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Aviation History
1964
1964 - 1016.PDF
FUGHT International, 9 April 1964 571 27- 5 © Iliffe Transport Publications Ltd 1964 technique of machined integral skin/stringer construction from solid slab and shot-peen-forming to curvature, hitherto applied to the comparatively thick skins of Vanguards, VClOs and One-Elevens, has been extended to much thinner skins and sections, stiffness being achieved by machining out to form deep flanged stringers. This skin-milling technique, new to BAC's Preston Division, has been taken up in a big way by their "very preferred" subcontractor, the English Electric Co at Accrington, Lanes. Here, numerous Marwin skin millers have been installed specially for the produc- tion of TSR.2 wing and fuselage planks. It is planned eventually to apply Ferranti tape-control to these machines. At this works, also, an automatic-scanning ultrasonic testing machine has been installed for inspecting all incoming billets. This machine displays flaws on an oscilloscope, and also pin-points on the metal the approximate zone of the flaw. Fins, tailerons and airbrakes are also made at Accrington, to a very high standard of interchangeability. The forming of the milled planks to the required curvature is carried out by the main con- tractor at Samlesbury works, which is equipped for shot-peen- forming and presswork. The all-moving "taileron" surfaces are supported on plain bearings, since ball or even needle-roller bear- ings would occupy too much bulk inside these extremely thin struc- tures. For these bearings, Ampep licence-produce new p.t.f.e.- based materials which minimize friction and breakout forces. Production of TSR.2 is accelerating the introduction of numeri- cally-controlled machine tools. The probability of their introduction at Accrington has already been mentioned. At the BAC Preston Division, Ferranti-tape-controlled Kearney & Trecker milling machines have been brought in. At one time the machining of hard titanium alloy presented problems. To get satisfactory results the cutting tool must have a very uniform speed. The tape-controlled machine provides the best way of achieving this improved control of cutter movement, resulting in longer cutter life, closer tolerances, a better finish on the workpiece and reduced tooling costs. Landing Gear One of the most unusual—if not unique—features of the TSR.2 undercarriage is the extending nose leg. This incorporates not only hydraulic retraction (forward) and steering, but also a hydraulic extension, shortening and locking capability which enables the TSR.2 to sit on the ground at two quite different angles. In the nose-high attitude both lift and drag are increased, to reduce the field-length required. Each main gear has a single leg attached to one of the main fuse- tege/wing frames, carrying two wheels in tandem. The unit retracts forwards into a compartment close beside the armament bay and intake duct. Supersonic wave-drag considerations demand mini- mum cross-section in this region, and this has posed installational This illustration was prepared by a "Flight Inter- national" artist last October, and first appeared in this journal on October 31. Although of a provisional nature, it gives a clear indication of the general design of the aircraft I, Slab rudder; 2, pivots; 3, slab tailpianes (together for pitch, differential for rcll); 4, tailplane flap (locked at high speed); S, p.c.u.s; 6, full-span flaps; 7, flap blowing; 8, fuel system vents; 9, aerials; 10, electronics door; II, terrain-clearance and attack radar; 12, electronics bay; l3,Doppler; 14, navigator's cockpit; IS, pilot's cockpit; 16, variable intake (inset); 17, fuel fillers; 18, tankage (shaded); 19, pre-closing wheel doors; 20, undercarriage bay; 21, articulated main gear; 22, l-p tyres; 23, ncse-gear bay; 24, extendable leg; 25, air-conditioning spill; 26, Olympus 22R engine; 27, reheat jetpipe; 28, weapons bay. • 17 problems accentuated by the nesd to splay the legs out to give adequate track. In order to achieve adequate strength for operating this very heavy aircraft from rough surfaces, without exceeding the severe restrictions on available cross-section, all major leg members are forged and machined in a very high quality ultra-high-tensile steel to an English Steel Corporation Ni-Cr-Mo-Va specification. This is the first time that steel of such strength has been used in a major production application in Britain. It is no easy task to work in steels of this kind, and the manufac- ture of the complete units has been subcontracted to Electro- Hydraulics Ltd of Warrington, Lanes. EH have undertaken con- siderable development work in this field during the past few years, and have also installed a number of advanced machine tools necessi- tated by the high-grade materials. Heat-treatment methods have been developed in co-operation with BAC and English Steel Corp. BAC designed the legs to have very long stroke, in order to accom- modate the undulations of long wavelength met with in semi- prepared surfaces. The oleo has a soft characteristic over most of its travel, but it stiffens towards the limit of its stroke. To meet the requirement of withstanding high impact and single- wheel loads at high speeds while operating from soft dispersed areas, TSR.2 has relatively large wheels with low-pressure tyres. The latter have been under development at the Goodyear Tyre & Rubber Co (Great Britain) Ltd and the Dunlop Rubber Co Ltd since the original GOR.339 type of aircraft was first considered. From the outset it was realized that the tyre designers would be faced with new and formidable problems. The required type of tyre became known as the "high-speed puff bag." It was necessary to devise a shape and type of construction which would operate at low inflation pressure without the formation of destructive traction waves in the tyre during high-speed and high- load conditions during take-off and landing. The take-off condi- tions are the most difficult to meet. Traction waves give rise to excessive shear, tensile and compressive stresses in the tyre carcase, and accelerations of a very high order are experienced on portions of the tread. All this generates considerable heat, and ply and tread start to separate. In these conditions tyres can disintegrate ex- tremely quickly. These problems have now been surmounted, and Goodyear claim to have been the first to meet the TSR.2 specifica- tion during realistic and exhaustive dynamometer testing. Goodyear and Dunlop tyres are being used alternately on the first batch of aircraft. The Dunlop contribution also includes
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