On the Conventional Definitions of Thrust/Drag of an Aircraft Equipped with a Turbojet Engine

The identification of the jet propulsion forces from those of the aerodynamic forces of body to which the propulsion system is fitted, is still one of the most controversial subjects involved in aircraft performance predictions and thrust/drag flight test results. In fact the inter‐action between airframe and engine aerodynamics makes the use of independent airframe and propulsion performance impossible.