The effect of ambient temperature on the matching requirements of inlet-engine combinations has been analyzed for two typical turbojet engines up to a Mach number of 3.5. The changes in ambient temperature ordinarily encountered in flight can markedly influence the performance of matched inlet-engine combinations for engines operated at constant mechanical speed. Up to 30 percent of the capture mass flow may be spilled at the design Mach number because of typical variations in the ambient temperature. Thus, to avoid subcritical operation, the use of variable inlet features are required even at the design Mach number.
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