally intended to total seven members; this
was subsequently increased for later versions of the Sunderland to around 11
crew members and sometimes greater, dependent upon the specific mission being
undertaken.

The Sunderland featured all-metal, mainly flush-riveted construction, except for
the flight control surfaces, which used a fabric-covered metal frame
construction. Of these, the flaps employed unusual Gouge-patented devices that
slid backwards along curved tracks, moving rearwards and downwards to increase
the wing area and generating 30% greater lift for landing. The thick wings, upon
which the aircraft's four nacelle-mounted Bristol Pegasus XXII radial engines
were carried, also accommodated a total of six drum-style fuel tanks, which
possessed a total capacity of 9,200 litres (2,025 Imperial gallons, 2,430 U.S.
gallons). In addition to the main fuel tanks, an arrangement of four smaller
fuel tanks were installed behind the rear wing spar later on; with the extra
tanks fitted, the Sunderland possessed a combined total fuel capacity of 11,602
litres (2,550 Imperial gallons, 3,037 U.S. gallons), which was enough to enable
the type to conduct eight- to 14-hour patrols.

The specification to which the Sunderland was developed to conform with 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 purpose-built 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 & Thompson FN-13 powered turret with four .303 British Browning
machine guns in the extreme tail and a pair of manually-operated .303 set on
either side of the fuselage, firing from ports just below and behind the wings.
These machine guns 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.


Role
Military flying boat bomber

Manufacturer
Short Brothers

Designer
Arthur Gouge

First flight
16 October 1937

Introduction
1938

Retired
RAF: 1959
RNZAF: 1967

Status
Retired

Primary users
Royal Air Force
French Navy
Royal Australian Air Force
Royal New Zealand Air Force

Produced
1938–1946

Number built
749

Variants
Short Sandringham
Short Seaford

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; during the engagement, it shot one down, damaged another enough
to cause it to retreat and later perform 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 as many as 82
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.

1943 encounter with Ju 88s

The type's capacity to defend itself was demonstrated in particular by an air
battle over the Bay of Biscay on 2 June 1943, when eight Junkers Ju 88Cs
attacked a single Sunderland Mk III of No. 461 Squadron RAAF: EJ134, squadron
code: "N for Nuts". The 11 crew, led by F/Lt Colin Walker, were on an
anti-submarine patrol, while also watching for any signs of a missing airliner,
BOAC Flight 777. At 1900 hours, the rear gunner saw the Ju 88s, which belonged
to V.Kampfgeschwader 40 and were led by Leutnant Friedrich Maeder. Walker
ordered the dumping of the bombs and depth charges, and took the engines to full
power. Two Ju 88s made simultaneous passes at EJ134 from both sides, scoring
hits and disabling one engine, while the pilots fought fires and took the
Sunderland through corkscrew manoeuvres. On a third pass, the dorsal turret
gunner badly damaged or shot down a Ju 88, although the Sunderland's rear gunner
was knocked unconscious.

The next Ju 88 that attacked was hit by fire from the dorsal and nose turrets,
and appeared to have been shot down. By this time, one crew member on the
Sunderland had been mortally wounded and most of the others were wounded to
varying degrees, while the aircraft's radio gear had been destroyed, among other
damage. However, the rear gunner had recovered, and when EJ134 was attacked from
behind, another Ju 88 was badly damaged and left the fight. The remaining Ju 88s
continued to attack and the front gunner damaged one of these, setting its
engines on fire. Two more Ju 88s were also damaged and the Germans disengaged.
EJ134 was badly damaged and the crew threw everything they could overboard,
while nursing the aircraft over the 350 mile journey to Britain. At 2248 hours,
Walker managed to beach the aircraft at Praa Sands, Cornwall. The 10 surviving
crew members were able to wade ashore, while the Sunderland broke up in the
surf. Walker received the Distinguished Service Order and several other crew
members also received medals. They claimed three Ju 88s destroyed. (With the
exception of Walker, the crew returned to operations in a new "N for Nuts",
which was lost over the Bay of Biscay two months later, in an attack by six Ju
88s. On 2 June 2013, a memorial was opened on the green at Praa Sands.

Specifications (Sunderland III)

General characteristics
Crew: 9–11 (two pilots, radio operator, navigator, engineer, bomb-aimer, three
to five gunners)
Length: 85 ft 4 in (26.0 m)
Wingspan: 112 ft 9½ in (34.39 m)
Height: 32 ft 10½ in (10 m)
Wing area: 1,487 ft2 (138 m2)
Empty weight: 34,500 lb (15,663 kg)
Loaded weight: 58,000 lb (26,332 kg)
Powerplant: 4 × Bristol Pegasus XVIII nine-cylinder radial engine, 1,065 hp (794
kW) each

Performance
Maximum speed: 210 mph (336 km/h) at 6,500 ft (2,000 m)
Cruise speed: 178 mph (285 km/h) at 5,000 ft (1,500 m)
Stall speed: 78 mph (125 km/h)
Range: 1,780 mi (2,848 km)
Service ceiling: 16,000 ft (4,880 m)
Rate of climb: 720 ft/min (3.67 m/s)
Wing loading: 39 lb/ft2 (191 kg/m2)
Power/mass: .073 hp/lb (.121 kW/kg)

Armament

Guns:
16× 0.303 inch (7.7 mm) Browning machine guns
2× Browning 0.5 inch (12.7 mm) machine guns

Bombs: up to 2,000 lb (910 kg) of bombs, mines and depth charges internally and
winched out underneath the wings through hatches in the fuselage sides.




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