Manoeuvrability at High Speeds

FORTY years ago the pilots of the earliest aeroplanes were embarrassed by the very restricted speed range of their aircraft. Often the maximum level speed obtainable was a mere ten miles per hour above the stalling speed. As the art progressed the aerodynamicist and the power plant designer joined forces to raise the top speed while the invention of flaps and slots helped to offset the effects of increasing wing loading and kept the stalling speed to a reasonable value. For many years our pilots have enjoyed a comfortable speed range of several hundreds of miles per hour which even the increased stalling speed in steep turns has not seriously reduced. In the last few years, however, the pilots of the latest high speed, high flying fighters and bombers are worried by finding that the speed range of their aircraft is again becoming constrained, not only by the familiar boundaries of the stall and the maximum available speed, but by new and more fearful boundaries. What is the cause of the return of this aeronautical claustrophobia?