Hawker P.1127 / VZ-12 / XV-6 / Kestrel
A design by Sir Sydney Camm, the P.1127 incorporated vectored thrust, which enabled one engine to lift and pro-pel the aircraft by means of rotatable exhaust nozzles. The airframe of the P.1127 was designed round the unique character of its Bristol Pegasus engine, which had four nozz1es (the forward pair exhausting cold air from the engine’s fan stage and the aft pair exhausting hot gases from the engine’s turbine stage) arranged two on each side fore and aft of the centre of gravity.
Hovering trials with the first P.1127 (XP831) began on October 21st, 1960, over a specially prepared hovering platform with the aircraft tethered. Free vertical hovers on the vectored thrust of an 5126kg Pegasus 2 engine were made in November and the first conventional take-off was made on March 13th, 1961. For low-speed con-trol, the aircraft has jet reaction nozzles at each wing tip and at the nose and tail.
The second P.1127 (XP836) flew on July 7th, 1961, and continued conventional flight trials while the first reverted to hovering trials in September. This aircraft made the first complete transition from hovering to horizontal flight and back on September 12th, 1961. The third P.1127 (XP972) flew on April 5th, 1962.
Such was the promise of the type that a pre-production derivative was built as the Kestrel. The P.1127 was renamed Kestrel after Hawker Siddeley Aviation was created.
Three examples were ordered in 1962 by the U.S. Department of Defense, with the U.S. Army financing 50 per cent of the programme and the USAF and Navy sharing the remainder. Compared with these aircraft and three sub-sequent prototypes, the three XV-6As have a 9-in longer fuselage, anhedral on the tailplane and more powerful versions of the Bristol Pegasus.
Of the six prototypes built in total, one of which was lost at an air display.
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 5 engine. The first of these flew on 7 March 1964.
Due to interest from the US and Germany the Tri-partite Evaluation Squadron was formed, staffed by military test pilots from Britain, the US and West Germany. A Tripartite Trials Squadron existed from 15 October 1964 until 30 November 1965, after which six of the Kestrels were transferred to the USA where they were designated XV-6As. After testing at RAF West Raynham, the eight surviving Kestrel FGA Mk 1s evaluation aircraft were transferred to the USA for evaluation by the Army, Air Force and Navy (including USMC). After Tri-Service evaluation they were passed to the USAF for further evaluation at Edwards AFB.
The Kestrel featured two wing hardpoints each capable of lifting gun pods or stores of up to 450kg.
The Kestrel FGA Mk 1 ground attack fighter was an operational evaluation derivative of the P.1127 V/STOL.
An order for 60 aircraft was received from the RAF in 1966, and the first pre-production Harriers were flying by mid-1967.
Engine: Bristol Siddeley Pegasus, 12,000 lb thrust.
Max take-off weight: 5625-7031 kg / 12401 - 15501 lb
Empty weight: 4445 kg / 9800 lb
Wingspan: 6.96 m / 22 ft 10 in
Length: 12.95 m / 42 ft 6 in
Height: 3.28 m / 10 ft 9 in
Wing area: 17.28 sq.m / 186.00 sq ft
Max. speed: 1067 km/h / 663 mph
Hawker P.1127 prototype