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Aviation History
1941
1941 - 2008.PDF
FLIGHT. Sept. 4th, 1941 Advt. 12 THE XMAJOR No. I. ON PETROL COCKS Taking poison to discover the consequences is an antiquated mode of scientific research. It may have j contained an element of humour for/ him who watched but none for him who stood and waited. Nor can we afford to crash planes from 40,000 ft. in an effort to find the answer to the seizing of petrol cocks at high altitudes. Luckily, the science of engineering is less empirical than toxicology. We have a few guiding principles and more appliances. A first essential in a petrol cock is that it be turned on and off easily; the operational effort must be the minimum compatible with petrol tightness. By dint of much patience and many patents, we perfected a mechanism to operate at 12 inch lbs. at ordinary room temperatures. Then, instead of going up, we went . down. Using a freezing mixture, we took the tempera- ture of the petrol cock down to —10% — 20 °, -30°, - 40 °, — 50° Centigrade. The operational effort needed to turn the cock rose sharply to 60 inch lbs. at — 40 ° C. At -500 C. the cock completely seized; the effort needed to turn it was beyond the capacity of the apparatus, 150 inch lbs. Thereupon, the problem was referred to our enthusiastic if somewhat shaggy metallurgist. For once we did not have long to wait for an answer. For once it was the correct answer. This time the operational effort at — 50 ° C. was only 17 inch lbs. i.e. well below the maximum effort of 30 inch lbs. which it is estimated a pilot with gloved hands can exert. It was a matter of using the right metal in the right place and in the right way. Simple, isn't it ? fuel Systems for Aircraft etc. POWER ROAD, LONDON, W.4 DESI DEVELi JPMENT JCTION FOR AIRCRAFT High Pressure Pipe Couplings Electrically Heated Pressure Heads Oxygen Equipment Control Dampers FOR AERO • ENGINES Carburetters Starters Flame Traps Sand Traps Screened Harness TAUNTON.SOMERSET Telephone :TAUNTON 3634
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