Hawker P.1127

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Hawker P.1127

Type	experimental VSTOL aircraft
Manufacturer	Hawker Aviation
Maiden flight	November 19 1960 (P.1127) March 7 1964 (Kestrel)
Primary users	RAF USA DOD/NASA, West Germany
Number built	5 P.1127 prototypes plus 9 Kestrels
Variants	Hawker-Siddeley Harrier

The Hawker P.1127 and the Hawker-Siddeley Kestrel FGA.1 were the development aircraft that led to the Hawker-Siddeley Harrier, the first VTOL jet fighter-bomber.

1 Background
2 Variants
3 Survivors
4 Specifications (Kestrel FGA.1)
5 References
6 External link
7 Related content

[edit] Background

In 1957, the Bristol Engine Company informed Sidney Camm of Hawker that they had a project to combine their Olympus and Orpheus jet engines to produce a directable fan jet (an idea that had been approached theoretically by the Frenchman M. Wilbaut). Hawker took the planned engine as a basis for a plane that could meet the current NATO specification for a Light Tactical Support Fighter. At the time there was no financial support for the development from the Treasury, but aid was found through the Mutual Weapon Development Project (MWDP) of NATO to keep the project running, in spite of the atmosphere post the 1957 Defence White Paper which was leading to cancellations of many other projects. By 1958, the British Air Staff showed some interest, but no further MWDP funds were available - much of the money was tied up for the Vickers Swallow swing-wing aircraft project. Some model work was done by NASA at Langley Field for the project. In April 1959 a formal request for the manufacture of prototypes was received and Hawker test pilots travelled to the US to gain VTOL experience on the Bell X-14.

[edit] Variants

[edit] P.1127

The first prototype P.1127 was delivered in July 1960 for static engine testing and joined in October that year by the actual Pegasus flight engine designed by Sir Stanley Hooker. The first tethered flight took place the same month, and free flight hover in November following which publicity photos were made available.

NATO now had a requirement, NBMR-3, specified for a VTOL aircraft, but one that was expected to have the performance of an aircraft like the F-4 Phantom along with the VTOL capability. Hawker drafted the P.1150, a supersonic P.1127 and the P.1154 which would meet NBMR-3. The latter was a winner of the NATO competition and development continued until cancelled at the point of prototype construction in 1965.

Four more prototypes were ordered and the first true (conventional take off) flight of the P.1127 took place in February 1961. Its first complete VTOL to forward flight took place in September 1961. Through this period improved Pegasus engines were being delivered, the Pegasus 3 capable of 15,000 lbf (67 kN) of thrust. In 1963 a vertical landing was demonstrated on HMS Ark Royal, but later that year, the first prototype plane, XP831, crashed, without loss of life, at the Paris Air Show.

[edit] Kestrel FGA.1

Nine evaluation aircraft were ordered as the Hawker-Siddeley Kestrel FGA.1, which was an improved version of the P.1127, the first flying on March 7, 1964. The Kestrel had fully swept wings and a larger tail than the P.1127, and the fuselage was modified to take the larger 15,000 lbf (85 kN) Pegasus 6 engine.

Due to interest from the US and Germany the Tri-partite Evaluation Squadron (TES) was formed, staffed by military test pilots from Britain, the US and West Germany. After testing at RAF West Raynham, during which one aircraft was lost, the eight surviving evaluation aircraft were transferred to the USA for evaluation by the Army, Air Force and Navy (including USMC) as the XV-6A Kestrel. After Tri-Service evaluation they were passed to the USAF for further evaluation at Edwards AFB.

[edit] P.1127(RAF)

At the time of the development of the P.1127, Hawker had started on a design for a supersonic version, the Hawker P.1154. After this was cancelled in 1965, the RAF began looking at a simple upgrade of the Kestrel as the P.1127(RAF).

In mid-1966, the P.1127(RAF) was ordered by the RAF as the Hawker-Siddeley Harrier GR.1, with the first preproduction aircraft flying the following year.

[edit] Survivors

Three prototypes have survived to the present day, and one of these, XP984, is on display at the Brooklands Museum, Surrey.

[edit] Specifications (Kestrel FGA.1)

General characteristics

Crew: 1
Length: 42 ft 6 in (12.95 m)
Wingspan: 22 ft 11 in (6.99 m)
Height: 10 ft 9 in (3.28 m)
Empty weight: 10,000 lb (4,500 kg)
Loaded weight: 15,000 lb (6,800 kg)
Max takeoff weight: 17,000 lb (7,700 kg)
Powerplant: 1× Bristol Siddeley Pegasus 6 vectored-thrust turbofan, 15,000 lbf (67 kN)