93-139
Load Alleviation Maneuvers For A Launch Vehicle*
Hans Seywald** and Robert R. Bless***
Abstract
This paper addresses the design of a forward-looking autopilot that is capable of employing a priori knowledge of wind gusts ahead of the flight path to reduce the bending loads experienced by a launch vehicle. The analysis presented in the present paper is only preliminary, employing a very simple vehicle dynamical model and restricting itself to wind gusts of the form of isolated spikes. The main result of the present study is that LQR based feedback laws are inappropriate to handle spike-type wind perturbations with large amplitude and narrow base. The best performance is achieved with an interior-point penalty optimal control formulation which can be well approximated by a simple feedback control law. Reduction of the maximum bending loads by nearly 50% is demonstrated.
*Performed under NASA Contract NAS1-13935.
**Senior Project Engineer, Analytical Mechanics Associates, Inc., 17 Research Drive, Hampton, Virginia 23666 working under contract at the spacecraft Controls Branch, NASA Langley Research Center. Member AIAA.
***Engineer, Lockheed Engineering and Sciences Company, 144 Research Drive, Hampton, Virginia 23666, working under contract at the Spacecraft Controls Branch, NASA Langley Research Center. Member AIAA