Selection of ejector-ramjet mode transition interval on RBCC

The performance evaluating method that takes into account the RBCC restrictive real operation condition of ejector and ramjet mode was set up based on aircraft design flow chart. The change of specific impulse and thrust coefficient of motor using different fuels with flight trajectory were discussed. The selection method based on optimum specific impulse and minimum thrust fluctuation of ejector/ramjet mode transition interval was put forward.In considering the reference flight trajectory of a certain mission, the reasonable mode transition interval in condition of Ma=2.6±0.1 flight velocity and 11.7~12.9 km flight height was resulted.