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Aviation History
1965
1965 - 0838.PDF
456 FLICHT International, 25 Worch I9t5 AIRCRAFT GROUND POWER UNITS... more of these expensive "one-basket" vehicles than of any one type of separate unit. Whatever the eventual trend, there is a big market for British manufacturers with, as a start, more than one-quarter of the world's international airports within the British Commonwealth. To hold this market, manufacturers will have to maintain the highest standards of serviceability, pay close attention in design to operating conditions very different from our own, and provide over-the- counter parts support. The review and tabulation of British GPUs which follows includes at least 80 different types with electric output, 14 air starters, and eight air conditioning units: a wide choice for any operator. G.c.s. MAKERS' PRODUCTS REVIEWED Aircraft Ground Equipment Ltd, Blackswarth Road, Bristol, 5 (Bristol 51912) This company's output of hangar and apron equipment includes several electric GPUs and—although AGE specialize mainly in units to meet customer's individual requirements —a selection of standard units is available. Alternator sets (400 cycles) may be supplied trailer-mounted or as static units, and either diesel or electrically driven, employing brushless, self-exciting electronically controlled alternators. Single- and dual-voltage generator sets are diesel-powered and trailer-mounted; screen- protected, shunt-wound, or tandem-compound-wound interpolar self-excited generators are employed, and output is controlled by transistorized units or automatic carbon-pile voltage regulators as required. Associated Electrical Industries Ltd, Aircraft Equipment Group, Raglan Street, Coventry, Warwickshire (Coventry 24181) Steam is a source of energy not normally associated with aircraft, and AEI appear to be the first to harness its power for ground support. Their steam generator—mounted on a Land-Rover chassis—has been developed for steam starting any aircraft turbine fitted with an air starter motor. A vee-belt power take-off from the vehicle drives water and fuel pumps and a centrifugal blower. Blower delivery enters* a reverse-flow combustion chamber which exhausts through the evaporator. Full steam output is available within 5sec from start-up, operations being controlled by a single lever. The unit consumes 4.5gal of water and 0.45gal of kerosene to start a Conway-sized engine, and carries sufficient fuel and water for 30 engine starts. Atlas Copco (Great Britain) Ltd, May lands Avenue, Hemel Hemp- stead, Herts (Boxmoor 6040/5) Specialists in compressed-air generators and tools for a variety of industrial applications, this Swedish-born company also manufacturers the Air Partner com- pressor unit, with trailer or truck mounting, for air starting large turbojets. Petrol- or diesel-powered, and designed for continuous running, a water-cooled, surge-free, single-stage rotary-screw compressor is driven via an automatic coupling and supplies a constant flow of warm, oil-free air at automatically regulated output pressure. Capable of starting four engines in about 60sec, the unit may also be used for engine motoring, limited ground air-condition- ing, and de-icing either through the aircraft system or by external blowing. Compressor time-between-overhauls is normally about Murex 20900 GPU in use for servicing a BEA Trident 10,000hr, and maintenance is limited to periodic oil changes. The Atlas Copco Group provides worldwide service to oper- ators, which include 15 major airlines and six international airports. Auto Diesels Ltd, Braby House, Smithfield Street, London EC1 (Central 2388) One of the few manufacturers in the world pro- viding both electric and air ground power, Auto Diesels manufacture a range of self-contained units to satisfy virtually every demand. Petrol or diesel engine power provides adequate reserve in electric units to meet peak generator loadings in any climate, and to allow for normal performance-drop between overhauls. A choice of d.c. generators is available, using over-compounded machines designed to meet shock loads, or under-compounded, using separate excita- tion and transistorized automatic voltage regulators. Both types allow for voltage-drop in the supply cable to provide constant voltage at the aircraft. Alternating-current units are fitted with high-frequency alternators, rotating-diode exciters and transistorized AVRs. Push-button control gear incorporates full protection. The company's jet air starters use Cummins diesels driving Ingersoll-Rand air-cooled, surge-free helical-rotor compressors, to supply high-mass-flow oil free air for engine starting. Air condition- ing and de-icing are additional uses. Automatic regulation follows selection of the required control position. The STAD A/250 is a simple, compact and light industrial gas turbine giving approximately 230 b.h.p. at 26,000 r.p.m. in its basic form. A single-stage centrifugal compressor and centripetal turbine are bolted back-to-back on a cantilever mainshaft. Compressor delivery (3.16 : 1 ratio,) passes through a radial diffuser to twin tangential combustion chambers, and out through a volute to the turbine at 800C° entry temperature. Output to the aircraft is taken from a compressor bleed. All units are available trailer- or truck-mounted, and several of the electric models can also be supplied self-propelled, combining the additional function of tug if desired, the single engine powering both traction and generator drive. Interlock systems prevent generation during traction and vice-versa. Seventy per cent of the company's production is exported, and it is claimed that some 60 per cent of the world's airlines outside the USA use Auto Diesels equipment. Aviation Traders (Engineering) Ltd, Soutfiend Airport, Southend-on- Sea, Essex (Southend-on-Sea 49471) A 60kVA GPU suitable for operation in any climate, and as in service with British United Airways, is available trailer-mounted, or as a self-propelled vehicle using the hydrostatic wheel principle. A lock-on circuit automatic- ally adjusts to the power requirements of the majority of 400-cycle aircraft. Separate power (28V d.c., 9kW) is also available for starting AAPUs in the One-Eleven and Trident. Bristol Siddeley Engines Ltd, Leavesden, Herts (Garston 4000) Bristol Siddeley's Small Engines Division has developed three gas turbines of Turbomeca descent for operation as auxiliary power plants, the Palouste in ground and airborne units, and the Artouste and Cumulus for airborne use. The Palouste is primarily a low-pressure air generator for turbojet starting and cabin conditioning, approximately one-third of the air mass flow being bled from an annular casing around the combustion chamber. Limited demands for high pressure air, and for electric and hydraulic power, can also be met if desired, by accessories mounted on the front of the gearbox casing. An automatic safety device will protect the engine against over-heating should the delivery hose burst. A Palouste mounted in a tubular steel frame, complete with fuel tank, batteries, control panel, and electric starter with hand crank stand-by, is, at 4701b, one of the lightest and smallest GPUs in existence. This unit can be carried slung alongside a helicopter, and may also be stowed in an airliner's baggage compartment. A slightly larger hand trolley version is available, weighing 9001b; with anti-surge control incorporated, it will start a VC10. Fuel demand is less than Igal per engine start. Although Palouste air starters may be fitted with intake and exhaust silencing, noise is not a serious problem, because running times are short. Special Palouste pods have been designed for attachment to weapons pylons on naval aircraft. The streamlined nose section accommodates the fuel tank, batteries and instrument panel, and stowage space for the nosewheel, towbar and starting handle. Main wheels and delivery hose are stowed in the exhaust duct at the rear, during flight. Large numbers of Paloustes are operated by the Services,
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