The Supermarine Seafire Mk.III was the first version of the aircraft to be produced with folding wings, and was produced in larger numbers than any other version of the Seafire.
The first folding wing for a Seafire had been designed in 1939-40, but nothing came of it until late in 1942, by which time the first Seafire Ibs and IIcs had already entered service. In October 1942 the first production Seafire IIc was taken to Worthy Down, where it was given a double folding wing. The wing founded upwards at a point just inside the inner cannon bay. The wing tips then folded downwards to allow the aircraft to fit inside carrier hangers. The wing was manually operated and needed five men and one minute to fold.
Eventually 1,218 Seafire IIIs were produced in all three versions (some sources say 1,220), along with the 32 Mk.IIc (Hybrids).
The Seafire Mk.III entered service with No.894 Squadron, and went on to equip Nos.801, 887, 889 and 890 Squadrons. It made its combat debut during the Salerno landings, and remained in service to the end of the war, fighting in the Pacific at the end of the war. After the war it was quickly replaced by Griffon powered Seafires. The last squadrons to use the Seafire III were Nos.887 and 894, which retained it until March 1946.
The Seafire Mk.III was also used by the French Naval Air Service, and was used in combat from the carrier Arromanches over Indochina in 1948-49.
Twelve Seafire Mk.IIIs were ordered by the Irish government in August 1946. Stripped of their naval equipment these were essentially Spitfive Vcs, and were delivered during 1947. They served on land from 1947 to 1955.
The Mk.III was produced by Westland and Cunliffe-Owen. Problems with the wing jigs meant that the first thirty Westland and two Cunliffe-Owen aircraft were built with fixed wings, and were later redesignated as the Mk.IIc (Hybrid). Early production aircraft used the Mk II 20mm cannon, but the short barrelled Mk V was soon adopted to save weight. The Mk.III could also carry one 500lb bomb under the centre line, while each wing could carry two 25lb, two 60lb or one 250lb bomb. It was powered by the standard Merlin 55 engine.
A low altitude version of the Mk.III was produced, powered by the Merlin 55M engine. This had multi-ejector exhaust stacks and a cropped supercharger impeller and could produce 1,585hp at 2,750ft. The LF.Mk.IIIc was produced by Cunliffe-Owen and Westland.
The FR.Mk.III was similar to the FR.Mk.IIc, and carried one vertical and one oblique F.24 camera. One hundred and twenty-nine were produced by Cunliffe-Owen and a small number by Westland.
Supermarine Type 358
Engine: Single-speed single-stage supercharged Merlin 55
Wing span: 36ft 10in
Length: 29ft 11in
Height: 11ft 5.5in (tail up)
Max Speed: 348mph at 6,000ft
Service Ceiling: 32,000ft
Range: 493 miles
Armament: Two 20mm Hispano cannon and four 0.303in Browning machine guns
Bomb-load: One 500lb on centreline and four 25lb or 60lb 3in rockets or two 250lb bombs under the wings
LF Mk III as above apart from
Wing span: 36ft 10in or 30ft 6in clipped
Engine: single-speed single-stage supercharged Merlin 55M
Empty weight: 5,449lb
Loaded weight: 7,221lb
FR Mk III or PR Mk III
Engine: Single-speed single-stage supercharged Merlin 32 or 55m
Power: 1,645hp or 1,585hp
Empty weight: 5,310lb
Loaded weight: 7,043lb
Camera: One F.24 (8 or 14in focal length) oblique and one F.24 (5, 8, 14 or 20in focal length) vertical
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