1. ERV Design Chris Heidelberger Dynamics & Control 01-23-01
AAE 450
ERV Design
Chris Heidelberger
Dynamics & Control

2. Design Considerations
Launch trajectory
Planetary transfer trajectory
Attitude control
Capture options

3. 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.

4. 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.

5. Attitude Control Vehicle Shape -Outbound -Return
Control Means -Thrusters -Rate Gyros
Control Algorithms

6. 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

7. 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

8. 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

9. Control Methods
Existing systems -well tested and proven -off the shelf technology and price
Outbound -small thrusters to spinup, station keeping
Return -more complicated

10. 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

11. Applicable Skills
Previous Experience - 440, 490e, 507, 508, 532, 564 -Three summers working ISS GN&C at Boeing
Currently taking AAE666