CORRECT matching of inlet ductwork to jet engine demands and accurate control of variable inlet geometry are prime requirements for maximum thrust under all operating conditions. The first step is to design a variable inlet to meet changing speed, altitudes, airplane attitudes, and power requirements.
Efficient designs will have a large number of shock waves of equal strength to minimize the total pressure loss across the shocks. The geometry of the inlet, its boundary layer control, and bypassed air must be varied with changing flight conditions to meet the efficiency objective.
External shock inlets have simple internal flow patterns but can starve the engine if their shock pattern does not intersect the cowling. Internal shock inlets are not bothered with this problem but require careful compression surface control to prevent expelling the shock. The authors describe two methods of inlet controls, the closed-loop and scheduling types.
The authors of this paper were awarded the 1957 Manly Memorial Medal.