Control Optimization for a Dual-Mode Single-State Nuclear Shuttle,
TENNESSEE UNIV SPACE INST TULLAHOMA
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The performance of a single-stage surface-to-orbit shuttle--whether chemical-propellant or nuclear--can be considerably improved by mixed-mode propulsion. A mixed-mode shuttle would be fitted with engines designed to use two different propellant combinations--a highthrust mode 1 propellant, such as ammonia, and a high-specific-impulse mode 2 proepellant, such as hydrogen. The first step in the evaluation of the mixed-mode nuclear shuttle is a preliminary trajectory optimization study. This study, using a simple mission and a simple shuttle model, would be the basis for more complex trajectory optimization studies. The problem considered in this thesis is that of minimizing the propellant expenditure of a mixed-mode nuclear shuttle for a given orbit. The starting point for any optimization problem is a mathematical modle of the system, in state variable form. Application of the methods of optimal control theory results in a two-point boundary-value problem and an associated algebraic problem. Three numerical methods are briefly described which could be used to solve these problems. The analysis of the problem is given in detail, along with numerical results for various combinations of the input variables, and the finite-differece computer program, properly documented.
- Liquid Propellant Rocket Engines
- Solid Propellant Rocket Engines
- Unmanned Spacecraft