Abstract:
This thesis describes the
development of a computer program to optimise the design of
a rocket
powered orbiter vehicle, by combining a design synthesis with consideration
of both the ascent and
re-entry trajectories. This work is a extension of an existing
trajectory optimisation program.
Firstly the background to the problem is examined and a summary of previous work is
presented. The objectives of this research program are examined and there follows a
discussion of the mission
requirements for such a vehicle and a description of the
baseline
design.
The
development of this problem as a integrated optimal control problem is discussed
and is followed
by a description of the mathematical models which are used to evaluate
the vehicle. These include the geometry and packing model, the estimation of the
orbiter's mass
properties, the evaluation of the aerodynamics and the simulation of the
trajectories. The mathematical details of these models are presented in detail i the
appendices. The architecture and philosophy behind the writing of the program are
then discussed. A user's
guide is also presented as an appendix.
Results are
given for the solutions to a variety of orbiter design problems. These
problems include a variety of separation conditions for air-launched vehicles, various
re-entry cross-range conditions and a number of differing objective functions. A
investigation into the optimality of the solutions and their sensitivity to changes in the
optimisable parameters is also considered. The difficulty in obtaining optimal solutions
is discussed in full.