INTRODUCTION

Data Items in the group ESDU PERF RP 1/1, 1/2 and 1/3 (References 2, 3 and 4) give the standard British methods of performance reduction for piston-engined aircraft with constant-speed propellers. Besides ignoring compressibility effects these methods contain certain other assumptions, for example average values are assumed for the variation of propeller efficiency with speed and for the effect of forward facing intakes and the relations assumed for the engine performance do not apply to turbo-blown or compounded engines, or to engines with charge temperature control. Because of these limitations there are some cases in which it is necessary to use a more general form of the performance reduction equation, and ESDU PERF RP 2/0 (Reference 5) suggests a method of doing this.

The formulae given in Data Items of the group ESDU PERF RP 1/1 to 1/3 enable corrections to be made for temperature differences from standard, for change of weight, and for the effect of wind gradient on rate of climb.

It will be noticed that the notation used is slightly different from that of Reference 6; in particular the minimum drag speed, (V_i)_md, has been used instead of the minimum power speed, (V_i)_mp.