Page 182 - Understanding Flight
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High-Speed Flight 169
the ground. The thermal expansion of this surface in flight will The Concorde fuselage expands
remove the corrugation to produce a smooth surface. The as much as 10 inches due to
SR-71 fuel tanks must also take into account thermal heat from skin friction in
expansion. On the ground, when the SR-71 is cold, the fuel cruise.
tanks have gaps that leak fuel. By the time the SR-71 has
reached cruise, the fuel take has expanded to close all the gaps.
Wrapping It Up
Newton’s laws are still applicable in describing lift on high-speed air-
planes. But high-speed flight involves some additional physics such as
shock waves, wave drag, and high temperatures. The shock waves
arise because the vehicle travels faster than the air can pass informa-
tion: the speed of sound. High temperatures result from the energy
exchange of the fast vehicle with the still air.
Next we look at the overall performance of airplanes and consider
tradeoffs that occur when designing for specific missions.
