Supermarine Attacker


The Supermarine Attacker is a British single-seat naval jet fighter designed and produced by aircraft manufacturer Supermarine for the Royal Navy's Fleet Air Arm. The type has the distinction of being the first jet fighter to enter operational service with the FAA.
Performing its maiden flight on 27 July 1946, the flight testing phase of development was protracted due to several issues, including handling difficulties. The first Attackers were introduced to FAA service during August 1951. Common to the majority of other first-generation jet fighters, the Attacker had a relatively short service life before being replaced; this was due to increasingly advanced aircraft harnessing the jet engine being rapidly developed during the 1950s and 1960s. Despite its retirement by the FAA during 1954, only three years following its introduction, the Attacker would be adopted by the newly-formed Pakistan Air Force, who would continue to operate the type possibly as late as 1964.

Development

Origins

The origins of the Attacker can be traced back to an wartime fighter jet project performed on behalf of the Royal Air Force. Many of the design's key features and performance requirements were stipulated under Specification E.10/44 issued by the Air Ministry during 1944, which had called for the development of a jet fighter furnished with a laminar flow wing and a single jet engine. In response, British aircraft manufacturer Supermarine decided to produce their own submission, which involved designing a brand new fuselage, complete with intakes to provide airflow to the Rolls-Royce Nene turbojet engine powering the type. This fuselage was mated with the pre-existing laminar flow straight wings which had been designed for the Supermarine Spiteful, a piston-engined fighter that had been intended to replace the Supermarine Spitfire. Prior to the design being officially named Attacker, the aircraft had been originally referred to as the "Jet Spiteful".
As originally intended, the Attacker programme was supposed to provide an interim jet fighter to equip the RAF while another aircraft, the Gloster E.1/44, that was also powered by the same Rolls-Royce Nene engine, completed development. On 30 August 1944, an order for three prototypes was placed with Supermarine; it was stipulated that the second and third prototypes were both to be navalised. On 7 July 1945, a follow-on order for a further 24 pre-production aircraft, six for the RAF and the remaining 18 for the Fleet Air Arm, was also placed.
Handling problems with the Spiteful prototype delayed progress on the jet-powered version, leading to the pre-production order of 24 being stopped, although work on the three prototypes continued. Due to the delay, the FAA instead procured a batch of 18 de Havilland Vampire Mk. 20s for the purpose of gaining experience with jet aircraft. After evaluating both the Jet Spiteful and the E.1/44, the RAF decided to reject both designs since neither aircraft offered any perceptible performance advantage over contemporary fighters such as the Gloster Meteor and the de Havilland Vampire, which were the RAF's first two operational jet aircraft.

Into flight

Following the design's rejection by the RAF, Supermarine decided to approach the Admiralty with an offer of developing a navalised version of the project. On 27 July 1946, the maiden flight of the type was performed by prototype Type 392 serial number TS409, a land-based version, by test pilot Jeffrey Quill. The Air Ministry issued Specification E.1/45 to cover production aircraft; meeting its various requirements necessitated a range of extensive modifications to be made to the design, including a revised fin and tailplane arrangement, as well as an increased internal fuel capacity. Accordingly, a large external ventral fuel tank was adopted, along with an extended dorsal fin and folding wing tips.
Flight testing was largely conducted at Supermarine's newly-created experimental establishment at the former RAF Chilbolton. The Attacker had several deficiencies, one of which was using the Spiteful tail-wheel undercarriage rather than a nose-wheel undercarriage, a configuration that resulted in the Attacker being considerably more difficult to land on an aircraft carrier. According to aviation author Bill Gunston, this tail-dragger undercarriage meant that, when operating from grass airfields, the jet exhaust would create a long furrow in the ground that "three men could lie down in". However, according to aviation periodical Flight, claims of scorched or ploughed surfaces, even grass, were exaggerated. The Attacker was neither the only nor the first jet aircraft to be equipped with such an undercarriage, which was also used on the experimental Heinkel He 178 and several early Messerschmitt Me 262 aircraft. The chief designer at Vickers-Supermarine, Mr. J. Smith, claimed that testing had validated the performance of the tail-dragger undercarriage as acceptable.
On 17 June 1947, the first navalised prototype, Type 398 TS413, conducted its first flight, flown by test pilot Mike Lithgow; occurring four years after the Meteor had performed its first flight. During November 1949, production orders on behalf of the FAA were received by Supermarine. On 5 May 1950, the first production variant of the aircraft, designated Attacker F.1, performed its first flight; one year later, deliveries of the type commenced.

Design

The Supermarine Attacker was a navalised jet-propelled fighter aircraft, the first jet-powered aircraft to be introduced into FAA service. While originally designed to a wartime requirement for the RAF, it was not introduced until the early 1950s, and was ultimately developed for use aboard aircraft carriers. For a jet aircraft, the Attacker's design was unusual, with a tail-dragger undercarriage with twin tailwheels, as well as an unswept wing. The flight controls were relatively conventional, based on those of the Spiteful. The forward position of the cockpit was well-received, and provided an exceptionally good view for the pilot.
The Attacker had a relatively strong structure, making extensive use of heavy-gauge materials, principally aluminium alloy, which were used with stressed-skin construction and supported by 24 closely spaced stringers and formers. The nose had an unusual lobster-claw structure, comprising thick laminated aluminium-alloy sheet at the top and bottom, with no stiffening members; it gave armour protection to the pilot and carried pressurisation loads. The tip of the nose was detachable to accommodate a gun camera or ballast; between this and the cockpit was an avionics bay. Aft of the cockpit was the semi-monocoque fuel tank, followed by the engine bay.
In terms of its aerodynamics, the Attacker was well streamlined, described by Flight as being "perhaps more perfect than any other fighter". The fuselage was continuously curved with no straight lines. It was shaped to have some of the wing's laminar flow characteristics and its lines were interrupted only by the faired cockpit canopy and the engine air intakes on either side of the cockpit. The intakes diverted the front fuselage boundary layer to prevent it entering the engine; tests with the diverters faired-over gave reduced engine performance including thrust.
The design of the wing was largely unchanged from the Spiteful, save for being slightly enlarged to match the bigger Attacker. It used split flaps along the trailing edge, as well as slotted ailerons and electrically-operated trim tabs. With a single main spar and one auxiliary spar, the wing was bolted directly onto stub spar booms as there was no centre-section. The exterior skins were flush-riveted and manufactured with considerable care in an attempt to achieve the laminar flow predicted from wind tunnel tests. Flight attributed the laminar-flow wing to enabling the Attacker to exceed the maximum speed of the Spiteful by more than 100 mph. However, other reports claim that the Attacker's wing was aerodynamically inferior to the original elliptical wing of the Spitfire, possessing unfavourable characteristics such as a lower critical Mach number.
The Attacker was powered by a single Rolls-Royce Nene Mk. 101 turbojet engine; at the time, the Nene was the most powerful jet engine in the world, with a thrust of 5,000 lb. The engine was supported by a heavy box-section rear spar frame, which was braced fore and aft to the main spar. As the jet-pipe was relatively long, a manually-operated variable exhaust outlet was used during engine starting to prevent jet-pipe resonances and excessive turbine temperatures. The exterior skin surrounding the intake had several louvres to regulate pressures during starting; they automatically closed to seal the engine bay after starting. The engine bay incorporated a pilot-operated fire extinguisher system. Although an automatic fuel transfer system was not originally incorporated, experience with the initial prototypes led to its incorporation.
In terms of armament, the Attacker F.1 had four 20 mm Hispano Mk. V cannon; at the time, this was viewed as the standard armament for a frontline RAF fighter. These cannon were fired using electronically-operated Maxifiux-Star units. The inboard cannon had a maximum capacity of 167 rounds of ammunition each, while the outboard cannon had up to 145 rounds each. External stores included two 1,000 lb bombs or four 300 lb rockets.

Operational history

Britain

During August 1951, the Attacker entered operational service with the FAA; the first squadron to receive production aircraft was 800 Naval Air Squadron, based at RNAS Ford. Following the introduction of the Attacker F.1, two further variants of the aircraft were developed and produced for the FAA. The Attacker FB.1 was a fighter-bomber which differed little from the original F.1 model, except that it was expected to operate as a ground attack aircraft. The third, and last, variant was the Attacker FB.2, which was powered by a more capable model of the Nene engine that was accompanied by various modifications to its structure. On this model, the Supermarine Attacker was furnished with a total of eight underwing hard points, which could carry a pair of 1,000 lb bombs or a maximum of eight unguided rockets.
Across the three variants to be adopted by the FAA, a total of 146 production Attackers would be delivered to the service. It had a relatively brief career with the FAA, none of its variants seeing any action during the type's service life with the FAA and being taken out of first-line service during 1954. The type had been replaced in front line squadrons by multiple more capable jet-propelled fighters, including the Hawker Sea Hawk and de Havilland Sea Venom. For several further years, the Attacker remained in service with squadrons of the Royal Naval Volunteer Reserve, the type being finally taken out of reserve service during early 1957.

Pakistan

During the early 1950s, the newly-formed Royal Pakistan Air Force sought to acquire jet fighters. A combination of a lack of funds and political pressure that was exerted by British suppliers persuaded the service to acquire a variant of the Attacker, known as the Type 538, which was essentially a "de-navalised" variant of the aircraft used by the FAA.
Only a single squadron was ever equipped with these aircraft, an interceptor unit, No. 11 "Arrows" Squadron; it received its first Attackers during 1953. A total of 36 Attackers had been acquired when "Arrows" Squadron officially converted to the American-built North American F-86F Sabre on 18 January 1956. However, some sources state that Attackers were used by PAF until as late as 1964.
It has been claimed that the Attacker was regarded as being unsatisfactory by the RPAF, attributing this negative attitude to the type's frequent maintenance problems and a relatively high attrition rate.

Variants

;Type 392
;Type 398
;Type 510
;Type 513
;Type 398 Attacker F.1
;Attacker FB.1
;Attacker FB.2
;Attacker Mk.538

Operators

Following its retirement from service in 1956, Attacker F.1 Serial number WA473 was placed on display on the gate at RNAS Abbotsinch. Completed at VAs South Marston factory in July 1951, it had served with 702 and 736 Naval Squadrons. In late 1961 it was moved to the Fleet Air Arm Museum in Somerset, UK.

Specifications (F.1)