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Aviation History
1948
1948 - 1852.PDF
548 FLIGHT November ^th, 1948 THE FASTER THE HOTTER THE cleverly devised graph which we reproduce wasrecently published by the Airesearch Mfg. Co., ofLos Angeles. Intended to show the temperature rise consequent upon air speed at varying altitudes, the temperature curves are said to have been computed on the following basis: the temperature at any altitude and speed is the sum of the Standard Army Summer Day tem- perature at that altitude and the ram temperature rise for the given speed. Ram temperature rise in degrees F. is found by dividing the true air speed in m.p.h. by 5,650. We do not know how the American Standard Army Summer Day temperature scale compares with the I.C.A.N. temperature scale, which is normally taken as the inter- national standard for performance calibration ; but it may be seen from the graph that the tropopause is given at about 47,000ft instead of the normally accepted standard of 36,000ft. This, however, is not a critically important point, and would affect the intersection points of the tem- perature curves in minor degree only. The real import of this matter is, of course, the problem of coping with the large temperature rise due both to ram compression and skin friction at the higher air speeds. Mr. Garrett, president of Airesearch, expressed the effects of the problem : " In to-day's high-speed jet planes the cockpit temperature would rise to at least 165 deg. if it were not for a new method of refrigeration." The new method of refrigeration referred to is the Airesearch air-cycle turbine cooling unit which, weighing less than 16 lb, is said to produce 4.2 tons of refrigeration. One ton of refrigeration is equivalent to dissipation of the heat required to melt one ton of ice at 32 deg F. in 24 hours (in this instance, the American ton of 2,000 lb applies).
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