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Aviation History
1963
1963 - 0684.PDF
656 FLIGHT International, 2 May 1963 INDUSTRY International Flight Systems Products Company News Great Britain PRODUCTS Lucas Trident Contribution The CASC (combined acceleration and speed control) system for the Rolls-Royce Spey engines of the de Havilland Trident, which is the subject of a detailed description in this issue, has been supplied by Lucas Gas Turbine Equipment Ltd, Shaftmoor Lane, Birmingham 28, who have provided the following details:— "This system is a somewhat new approach to fuel control in that direct mechanical methods of operation are used rather than hydraulic servo systems (the fuel pump stroke-control is, however, still servo-operated for simplicity). In addition, the main fuel control valves rotate contin uously, thus rendering the system imper vious to dirt and icing effects and providing considerable anti-hysteresis properties. Four assemblies make up the system, these being the high-pressure fuel pump, fuel control unit, low-pressure shaft governor and high-pressure fuel shut-off cock. "The following various functions are performed by the system: (1) the fuel flow is split into the proportions required for the Duplex type of burner; (2) a metered quantity of fuel is supplied to the burners to maintain a given engine condition for any selected throttle position at all altitudes; (3) the supply of fuel during acceleration is made to match complex engine surge characteristics at all altitudes, thus ensuring that the degree of over-fuelling is such that the engine accelerates to the required speed in the shortest possible time without the risk of high-pressure compressor stall or excessive temperatures being generated in the region of the turbine blades; (4) vir tually isochronous governing is achieved— i.e., each position of the throttle provides an almost constant h-p shaft speed regard less of intake or ambient conditions; (5) a rising engine idling r.p.m. is obtained with altitude to suit engine requirements; (6) compensation for fuels of differing specific gravities is provided; and (7) pro vision is made for the coupling of a control which feeds j.p.t. signals directly to the throttle mechanism of the fuel control unit. This device overrides the normal sched uling function of the fuel control unit, should exceptional conditions arise, and so safeguards against engine damage."' Trident Seating Passenger seats for the BEA Trident are designed and manufac tured by Flight Equipment and Engineering Ltd, 142 Cromwell Road, London SW7, in close co-operation with the corporation. The tourist cabin is largely composed of six-abreast seats (two units of three each) of both forward- and aft-facing types, designed to provide the highest possible standard of comfort, at standard tourist 34in pitch. The seat contours neatly match the cross- section of the fuselage sides. The most revolutionary visual feature is the seat-back, which consists of a sheet metal structure, the rear surfaces of which are padded for safety reasons, the whole being covered with a hard-wearing, wash able, pre-formed skin, which is readily replaceable. Rotox l-p air starter for the D.H. Trident. Air supply is 231b jsq in (1.05 to I Jib/sec) at I50°C; cut-off speed at drive coupling, 4,700 r.p.m.; clutch disengagement speed, 5,700 r.p.m.; gear ratio, 9:1; peak torque (stall), I35lb-ft; shocktorque (max), 300lb-ft; weight, 2l\lb maximum dry. Rotax are also responsible for high-energy ignition units, air control valves, locking solenoids and a screwshaft for the tail- plane autopilot trim The forward side of this seat-back provides a recess for the back squab, which is composed of varying grades of Polyether accurately contoured for comfort. Both back squab and seat cushion are quickly removable from the seat, as are the upholstery covers. The folding rear tables, designed to accommodate BEA meal trays, fit snugly into the recess provided in the seat-backs, and as a further safety precaution the whole Fluoroflex hose, made by Palmer Aero Products Ltd under licence from Resisto- flex Corp and lined with Fluon p.t.f.t- tubing, was specified for the pressure, return and drain lines of the hydraulic systems for the powered controls, under carriage (picture, left), wheel brakes and spoilers of the D.H. Trident. These hoses—about 150 in all—hove qualified for a flying life of 5,000hr at maximum pressure of 3,500lbjsq in and a temper ature range of —55° to — 150 C D.H. Trident seating by Aircraft Equip ment Ltd (see description above), show ing the seat-back with recessed table and p.v.c.-net stowage
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