With development work on the P.1 research aircraft well advanced and the F.155T in-service date looming, English Electric designed the P.8, an interceptor which was, effectively, a heavily modified Lightning.
The West was stunned when the Soviet Union dropped its first atomic bomb in August 1949 and a year later the Korean War showcased Russia’s incredible technological progress in the form of the MiG-15 – a fighter capable of besting anything the RAF could offer at that time. In the wake of the Second World War, funding for the RAF’s Fighter Command had fallen away dramatically but now there was an urgent need for new jet fighters to meet the threat of Russian bombers head-on.
The result was Operational Requirement (OR.) 329/F.155T and some of the most outlandish designs ever committed to paper.
Britain’s top aircraft manufacturers, including Hawker, English Electric, Fairey, Vickers Supermarine, de Havilland, Saunders-Roe and Armstrong Whitworth, set to work on designing powerful supersonic aircraft with all-new guided missile systems capable of intercepting a Soviet assault and shooting down high-flying enemy aircraft before they could unleash a devastating nuclear firestorm on British soil.
With development work on the P.1 research aircraft well advanced and the F.155T in-service date looming, English Electric designed the P.8, an interceptor which was, effectively, a heavily modified Lightning.
As told by Dan Sharp in his book Cold War Interceptor, English Electric “agreed” with the specification that guided weapons would be the best and only form of armament for the P.8 “since this will considerably improve the efficiency of the system. We share the hope, with Air Staff and MoS, that the simpler forms of these weapons will have been developed to a sufficient state of reliability in the time scale. As an insurance policy in this respect it is assumed that sufficient numbers of F.23/49 aircraft will be in service, with Aden guns and rocket batteries to fall back on.
“Attempt has been made to reconcile the carriage of both IR and radar weapons, but this has been found impossible. We agree with RAE that it is impossible to obtain the specified pursuit performance, whilst carrying a radar weapon system, in any practical size of aircraft.
“This analysis is based on first-hand knowledge of the design of a practical supersonic fighter system, for which even 10% optimism on engine and structure weights or drags can show a completely unrealistic picture.”
The sheer size of radar-guided weapons, particularly Vickers’ Red Dean/Red Hebe, made them unattractive for a fast interceptor and a system based on much smaller infrared homing missiles “must therefore be much quicker, less costly, more reliable and more certain of success than the larger and more complex radar collision system, all of which is completely new”.
This appeared to be English Electric committing itself to a pursuit-course attack when the F.155T Issue 2 specification called for the use of “all-round collision-course tactics” but this was not necessarily the case.
The brochure went on: “Design is therefore based on the use of the IR weapon, but this is not restricted to that at present represented by Blue Jay. In this form, the weapon may be regarded as the first logical step in the development from the gun, in that it may be fired at rather greater ranges and closing speeds with improved accuracy.
“This greatly improves the fighter’s chances of success, particularly in the face of tail armament, but does not otherwise help the fighter system. Since the present Blue Jay must be fired from short range within a narrow cone dictated by the target, the fighter must still follow out a complete pursuit interception, usually involving sharp turns in a high drag condition, followed by a chase back from behind the target.”
Evidently when it was fitted to the P.1 for testing, the Blue Jay had created such a degree of extra drag that the aircraft burned 100 gallons more fuel when climbing to 50,000ft than it did without it. The use of rocket motors to intercept targets above 55,000ft would require the aircraft to carry 2700lb of rocket fuel in place of kerosene — making the situation even worse.
However, English Electric had the solution: make the missile do the work. It was stated that “the next logical step in the development of the IR weapon is therefore to convert this performance penalty on the aircraft into a performance gain. This may be done by giving the weapon greater firing range from all round the target”.
Guidance range could be improved through the use of a system which locked-on to the CO2 emissions produced by the jet engines of the target – something that could not be masked and would be visible to the missile from a wide range of angles, even the front, as long as the fighter attack from below.
English Electric had worked with the Radar Research Establishment and the Blue Jay’s manufacturer, de Havilland Propellers, to determine that this would actually allow the missile to be released from much further away without reducing its chance of a kill. Releasing it from further away would still mean more fuel had to be carried – but it would be a small additional amount inside the missile itself rather than a much larger amount in the aircraft’s own tanks.
“It is therefore possible to investigate the proper division of had interception performance between the fighter and weapon in order to give a better two-stage weapon,” the brochure argued. “In the case at present envisaged, the addition of rocket fuel to the weapon will save about 100 times as much rocket fuel in the fighter to complete a given interception, so that a relatively small penalty on the weapon can eliminate the need for rocket boost in the fighter.
“Similarly, if the interception is limited by manoeuvrability then it is a much smaller overall penalty to increase the wing area of the weapon, rather than that of the fighter. Any improvement in weapon performance should not however cause appreciable deterioration in performance of the fighter, or its flexibility will suffer.”
With all this in mind, English Electric went on to boldly state: “It is not generally realised that the present AI.23-Blue Jay system is already a weapon collision system, although it is at present being used in a manner approximating to simple pursuit, due to the narrow angle and range limitations of guns and of the sulphide cells in Blue Jay Mk.I.”
Whether pursuit or collision course was necessary would depend on the target, but English Electric was confident that Blue Jay could handle either. Slow targets would require pursuit from behind, where all the heat and CO2 was coming from, but “higher performance targets, such as those specified, should give sufficient radiation from below for a lead pursuit attack from the side.”
In other words, the interceptor would approach the bomber at right angles from the side but ahead. Anticipating the target’s speed it would then fire its missiles at the place where the bomber was about to be.
At the uppermost end of the spectrum however: “The high supersonic speed bomber may be attacked from any direction, but it will be very desirable to try and attack from in front before it reaches the target. Interception is very difficult even with more complicated systems and precise radar control, but it may be necessary to try and develop the present system if other systems do not materialise, or are unserviceable.
“It may be possible to do this, since a high-speed bomber will give a much larger amount of IR radiation to the front, and the lead pursuit system can follow a fighter collision course initially, turning automatically towards a weapon collision course as the target comes within firing range. This prospect of development will be examined in more detail at a later stage.”
It should be pointed out that English Electric wanted to develop Blue Jay based on the Mk.2, rather than the Mk.4 (Blue Vesta), be commonly specified by other F.155T competitors – even though the brochure drawings clearly depicted the P8 with Blue Jay Mk.4s rather than Mk.2s.
According to the brochure: “The IR weapon developments already described are different from those proposed for Blue Vesta, but are less extensive, particularly in relation to the insulation requirements. It is possible that if this weapon were developed only to our own requirements, it would be no larger than Blue Jay and differ only in detail.
“It seems certain that airborne guided weapons can be designed successfully only with the emphasis on one supersonic fighter system, so that this problem must be solved by the tender competition.”
This approach to Blue Jay/Blue Vesta would later lead to conflict between English Electric and de Havilland Propellers.
The F.155T specification was very definite about the number of crew that the Air Ministry expected to have aboard their new interceptor: two. English Electric had not been privy to the months, years even, of heated debate which had resulted in this particular aspect of the spec. If it had, it might not have so easily dismissed the two-crew option, presenting instead a single-seater.
From a technological standpoint, English Electric struggled to understand why the ‘back seater’ was necessary since automated electronic and hydraulic actuation systems were available which could ease the pilot’s workload: “The performance and handling problems resulting from trying to add a second crew member are being investigated in the present airframe, since there appears to be no advantage in increasing the size of the fighter for this purpose. Our wind tunnel tests suggest that these problems will delay the development [of the interceptor] and that the penalties may not be justified in a simple pursuit supersonic fighter, particularly if the pilot is aided by auto-control.”
The P.8 was designed as a thoroughly practical, buildable solution to Britain’s interceptor problem. It relied on relatively modest developments of existing technology and might well have been ready to enter service exactly when the company said it would. However, it failed to meet the specification in terms of both the guided weapons it could carry -no radar guided missiles – and the number of crew it was designed to carry. And the Air Staff were very particular about both.
Cold War Interceptor is published by Mortons Books and is available to order here along with many other beautiful aviation books. Save 10% on all books with exclusive promotional code ‘AVGEEK10’!
Photo credit: BAE Systems and Crown Copyright
