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Aviation History
1957
1957 - 1259.PDF
30 August 1957 347 from one inch to 12in blade tip diameter.They vary in application from the cooling of radio and radar equipment to flightdeck boost ventilation and cabin air recir- culation. A specific cabin airflow applica-tion is for the 800 series Viscount. The Plessey Co., Ltd. Becoming well-established as an ancillary manufacturer to the guided missile as well as to the air-craft industry, the Plessey Group of com- panies have developed a power pack forrecharging servo-hydraulic accumulators. This is a turbine unit using iso-propyl-nitrate monofuel with combustion initi- ated by an electrically fired cartridge; theturbine drives a hydraulic pump through a reduction gearbox.A fuel control valve is incorporated to vary fuel flow to the combustion chamber(and the power output of the turbine) with changes in hydraulic loading. Thespeed range is thereby governed to within five per cent, both on and off load. Thepower pack can be assembled into a mis- sile and left in store in a safe condition.Provision is made for test running of the unit, using an external fuel supply, up tofull hydraulic pressure with the unit charged with fuel. The specified poweris 20 hydraulic h.p. at pressures up to 4,500 lb/sq in, and the dry weight is 16 lb. A new development is a low voltageself-contained fluorescent lighting unit Plessey iso-propyl power pack. operating from a 24V D.C. supply. Avibrator oscillating at 200 c.p.s. converts the supply to A.C. and then transformsit to provide a suitable voltage for the lamp filaments and discharge currents.The 8-watt fluorescent tube is 14 mm in diameter and 12in long. Rapid technical progress has been madein electronic and communication equip- ment. In this field are a "Castanet" TypeA disc-type tantalum capacitor, embrac- ing capacity values from 50 to 750 /*Fand with various mountings; radar- absorbing materials which eliminate un-desirable permanent images from radar screens; and materials such as indiumantimonide—a compound which is a sen- sitive detector of infra-red radiation. Thelast-named material is used as a single crystal filament in Plessey's infra-red cellType PC21. This detector has a useful application in the spectroscopy field, ininstruments for the detection and analysis of gases, and in pryrometry.Other new products from the Plessey Group are a 3 kVA inverter similar to atype to be supplied for use in the Van- guard. The unit weighs less than 60 lband, from a D.C. input supply between 25 and 29V, provides a three-phase out-put of 200V, 400 c.p.s. at any power fac- tor between 0.8 lag and 0.95 lead. For^mall gas turbines a fuel-control unit is being developed. Operating at 4,000r.p.m. and delivering fuel at 500 lb/sq in it will control turbine speed to ±0.5 percent and will give a 50 per cent change in fuel flow (up to a maximum of 25gal/hr) for a one per cent speed change. The Pyrene Co., Ltd. The latest itemin this company's range of fire-fighting and crash-protection equipment is theimpact crash switch, Type PCS/1. It con- sists of a lever projecting underneath thebelly of the aircraft which, on striking the ground, breaks a cathodeon frangibleswitch and initiates the electrical crash circuit. To avoid false alarms from birdstrikes in mid-air the tripping of the lever produces another lever in its place, andit is the deflection of this second lever which actually initiates the crash circuit;thus a single strike in mid air would move only the first lever, but solid impact withthe ground would, of course, trip both. Pilot-operated switches are provided toarm, de-arm or test this device. The com- plete switch can be mounted flush withthe aircraft skin and connected to the crash circuit with a single four-pin plug. Rotol and British Messier, Ltd. Rotol,Ltd., are responsible for the design of the propellers for the F.27 Friendship. Theyare similar to those on the Viscount, but are two feet greater in diameter and theblade bearings are slightly larger. The propeller operates from a starting pitchangle of 0 deg to the feathered angle of British Messier nose undercarriage for English Electric P.1B. approximately 84 deg. The blade leadingedges, the spinner nose and the engine air intake are electrically de-iced. Also for the F.27 is the automatic r.p.m.synchronizing equipment. A small three- phase alternator is fitted to each engine;one of which is selected as the master. A further small connector motor is incor-porated in the control system of the slave engine. A switch in the cockpit gives on-off control and, in operation, automatically adjusts the r.p.m. of the slave engine tothat of the master. This equipment can be adapted to four-engined aircraft. Production of bleed air turbine and fuelflow proportioning equipment continues. The latter equipment has lately beenmodified by the addition of hydraulic power to drive the proportioning valves. The unit no longer takes power from thefuel line, but can impart a pressure rise as the fuel passes through its cells.Apart from manufacturing the P.I, Britannia and Gnat undercarriages, BritishMessier have developed their 4,000 p.s.i. motor pump unit 4873—among a widerange of hydraulic equipment—for long periods of operation. Special features areglass and silicone insulation. Rotax, Ltd. Continuing their develop-ment of variable-speed, constant-fre- quency alternators (to supplement theirwidely-used D.C. generating equipment), Rotax have produced the new 80 kVA unit Rotax 80 kVA variable-speed alternator. shown in the photograph. Rectified A.C.schemes have been designed for outputs of up to 900 amp, 112V D.C. and 400 amp,28V D.C. Rotax alternators running at constant speeds of 8,000 r.p.m. and 24,000r.p.m. give outputs of 0.5 kVA to 130 kVA and 15 kVA to 55 kVA respectively. The company claim that every Britishgas turbine engine has been started with Rotax electrical starters, of which 28VD.C., 112V D.C., and 208V three-phase A.C. types are manufactured. Enginestarting is one of Rotax's special interests; they have also developed cordite, fuel/ airand low pressure air starting systems, including the new 5712/1 pneumatic unit. Among the range of electrical equip-ment developed is a wide range of rotary and linear actuators, motors, inverters andcontrol panels. The latest versions of the last-named utilize magnetic amplifiers andcan maintain an almost constant output voltage and frequency irrespective of widevariations in load and input voltage. Saunders Valve Co., Ltd. Reallyefficient valves are Saunders' concern. They have, it is claimed, now realized100 per cent efficiency in their spherical Saunders motorized spherical plug valve. two-way plug, and 95 per cent in a "Y"-ported multi-way type. These valves meet British and American specificationrequirements and are supplied in manu- ally and electrically operated forms. A
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