Reentry Applications

3DOF and 6DOF reentry trajectory optimization

With this ASTOS application for high L/D vehicles you easily determine

optimal 3-DOF and 6-DOF trajectories from entry interface to the terminal energy management interface,
optimal bank angle and angle-of-attack commands as a function of time,
optimal parameters of the initial orbit,
optimal magnitude and direction of the deorbit impulse,
for instance minimizing the accumulated heat load or maximizing crossrange or downrange,
In 6-DOF simulation and optimization, a sophisticated flight-control system is automatically included in the dynamic system model. It determines the required moments to control the vehicle to the commanded angle of attack and bank angle. The magnitude of these control torques can be restricted to study the effect of limited control authority on the optimal trajectory.

The application also provides an automatic start-up based on the mission specifications. A Shuttle-type reentry guidance law is used to determine an initial trajectory and control functions. This trajectory serves as an initial guess for the optimization.

The model has been verified with several optimization comparisons performed at ESTEC as well as with a simulation comparision with the NASA tool POST (applied to the X38 cycle 8 trajectory).