Operational Requirement F.155
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The Operation Requirement F.155 was an identified need by the British Ministry of Supply for an interceptor aircraft for the defence of the United Kingdom.
The need as determined in 1955 was for an aircraft that could intercept high flying supersonic nuclear bombers from the Soviet Union before they could threaten the UK. The in service date would be the start of 1962. In practice the 1957 Defence White Paper cancelled development of aircraft towards F.155 and there was a change from high level attack to low level attack and intercontinental ballistic missiles as the means for delivering nuclear weapons.
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[edit] Background
At the time, the existing RAF interceptor was the Gloster Javelin all-weather fighter. The English Electric Lightning for point defence was nearing completion of development. The Saunders-Roe SR.177 mixed-power was planned to enter service in a few years and would cover the interim period taking over from the Javelin. The Canadian Avro Arrow was a possible contender to cover the interim but its capability was for an intruder at 50,000 ft travelling a Mach 0.9.
[edit] Requirement
The requirement expected the aircraft that won the contract to be capable of intercepting in a short time, about 20 minutes, a target while still some 250 miles away flying at supersonic speeds at an altitude of 60,000 ft. The aircraft would carry both infra-red guided missiles and radar guided missiles so that it could attack from any aspect including collision course. A crew of two was assumed because of the necessary workload.
The missiles were covered by OR.1131. The two missiles would be de Havilland's "Blue Vesta" and Vickers Red Hebe, a scaled down version of Red Dean. A smaller version of Red Hebe would eventually also come into the equation. Blue Vesta was a 150 kg Infra-Red guided weapon for attack from a pursuit angle - in the event it was largely displaced in the designs by the Mark 4 version of Blue Jay (which would enter service as Red Top). Red Hebe was nearly 600 kg in weight but as radar guided would be able to hit its target from any firing angle. The Ministry made clear in the requirement that the plane and missiles should be treated as a "weapon system" i.e., a cohesive whole.
[edit] Designs
Most British manufacturers provided their own suggestions for planes that would meet the specification. At the same time the engine manufacturers were encouraged to develop the necessary powerplants. These included the de Havilland Gyron and Rolls-Royce RB.106.
Saunders-Roe came up with the P.187: a logical progression from the SR.53 and SR.177 mixed power (rocket and jet engines) interceptors. This gave both rapid acceleration and the capability to operate at high altitudes were jets would be troubled. Saunders-Roe judged that a big aircraft would be needed to carry 2 IR and 2 radar-guided missiles and the fuel required. A highly streamlined futuristic looking design it was judged, at 98,000 lb and 84 ft long, as too big.
Fairey drew on their experience with the Fairey Delta 2. First a development of the FD2 and then a bigger design derived from it known as the "Delta III". Fairey like some of the other manufacturers felt that carrying 4 missiles onerous especially given the size of the radar version and provided designs based on a payload of only two missiles. They also took the mixed power route.
Going on the basis of the smallest aircraft that could do the job, Hawker's design (P.1103) used a single albeit powerful engine - the Gyron. Alternative engines from Rolls-Royce Ltd, Armstrong-Siddeley and Orenda were also options. Two rocket boosters were carried in midwing nacelles.
Armstrong-Whitworth put forward the AW.169. A razor-thin straight wing carried the engines in nacelles - two Gyron Juniors each side - with a rocket booster under the long narrow fuselage. Two missiles were carried, one on each wingtip.
The AW.169 and Fairey's design were considered to be the best two contenders taking into account the design of the aircraft, the development risks, the capabilities of the design teams and the manufacturers workloads - Bristol had not been invited to tender because of the importance of the Bristol 188 high speed research plane they were working on. Initially further work was contracted on both designs but by the end of the year the AW.169 was dropped and the Fairey and become a firm choice. In April the following year the 1957 Defence White Paper terminated most all manned fighter development projects.
[edit] References
- Buttler, Tony. British Secret Projects: Jet Fighters Since 1950. Leicester, UK: Midland Publishing, 2000, ISBN 1-85780-095-8.
- Wood, Derek. Project Cancelled: British Aircraft That Never Flew. Indianapolis: The Bobbs-Merrill Company, 1975. ISBN 0-672-52166-0.
