By the outbreak of the Korean War in 1950, most of the jet aircraft described in Chapter 4 had entered service or were undergoing development, and the design of their potential successors was already well underway. This new generation would have the benefit of more powerful engines and would be able to take advantage of some major aerodynamic advances.

In the case of the Royal Navy, an incremental approach was adopted, which led to a series of interesting prototypes but no production orders. This was partly due to financial constraints but also because policy was geared to the idea that any major conflict would not break out until 1957 and so aircraft development was concentrated on the most advanced types that could be available by that date. The incremental approach is clearly illustrated by a series of prototypes developed from the Royal Navy’s first jet fighters, the Attacker and the Seahawk, although in the event neither resulted in an operational carrier borne fighter. Design work on the new aircraft began as a result of specifications issued by the Air Staff in 1946. Of these, E.41/46 called for a swept wing development of the Attacker and this resulted in the Supermarine Type 510, which flew on 29 December 1948. A major change was that all the flying surfaces (wings, tailplane, fin) were swept back at forty degrees but in most other respects the basic Attacker configuration was retained, including the tailwheel undercarriage. The same Rolls-Royce Nene jet engine was also installed but, even so, a considerable increase in performance was soon demonstrated, including a top speed in excess of 630 mph at medium altitudes and a limiting Mach number of 0.93. In general the handling characteristics received favourable comment except for longitudinal instability near the stall, which affected manoeuvrability at high altitudes where aircraft were operating much closer to their stalling IAS due to the much thinner air.

The Royal Navy closely monitored progress with the Type 510 and the prototype was modified for naval trials leading to the first deck landing by a swept wing aircraft on 8 November 1950, aboard HMS Illustrious. For these trials the aircraft was fitted with Rocket Assisted Take Off Gear (RATOG) and a total of fifteen landings and rocket assisted take-offs were successfully completed. On the last take-off some of the rockets failed to ignite and the aircraft yawed dangerously, causing one wingtip to strike the top of a gun turret before the pilot was able to recover and fly the aircraft ashore. Subsequently the aircraft returned to the RAE at Farnborough for further high-speed flight tests and the naval equipment was removed. Despite the take-off incident, the deck landing trials had gone well but the Admiralty took no further interest in this particular line of development. Fitted with an all-flying tailplane and a tricycle undercarriage, the second prototype became the Supermarine Type 525, which formed the basis for the Swift that entered service with the RAF in 1954, although persisting problems with high-altitude manoeuvrability limited its usefulness.

In an almost parallel scenario, Hawker also evolved and flew a swept wing development of the P.1040 Seahawk. The origins of the swept wing project actually went back to October 1945 when Hawker proposed such a project, although powered by a rocket engine, perhaps inspired by the German Messerschmitt Me.163 interceptor. Although this was not followed through in its original form it did lead to the issue of Specification E.38/46, which resulted in an order for two prototype Hawker P.1052s. This was very similar to the basic Seahawk design with the single exception that wings swept thirty-five degrees at quarter chord was fitted, although the original tail surfaces with a straight tailplane were retained. The first flight was on 19 November 1948 by which time serious consideration had been given to placing a production order as the promised performance was expected to be well in advance of that of the Seahawk or the RAF’s Meteor. Had that been done, swept wing Seahawks could have entered service during the Korean War period but no order was forthcoming as it was decided to wait for other more advanced aircraft to become available. Although the Royal Navy was eager to assess the P.1052 aboard a carrier, such trials were delayed due to accidents in the flight test programme. It was therefore not until May 1952 that the first prototype (VX272), modified for naval use and painted in Royal Navy colours, made its first landing aboard the new carrier HMS Eagle. The following month it was fitted with a new swept tailplane and carried out high-speed testing with the RAE before being grounded after a forced landing in the September. Subsequently the second prototype (VX279) was rebuilt with a straight-through jet exhaust (instead of the bifurcated exhaust) and a swept fin and tailplane. This was designated P.1081 and flew in June 1950 but was lost in an accident the following year. By this time Hawker had moved ahead with the Avon-powered Type 1067, which became the Hunter and was ordered in quantity by the RAF although at the time no naval development was ever considered. As a footnote, Hunter single-seat fighters did eventually serve with the Royal Navy in the 1960s in the shore-based operational training role.

Although both the Supermarine Type 510 and the Hawker P.1052 provided valuable data on the operation of swept wing aircraft aboard carriers, as well as offering a significant increase in performance, the Admiralty did not consider placing production orders as there were more advanced aircraft already under development. One of these was from the Supermarine stable but was to have an extremely convoluted career before eventually entering frontline service as the Scimitar in 1958. Interestingly the genesis of this aircraft went back to the flexible deck concept described in Chapter 4 and in response to Admiralty requirements a twin-engined straight winged design was evolved as early as 1945. This was the Type 505 in which two Rolls-Royce AJ65 turbojets (an early version of the Avon series) were mounted side by side in the central fuselage and an unusual Vee tail arrangement was adopted to keep the tail surfaces clear of the jet exhaust. Although a conventional straight wing was used, it was very thin and had a thickness chord ratio of only 7 per cent. This was one of the benefits of dispensing with the undercarriage, which would have required a thicker wing to accommodate it.

By 1947, despite the fact that the flexible deck trials had not yet started, the Admiralty decided that the Supermarine design should be modified to include a tricycle undercarriage. This involved a new wing with thickness/chord increased to 9 per cent and also an increased wing span to cope with revised low-speed handling requirements. In this form the aircraft flew on 31 August 1951 and subsequently carried out deck landing trials aboard HMS Eagle in May 1952. However, by that time Supermarine had gained experience of swept wing aircraft with the Type 510 modified Attacker and decided to proceed with a swept wing version of the Type 508, which then became the Type 525. The adoption of a swept wing necessitated many changes, including a taller undercarriage with a wider track due to the geometry of the swept wings. Extensive conventional high lift devices such as double-slotted flaps and leading edge slats were incorporated but subsequently the idea of ‘blown flap’ was developed. In this system air was bled off from the engine compressor stages and was fed out of a narrow slot in the wings just ahead of the trailing edge flaps. This stream of energised air prevented a breakdown in the airflow over the flap (retaining the laminar flow effect beyond the point where it would normally break away and cause loss of lift) and the result was a substantial reduction in stalling speed and angle of attack while on final approach to land. The speed reduction was in the order of 15 knots and this was a highly desirable benefit for carrier landings.

The Admiralty was sufficiently interested in the Type 525 to issue a draft Specification N.113D around the proposals and ordered two (later increased to three) prototypes in 1951. The first of these (VX138 - originally ordered as the third Type 508) flew in April 1954. While the performance was generally up to expectations, there were numerous problems associated with the handling of the aircraft at high speed and these resulted in a number of modifications that were incorporated in the production examples, which became the Type 544 Scimitar. The most obvious external feature was a change from 10 degrees dihedral to 10 degrees anhedral on the swept tailplane. Other aerodynamic improvements included a saw tooth leading edge and re-profiled wingtips. Less obvious was the inclusion of powered flying control surfaces with fully duplicated systems.

The N.113D Scimitar was originally intended as a swept wing successor to the Seahawk but while under development its role was changed from being a pure single-seat fighter to include the ability to undertake low-level strike missions, armed with nuclear bombs if necessary. Consequently the airframe needed to be extremely strong to cope with the stresses associated with operating at high speed in turbulent air at low level and several innovative manufacturing techniques were introduced. The profile of the fuselage was altered to comply with the new concept of area rule and the lateral air intakes were enlarged to cope with the demands of the latest Rolls-Royce Avons, which would be initially rated at 10,000 lb thrust. The first true Type 544 Scimitar, fully representative of the operational aircraft, flew on 19 January 1956. Subsequently, production examples reached the Royal Navy early in 1958 and the first operational squadron, 803 NAS, embarked in HMS Victorious in the following September. At the time of its introduction into service the Scimitar was the fastest, heaviest and most powerful aircraft ever to enter service with the Royal Navy. Armed with four 30 mm cannon as a fighter, it could also carry up four 1,000 lb bombs and subsequently was also armed with Bullpup air-to-surface or Sidewinder air-to-air missiles. On paper it was a very potent interceptor with an initial rate of climb in excess of 12,000 feet/min but its handling at high altitudes was unsatisfactory (a feature it shared with its stablemate the Swift) and its true forte turned out to be as a low-level strike aircraft with a nuclear capability. Despite the high thrust available and the area ruled fuselage, the Scimitar remained stubbornly subsonic except in a dive, leading one American pilot to comment, ‘Jeez, only you Brits could build an aircraft with so much power which won’t go supersonic!’ The Scimitar’s operational career falls outside the time scale of the book but it does earn a place as the Royal Navy’s first swept wing fighter.

The Scimitar was always intended as the replacement for the Seahawk and the latter was usually paired aboard carriers with the de Havilland Sea Venom all-weather fighter. It was natural therefore that the de Havilland company would be interested in providing a successor for the Sea Venom, although the initial project proposed in 1946 was also put forward to meet an RAF requirement for an advanced night fighter and it was the Air Ministry that ordered two prototypes in 1948. The resulting de Havilland DH.110 followed the twin boom layout of the Vampire and Venom series but introduced a sharply swept wing based on that used in the DH.108, the first British aircraft to exceed the speed of sound. However, the DH.110 was much larger than its predecessors and was powered by two Rolls-Royce Avon turbojets in the rear of the fuselage nacelle. Unusually, the pilot’s cockpit was offset to port to allow space, popularly known as the ‘coal hole’, for the radar operator and his equipment in the lower starboard side. Powered controls were fitted and the tailplane rode high up between the swept fins so as to be well clear of the jet efflux. An armament of four 30 mm cannon was proposed. The DH.110 prototype (WG240) flew in September 1951 and in April the following year demonstrated a transonic capability by exceeding the speed of sound in a shallow dive. A second prototype flew in July 1952 but was destroyed in a horrific accident when it broke up in the air while participating in the Farnborough Air Display. Pieces of wreckage, including the engines, scythed through the crowd, killing several spectators as well as the pilot, John Derry, and his observer.

This accident was a severe setback to the programme and the remaining aircraft was grounded for extensive modifications, including an all-flying tailplane and wing leading edge extensions outboard of the wing fences. By the time it was flying again in June 1954 the RAF had decided against placing any orders, preferring the delta-winged Gloster Javelin instead. However, the Royal Navy was now waking up to the performance potential of the DH.110 and the design was substantially modified to meet naval requirements, the name Sea Vixen being subsequently adopted. Up to this time the Royal Navy had been actively pursuing a project to produce a modified Sea Venom that would have had a new thin section swept wing and this had got to the stage where two prototypes had been ordered, although these were now cancelled in favour of the twin-engined DH.110. Changes to the new aircraft included the provision of an arrester hook, power folding wings, hydraulic nosewheel steering and a long stroke undercarriage for carrier landings. A major change was in the armament, the 30 mm guns being removed in favour of an all-missile armament. The space previously occupied by the guns was used to install retractable housings for a total of twenty-four 2 inch unguided air-to-air rockets, while up to four de Havilland Firestreak air-to-air missiles with an infra-red homing system would be carried on underwing pylons. For the strike role, the missiles could be replaced with four 500 lb or two 1,000 lb bombs, or a variety of air-to-air or air-to-surface rockets. All in all, the Sea Vixen was to be one of the most capable aircraft ever to serve with the Fleet Air Arm.

The first pre-production naval aircraft flew on 20 June 1955, by which time orders had already been placed for forty-five Sea Vixen FAW.1s and ultimately 114 were built. Later developments included the FAW.2 with the booms extended forward over the wings to give additional fuel tankage and fifteen of these were built while a further sixty-seven were produced by converting some of the earlier aircraft. In time scale the Sea Vixen was almost two years behind the Scimitar with the first operational squadron forming in July 1959 and embarking in HMS Ark Royal in March 1960. Thus by the end of the 1950s the Royal Navy was at last introducing swept wing transonic fighters into frontline service and had two powerful and capable aircraft to form the backbone of the carrier air groups. Both gave excellent service in the following decade. However, during the 1950s the US Navy had introduced no fewer than five advanced swept wing fighters and by 1960 the first of the supersonic Mach 2 world record beating McDonnell F4H Phantoms were being delivered. Indeed, they had even experimented with vertical take-off fighters and a transonic seaplane jet fighter. Bearing in mind the original British lead in jet propulsion immediately after World War II, it is instructive to see how the Americans began to forge ahead so quickly.

In fact, the US Navy was inexplicably slow off the mark to apply the principle of swept wing aerodynamics and its arch rival, the USAF, initially made all the running. This is even more surprising when it is realised that the fighter that effectively gave them command of the skies in the Korean War was actually developed from a naval jet fighter. This was the famous North American F-86 Sabre, which had its origins in the FJ-1 Fury that had been ordered by the Navy in 1944 (see Chapter 4). This was a straight-winged single-engined fighter characterised by its then unique nose intake and straight-through jet configuration. The USAAF ordered a land-based version under the designation XP-86 but a courageous decision was taken to delay delivery and production for a year so that the design could be recast to incorporate a 35-degree swept wing and powered flying controls. Even so, the first XP-86 flew as early as 1 October 1947 and a few months later became the first US fighter to exceed the speed of sound in a shallow dive. The initial production version became the F-86A Sabre and by the end of 1949 two USAF fighter groups were equipped with the new fighter, which proved to have excellent handling characteristics. Subsequently several thousand were built in the United States with licence production being undertaken in Canada, Italy, Australia and Japan. The Sabre can be regarded as one of the most famous aircraft ever built.

Despite its naval origins, the US Navy did not take a serious interest in the Sabre until after the outbreak of the Korean War and eventually ordered three prototypes of a naval version in March 1951. These were designated FJ-2 Fury and eventually some 200 were produced. In most respects they were standard F-86E Sabres powered by 6,000 lb thrust General Electric J47-GE-2 turbojets, which gave a maximum speed of 676 mph at sea level, an initial rate of climb of 7,250 feet/min and a combat ceiling of 41,700 feet. The only modifications for naval service were the obvious ones of an arrester hook, catapult attachment point and power folding wings, as well as a lengthened nosewheel oleo to increase the angle of attack for catapult launches. In addition the armament was changed from six 0.5 inch machine-guns to the standard US Navy fit of four 20 mm cannon. Despite these limited changes, FJ-2 Furies did not begin to reach operational units until January 1954 due to the priority accorded to Sabres for the Air Force and most were allocated to USMC squadrons. Later that year US Navy squadrons began to receive a more advanced version of the Fury under the designation FJ-3. Development of this had started in March 1952 and the main change was the installation of a much more powerful Wright J65-W-2 engine rated at 7,800 lb thrust. This necessitated an enlarged nose intake and a slightly deeper fuselage profile and production aircraft were powered by the slightly derated J65-W-4 engine. In passing it should be noted that the J65 was in fact a licence-built version of the British Armstrong Siddeley Sapphire turbojet and this was used by several other US Navy jets.

Some 538 FJ-3s were built between 1953 and August 1956 and the aircraft equipped no fewer than seventeen US Navy and four Marine squadrons. The first unit was VF-173, which received its Furies in September 1954 and was deployed aboard the USS Bennington in May 1954. An aircraft from another US Navy fighter squadron (VF-21) was the first jet to land aboard the new carrier USS Forrestal, this event occurring on 4 January 1956. In that year also missile-equipped FJ-3Ms began reaching the fleet, these being fitted to carry up to four Sidewinder air-to-air missiles. The final Fury variant was the FJ-4, which first flew in October 1954 and represented a complete redesign with the objective of increasing range and endurance. The requirement to carry 50 per cent more fuel resulted in a new fuselage outline while thinner wings and tail surfaces were also fitted. To improve handling aboard carriers, a wider track undercarriage was fitted. A total of 152 FJ-4s were produced but these were used almost exclusively by Marine squadrons, replacing the earlier FJ-2. Deliveries began in February 1955. These were intended for use in the close support role and the four underwing pylons could carry either bombs or missiles. The ultimate attack version was the FJ-4B, which did not appear until the end of 1956 but this had six weapons stations and was fitted with a Low Altitude Bombing System (LABS), which enabled the Fury to use the toss bombing technique to deliver a tactical nuclear weapons. The FJ-4B was issued to nine US Navy and three Marine attack squadrons and when production ended in May 1958 a total of 1,112 swept wing Furies had been delivered, making it one of the most significant naval fighters of the period.

To some extent the development of a naval version of the F-86 Sabre was driven by the sudden appearance of the swept wing MiG-15 over Korea and the realisation that the US Navy’s current straight-winged jets were outclassed. The same motive also led directly to a swept wing development of the existing Grumman F9F-5 Panther. In fact, Grumman had investigated the possibility of swept wing variant when the original Panther design had been proposed but although some design work was done, the decision was made to concentrate on getting the Panther into service. There were also doubts about the suitability of swept wing aircraft for carrier operations due to the problem experienced at that time with low-speed handling. However, the appearance of the Russian-built MiG swept such concerns aside and Grumman was authorised to proceed with the construction of three swept wing Panthers in December 1950. The project was given the highest priority with the result that the prototype F9F-6 Cougar flew in September 1951 and VF-32 received the first production examples in November 1952, although by the time the aircraft was ready for operational deployment the Korean War had ended.

Compared with the Panther, the most obvious change was fitting a new wing with 35 degrees of sweepback at quarter chord, as well as a similarly swept tailplane, although the vertical tail surfaces were substantially unchanged. Inevitably the stalling and approach speeds increased but to assist low-speed handling the chord of the leading edge slats and trailing edge flaps was increased, larger flaps were fitted below the centre section, and rudder controls were boosted by the addition of a yaw damper. The forward fuselage was lengthened by 2 feet and the wing centre section, which included the air intakes, was also extended forward. The lengthened fuselage allowed internal fuel capacity to be increased to allow for the fact that wingtip tanks (as on the Panther) could not be fitted. Flight testing resulted in changes, including the adoption of an all-flying tail and the introduction of spoilers to replace conventional ailerons and improve lateral control. Finally, it was found necessary to fit conspicuous wing fences to reduce a tendency for the airflow to spread spanwise and cause difficulties with lateral control. Taken together, these changes substantially improved handling to the extent that most pilots found the Cougar easier to handle in the carrier environment than its straight-winged predecessor. It should be noted that the problems that the Grumman team experienced echoed those that had affected the British Supermarine Type 510 and Hawker P.1052, and the solutions adopted were much the same.

The Cougar was powered by a 7,000 lb thrust Pratt & Whitney J48 turbojet, which had also been installed in the later Panther variants and was actually a development of the Rolls-Royce Nene of which the British equivalent was named the Tay. However, by the early 1950s new British jet fighters were being designed around axial flow engines such as the Avon and Sapphire and the only British application of the Rolls-Royce Tay was in an experimental jet-powered version of the Viscount airliner (Type 633), which flew in March 1950 but did not enter production. On the other hand the Cougar proved extremely adaptable and ultimately a total of 1,988 were built, the last being delivered as late as February 1960. Although too late to see service in the Korean War, the Cougar rapidly replaced Panthers and Banshees in some twenty US Navy squadrons, these all receiving the F9F-6 and -7 versions. In a parallel with Panther experience, the F9F-7 was powered by an American-designed Allison J33-A-16 turbojet rated at 6,350 lb thrust. However, most of these were eventually refitted with J48s and the last fifty produced were completed with the more powerful Pratt & Whitney engine.

Once the basic F9F-6 was established in production, Grumman had time to look at improving the design and this resulted in the F9F-8, which first flew on 18 January 1954. This incorporated several changes to the wing, including a thinner profile, increased wing area, and extended and cambered leading edges. Additional fuel tankage was incorporated in the extended leading edges and the fuselage tank was enlarged, increasing total capacity from 919 to 1,063 US gallons. The wing modifications resulted in a useful increase in critical Mach number and the additional fuel increased range by almost 300 miles. However, the extra weight reduced the rate of climb and service ceiling but this was offset to some extent by much improved handling and manoeuvrability. There were several sub variants of the F9F-8, including a photo reconnaissance version (F9F-8P), which flew in February 1955, and a two-seat trainer (F9F-8T), which flew in February 1956. Finally, some Cougars were modified for the tactical nuclear strike role with the fitting of LABS as in the FJ-4B Fury and these were designated F9F-9B. Although fighter versions of the Cougar were phased out of frontline service with the Atlantic and Pacific Fleets service by 1959 in favour of more advanced types, the F9F-8P was operational until 1960. The trainer version (later redesignated TF-9J) served with five training squadrons and the last of these, VT-4, did not relinquish its Cougars until 1974. In addition, many reserve units continued to fly Cougars throughout the 1960s.

Although too late to see combat, the swept wing Grumman Cougar and North American Fury provided the backbone of the US Navy’s carrier air groups in the years following the Korean War. As already related, both were developed from straight-wing, first-generation jets under the impetus of the challenge presented by the Russian-designed MiG-15. However, by the early 1950s the US Navy had other projects underway for even more advanced aircraft, although none of these would see full-scale service until the latter half of the decade. The benefits of swept wings had become apparent when allied engineers and scientists gained access to the results of German wartime experience and research, but there were other advanced aerodynamic features that the Germans had applied and a number of US designers attempted to make use of these. Foremost amongst these was the concept of the delta wing pioneered by Dr Alexander Lippisch and when the US Navy needed a fast-climbing interceptor, this configuration appeared to offer some significant advantages. During World War II, the principle of a standing Combat Air Patrol (CAP) was established with waiting interceptor fighters being directed by radar onto incoming targets. However, the new jet fighters had limited endurance so a standing airborne CAP was difficult to organise and costly in fuel consumption. Perhaps more significantly, the performance gap between fighters and jet bombers had narrowed considerably to the extent where the bomber would be difficult to catch in a pursuit scenario. From this problem evolved the concept of a Deck Launched Interceptor (DLI), which remained on short-notice standby on the carrier’s deck. Assuming an inbound missile-armed bomber flying at 550 mph at 40,000 feet was detected by radar at a range of 100 miles, a further nine or ten minutes would elapse before it was close enough to launch its missiles. If the DLI was at five minutes’ notice, this left less than four minutes for it to launch, climb to 40,000 feet and destroy its target. This implied a minimum rate of climb of around 15,000 feet/min, as well as high speed and good manoeuvrability at that altitude.

To meet this requirement the Douglas company proposed a delta-wing fighter powered by a Westinghouse J40 axial flow turbojet, which was expected to provide 7,000 lb thrust, increasing to 11,600 lb with afterburning. A development contract was awarded in June 1947 but as design work got underway the wing planform was progressively modified. Instead of a pure delta wing, the final configuration was more akin to a tailless aircraft with low aspect ratio wings having a sharply swept leading edge and rounded wingtips. The pilot sat well forward with bifurcated leading edge intakes just behind the cockpit. A tricycle undercarriage with a long nosewheel oleo for catapult launches was fitted, and the resulting high angle of attack on the ground required a small retractable tailwheel to guard against excessive pitch up at launch. The standard armament was four 20 mm cannon - a missile armament not being contemplated at this time. With the design finalised, a contract for the construction of two prototype XF4D-1 Skyrays was awarded in December 1948, although the first of these did not fly until 23 January 1951. Even then flight testing was limited due to the fact that the intended Westinghouse J40 engines were not ready and both prototypes were initially powered by Allison J35-A-17 turbojets, which were only rated at 5,000 lb thrust so that the full performance envelope could not be demonstrated.

As will be seen, the Skyray was not the only aircraft to suffer from problems with the J40 engine, which also formed the basis of several other contemporary projects. Even when production examples of the engine became available, they proved to be very unreliable with an alarming tendency to shed turbine blades in flight. Eventually the whole engine project was cancelled in 1953. Nevertheless, the availability of early J40s allowed the Skyray to demonstrate its potential, which it did in spectacular fashion on 3 October 1953 by wresting the absolute world airspeed record from Britain (set by a Supermarine Swift on 26 September 1953 with a speed of 735.7 mph). The average speed achieved by the Skyray over a 3 km course was 752.944 mph. It is interesting to note that both records were set at very low level in very high ambient temperatures where the speed of sound would be in excess of 760 mph so that Mach numbers in the region of 0.98 were attained. In fact, neither aircraft was supersonic in level flight at that time, although they could exceed Mach 1.0 in a dive, especially in colder air at high altitude where the speed of sound reduced to around 660 mph. Despite this success, the cancellation of the J40 engine programme forced the Douglas team to find a suitable alternative and this was to be the Pratt & Whitney J57-P-2. In fact, this was a much better engine, offering 9,700 lb thrust, which could be boosted to 14,800 with afterburning, and was to prove a very reliable powerplant. The later J57-P-8 offered 10,200 lb dry thrust and 16,000 lb with afterburning. Although the physical integration of the new engine with the Skyray airframe posed few difficulties, trials with the first production aircraft (first flight 5 June 1954) revealed aerodynamic problems with the air intakes, which were eventually solved by the addition of a splitter plate between the fuselage and intake, a device applied to many subsequent supersonic aircraft. However, this added further delays to the Skyray’s service debut and it was not until mid 1956 that it finally became fully operational, five years after the first prototype and almost two years after the first re-engined production aircraft had flown (although initial carrier trials were carried out by one of the J40-powered prototypes aboard the USS Coral Sea in October 1953). Nevertheless, the US Navy now possessed a remarkable interceptor. With the J57 engine, the Skyray was now just supersonic in level flight at altitude and had an initial rate of climb in excess of 18,000 feet/ min. In May 1958 a Skyray set a series of time to height records, reaching 15,000 metres (49,212 feet) in only two minutes and thirty-six seconds! The capturing of the world airspeed record was the first time that this had been achieved by a carrier-capable aircraft and the production F4D-1 was the US Navy’s first supersonic fighter, although only just so. Outside the time scale of this book, it is interesting to note that Douglas produced an advanced version of the Skyray, which was the F5D-1 Skylancer. The prototype flew in 1956 and reached speeds of Mach 1.5 at 40,000 feet, as well as possessing a limited all-weather capability, but was not ordered into production.

The US Navy could not be accused of being unwilling to try out new concepts. Even before the Skyray development was initiated, it had commissioned the construction of three prototype fighters from Chance Vought in June 1946. These were again based on German work and the result was a revolutionary tailless design with directional control achieved by twin fin and rudder assemblies at mid span on each wing. Like the Skyray, the new XF7U-1 Cutlass was intended as a deck-launched interceptor and to achieve the required performance a twin-engine configuration was adopted, two Westinghouse J34-WE-32 turbojets with afterburning being set side by side in the fuselage nacelle. The result was unlike anything flown before or since and, considering the unorthodox layout, performed better than might have been expected, although several serious problems were encountered. The prototype XF7U-1 flew on 29 September 1948 and was followed by the first of fourteen production F7U-1s in March 1950. These were eventually allocated to the Navy’s Advanced Training Command at Corpus Christi in 1952 as problems with the J34 engine as well as handling difficulties made the Cutlass unsuitable for carrier deployment. These caused the cancellation of the F7U-2 with more powerful J34s and development was centred on the F7U-3, which was re-engined with Westinghouse 4,660 lb thrust J46-WE-8A engines. The centre fuselage was entirely re-designed and the underwing section of the vertical tail surfaces was virtually eliminated. The F7U-3 was first flown in December 1951 and initially four Navy squadrons (VF-81, VF-83, VF-122, VF-124) were equipped with the Cutlass, although operational deployments did not commence until May 1954, the first being VF-81 aboard the USS Ticonderoga. A total of 290 F7U-3s were delivered, which included ninety-eight F7U-3Ms with provision to carry four Sparrow air-to-air missiles and twelve F7U-3P photo reconnaissance aircraft. However, the type’s record in service was very poor with serious maintenance problems and a frighteningly high accident rate so that production ceased in 1955 and it had been entirely replaced before the end of the decade. Originally intended as a pure interceptor, it was outclassed in this role by the Skyray and subsequently was more often utilised in the attack role, carrying two 1,000- or 2,000 lb bombs, and it could also be fitted with a centreline pod carrying forty-four 2.75 inch air-to-air unguided rockets.

Although the US Navy was never able to field a swept wing jet fighter in the Korean War, things might have been different if development of another design had progressed as hoped. This was the McDonnell F3H Demon, which was ordered in prototype form in September 1949 following the company’s response to an earlier request for proposals issued by the Bureau of Aeronautics in May 1948 for a swept-wing naval interceptor. For its time, the Demon was an advanced design with sharply swept flying surfaces, wide lateral air intakes and provision for afterburning with the tailplane and fin being set well above the jet efflux. The prototype XF3H-1 flew on 7 August 1951 but even by that time the programme was in deep trouble. Things were not helped by a BuAer requirement that the Demon should be redesigned as an all-weather fighter under the designation F3H-1N. This significantly delayed development, the first production examples not flying until December 1953. In the meantime a much more serious problem had arisen in the shape of the failure of the Westinghouse J40 engine programme. The afterburning 9,200 lb thrust J40-WE-8 had initially been selected as the powerplant for the Demon but the XF3H-1 prototype was only fitted with the unreheated 6,500 lb thrust J40-WE-6. Eventually the afterburning variants were fitted to both prototypes and initial carrier trials were carried out aboard the USS Coral Sea in October 1953. Even by that time the J40 was proving unreliable, resulting in damage to one aircraft, and both being grounded for various periods. When testing of production F3H-1Ns began, the results were even more disastrous with no fewer than five aircraft being destroyed in accidents, including three in which the pilot was killed. In most cases the root cause of the accident was a failure of the J40 engine and it was quite clear that the Demon was seriously underpowered. Matters were so bad that many of the fifty-eight F3H-1Ns completed were never even flown, but were shipped by barge down the Mississippi from St Louis to Memphis where they were used as instructional airframes.

The US Navy had a major commitment to the J40 engine, which was the prime powerplant for several projected aircraft (including the F4D Skyray and twin-engined A3D bomber), and was reluctant to abandon development despite the evidence of flight tests. However, the McDonnell team was determined to salvage the Demon programme and persuaded the US Navy to allow two F3H-1N airframes to be converted to accommodate an Allison J71-A-2E rated at 9,700 lb thrust (14,400 lb with afterburning). Thus powered, the first F3H-2N flew on 23 April 1955 and proved to be a much better performer, although the Demon would have benefited further if an even more powerful engine could have been fitted but this was not possible without a major redesign. Eventually the F3H-2N began to reach squadrons in late 1956, subsequently embarking in the USS Forrestal for a Mediterranean deployment in January 1957. The standard F3H-2N was armed with fuselage-mounted 20 mm cannon but in August 1955 the missile-armed F3H-2M made its first flight. This could carry four AAM-N-2 Sparrow 1 semiactive homing guided missiles, which relied on the target being illuminated by the aircraft’s AN/APG-51B radar. In this guise the Demon became the US Navy’s first all-weather missile armed interceptor and remained in service until replaced by more capable fighters in the early 1960s. Thus the Demon was too late to see service in the Korean War and had been phased out of service by the time the United States became involved in Vietnam.

Despite the fact that the Demon had a relatively inauspicious career, it did provide the springboard for another project that was to become not just a first-class naval fighter, but one of the most successful all-round combat aircraft ever flown - the Mach 2 capable McDonnell F4H Phantom II. Although the first flight and subsequent development of this superb aircraft lie outside the period covered by this book, its initial development can actually be traced back as far as 1953 when McDonnell began a series of studies aimed at offering a substantial improvement in capability and performance of the F3H Demon. Under the designation Model 98, a series of single- and two-seat, single and twin-engined proposals were made. Of these, and after discussions with the US Navy, the Model 98B powered by either two Wright J67s or two General Electric J79s was taken as the basis for a new single-seat aircraft initially designated AH-1 in recognition of its planned attack role. However, by May 1955 when the construction of two prototypes was authorised, it was decided that they would be completed as two-seat, missile armed, all-weather fighters under the designation YF4H-1. Subsequently the prototype flew on 27 May 1958 and its startling performance led to substantial US Navy orders and, in a remarkable achievement, it was also ordered in quantity for the USAF - the first time that a naval fighter had achieved this distinction.

In fact, successful as the Phantom was to prove, it would not be the US Navy’s first fully supersonic fighter as it was preceded by two other types, both of which were easily capable of exceeding Mach 1 in level flight. The first of these to enter service was the Grumman F11F-1 Tiger, which had first flown on 30 July 1954 and subsequently entered operational service in early 1957. Development of the F11F had commenced in December 1952 when the possibility of applying the area rule principle to the swept wing F9F was investigated. It quickly became apparent that a fresh design would be required and this evolved as a slim-fuselaged, swept wing jet fighter with an empty weight of around 13,000 lb. The incorporation of area rule led to distinctive narrowing of the fuselage where the wings were mounted in order to eliminate rapid changes in the total cross-sectional area presented to the airflow. The slim fuselage was achieved by using an axial flow jet engine, in this case an afterburning Wright J65, which was actually a licence-built version of the British Armstrong Siddeley Sapphire. Considerable attempts were made to reduce weight and one unusual feature was that the wingtips were folded down manually, saving the complexity of the more conventional power-actuated upward-folding wings. The first prototype was lost in an accident in October 1954 due to an engine flameout - a recurrent problem with the J65. However, the second prototype had flown by then and was able to carry on the test programme, exceeding Mach 1 for the first time before the end of the year. A third prototype flew in December 1954 and incorporated various modifications, including redesigned tail surfaces, a longer nose, air intake splitter plates, a new clear-view canopy and had provision for an air-to-air refuelling probe to be fitted. A standard armament of four 20 mm cannon was fitted and the F11F-1 could carry four Sidewinder missiles or two missiles and two drop tanks of 150 US gallons.

Carrier trials aboard the USS Forrestal in April 1956 highlighted the need for further modifications, notably increasing the fuel capacity to make good shortfalls in range and endurance. As already related, service entry followed in 1957 but the Tiger’s operational career was relatively short and it was withdrawn from frontline units by 1961, although it enjoyed a longer career with second line training units and was adopted as the mount for the famous Blue Angels naval demonstration team. When the Tiger passed out of frontline service, it was the end of an era for Grumman who had provided naval fighters continuously from 1933 and it was not until the 1970s that another Grumman jet fighter (the F14 Tomcat) was to serve aboard US carriers. The reasons for the Tiger’s premature withdrawal were varied but included poor handling, which made it an unsteady gun platform, and the unreliability of the J65 engine. However, the main reason was that it was totally eclipsed by another fighter that had entered service at the same time.

This was the Chance Vought F8U Crusader, which originated from a US Navy requirement for a supersonic air superiority fighter issued in 1952. This company had, of course, made its name as the builder of the famous Corsair piston-engined fighter but had experienced less success with its subsequent jet designs. Awarded a contract in May 1953 for further development of its proposals, Chance Vought produced a fairly conventional design based around a single Pratt & Whitney J57-P-11 turbojet, which could produce 18,900 lb thrust with afterburning and was positioned towards the rear of the long fuselage. A pointed radome with a semi-circular chin air intake below gave the Crusader a distinct profile but its most unusual feature was the high-mounted swept wing with noticeable anhedral. This was unusual in a jet fighter but was accounted for by a unique feature intended to make the task of landing this hot ship aboard a carrier easier than it might otherwise have been. In normal flight the top surface of the wing centre section lay flush with the top of the fuselage but at slower speeds the leading edge could be raised by means of screw jacks, so increasing the angle of incidence of the whole wing relative to the fuselage. This in turn effectively reduced the nose-up attitude of the whole aircraft, improving the pilot’s view of the deck while also increasing lift. The high wing layout did mean that the main undercarriage legs had to retract in the fuselage, which resulted in a relatively narrow wheel track.

In service the F8U Crusader offered a substantial increase in performance over previous naval fighters. The top speed was around Mach 1.7 at altitude, although the initial rate of climb was only 12,000 feet/min, still very good but well below that achievable with the Skyray. This difference was accounted for by the weight of the Crusader, which grossed at 34,000 lb compared with the 25,000 lb MAUW of the Skyray. However, the Crusader had a much better endurance and was capable of carrying a wide variety of weapons apart from the internal four 20 mm cannon. The standard fit was either two (later four) Sidewinder infra-red homing homing missiles, or up to 5,000 lb of bombs or rockets, or any combination of these. Given the advanced performance of the Crusader, its development and entry into service was completed in an amazingly short time, especially when compared with earlier jets such as the Skyray and Demon. The prototype XF8U-1 flew in March 1955 and production standard aircraft were coming off the assembly lines by the end of 1956 with the first squadron (VF32) forming in March 1957. By the end of the year the squadron was deployed aboard the USS Saratoga and subsequently various versions of the Crusader flew with no fewer than seventy US Navy and USMC squadrons in a career that lasted until the mid 1980s. A total of 1,261 Crusaders were produced, which included forty-two for the French Navy, one of the few cases where US Navy fighters were exported. One of the most important variants was the RF-8 in which a battery of five cameras replaced the 20 mm cannon and provision was made for additional fuel. Both fighter photo reconnaissance versions saw considerable action during the Vietnam War, some units serving right through to the end in 1973.

The variable incidence wing of the Crusader was one example of altering wing characteristics to overcome the problem of landing high-performance swept wing aircraft on a carrier deck. A more ambitious solution dated as far back as 1946 when Grumman were asked to build a research aircraft to test swept wings with an eye to their later application to the XF9F-2 Panther. The initial proposal was for a single-engined, high-mounted, modified delta-wing aircraft with a T-tail and a contract was issued in April 1948 for two prototypes. However, by 1950 a new specification was issued calling for a fighter that would have good low-speed handling qualities and be capable of transonic speeds. At the same time a heavy armament and long range was required so that the final Grumman design increased in weight from around 18,000 lb MTOW to over 31,000 lb. After investigating the possibility of using variable incidence, the Grumman team went a step further and proposed a variable sweep wing with full-span leading edge slats and flaps along 80 per cent of the trailing edge.

The prototype XF10F-1 Jaguar eventually flew on 19 May 1952 but almost immediately severe problems were manifest. These were both technical failures and stability problems, although the wing sweep mechanism itself caused no trouble and turned out to be very reliable. The Achilles’ heel of the project was the use of the ill-fated Westinghouse J40 engine. The cancellation of this engine in 1953 and the subsequent grounding of all aircraft fitted with it effectively ended the Jaguar programme. Nevertheless it should be recognised as a pioneering attempt at what was actually a viable proposition and the concept of variable sweep was incorporated in the American F-111 and B-1 bombers, and the European Tornado.

At this point brief mention should be made of two significant aircraft that were built in prototype form to explore the concept of a VTOL combat aircraft. These were the Convair XFY-1 and the Lockheed XFV-1. Both came about as a result of studies made by both the US Navy and Air Force in the late 1940s and with the outbreak of the Korean War development funds became available. The two designs were very similar in concept, power for take-off and conventional flight being provided by turboprops driving a pair of three-bladed contra-rotating propellers. With broad chord blades these acted as helicopter rotors to lift the aircraft from the ground, the transition to horizontal flight being made gradually as speed and altitude increased. The Lockheed XFV-1 had short stubby wings with wingtip tanks, and a cruciform tail assembly that incorporated four wheels on which the aircraft rested when on the ground. The pilot was provided with an ejector seat. For initial flight trials a 5,850 hp Allison XT40-A-6 turboprop was installed with a more powerful YT40-A-14 scheduled for later tests, although this never actually became available. The production FV-2 would have had an even more powerful T54-A-16. The prototype was fitted with a temporary fixed undercarriage to permit conventional take-off and landings for the initial test flights and officially flew on 16 June 1954, although it had previously become airborne in high-speed taxi trials. Although transitions from horizontal to vertical flight modes and back again were made in the air, vertical take-offs and landings from the ground were never attempted as the trials engine did not produce enough power. The programme was cancelled in mid 1955 when it was realised that even if full transitions could be achieved, the performance of the turboprop fighter would lag well behind that of contemporary jets.

The Convair XFY-1 was much more successful and featured a broad delta wing, together with upper and lower vertical fins. This made a much more stable base (an important consideration aboard ship) but in other respects the design was similar to that of the Lockheed aircraft with the same powerplant and a tilting ejector seat for the pilot. Initial tethered flights commenced in April 1954 and these culminated in the first free flight in which transition to horizontal mode was successfully accomplished and was then followed by a vertical landing. This occurred in November 1954 and subsequently the XFY-1 recorded a maximum speed of 610 mph at 15,000 feet and had an excellent rate of climb, reaching 30,000 feet in 4.6 minutes. Despite the apparent success of the programme the project was cancelled in 1956, one possible reason being that the widespread adoption of VTOL combat aircraft might result in a reduction in the size of the US Navy’s carrier fleet - something that many Admirals did not wish to see. A similar attitude prevailed in Britain in the 1960s when aircraft such as the P1127 and Kestrel (forerunners of the Harrier) were seen by some as a possible threat to the Royal Navy’s carriers.

Convair were to achieve considerable success with the production of delta-winged jet fighters for the USAF (F-102 and F-106) and applied some of their experience to produce a jet-powered water borne fighter, the XF2Y-1 Sea Dart. Powered by two 3,400 lb thrust J34-WE-32 engines, the Sea Dart was very similar in outline to the F-102 Delta Dagger except that the engine intakes were on the top of the fuselage to prevent spray ingestion on take-off. Instead of a conventional flying boat hull, the XF2Y-1 was fitted with retractable hydro skis, which offered less drag in the air and permitted higher speeds on the water. The official first flight was on 9 April 1953, although the aircraft had previously been briefly airborne during taxi trials. There were problems both with the engines, which failed to develop the expected thrust, and with controlling the aircraft on take-off while running on the skis. Consequently only three development YF2Y-1s were built and one of these crashed in November 1954. Although the US Navy continued test and evaluation trials, the project was finally halted in 1956.

By the mid 1950s, the development of jet combat aircraft for naval use had advanced considerably in the decade following the end of World War II. By 1955 high-performance swept wing aircraft, some with supersonic capability, were either in service or under active development in both Britain and America. However, it was almost inevitable, given the strength of their industrial base, that the Americans should forge ahead. Thus in 1955, while the Royal Navy was still operating straight-winged Seahawks and Sea Venoms, the US Navy had swept wing Furies and Cougars and was about to introduce the fast-climbing Skyray, while the supersonic Crusader (capable of speeds in excess of 1,000 mph) had already flown in prototype form.

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