Ballistic Skip Guidance for Atmospheric Re-Entry
AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING
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The feasibility of a re-entry guidance scheme that uses ballistic flight to attain a variable surface range is investigated. The equations of motion are derived, and the re-entry trajectory is divided into four phases pull up, skipout, ballistic, and terminal. The pull up, skipout, and terminal phases are within the atmosphere, while the ballistic phase is outside the atmosphere. The conjugate gradient optimization method is used in the skipout phase to determine the re-entry vehicle control needed to achieve the desired initial ballistic phase conditions. The cost function uses the errors between the actual trajectory and a reference trajectory which is obtained by projecting a ballistic path into the atmosphere. The equations for the reference trajectory are presented. Ballistic theory is discussed and a parametric selection technique is presented as a means of determining the ballistic parameters needed for a specific range. An optimal control solution is found for one set of ballistic initial conditions.
- Spacecraft Trajectories and Reentry