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Aviation History
1961
1961 - 0944.PDF
44 FLIGhi 13 July i Lightning F.I A of No 56 Sqn LIGHTNING "THE BEST FIGHTER IN THE WORLD" BRITISH aeronautical technology has always advancedsteadily, in parallel with that of other major nations.Nevertheless, for financial reasons, our programmes involving actual combat aircraft have been forced to progress in leaps and jumps, rather than in a series of orderly steps. Thus, the RAF had to take in one leap the transition from the Meteor 8 to the Hunter; and today young, first-tour Hunter pilots are converting to the 1,500 m.p.h., missile-armed, all- weather English Electric Lightning intercepter. This advance is an even greater one, and it is giving Fighter Command a defensive weapon system of tremendous effectiveness. When a nation is constrained to attempt large technologicaljumps, lead-times become even longer than the inevitable minimum of some six years for any advanced type of aeroplane. In fact, thehistory of the Lightning can be traced back 13 years, to the days when the Vampire F.3 was taking its place alongside the Meteor F.4,and Britain had officially abandoned the idea of producing a piloted supersonic aeroplane. But during 1948 this decision increasinglyappeared to be an error of the first magnitude, for the Bell XS-I had exceeded Ml the previous October and the transonic F-86 Sabrewas about to enter USAF squadron service. In fact, the Ministry of Supply picked up the threads of mannedsupersonic flight late in 1947, and started preliminary discussions with manufacturers. These talks eventually led to ExperimentalRequirement 103, calling for an aeroplane capable of research at transonic and low supersonic speeds. In 1957 this journal said, "By 1949 such manufacturers asEnglish Electric and Fairey had given the problem a great deal of thought, and both companies submitted proposals. Fairey's aero-plane became the record-breaking F.D.2, virtually a minimum supersonic envelope for a pilot, engine and fuel."1 The article wenton to discuss the English Electric aeroplane, and further details of the early history of both research aircraft prefaced our full descriptionof the F.D.2 the following year.2 From the outset. English Electric's design team, then led by MrW. E. W. Petter, were convinced that there would eventually be an Air Ministry requirement for a supersonic fighter, and they plannedtheir E.R.103 submission—which was known as the P.I—to facili- tate its eventual conversion to fulfil an operational role. In theevent they were quite right, and specification F.23/49 called for a supersonic day fighter in the summer of 1949.By this time English Electric had received a contract for two P. 1 aircraft, plus a static-test airframe, against the original researchrequirement. The configuration chosen3 was one of striking appearance and, although it has been adopted by no other manu-facturer, it offers a unique combination of advantages. It was very early appreciated that two engines would burn less fuel than onelarge engine with a high degree of reheat, and would also permit control duplication. It was not long before the decision was takento mount the pair one above the other. The fact that both then lay on the aircraft centreline eliminated all engine-out asymmetry, andby tucking the upper engine down behind the lower engine it was found that twice the thrust of a single powerplant could be had forbarely 1.5 times the frontal area. This gave a slab-sided body, on which the wing was mounted above the centreline. Aerodynamically the P.I is a considered compromise between thedemands of the upper and lower parts of the performance spectrum. Bearing in mind that the original requirement was for a very modestsupersonic performance, it was calculated that the optimum wing would have a leading-edge sweep of 60°, allowing a relativelygenerous depth and a leading edge of substantial radius. Neverthe- less, the then-popular delta shape was rejected on the grounds that itwould give inadequate control in the pitching plane, especially at extreme altitude and in the approach. The P.I was given a tailplane,and this was mounted low on the fuselage in order to avoid the pitch- up moments which have since been suffered by fighters with hori-zontal tails mounted high on the fin.3 The trailing edge of the wing was cut back at almost the same sweep-angle as the leading edge,and the ailerons were mounted transversely at the tips (i.e., joining the leading and trailing edges). All controls were fully powered. Other design choices were a direct pitot intake in the nose (ade-quate for the range of Mach numbers originally envisaged), split flaps, airbrakes on either side of the propelling nozzles, and a ratherunusual landing gear in which the long main legs were pivoted near the geometric centre of each mainplane and folded outwards, andthe nosewheel retracted forwards and turned to lie flat beneath the air duct. For obvious reasons, there was little or no volume avail-able in the fuselage for fuel, but the wing was designed as an integral- tank box between the spars. Although the immediate commitment was merely the manufac-ture of an experimental aircraft, English Electric and the Ministry of Supply were faced with the need to undertake a very largeprogramme of research before much metal could be cut. The company decided to finance the construction of a turbojet-poweredtunnel, initially commissioned in 1949 as a high-subsonic installa- tion but modified the following year to have a slotted lft-sq workingsection for transonic operation. This was the first privately owned transonic tunnel outside the USA and with it English Electricperfected new methods of instrumentation for Mach numbers between 0.6 and 1.1. In 1954 an even greater expenditure wasauthorized for a tunnel powered by two Nene engines, with an 18in slotted working section capable of being replaced by solid liners forM1.4, Ml.6 and Ml.7. Further investment was made in a complete simulated P.Icockpit and flying-control system. A comprehensive analogue computer was incorporated, and the arrangement had six degrees offreedom in order to explore behaviour fully. With this apparatus a
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