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Aviation History
1952
1952 - 0929.PDF
4 APRIL 1952 FLIGHT 61 Essolutely! BY BERNARD HOLLOWOOD TTTE'RE all agreed, I take it, that one of the most ' " endearing features of any aircraft is its retractable undercarriage. We are also agreed, I hope, that this retractable undercarriage should not only retract when necessary but should tract and be tractable at all times. We are ? Good. Well, this goes, too, for other airframe accessories—wing flaps, control tabs and so on. Now these gadgets, if the term is permissible, are usually operated hydraulically—you know, according to the principles of hydraulics, hydrodynamics and hydro statics (cross out those that do not apply), as adumbrated by the great scientists . . . or . . . how ridiculous, I shall be forgetting my own name next. Why ? Because, as any hydraulician will tell you, there is no simpler or more efficient way of converting the high speed rotary power of a motor into the slow speed linear power needed to operate these airframe accessories—these gadgets. Hence the hydraulic pump and ram ; and hence the bewildering range of plumbing which lies before me, in diagram matic shape, as I write, and which some revolt- ingly smug hydraulician > K^^^-iB H^Cf has had the nerve to label: \\ fl Br "Simple chart showing IV Hill ^ow °^ °^**n hydraulic .] ^^_J 111 system of Large Modern K_ JSIIL. 'Plane." I will say no more about this masterpiece of modern design except that it contains more arrows than a penal settlement, and that any fluid capable of finding its way round the maze must be essolutely marvellous. Essolutely ! Like the fuels and lubricants with which it is associated, the hydraulic fluid must do its job under all possible conditions—at great heights, at temperatures as low as minus sixty degrees C. (and lower !) and as high as one hundred degrees C. It must remain completely unruffled and behave with the utmost sang-froid even when sorely tempted to stage a sit-down strike or go all temperamental. In other words it must never betray its feelings by any marked change in viscosity : otherwise, of course, the gadgets or airframe accessories (including the retractable undercarriage) will not function with their accustomed and very necessary smoothness. For reasons of economy, and in order that the size of pumps, pipes and jacks can be kept reasonably miniature, hydraulic systems are worked at very high pressure —which means another strain on the poor old fluid. But the oil technicians manage somehow to bolster up its resistance and aplomb in their own inimitable fashion. There is one possible snag. Inflammability. High- pressure systems can leak, and when they leak the fluid is finely atomised and susceptible to ignition. What are the researchers doing about this ? Well, they're working resolutely to develop new fluids—fluids endowed with all the virtues, including non-inflam mability, and at the time of going to press success is very much in sight. So it pays to fill up with the right hydraulic fluid, and frpays lb say £sso, FOR ALL PETROLEUM PRODUCTS ESSO PETROLEUM COMPANY, LIMITED, 36 QUEEN ANNE'S GATE, LONDON, S.W.I
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