Abstract:

The cruise trajectory model of a hypersonic vehicle, which couples the vehicle’s aerodynamic characteristics, propulsion characteristics and flying conditions, is established under the certain geometry constrains. Then the scramjet-powered cruise trajectories of the fixed-altitude flight and skipping flight are analyzed subject to maximizing the flight range. Results show that the skipping flight has the advance to fixed-altitude flight on flight range by 18.5%, and the flight time increases by 15.5%. In fixed-altitude flight, the vehicle quickly transits from the initial state to a quasi-constant-velocity state, in which the lift-gravity force and thrust-drag force are both in balance. In skipping flight, the lift and gravity force keep in balance through changing flight altitude. This makes the flight altitude in skipping flight is higher than fixed-altitude flight and the drag force is relatively smaller, then the thrust force and fuel consumption rate in skipping flight is less than fixed-altitude flight, which leads to the longer flight range and flight time in skipping flight.

Key words: Hypersonic vehicle, Couple, Scramjet, Fixed altitude flight, Skipping flight