Abstract:

ESDU 70021 outlines the method of performance measurement used when drag is determined from a knowledge of thrust. The thrust may be obtained from flight measurements or it may be estimated. It involves more computational work than the methods discussed in ESDU 70022, ESDU Perf RJ2/0 and ESDU Perf RJ2/1, but it enables greater use to be made of the flight time and is less demanding on pilot technique. It is applicable in the subsonic and supersonic flight regimes. The theory is outlined in ESDU 70020 which also indicates the limitations of the non-dimensional approach used in ESDU 70021. Various additional factors (Reynolds number, thrust angle, centre of gravity variation, power plant operation, gravity variation, flight path length, buoyancy) that affect the analysis of measured performance are discussed in ESDU 70020 and methods by which they may be taken into account in applying the approach of ESDU 70021 are indicated there. The extensive worked example shows how the results of such testing on a jet fighter are used to predict operational performance.