The Downrange Capability with the Influence of Reentry Initial Conditions of Reusable Launch Vehicle during the Primary Entry Phase

Paper number

IAC-05-E2.2.04

Author

Ms. Hongbo Li, Beijing University of Aeronautics and Astronautics, China

Year

2005

Abstract

For a Reusable Launch Vehicle similar to the Space Shuttle orbiter, the downrange capability is defined as difference of the maximum and minimum downrange with given boundary conditions. The capability is investigated for the influence of reentry initial conditions during the primary entry phase in order to evaluate the appropriate downrange parameter for entry trajectory design and to choose the reentry initial conditions for optimal downrange capability. 

A downrange parameter is necessary for the general entry trajectory design and usually comes directly from a certain reference mission. However, the downrange capability is determined by the entry flight corridor and entry initial and final conditions for a certain entry vehicle during the primary entry phase, while the boundary conditions satisfy the restriction of entry corridor. Therefore, a downrange parameter from an inapposite reference mission could exceed the downrange capability. Though abundance papers discussed the problem of entry guidance and control, few discussions have been developed on the downrange capability.

As an optimization problem, the downrange and the downrange capability are used as cost function and the solution is constrained by initial and final conditions and entry flight corridor. The optimization problem is solved by a sequential quadratic programming method. In addition, the boundary conditions have their own limits in order to satisfy the restriction of entry corridor. According to different reentry altitude, speed and angle, a series of reentry initial conditions are enforced during the optimization. 

Based on optimization results, sequential curves of the maximum and minimum downrange and downrange capability vs. reentry altitude, speed and angle are separately acquired. Based on the curves, the maximum and minimum downrange and the downrange capability can be searched according to the reentry initial conditions for a certain reentry vehicle. 

In addition, the curves of the downrange capability vs. the reentry initial conditions are not monotone. Therefore, with combination of the reentry initial conditions, the downrange capability can be optimized further. The optimization solution is the optimal downrange capability for a certain reentry vehicle and the corresponding initial conditions are acquired.The above method has been illustrated by an example of a hypothetic reentry vehicle.

Abstract document

IAC-05-E2.2.04.pdf

Manuscript document

IAC-05-E2.2.04.pdf (🔒 authorized access only).

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