In 1962, a special squadron was formed from pilots of the Luftwaffe, the RAF, and the USAF for service evaluation of the P.1127 prototypes. The interest had been sparked by a NATO competition for a V/STOL tactical strike aircraft. Numerous designs had been offered, the most promising of which was the supersonic Hawker P.1154. However, the severe defense cutbacks of 1965 doomed the P.1154 project.
Nevertheless, the basic VTOL concept was deemed worth pursuing, and the Ministry of Defence ordered nine developed examples of the P.1127, designated the Kestrel F(GA).Mk 1. Serials were XS688/XS696. Since the aircraft was going to be able to carry armament, more powere was needed, and the Pegasus 5 was developed by Briston. It had a completely new three-stage front fan and a revised combustion chamber. It offered a thrust of 15,500 lb.s.t. In order to improve the handling, the rear nozzles were moved slightly forward.
The Kestrel had a new wing with a deeper root, a slightly increased wing sweep and an underwing pylon underneath each side. The wing had its span reduced by 1 feet 6 inches to 22 feet 10 inches. The wing area was increased from 185 to 186 square feet. The fuselage was longer by 10 inches to 42 feet 0 inches. The tailplane anhedral, which had been introduced at 18 degrees on the second P.1127, was reduced to 16 degrees. The tailplane design was retrospectively dchanged with an extension of reduced sweep back, increasing the span from 12 feet 0 inches to 13 feet 11 inches to improve low-speed controllability.
The Kestrels were completed during 1964 and 1965, the first example being flown on March 7, 1964. The Tripartite Squadron came into existence at West Raynham on October 15, 1964, consisting of pilots from the RAF, the USA and from Germany. The American contingent was represented by pilots from the Army, the USAF, and the Navy. Over the next year, the team carried out numerous evaluations to determine the aircraft's suitability for operational service.
After the completion of the trials, the squadron was disbanded, and it was planned that each nation would purchase an allotment of Kestrels. However, Germany decided not to participate any further in the program, and all nine of the Kestrels were turned over the the United States. They were assigned the USAF serial numbers 64-18262/18270. Hoiwever, only six of them were actually delivered, with the remaining three being retained in the UK. They were initially assigned the designation VZ-12, but were later redesignated XV-6A, because the VZ-12 designation was allocated long before adoption of the Tri-Service aircraft designation system. During the next three years, these airplanes were used in an extensive evaluation program with the USAF, US Army, US Navy, and US Marine Corps. Most of the flights were carried out from NAS Patuxent River, Maryland. They were flow onto aircraft carriers, notably the USS Independence. A couple were turned over to NASA as Nos 520 and 521. Four of them are now in museums.
Serial numbers of Hawker Siddeley VZ-12 Kestrel
64-18262/18270 Hawker-Siddeley VZ-12 Kestrel Redesignated XV-6A Nine former RAF Kestrel FGA.1s (RAF serials XS688/XS696) used for Tri-Service tests by USAF, US Army, and US Navy, but only 6 were delivered.
Specification of Hawker Siddeley Kestrel
One Bristol Siddeley Pegasus 5 vectored-thrust turbofan, 15,500 lb.s.t. Performance: Maximum speed 710 mph at sea level, 635 mph at 36,000 feet. Initial climb rate 30,000 feet per minute. Service ceiling 55,000 feet. Dimensions: Wingspan 24 feet 4 inches, length 49 feet 0 inches, height 10 feet 3 inches. Weights: 9800 pounds empty, Loaded 14,500 pounds (VTOL), 17,000 lb (STOL).
Sources:
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Hawker Aircraft Since 1920, Francis K. Mason, Naval Institute Press, 1991.
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Swanborough, F. G. and Peter M. Bowers, 1989. United States Military Aircraft since 1909. Washington, DC: Smithsonian Institution Press. ISBN 978-0-87474880-2.
- Wagner, Ray. American Combat Planes of the 20th Century: A Comprehensive Reference. Reno, Nevada: Jack Bacon & Co, 20
