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Aviation History
1956
1956 - 0777.PDF
15 June 1956 Makers' drawing of cockpit layout of the Wyyern S.4. Details are:— 777 1 Arrester hook control. 2 Clock. 3 Toilwheel lock. 4 Emergency hand-pump. 5 Gyro angling unit. « Rudder and aileron trim switches. 7 Elevator-trim wheel. 8 Armament master-switch. 9 Engine power-control (with "press- to-speak" button, and gun-sight range control). 10 H.P. cock and friction damper. 11 Air brakes. 12 Airscrew fire-pitch stop selector. 13 Airscrew starting pitch, and brake button. 14 Flap selector. 15 R.A.T.O. jettison button. ii Undercarriage and flap position indicators. 17 Fuel-tank selector. 18 A.P.I. unit. 19 Engine starting group. 20 Undercarriage selector. 21 R.A.T.O. firing switches. 22 Contacting and radio-altimeters, 23 Altitude limit warning lamps. 24 Mach meter. 25 Brake pressure. Ik Windscreen wiper control. 27 Cockpit floor heating control. 28 Gun-sight master switch. 29 Gyro gun-sight Mk 4B. 30 Chart-board. 31 Chart-board lamps switch. 32 Contacting altimeter warning lamps. 33 Standard blind-flying instruments. 34 Engine instrument group. 35 Fuel contents and pressure group. 36 Oxygen control panel. 37 Gyro selector dimmer. 38 External lamps switch panel. 39 Hood-winding handle. 40 Armament and camera control panel. 41 Radio and radar control panel. 42 Very pistol. 43 Wing folding controls. 44 Rudder-bar adjusting wheel. 45 Seat adjustment. 44 Control column, with armament selector switch. 47 Brake lever. 48 Sanitary tube. light-alloy boom extensions. The lower engine-mounting attach-ment points are carried on the front face of the front spar and, as already described, a cruciform bracing of diaphragm webs andextruded booms is interposed between the front and main spars in way of the fuselage. The rear spar, the chief purpose of whichis to accommodate the loads of the Youngman flaps, is a smaller version of the main spar incorporating a plate web and extrudedlight-alloy boom. Almost the entire volume between the front and main spars istaken up by the undercarriage wells. While the legs themselves are of unusual design, so too are one or two other aspects of the-undercarriage system. For example, the undercarriage jacks are employed as radius struts and, despite the cruciform bracingrendering additional space unavailable, the legs are arranged to contract during retraction by means of a lever linkage between themain pintle and the head of the liquid-spring capsule. The inboard fairing doors are much stronger than is conventional and,hinged on the cruciform bracing, are locked by latch mechanisms on the front and main spars. They are, in addition, hydraulicallyoperated in sequence so that after the undercarriage has been locked the doors close; conversely they are opened before theundercarriage is retracted. When retracted, the leg and wheel assemblies are normally supported by hydraulic pressure. Shouldthis pressure fail, the inboard doors and latches are strong enough themselves to hold up the undercarriage units. Outboard fairingpanels are directly linked to the shock absorber housings of the legs themselves. Dunlop wheels, tyres and pneumatically-operated segmental brakes are employed. The Youngman flaps are interconnected by a bridging torquetube across the fuselage, but each surface is individually actuated by a Dowty through-rod jack carried on the rear spar. Fromeach end of the jack-rod, a connecting rod system in roller guides transmits motion to bell-cranks from which driving links arepivoted to the flap suspension links. An emergency air system is incorporated in the circuits of both undercarriage and flaps. Per-forated inner airbrakes, solenoid-operated from a trigger switch on the pilot's column, are fitted to the centre section and housedbeneath the ammunition bay. With the outboard cannon in the outer wing panels and theinboard cannon in the centre section, some complexity of wing- fold arrangement was inevitable but, on examination, the solu-tion is commendable. The wing-folding jack is carried along the front face of the main spar and picks up to a T-crank, the inboardend of which is pivoted in a forged fitting adjacent to the spar- attachment fork, while the outboard end is pivoted to a trans-mission link pinned to the top boom of the outer wing main spar. The spar join is made with twin-fork end-fittings which are through-bolted with the boom ends, the hinge axis beingabout 6in inboard of the latch pin on the lower booms. Port and starboard wings can be folded independently and stopped atany intermediate position. Just forward of the rear spar on the centre-section end-rib is anchored the locking jack which,through a swing lever, operates a roller carriage, to the forward end of which is fitted the locking pin. Aileron control transmis-sion is broken at the joint and is ingeniously arranged so that, when the wings are folded, the ailerons are centrally locked andthe transmission from cockpit to joint is also locked and centralized. The outer wing panels are of monospar form and, as alreadymentioned, a portion of the leading edge is fashioned as an integral fuel-tank. The break necessitated in the fuel line at the wing-fold is effected by means of a self-sealing Exactor coupling, and the Exactor company also supplies the coupling in the adjacentair line for tank pressurizing. The fuel coupling is furnished with a cam-latching mechanism, so that the coupling can bebroken and swung down through an access door with the wings spread, in order that the tank may either be drained or pressure-fiUed. A plain flap is combined with a hinged upper-surface of thewing, outboard of the gun bay, to form an air-brake. The ailerons are structurally similar to the elevators and rudder, andlike these surfaces, are fitted with Westland-Irving balances. The port aileron is fitted with a trim tab operated by a Metrovickelectric actuator, while both ailerons are fitted with torsion-bar- sprung servo tabs. Barrier fences are fitted to both upper andlower surfaces between the ailerons and the air-brakes. A minor modification to the wing root fillet, made in conjunc-tion with the extension of the jet tailpipes, was the introduction of a double fillet skin through which air passes for coolingpurposes. The leading edge of the wing is now rubber-sprayed; a process designed to cure erosion by salt-water but which broughtwith it an incidental improvement in the handling qualities of the machine at low airspeeds. (A cut-away drawing of the Wyvern appears overleaf.)
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