A STUDY OF THRUST VECTOR STEERING FOR RENDEZVOUS WITH A NEAR-EARTH SATELUTE UTILIZING A THREE-STAGE VEHICLE LAUNCHED OUT OF THE SATELLITE PLANE

摘要

A study of the problem of direct rendezvous with a near-earth satel¬lite for the case where the ferry vehicle is launched out of the satellite plane has been made. This investigation was concerned with the efficiency of steering the ferry vehicle's velocity vector into the satellite plane at burnout by properly turning the main thrust vector during a portion of the power-on ascent trajectory. A typical three-stage booster system was utilized with the thrust steering employed only during the third-stage phase of the ascent. For the two techniques of thrust vector steering considered, which were essentially:(l) a slow constant turning of the thrust vector in the lateral direction during third-stage burning and (2) a turn of the thrust vector in the lateral plane just prior to third-stage ignition and holding the direction fixed in inertial space, it was found that the cost in terms* of the idealized velocity increment AV required after third-stage burnout to effect final rendezvous was very nearly the same. The total cost of the maneuver was critically dependent on the cross-plane angle Ψv that remained at burnout and the minimumnAV was obtained when this angle approached zero. It was found that for these cases where the angle was -nearly zero the velocity losses incurred (and hence the AV required for rendezvous) as a result of the thrust vector steering were approximately 400 feet per second and 1,600 feet per second for the initial offsets of 2° and 4°, respectively. The methods used in this investigation were compared with the "adjacency" technique and were found to be more efficient.