An Attitude Control System for Extremely Small Control Forces
- Paper ID
IAF-60-40
- author
- company
The Martin Company
- country
U.S.A.
- year
1960
- abstract
Te keep a satellite in space properly oriented to a reference system, corrective forces are necessary when disturbances occur. In general, these forces are very small, in the magnitude of F < 0.1 lb thrust, and are needed over a period of many months at intervals that are determined by an attitude sensing system. These control forces may be created by several methods. One method uses gas jets as a controlling force. This paper presents a detailed study of the gas storage system necessary for gas jet operation. The ratio of the weight of the high-pressure storage vessel to the weight of the gas for a specific mission is derived. The weights of storage systems for 35 different gases are determined for a total impulse of the control system of 7t=18 000 lb-sec, corresponding to a total operational time of 100 hours at 0.05 lb thrust. It is shown that gases with a high specific heat and high molecular weight are desirable to obtain minimum overall system weights. Furthermore, the use of gas mixtures was investigated and a relationship was derived which demonstrates that, under certain conditions, a mixture of two or more gases leads to a lighter overall systems weight than that obtained for each of the gases individually. Several examples are included. Graphs were developed that are useful in determining gas mixtures with overall systems weights lighter than those of single gases. The study is concluded by the presentation of two numerical examples of stored-gas attitude control systems.