Accession Number : AD0860122

Title :   Optimal Control of Ablation during Hyperbolic Entry.

Descriptive Note : Master's thesis,

Corporate Author : AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING

Personal Author(s) : Boivin, Richard H. ; Fuller, Keith F.

Report Date : JUN 1969

Pagination or Media Count : 110

Abstract : Methods of controlling the ablation rate of a spherical body entering the earth's atmosphere at hyperbolic velocities are investigated. Expulsion of air to force the shock wave away from the body and increase drag is shown to be impractical as a means of control for minimizing the ablation rate. Optimization by the gradient method with density of the ablation material as the control results in the maximum terminal diameter of the vehicle being achieved by selection of the ablative material with the highest density, other parameters being equal. However, density is shown to be a relatively ineffective control when compared with the material's heat of ablation. Empirical equations for calculating the heat transfer due to convective and radiative processes are used. Approximate equations are developed to express the relationships between heating rates, ablation rates, shock standoff distance, and drag, providing a means of relating material qualities to the equations of motion of a spherical entry body. (Author)

Descriptors :   *ATMOSPHERE ENTRY), (*REENTRY VEHICLES, PAYLOAD), (*PAYLOAD, (*ABLATION, OPTIMIZATION), AERODYNAMIC HEATING, HYPERSONIC CHARACTERISTICS, SHOCK WAVES, CONTROL, DRAG, HEAT TRANSFER, MATERIALS, DENSITY, EQUATIONS OF MOTION, THESES.

Subject Categories : Thermodynamics
      Unmanned Spacecraft

Distribution Statement : APPROVED FOR PUBLIC RELEASE