AIRCRAFT ENVIRONMENT, THERMAL EFFECTS

Aircraft which are not narrowly restricted in latitude and altitude of operation must withstand the effects (1) of ambient temperatures which extend from -100°F to +200°F, and (2) temperature changes which under adverse conditions will become very rapid (of the order of 40F° per 1000 ft). Temperatures are low and relatively stable at high altitudes and are moderate and stable at ground level in the tropics. The widest variation occurs, however, at ground level in Temperate and Polar regions; and aircraft which must operate in Arctic regions, such as those adjacent to the Bering Sea, must cope with temperature inversions of considerable severity.

Extremes of compartment temperature are even more widely separated than extremes of ambient temperatures because of the effects of solar radiation and of aerodynamic or kinetic heating--so that allowances must be made in fully enclosed areas for temperatures as high as +200°F.

The effects of changes in steady-state temperature upon stresses exerting on fixed structural members and upon fittings employing such structural features as force fits are shown to be of great magnitude and are illustrated by specific examples. The probable effect of temperature transients upon such members is suggested.