The results of a study to investigate concepts for minimizing trim drag of horizontal takeoff single-stage-to-orbit (SSTO) vehicles are presented. A generic hypersonic airbreathing conical configuration was used as the subject aircraft. The investigation indicates that extreme forward migration of the aerodynamic center as the vehicle accelerates to orbital velocities causes severe aerodynamic instability and trim moments that must be counteracted. Adequate stability can be provided by active control of elevons and rudder, but use of elevons to produce trim moments results in excessive trim drag and fuel consumption. To alleviate this problem, two solution concepts are examined. Active control of the center of gravity (COG) location to track the aerodynamic center decreases trim moment requirements, reduces elevon deflections, and leads to significant fuel savings. Active control of the direction of the thrust vector produces required trim moments, reduces elevon deflections, and also results in significant fuel savings. It is concluded that the combination of active flight control to provide stabilization, (COG) position control to minimize trim moment requirements, and thrust vectoring to generate required trim moments has the potential to significantly reduce fuel consumption during ascent to orbit of horizontal takeoff SSTO vehicles.
Trim Drag Reduction Concepts for Horizontal Takeoff Single-Stage-to-Orbit Vehicles
1991
32 pages
Report
No indication
English
Spacecraft Trajectories & Flight Mechanics , Aerodynamics , Aerodynamic drag , Aerodynamic stability , Air breathing engines , Drag reduction , Flight control , Fuel consumption , Horizontal flight , Hypersonic vehicles , Single stage to orbit vehicles , Active control , Aerodynamic balance , Ascent , Center of gravity , Conical bodies , Elevons , Orbital velocity , Rudders , Thrust vector control