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Aviation History
1963
1963 - 0668.PDF
640 FLIGHT International, 2 May 1963 TRIDENT... including fatigue to 60,000 l£hr flights, following deliberately inflicted damage; and (8) testing to ultimate static strength. Apart from the main fuselage and wing, which has still to do 10,000 more flights in its tank, the programme is complete up to stage 6 in all cases and up to stage 8 on the nose specimen. AH primary structure subject to fluctuating tensile stress is of Al-Cu alloys equivalent to the US 2024S and 2014S materials. Where fluctuating stresses are mainly compressive the higher strength of Al-Zn alloys can be used, and the top skins and stringers of the wing correspond to the US 7075S specification. The wing consists of a centre section the width of the body, a two-cell box out to 40 per cent semi-span, a single-cell box to the tip, and second ary leading and trailing structures. The 40 per cent station joint (Rib 8) is marked by a change in dihedral. The skins are continu ous through the body side but are joined on the aircraft centreline. The centre section is divided into six bays by five spanwise cabin-pressure beams which act as tank baffles (in the Trident 1C only the four middle bays are filled with fuel). The wing root ribs are integrally stiffened, but the remaining ribs are generally plate webs with extruded booms and vertical stiffeners attached by Redux bonding, riveting or bolting. The front spar, which runs to the tip, and the centre spar, which terminates at Rib 7, and the outer part of the rear spar are all plate webs with extruded and machined booms and with Reduxed vertical stiffeners inside the wing box. Out to Rib 8 a single stringer is Reduxed on the other side of the web at two-thirds of its depth to provide a fail-safe crack-stopper. In the outer wings this fail-safe duty is assumed by duplicated booms. The inboard rear spar is integrally machined, with extruded booms bolted back-to-back and the lower boom duplicated out to the undercarriage boxes at Rib 5. Wing skins are taper-milled from plate, pocketed to leave rein- forcings for the Redux-bonded spanwise stringers of "Welsh-hat" section and the booms of the ribs to which the skins are bolted. There are 12 skins in all: front and rear inboard, with a maximum thickness of 0.328in below and 0.248in on top in the Trident 1C, and single skins outboard of the dihedral break, with thickness tapering from 0.203in to 0.106in below and from 0.140in to 0.070in for the top skin. The stringers have varying thickness and section, but all run parallel and fade out into the front and rear spars as the wing tapers. The bottom skins include elliptical tank-inspection manholes. Leading-edge structures, including the four slat sections and Kriiger flap, are built up from chemically milled sheets leaving passages for the 190°C de-icing air. Aft of the main box the wing includes a light false spar supporting the stiffened skin over the undercarriage box, as well as a large machined light-alloy forging carrying the rear main-leg trunnion. Each flap section has three main spars and an intercostal nose, and its skin is etched with a wavy edge to each pan to avoid cracking along a line of rivets. Each flap can sustain proof load with any cell cracked. Ahead of it is a conventionally built slat-like vane, attached rigidly to the flap to make the latter double-slotted. Inner and outer sections are driven independently to a maximum of 50° by hydraulic motors located to port of the aircraft centreline, via torque tubes, gearboxes and ball-screwjacks with ice-scrapers on the threads. Each flap section runs on two steel rails which, although obviously safe-life parts, have redundancies in their attachment to the wing. In the fixed wing ahead of the flap the undersurface takes the form of deflector plates, made of metal honeycomb some 0.75in thick, which are slaved upwards by the flap mechanism. Ahead of the inboard flaps are narrow-chord lift dumpers to improve tyre adhesion (and hence braking) after landing. Ahead of the outer flaps are single four-spar airbrakes, which serve the same function as well as acting as speedbrakes and lateral controls in the air. The airbrakes open to 50° and bear proof load with any of the four hinges failed. The ailerons are conventional single-cell structures with fail-safe hinges. The main pressurized fuselage has a skin diameter of 145£in. It is designed to a pressure differential of 8ilb/sq in, and incorpor ates unpressurized underfloor sections for the retracted under carriage. The nose radome is a mixture of solid laminate and honey comb to withstand hail damage, and is attached to a short metal section ahead of the front pressure bulkhead. Body skins have thicknesses from 0.048in to a maximum of 0.080in in the side panel over the wing, and the ruling method of construction is Reduxed General-arrangement drawing of Trident IE TRIDENT VARIANTS IC IE IF Engines Type Guar, thrust Dimensions Span Length Height Fuselage length Freight volume Fuel capacity Wing area Leading edge Typical seats Weights Basic operating Capacity payload Max a.u.w. Max z.f.w. Max landing Performance Take-off. 15° flap Take-off for 1,000 n.m. 1.000 n.m., ISA + 20°C Landing field lengch Typical approach EAS Airline range, max PL Vno/Mno High-speed cruise Economical cruise Spey 1 Mk 506-5 10.4101b 89ft lOin Il4ft9in 27ft 103ft 6in 740 cu ft 4,840gal 1,358 sq ft Droop 20F/63T 67,5181b 19.3141b 115.0001b 89,5001b 102,0001b 7,250ft 6,400ft 7,750ft 5,920ft I29kt 1,040 n.m. 360kt/0-875 528 kt (609 m.p.h., M0.875 at 24,000ft) 508kt(585 m.p.h., M0.87 at 32,000ft) Spey 25 Mk 510-5 II,4001b (final) 95ft Il4ft9in 27ft 103ft 6in 740 cu ft 5,440gal 1,415 sq ft Slat 20F/69T 69,6081b 21.0621b 128.0001b 92,5001b 105,5001b 7.100ft 5,550ft 5,800ft 5,740ft I26.5kt 1,710 n.m. 340kt/0.875 522kt(600 m.p.h., M0.875 at 27,000ft) 502kt(579 m.p.h., M0.86 at 32,000ft) 95ft 123ft II in 27ft Il2ft9in 950 cu ft 5,440gal 1,415 sq ft Slat 20F/78T 75,1231b 24,4841b 128,0001b 100,0001b 112,0001b 7,350ft 6,570ft 6,990ft (wet) 6,100ft I32kt 960 n.m. 340kt/0.875 5l6kt(594 m.p.h., M0.865 at 27,000ft) 503kt(580 m.p.h., M0.855 at 30,000ft) top-hat stringers and riveted Z frames at a pitch of 20in, this design being capable of safe operation with cracks up to 20in long. A substantial proportion of the body, including large rectangles round every door, the flight deck, the trailing edge and the centre engine and duct, incorporates etched panels with peak thicknesses round the cut-outs of up to 0.256in. Windows in the flight deck are four-ply glass/Vinyl laminates with Triplex gold-film anti-icing, which have been extensively tested by sled-firing the complete nose 20 times against stationary 41b bird carcases—the reverse of the usual procedure. Passenger windows are 13|in by lOin, spaced one to each inter-frame bay. There are two transparencies each capable of withstanding the full cabin pressure, the outer being 0.5in Perspex. The surrounds have a typical total thickness of 0.196in. made up of a 0.048in skin, 0.036in reinforcing, 0.064in doubler and 0.048in peripheral pan, the whole being Reduxed. Frames 35 (front spar), 41 (rear spar) and 44 (main-gear bulkhead) are heavier than normal, and contain duplicate fail-safe load paths typically by consisting of back-to-back extrusions capped by a butt strap. Close to the end of the pressure hull is a large double- webbed bulkhead carrying the side-engine front mountings and bearing redistribution loads caused by the change in body section aft of the pressure bulkhead. The side-engine rear mountings are attached to a triangular-section beam across the sloping front fin spar bulkhead, to which are also anchored the side-engine thrust struts. The pressure dome lies between these heavy frames, ahead of the side-engine turbines, its web being stiffened by riveted hat sections laid vertically on the front and horizontally at the rear— another fail-safe arrangement. Fin and tailplane loads are diffused via the stub fin into two very stiff sloping bulkheads which are jointed to the front and rear spars of the fin itself. The stub fin has etched skins, and diffuses end loads from the fin stringers. Much of each bulkhead is made up of integrally machined sections duplicated back-to-back; where this is impracticable, the booms are duplicated and the wefs stiffened by Reduxed crack-stoppers. The front tubular steil mountings for the centre engine are attached to the rear fin spar bulkhead. The aft pick-up is a steel forging attached to a titaniui i and light-alloy box below the rudder.
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