Variation of Engine Power with Height as Determined in Flight by indirect Methods

THE variation of full throttle engine brake horsepower with altitude at constant rotational speed is a matter of great importance to aircraft designers and those concerned with the measurement of aircraft performance. For the former its main importance probably lies in the design of aeroplanes intended for high altitude use where accurate knowledge of the engine power available is of paramount importance in the evolution of a successful aircraft. In the measurement of aircraft performance it is necessary to reduce the observed results at non‐standard atmospheric conditions to those obtaining under the chosen standard conditions, and for this it is essential that the variation of engine power with altitude is well established.