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Aviation History
1949
1949 - 1135.PDF
7i8 FLIGHT JUNE I6TH, 1949 Revolutionary Refuelling —will be Demanded for Ultra-large Air- craft : The Principal Problems Reviewed By C. G. COLLINGS THE increasing size of aircrafthas presented a number of newproblems to those who have to service them. The Constellation at 93,000 lb has been eclipsed by the French S.E.2010 at 116,000 lb and the StFatocruiser at 142,500 lb. We are told that by 1951 the Brabazon at 285,000 lb and the S.R.45 at 310,000 lb all-up weight will be in operation. The fuel capacity of the Brabazon is 11,500 gallons. To refuel it com- pletely, therefore the normal type of 2,000-gallon road tanker delivering petrol at a total rate of about 120 gallons per minute from two pumps would take 96 minutes pumping time and would itself need refuelling five times. By the use of six such tankers the time can be brought down to about a quarter of an hour. This, however, would not be a very good way of securing a quick turn-round for aircraft of this size. Most of the airfield tanker vehicles would be monopolized for one air- craft and there would be serious duplication of very costly pumping equipment that is required. Here, then, is a problem for those engaged in the design and production of airfield refuellers and, more than ever before, it is one that will have to be solved in conjunction with the air- craft designers. In the past the problems of refuel- ling have always been something apart from those concerned with the actual aircraft. The big oil companies, with their own personnel and the backing of organizations that are larger than all civil aviation, have been considered by airfield staff as completely separate units which invariably lived '' over on the far side." Their problems have not been those of the airfield controller and, although they have been eager to co-operate, their coming and going, and the petrol they had available, has been entirely their own business, be- yond the knowledge of the controller. Now that several giant aircraft are an accomplished fact the mutual problems of the oil companies, the aircraft designers and the aircraft operators will have to be met together. Airfields in America—particularly La Guardia—have taken active steps to install pipe-runs and connection hydrants for refuelling. In this coun- try prototypes of new tankers and pumping arrangements are constantly being developed by specialist firms, at the insistence of the oil companies, in an effort to satisfy the changing de- mands. One of their difficulties IS Today's methods may suffice for the aircraft of today : the ultra-large machines which will shortly be appearing will demand new refuelling equipment and a different technique. lack of knowledge of the strength of aircraft internal tankand pipe connections under the considerable stress of high pressure, high-speed refuelling, and what the trend is inthis direction. It is to be hoped that aircraft design may be changed to include underwing or lower-fuselage refuelling-points, thus obviating the clumsy and dangerous business of drag- ging heavy pipes over de-icing equipment and clambering about on the upper surfaces of the wings. There is a 2Jin-diameter underwing connection produced which will take a delivery of 200 gall/min, but it is doubtful whether all internal pipe-runs can stand much increase on this rate of delivery. That is the problem of the aircraft designer. The refueller designer has the problem of increasing the rate of delivery through his air- eliminators, filters, flow-controllers and meters, and this is by no means simple. One firm has experimented with delivery through 2^in pipe of up to 300 gall/min. For rates greater than this, there are a host of attendant troubles. Liquid forced at this rate through a certain size of pipe soon reaches a limit at which it is discharged with terrific force, frothing and turbulent, and with the risk of generating a con- siderable charge of static electricity. The writhing hose of a fire engine, delivering at about 60 gall/min, is quite difficult to hold; delivery at about 300 gall/min makes a flexible hose almost entirely unmanageable. A nozzle is a considerable restriction and, for any high rates of delivery, it must be dispensed with in favour of some form of direct underwing con- nection. The necessity of such direct- connection fuel points is very apparent for all large-capacity aircraft. If two pumps are sufficient to dis- charge petrol at the rate of some 300 gall/min each, the 2,000gallon tanker, which is the normal large-capacity B 24 " It is to be hoped that aircraft design may be changed to include underwing or lower-fuselage refuelling points." The 200 galljmin underwing connection on the Martin 2-0-2.
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