Optimal Control of Ablation during Hyperbolic Entry.
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)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1969
- Accession Number
- AD0860122
Entities
People
- Keith F. Fuller
- Richard H. Boivin
Organizations
- Air Force Institute of Technology