Second-Stage Trajectories of Air-Breathing Space Planes
Abstract
Attention throughout the world has turned to the benefits that can be gained in space transportation by combining the features of aircraft and rockets. In the rocket-driven phase or stage, which follows the nearly horizontal air-breathing flight, a considerable change in the flight trajectory, a pullup maneuver, is necessary shortly before or after igniting the rocket engines. The change puts a burden on the first or the second stage and thereby reduces the payload. In this paper an optimal strategy for the rocket-propelled flight phase is developed that gives the smallest penalties on longitudinal acceleration and, therefore, on burnout mass. The strategy leads to a splitting of lift and thrust component normal to the flight direction. Two other control strategies are compared with the optimal procedure. Using a generic modeling of aerodynamic characteristics, the equations of motion are solved to assess the influence of initial conditions and of trajectory parameters on the burnout mass. Results of the study show the essential influence of the initial values of flight-path angle and Mach number on the rocket-propelled flight phase. Initial flight-path angle should not be lower than 5 deg. If a reasonable amount of payload and propellant for in-orbit operation should be carried, the dry-mass ratio of the second stage must come down to the range of 15 to 20, depending on the separation Mach number (5 to 6.5).
- Publication:
-
Journal of Spacecraft and Rockets
- Pub Date:
- December 1990
- DOI:
- 10.2514/3.26189
- Bibcode:
- 1990JSpRo..27..618S
- Keywords:
-
- Aerodynamic Characteristics;
- Aerospace Planes;
- Air Breathing Engines;
- Flight Paths;
- Rocket Planes;
- Equations Of Motion;
- Rocket Engines;
- Rocket Thrust;
- Trajectory Planning;
- Astrodynamics