John W. Young

John M. Eggleston

Methods of controlling the trajectories of high-drag--low-lift vehicles entering the earth's atmosphere at angles of attack near 90° and at initial entry angles up to --3° are studied. The trajectories are calculated for vehicles whose angle of attack can be held constant at some specified value or can be perfectly controlled as a function of some measured quantity along the trajectory. The results might be applied in the design of automatic control systems or in the design of instruments which will give the human pilot sufficient information to control his trajectory properly during an atmospheric entry. Trajectory data are compared on the basis of the deceleration, range, angle of attack, and, in some cases, the rate of descent. The aerodynamic heat-transfer rate and skin temperature of a vehicle with a simple heat-sink type of structure are calculated for trajectories made with several types of control functions.

Trajectory Control for Vehicles Entering the Earth's Atmosphere at Small Flight-path Angles

A Study of the Optimum Velocity Change to Intercept and Rendezvous

Robert Scott Dunning

A digital-computer simulation was made of the midcourse (or ascent) phase of a rendezvous between a ferry vehicle and a space station. The simulation involved a closed-loop guidance system in which both the relative position and relative velocity between ferry and station are measured (by simulated radar) and the relative-velocity corrections required to null the miss distance computed and applied. The results are used to study the effectiveness of the guidance equations and the effects of errors in launch conditions and errors in the navigation (radar) data. Trajectories are presented for rendezvous with a space station in a circular orbit and in an elliptic orbit. (Author).

John M. Eggleston

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