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Aviation History
1955
1955 - 0819.PDF
FLIGHT, 10 June 1955 817 CORRESPONDENCE ... that he has never known the firm who make such things to supplyanything in less than six weeks from the date of ordering. So far as I am concerned, therefore, rapid transit is of no importancewhatever; while the firm concerned will require considerable internal reorganization before it pays them to despatch their goodsby air, at any cruising speed. Horning, Norfolk. N. YOUNG. CORRESPONDENCE IN BRIEF Referring to a Royal Aero Club list of Committee memberspublished in our issue of May 6th, the Association of British Aero Clubs and Centres comments on the appearance, under theheading "Other Representatives," of an R.Ae.C. Committee member's name against the name of the A.B.A.C. The Asso-ciation state that co-opted members of their Council retire at the same time as elected members; these retired last December, andthe R.Ae.C. "have not again been invited to nominate a repre- sentative of their Committee for co-option to our Council." May 30- June 10. June 1-10. June 1-11. June June 1-18. 3-17. June 7-15. June 10-19. June 11. June 11. June 11. June 17-24. June 18. June 18. June 20- July 1. Sept. 5-11. FORTHCOMING EVENTS Canadian International Trade Fair and Air Show, Toronto. Aluminium 1955 Exhibition: Royal Festival Hall, London. British Plastics Exhibition and Convention: Olympia, London. Royal Tournament, Earls Court, London. Aeronautical Union of Jugoslavia: Sixth Federal Gliding Contest, Jugoslavia. French Aero Club: F.A.I. 50th Anniversary Rally, Paris. Paris Aero Show. R.Ae.C.: Third National Air Races meeting, Bristol. Royal Air Forces Association: Air Display, R.N.A.S. Syden- ham, Belfast. Aircraft Golfing Society: Match v. Racing Club de Paris, La Boulie, Paris. F.A.I.: General Conference. R.N.A.S. Eglinton, Northern Ireland: Air Day. R.N. Electrical School, H.M.S. "Ariel," Worthy Down, Win- chester: Air Day. I.A.S. and R.Ae.S.: Fifth Anglo-American Aeronautical Conference, Los Angeles. S.B.A.C. Show, Farnborough. AIR-DRIVEN FUEL BOOSTER PUMP DIFFERENCES in design between one type of fuel boosterpump and another have generally concerned details rather than fundamentals. Most such units have, in the past, employedcentrifugal impellers driven by adjacent electric motors, the com- plete unit then being mounted in the bottom of one of the fueltanks of the aircraft. In common with other airborne accessories, fuel booster pumps are having to meet ever-increasing demands.In particular, the flow rates required by modern military power- plants are enormously greater than anything visualized even tenyears ago, and the sheer power required to drive booster pumps capable of delivering over 3,000 gal/hr poses considerable prob-lems. Even discounting the accentuation of difficulties resulting from the trend towards high-speed wings of thin section, it isbecoming very hard to accommodate electrically driven booster pumps of the size and weight which are now required. A specialist firm in this field is the Self-Priming Pump andEngineering Co., Ltd., of Slough, Bucks, who have long been one of the world's principal suppliers of tank-mounted boosterpumps. They saw that the advantages of driving a high-rated booster pump by an air turbine running on compressor-bleed airmerited careful consideration, and that such a unit would be extremely attractive from the aircraft design standpoint. Thecompany have now developed such a unit, with a current rating of 3,500 gal/hr at 11 Ib/sq in. It embodies a two-stage centrifugalpump driven through bevel gearing by a two-stage impulse turbine which is supplied by air tapped from the main compressor of theengine. The air is normally bled off from the first or second compressor stage but air at a higher pressure—and consequentlyhotter—can be employed. The bleed air is ducted through a governing valve to the turbine rotor and then to the exhaustconnection via a heat-insulating jacket which surrounds the inlet elbow.After passing through the mesh filter, the fuel is picked up by a helical impeller which performs the dual functions of de-aeratingand pressurizing the fuel before the latter is fed to the main impeller. It is clearly desirable that the consumption of air in this photograph of the new S.P.E. development the turbine is on the left, together with its governor unit. should be kept to a minimum, and the pump incorporates agoverning unit which is acted upon by a pressure-sensing device to maintain a constant delivery pressure of approximately 11 lb/sqin. This governing unit restricts the supply of air to the turbine and closes automatically when the pump load is reduced, so pre-venting over-speeding. Lubrication of the gearing, turbine rotor and upper pump-shaft bearings is accomplished by mountingthese units in an oil bath. A carbon bearing is fitted at the lower end of the main spindle and this bearing is lubricated by the fuel.The whole assembly is moiinted on a sump plate, which is then attached to the tank floor in the usual manner, with the majorpart of the unit immersed in fuel. Equipment of this nature has to undergo the most thoroughtesting, and S.P.E. have now acquired a considerable background of experience in using their own altitude test chambers, in whichhigh rates of climb up to a simulated altitude of 60,000ft can be accurately reproduced. The air-driven booster pump has alreadybeen subjected to very thorough testing through all its stages of development, and it has now successfully completed its typeperformance tests and is fully approved by the M.o.S. At the present time, the improvement of the performance ofaccessories is a pre-requisite to better aircraft, and S.P.E. appear to have removed a significant restriction in power which previouslyapplied to orthodox booster-pump design. It is generally agreed that the delivery quoted above is by no means the limit to whichdevelopment may be restricted, and S.P.E. are considering the design of similar pumps widi varying capacities, and one of theseunits may possibly replace the several pumps now employed on many aircraft. At their Slough factory, the S.P.E. company employ this altitude test chamber in the development of fuel-system equipment for all tvoes of high-performance aircraft.
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