Determination of thrust characteristics of air-breathing jet engine

The traditional approach to measuring the thrust of air-breathing jet engines (ABJEs) was proposed by B.S. Stechkin in 1929. In this approach, the thrust is determined as the difference between the momenta of the gas flows at the engine inlet and outlet. This approach involves some methodological and terminological problems. Based on the critical analysis of available concepts, the present article proposes a new approach to the determination of ABJE thrust in the form of the reduction of the initial drag of the aircraft + ABJE assembly observed when the propulsion system operates with fuel supply and energy release. For the thrust thus obtained, we propose using the term “real thrust”. It is shown that the proposed approach eliminates terminological problems and simplifies the technique for measuring the thrust characteristics of ABJEs. The paper considers various options in applying the proposed approach to the determination of the “real thrust” for different cases of using and modeling ABJEs, including the calculation of flight trajectories of ABJE-powered aircraft.