English Electric Lightning
The English Electric Lightning is a British fighter aircraft that served as an interceptor during the 1960s, 1970s and into the late 1980s. It is capable of a top speed above Mach 2. The Lightning was designed, developed, and manufactured by English Electric. After EE merged with other aircraft manufacturers to form the British Aircraft Corporation it was marketed as the BAC Lightning. It was operated by the Royal Air Force, the Kuwait Air Force, and the Royal Saudi Air Force.
An unusual feature of the Lightning's design is the vertically stacked Rolls-Royce Avon turbojet engines, mounted with one over the other within the fuselage. The Lightning was designed and developed as an interceptor to defend the airfields of the British "V bomber" strategic nuclear force from attack by anticipated future Soviet nuclear-armed supersonic bombers such as what emerged as the Tupolev Tu-22 "Blinder", but it was also expected to intercept other bombers such as the Tupolev Tu-16 and the Tupolev Tu-95.
The Lightning has an exceptional rate of climb, ceiling, and speed, and pilots have described flying it as "being saddled to a skyrocket". This performance and the initially limited fuel supply meant that its missions are dictated to a high degree by its limited range. Later developments provided greater range and speed along with aerial reconnaissance and ground-attack capability. Overwing fuel tank fittings were installed in the F.6 variant and extended the range, but limited maximum speed to a reported.
Development
Origins
The specification followed the cancellation of the Air Ministry's 1942 specification E.24/43 supersonic research aircraft which had resulted in the Miles M.52 programme. Teddy Petter, formerly chief designer at Westland Aircraft, who was hired by English Electric in 1944 to develop aircraft rather than just make other manufacturers' designs, was a keen proponent of Britain developing a supersonic fighter. In 1947, Petter approached the Ministry of Supply with his proposal, and in response Specification ER.103 was issued for a single research aircraft, which was to be capable of flight at and.Petter initiated a design proposal with Frederick Page leading the design and Ray Creasey responsible for the aerodynamics. By July 1948 their proposal incorporated the stacked engine configuration and a high-mounted tailplane. Designed for Mach 1.5, the wing leading edge was swept back 40° to keep it clear of the Mach cone. This proposal was submitted in November 1948, and in January 1949 the project was designated P.1 by English Electric. On 29 March 1949 the MoS granted approval to start a detailed design, develop wind tunnel models and build a full-size mockup.
The design that had developed during 1948 evolved further during 1949 to improve performance, taking design cues from the CAC CA-23. To achieve Mach 2 the wing sweep was increased to 60° with the ailerons moved to the wingtips. In late 1949, low-speed wind tunnel tests showed that a vortex was generated by the wing which caused a large downwash on the tailplane; this issue was solved by lowering the tail below the wing. Following Petter leaving English Electric, Page took over as design team leader for the P.1. In 1949, the Ministry of Supply had issued Specification F23/49, which expanded upon the scope of ER103 to include fighter-level manoeuvring. On 1 April 1950, English Electric received a contract for two flying airframes, as well as one static airframe, designated P.1.
The Royal Aircraft Establishment disagreed with Petter's choice of sweep angle and tailplane position considering it to be dangerous. To assess the effects of wing sweep and tailplane position on the stability and control of Petter's design Short Brothers were issued a contract by the Ministry of Supply to produce the Short SB.5 in mid-1950. This was a low-speed research aircraft that could test sweep angles from 50 to 69 degrees and high or low tailplane positions. Testing with the wings and tail set to the P.1 configuration started in January 1954 and confirmed this combination as the correct one.
Prototypes
From 1953 onward, the first three prototype aircraft were hand-built at Samlesbury Aerodrome, where all Lightnings were built. These aircraft were given the aircraft serials WG760, WG763, and WG765. The prototypes were powered by un-reheated Armstrong Siddeley Sapphire turbojets, as the selected Rolls-Royce Avon engines had fallen behind schedule due to their own development problems. Since there was no space in the fuselage for fuel, the thin wings were used as the fuel tanks. Because the wings also provided space for the stowed main undercarriage, the fuel capacity was relatively small, giving the prototypes an extremely limited endurance. The narrow tyres rapidly wore out in a crosswind during take-off or landing. Outwardly, the prototypes looked very much like the production series, but they were distinguished by the rounded-triangular air intake with no centre-body at the nose, short fin, and lack of operational equipment.On 9 June 1952, it was decided that there would be a second phase of prototypes built to develop the aircraft toward achieving ; these were designated P.1B while the initial three prototypes were retroactively reclassified as P.1A. P.1B was a significant improvement on P.1A. While it was similar in aerodynamics, structure and control systems, it incorporated extensive alterations to the forward fuselage, reheated Rolls-Royce Avon R24R engines, a conical centre body inlet cone, variable nozzle reheat and provision for weapons systems integrated with the ADC and AI.23 radar. Three P.1B prototypes were built, assigned serials XA847, XA853 and XA856.
In May 1954, WG760 and its support equipment were moved to RAF Boscombe Down for pre-flight ground taxi trials; on the morning of 4 August 1954, WG760, piloted by Roland Beamont, flew for the first time from Boscombe Down. One week later, WG760 officially achieved supersonic flight for the first time, having exceeded the speed of sound during its third flight. During its first flight, WG760 had unknowingly exceeded, but due to position error the Mach meter only showed a maximum of. The occurrence was noticed during flight data analysis a few days later. While WG760 had proven the P.1 design to be viable, it was limited to due to directional stability limits. In May 1956, the P.1 received the "Lightning" name, which was said to have been partially selected to reflect the aircraft's supersonic capabilities.
OR.155 and project selection
In 1955, the Air Ministry learned of the Tupolev Tu-22, expected to enter service in 1962. It could cruise for relatively long periods at and had a dash speed of Mach 1.5. Against a target flying at these speeds, the existing Gloster Javelin interceptors would be useless; its primary de Havilland Firestreak armament could only attack from the rear and the Tu-22 would run away from the Javelin in that approach. A faster version, the "thin-wing Javelin", would offer limited supersonic performance and make it marginally useful against the Tu-22, while a new missile, "Red Dean" would allow head-on attacks. This combination would be somewhat useful against the Tu-22, but of marginal use if faster bombers were introduced. In January 1955, the Air Ministry issued Operational Requirement F.155 calling for a faster design to be armed with either an improved Firestreak known as "Blue Vesta", or an improved Red Dean known as "Red Hebe". The thin-wing Javelin was cancelled in May 1956.In March 1957, Duncan Sandys released the 1957 Defence White Paper which outlined the changing strategic environment due to the introduction of ballistic missiles with nuclear warheads. Although missiles of the era had relatively low accuracy compared to a manned bomber, any loss of effectiveness could be addressed by the ever-increasing yield of the warhead. This suggested that there was no targeting of the UK that could not be carried out by missiles, and Sandys felt it was unlikely that the Soviets would use bombers as their primary method of attack beyond the mid-to-late 1960s.
This left only a brief period, from 1957 to some time in the 1960s, in which bombers remained a threat. Sandys felt that the imminent introduction of the Bloodhound Mk. II surface-to-air missile would offer enough protection against bombers. The Air Ministry disagreed; they pointed out that the Tu-22 would enter service before Bloodhound II, leaving the UK open to sneak attack. Sandys eventually agreed this was a problem, but pointed out that F.155 would enter service after Bloodhound, as would a further improved SAM, "Blue Envoy". F.155 was cancelled on 29 March 1957 and Blue Envoy in April.
To fill the immediate need for a supersonic interceptor, the Lightning was selected for production. The aircraft was already flying, and the improved P.1B was only weeks away from its first flight. Lightnings mounting Firestreak could be operational years before Bloodhound II, and the aircraft's speed would make it a potent threat against the Tu-22 even in a tail-chase. To further improve its capability, in July 1957 the Blue Vesta program was reactivated in a slightly simplified form, allowing head-on attacks against an aircraft whose fuselage was heated through skin friction while flying supersonically. In November 1957, the missile was renamed "Red Top". This would allow Lightning to attack even faster bombers through a collision-course approach. Thus, what had originally been an aircraft without a mission beyond testing was now selected as the UK's next front-line fighter.
Further testing
On 4 April 1957 Beamont made the first flight of the P.1B XA847, exceeding Mach 1 during this flight. During the early flight trials of the P.1B speeds in excess of were achieved daily. During this period the Fairey Delta 2 held the world speed record of achieved on 10 March 1956 and held till December 1957. While the P.1B was potentially faster than the FD2, it lacked the fuel capacity to provide one run in each direction at maximum speed to claim the record in accordance with international rules.In 1958 two test pilots from the USAF Air Force Flight Test Center, Andy Anderson and Deke Slayton, were given the opportunity to familiarise themselves with the P.1B. Slayton, who was subsequently selected as one of the Mercury astronauts, commented:
In late October 1958, the plane was officially and formally named "Lightning". The event was celebrated in traditional style in a hangar at RAE Farnborough, with the prototype XA847 having the name 'Lightning' freshly painted on the nose in front of the RAF Roundel, which almost covered it. A bottle of champagne was put beside the nose on a special smashing rig which allowed the bottle to safely be smashed against the side of the aircraft. The honor of smashing the bottle went to the Chief of the Air Staff, Sir Dermot Boyle.
On 25 November 1958 the P.1B XA847, piloted by Roland Beamont, reached Mach 2 for the first time in a British aircraft. This made it the second Western European aircraft to reach Mach 2, the first one being the French Dassault Mirage III just over a month earlier on 24 October 1958.