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Title: Preliminary design methodologies for hybrid propulsion trajectories
Author: Owens, Steven Robert
ISNI:       0000 0004 5362 6672
Awarding Body: University of Strathclyde
Current Institution: University of Strathclyde
Date of Award: 2014
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In this dissertation, the Hohmann and bi-elliptic transfers are considered with the inclusion of a plane change. The evolution of critical limits which determine the transfer offering the lowest velocity requirement, previously defined for a co-planar analysis, is shown with the inclusion of a plane change. This has not been possible in previous work as analyses have been dependent on the intermediate orbit and numerical optimisation of the plane change distribution between impulses. It is shown that the critical limits found for the co-planar analysis reduce at different rates with increasing plane change and converge on a point where both transfers offer the same velocity requirement for a given final to initial orbit ratio and plane change. Between the two limits the Area Of Uncertainty (AOU) found for the co-planar analysis is shown to reduce to the convergence point which beyond, a second AOU emerges. A detailed analysis of these critical limits, determining when each transfer should be used is performed and a simple figure is presented which would allow a mission designer to select the fuel optimal transfer dependent on the final to initial orbit ratio and plane change only. The dissertation then introduces a novel orbit transfer using both high and low-thrust propulsion systems to accommodate the current development of platforms with this technology on-board. An analytical model is created which determines when the system offers a fuel mass saving compared to a single propulsion high-thrust only transfer. In addition to this, a critical limit analysis is performed which determines the limitations of analytical models based on a quasi-circular assumption. This analysis is developed into a numerical optimisation procedure which extends the application of the transfer to allow for eccentric orbits throughout the duration of the low-thrust phase. Case studies are presented which demonstrate substantial fuel mass savings compared to the single propulsion transfer: the largest fuel mass saving is found to be 27% of the spacecraft wet mass for a transfer from a Sun-Synchronous Orbit to a highly elliptical polar orbit.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available