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Aviation History
1963
1963 - 0674.PDF
FLIGHT International, 2 May 1963 641 TRIDENT... Fin structure follows that of the wing, and its single-cell box is extremely stiff and carries the forged steel tailplane pivot just ahead of its rear spar. There are no spanwise members in the rudder apart from the spar, but the ribs are closely spaced and the structure is specially designed to withstand noise damage. There are six rudder hinges, four of these being grouped in the centre around the three rudder power units behind the fin rear spar. The centre section of the slab tailplane is a stiff box with upper and lower skins machined in three dimensions by the Fairey/ Ferranti tape-controlled miller at Heaton Chapel. This box collects air loads from the outer panels, which have spars at 15 and 70 per cent chord, Reduxed stringers and etched skins. To the trailing edge is attached an elevator geared to the tailplane in a manner opposite to a conventional balance tab, with a single spar and a Reduxed doubler skin over the whole exterior. This elevator moves in the same sense as the main surface, so as to increase tailplane camber and power, which is increased further by a slot aperture between the main surface and the elevator. Each main-undercarriage unit has a single leg in 85-ton (190,0001b) steel, with levered suspension to an axle carrying two wheels each with two tyres. This levered-suspension unit was introduced on the third BEA aircraft and will be fitted to all Tridents. Dunlop Maxaret multi-pad disc brakes are fitted, with fans to boost brake cooling for quick turnrounds. The leg retracts inwards while a cam mechanism increases its length by 6in and turns the axle so that the wheels lie neatly fore-and-aft in the circular body cross-section. The arrangement is some 5001b lighter than a bogie, occupies 28 cu ft less body space, requires no fairings and imposes no restriction on turn radius. The main gears can free-fall, and may be lowered independently of the nose gear as an airbrake. De Havilland designed and manufacture the main undercarriage, but the steerable nose unit is by Lockheed Precision Products. The latter is equally unconventional, for the leg is offset 24in to port of the centreline and retracts sideways into a narrow transverse slot. This allows the forward electrical bay to be enlarged and entered in flight, provides stowage for the optional airstairs, makes a more economical cut-out in the fuselage and provides ready-made boundary members in the form of the frames which diffuse the nose-leg loads. Powerplant Planned specifically for this aircraft, the Rolls-Royce RB.163 is now known as the Spey. It may be described either as a turbofan or as a "by-pass jet engine", and its basic characteristics are given in the section drawing on page 645. A description of the original Spey -1 appeared in this journal on May 18, 1961. It has a four- stage 1-p compressor (or fan), a twelve-stage h-p compressor, a tubo-annular combustion chamber with ten flame tubes each served by a single nozzle, a two-stage h-p turbine, a two-stage 1-p turbine, and a mixer unit where the cool fan air is mixed with the hot jet. Although it was prepared from a clean sheet of paper to match the original BEA Trident 1, the Spey incorporates all the vast fund of experience gained by Rolls-Royce with the Dart, Avon, Conway and Tyne in commercial service. Well over 25m engine Indent IE take-off field-length for maximum-payload operation _i I I I III I I 500 1,000 1,500 2,000 STILL. AIR RANGE (run) Airline operating curves for the Trident IC (top), IE (centre) and IF (bottom). Curves A are for direct operating cost, according to I960 ATA formula; curves B are for takeoff (ISA, sea level), with space-limited payload as shown in C, the plot of payload against range. In the latter, reserves are 45min standoff at 15,000ft, 220 n.m. diversion, approach, land, taxi in, final reserve and 4j f>er cent en route allowance hours have been flown on short-haul routes with Comets, Caravelles, Viscounts, Friendships and many other types of aircraft. From the outset, Rolls-Royce have endeavoured to achieve an engine which, while having an unrivalled performance and the lowest possible specific consumption, would be immediately responsive to pilot demand, quiet on takeoff and approach, easy and cheap to main tain, and capable of reaching long times between overhaul, with parts lives in no way inferior to the world-beating lives already achieved with previous Rolls-Royce civil engines. Thrust at high altitudes and temperatures can be maintained by the use of a simple water-injection system. Bench running of the Spey began at the end of 1960, the engine flew in October 1961, and ARB special-category approved was obtained in July 1962. This approval confirmed Type Test approval, guaranteed weights, thrusts and consumptions, and enabled Rolls- Royce to start the delivery to de Havilland of production engines. Total flight and bench time is now approximately 10,000hr. When de Havilland prepared their first studies for the Trident IE and IF they based their calculations upon the Spey -1. In the course of 1962, however, Rolls-Royce prepared a major "growth' version of the Spey, designated RB. 163-25, and Government support of this engine was announced on November 19. The Spey -25 differs from the Spey -1 principally in having a fifth stage added at the rear of the 1-p compressor (a reversion, in fact, to the [Continued on page 645, reverse side of fold-out page
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