Overview
Wave drag is caused by the formation of shock waves around the body. Shock waves radiate a considerable amount of energy, resulting in drag on the body. Although shock waves are typically associated with supersonic flow, they form at a lower speed at areas on the body where local airflow accelerates to sonic speed. The effect is typically seen on aircraft at transonic speeds (typically about Mach 0.8), but it is possible to notice the problem at any speed over that of the critical Mach of that aircraft. The magnitude of the rise in drag is impressive, typically peaking at about four times the normal subsonic drag. It is so powerful that, prior to the 1940s, it was thought that aircraft engines would not be powerful enough to overcome the drag, which led to the concept of a sound barrier.
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