Carrier-based fighter aircraft
The Supermarine Seafire is a naval version of the Supermarine Spitfire fighter adapted for operation from aircraft carriers. It was analogous in concept to the Hawker Sea Hurricane, a navalised version of the Spitfire's stablemate, the Hawker Hurricane. The name Seafire was derived from the contraction of the full name of Sea Spitfire.
A carrier-capable version of the Supermarine Spitfire had been proposed by the Admiralty in May 1938. Despite a pressing need to replace various obsolete types in the Fleet Air Arm (FAA), some opposed the idea, including as Winston Churchill, although these disputes were often a result of the overriding priority for land-based Spitfires instead. During 1941 and early 1942, the Admiralty again requested naval Spitfires, resulting in an initial batch of Seafire Mk.Ib fighters in late 1941, which were mainly used to gain experience operating the type. There were concerns over weak undercarriages, which had not been strengthened to naval standards, but performance was acceptable.
From 1942 on, further Seafire models were ordered, including the first operationally-viable Seafire F Mk.III variant. This led to widespread use with the FAA. In November 1942, the first Seafire combat occurred during Operation Torch, the Allied landings in North Africa. In July 1943, the Seafire provided air cover for the Allied invasion of Sicily, and again in September 1943 during the Allied invasion of Italy. During 1944, large numbers provided air support to ground forces during the Normandy landings and Operation Dragoon in southern France. During the latter half of 1944, Seafire joined the British Pacific Fleet, where it intercepted "kamikaze" attacks which had become common during the final years of the Pacific War.
The Seafire continued to be used after the end of the war, but the FAA withdraw all its Merlin-powered Seafires and replaced them with Griffon-powered counterparts. The type saw further combat use during the Korean War, in which FAA Seafires performed hundreds of missions in the ground attack and combat air patrol roles against North Korean forces in 1950. The Seafire was withdrawn from service during the 1950s. In FAA service, the type had been replaced by the Hawker Sea Fury, the last piston engine fighter to be used by the service, along with the first generation of jet-propelled naval fighters, such as the de Havilland Sea Vampire, Supermarine Attacker, and Hawker Sea Hawk.
Development.
Origins.
The Admiralty first showed an interest in the idea of a carrier-borne Spitfire in May 1938 when, during a meeting with Richard Fairey (of Fairey Aviation), Fairey proposed that his company could design and build such an aircraft. The idea met with a negative response and the matter was dropped. As a result, the Fleet Air Arm (FAA), at that point still part of the Royal Air Force, was forced into having to order Blackburn Rocs and Gloster Sea Gladiators, both of which proved to be woefully inadequate in the circumstances in which they were subsequently used. Upon the outbreak of the Second World War, many of the aircraft operated by the FAA had been designed on the assumption that, Germany possessing no aircraft carriers, overall performance was to be of a secondary nature compared to the other duties required, such as observation and spotting, but, by 1941, these aircraft had become obsolete in comparison to the German and Italian land-based fighters they were occasionally required to operate against; thus, the need for more capable aircraft was readily apparent. As the Hawker Hurricane had quickly proven to be adaptable to carrier-based operations, there was considerable interest in navalising the Spitfire as well.
The matter of a seaborne Spitfire was raised again in November 1939 when the Air Ministry allowed a Commander Ermen to fly a Spitfire I. After his first flight in "R6718", Ermen soon learned that Joseph Smith, Chief Designer at Supermarine, had been instructed to fit an "A-frame" arrestor hook on a Spitfire and that this had flown on 16 October; a drawing of this aircraft had been shown to the FAA on 27 October. After further discussions, Supermarine submitted a drawing of a Spitfire with folding wings and an arrestor hook. In this case, the wings had been designed with a fold just outboard of the undercarriage bays; as such, the outer wings would have swivelled and folded backwards to face parallel with the fuselage. On 29 February 1940, the Admiralty requested that the Air Ministry formally sanction the production of 50 folding-wing Spitfires, the first of which was to be delivered in July that year. For various reasons, Winston Churchill, who was First Lord of the Admiralty, cancelled the order, writing to Lord Beaverbrook: "I regard it as of very great importance that the production of Fulmars should be kept going".
At a time of considerable demand for land-based Spitfires, due to the Fall of France and the subsequent Battle of Britain, the diversion of resources to facilitate the development and manufacture of a naval variant would have naturally reduced Spitfire production. To partially cover the gap until the Fulmar's replacement (Specification N.5/40 – which would be the Fairey Firefly) was able to enter service, it was decided to instead order a number of Grumman Wildcats from America to equip the FAA. These aircraft would enter service towards the end of 1940 as the "Martlet".
During late 1941 and early 1942, the Admiralty again assessed the Spitfire for possible conversion. In late 1941, a total of 48 Spitfire Mk.Vb were converted by Air Training Service Ltd. at Hamble to become "hooked Spitfires". This was the Seafire Mk.Ib and would be the first of several Seafire variants to reach the Fleet Air Arm. This version of the Seafire was mainly used to allow the Royal Navy to gain experience in operating the Spitfire on aircraft carriers. The main structural change was made to the lower rear fuselage which incorporated an A-frame style arrestor hook and strengthened lower longerons. It was soon discovered that the fuselage, especially around hatches, was too weak for carrier operations. In an attempt to alleviate this condition, reinforcing strips were riveted around hatch openings and along the main fuselage longerons.
A further 118 Seafire Mk.Ibs incorporating the fuselage reinforcements were modified from Spitfire Vbs by Cunliffe-Owen at Eastleigh and Air Training Service. These aircraft were equipped with Naval HF radio equipment and IFF equipment as well as a Type 72 homing beacon. In these and all subsequent Seafires the instruments were re-calibrated to read kn and nmi rather than mph and mi. The fixed armament was the same as that of the Spitfire Vb; two Hispano Mk.II cannon with 60 rpg fed from a "drum" magazine and four Browning machine guns with 350 rpg. Provision was also made to carry a "slipper" fuel tank under the fuselage. In June 1942, the first deliveries of the Seafire took place to 807 Squadron. Another front line unit, 801 Squadron operated this version on board from October 1942 through to September 1944.
Further development.
The second semi-naval variant of the Seafire and the first to be built as such, was the Seafire F Mk.IIc which was based on the Spitfire Vc. The Vc had several refinements over the Spitfire Vb. Apart from the modifications included in the main batch of Seafire Ibs this version incorporated catapult spools, and a single slinging lug on either side of the fuselage, just behind the engine bulkhead. Three subtypes were produced, the F Mk.IIc and FR Mk.IIc (fighter reconnaissance), powered by a Merlin 46, and the L Mk.IIc powered by a low altitude Merlin 32 specifically manufactured for naval use. This version of the Merlin used a "cropped" supercharger impellor to provide greater power at low altitudes than the standard engines; delivering at . Both engines drove a four bladed diameter Rotol propeller. Because this version used the "C" wing the Hispano cannon were fed from a 120-round belt magazine, otherwise the armament was the same as that of the Ib; the FR also carried two F24 cameras. After trials of "Rocket Assisted Take Off Gear" (RATOG - small solid-fuel rocket motors which could be attached to the fuselage or wings of aircraft to help shorten the take-off run) in February 1943, this equipment became a standard fitting available for all Seafires. However, many FAA pilots rarely used RATOG, in part as there was little need for it, and due to the risks posed by asymmetric ignition.
The IIc model was the first of the Seafires to be deployed operationally in large numbers, Supermarine constructed 262 of this model and a further 110 being built by Westland, who also built 30 Seafire Mk.III (Hybrid) (Mk.IIIs without folding wings). Although developed for aircraft carrier use, this version still lacked the folding wings needed to allow them to be used on board some Royal Navy carriers, some of which had small aircraft elevators unable to accommodate the full wingspan of the Seafires.
The Seafire F Mk.III was the first true carrier adaptation of the Spitfire design. It was developed from the Seafire Mk.IIc, but incorporated manually folding wings allowing more of these aircraft to be spotted on deck or in the hangars below. Supermarine devised a system of two straight chordwise folds; a break was introduced immediately outboard of the wheel-wells from which the wing hinged upwards and slightly angled towards the fuselage. A second hinge at each wingtip join allowed the tips to fold down (when the wings were folded the wingtips were folded outwards). This version used the more powerful Merlin 55 (F Mk.III and FR Mk.III) or Merlin 55M (L Mk.III), driving the same four-bladed propeller unit used by the IIc series; the Merlin 55M was another version of the Merlin for maximum performance at low altitude. Other modifications that were made on the Spitfire made their way to the Seafire as well including a slim "Aero-Vee" air filter and six-stack "ejector type" exhausts. The shorter barrelled, lightweight Hispano Mk.V cannon were introduced during production as were overload fuel tank fittings in the wings This Mark was built in larger numbers than any other Seafire variant; of the 1,220 manufactured Westland built 870 and Cunliffe Owen 350. In 1947 12 Mk.IIIs were stripped of their naval equipment by Supermarine and delivered to the Irish Air Corps.
After the Mk.III series, the next Seafire variant to appear was the Seafire F Mk.XV, which was powered by a Griffon VI – single-stage supercharger, rated at at driving a Rotol propeller. Designed in response to Specification N.4/43 this appeared to be a naval Spitfire F Mk.XII; in reality the Mk.XV was an amalgamation of a strengthened Seafire III airframe and wings with the wing fuel tanks, retractable tailwheel, larger elevators and broad-chord "pointed" rudder of the Spitfire VIII. The engine cowling was different from that of the Spitfire XII series, being secured with a larger number of fasteners and lacking the acorn shaped blister behind the spinner. The final 30 Mk.XVs were built with the blown "teardrop" cockpit canopy and cut down rear fuselage introduced on the Spitfire Mk.XVI. On the first 50 aircraft manufactured by Cunliffe-Owen a heavier, strengthened A-frame arrestor hook was fitted to cope with the greater weight. On subsequent Mk.XVs a new form of "sting" type arrestor hook was used; this version was attached to the reinforced rudder post at the rear of the fuselage and was housed in a fairing below the base of the shortened rudder. A vee-shaped guard forward of the tailwheel prevented arrestor wires getting tangled up with the tailwheel. 390 Seafire XVs were built by Cunliffe-Owen and Westland from late 1944. Six prototypes had been built by Supermarine.
One problem which immediately surfaced was the poor deck behaviour of this mark, especially on take-off. At full power the slipstream of the propeller, which swung to the left (as opposed to the Merlin, which swung to the right), often forced the Seafire to swing to starboard, even with the rudder hard over on opposite lock. This sometimes led to a collision with the carrier's island. The undercarriage oleo legs were still the same of those of the much lighter Merlin engined Spitfires, meaning that the swing was often accompanied by a series of hops. As an interim measure it was recommended that pilots avoid using full power on take-off (+ "boost" maximum was recommended). There were also problems involved with this swing being strongly accentuated in the