ERV Design Chris Heidelberger Dynamics & Control 01-23-01 AAE 450 ERV Design Chris Heidelberger Dynamics & Control 01-23-01
Design Considerations Launch trajectory Planetary transfer trajectory Attitude control Capture options
Launch Trajectories Earth launch trajectory is determined by launch vehicle, system and site. Using slightly modified, existing launch schemes, the launch trajectory is constrained to previously designed missions. Mars launch trajectory will be a function of g-loading, local terrain and final conditions.
Mars Launch Trajectory Assumptions -Flat Mars -No aero drag -Constant gravity field Final V at LMO=5.6 km/s ODEBVP optimization routine in Matlab (written by Prof Williams) Need GOOD initial guesses before routine can converge on solution.
Attitude Control Vehicle Shape -Outbound -Return Control Means -Thrusters -Rate Gyros Control Algorithms
Vehicle Shape Outbound Mission Cylindrical Spin stabilized Min. Comm. req. No human factors Even heating Structurally easier Return Mission Cylindrical, spin stabilized vs 3-axis stabilized
Return Mission Spin stabilized Control System Attitude Dynamics Structures Constrains Shape Human Factors Interior Design Pointing for Comm. 3-axis stabilized Human factors Comm. Req. More functional Lifting body Minimum 6 nonlinear, coupled equations (7) Complicated control
Three Axis Stabilization 2 Stable orientations - not very intuitive Unstable orientations - more “natural” - heating issues Can be stabilized with thrusters and gyros, similar to Shuttle Drawn by Chris Heidelberger
Control Methods Existing systems -well tested and proven -off the shelf technology and price Outbound -small thrusters to spinup, station keeping Return -more complicated
Control Method: Return Mixture of thrusters and moment gyros Thrusters for station keeping, fast maneuverability and gyro desaturation Moment gyroscopes for more efficient, precise attitude control Proven technology based on ISS systems
Applicable Skills Previous Experience - 440, 490e, 507, 508, 532, 564 -Three summers working ISS GN&C at Boeing Currently taking AAE666