No abstract

No abstract

The global economic environment combined with the rapid pace of technology advancement is placing importance on reducing the size and cost of access to space systems. Based on decades of practical experience with rocket-only launch vehicles, current technology is operated close to theoretical limits and only marginal further improvement is possible. A possible solution is to include an airbreathing stage into the launch system architecture. Performance wise, airbreathing hypersonic engines such as scramjets have an advantage over rocket propulsion in terms of a significantly higher specific impulse in the hypersonic flight regime. A reusable airbreathing stage could contribute to an increase in payload mass-fraction by using scramjet propulsion over a meaningful proportion of the launch trajectory and provides the flexibility of aircraft-like operations while being inherently reusable.Researchers at the University of Queensland investigated the use of a three stage to orbit rocket-scramjet-rocket system for transporting small payloads into LEO. The second stage scramjet powered accelerator of this system was the subject of a series of Multi-Disciplinary Optimisations (MDO) which involved flying complete trajectories. Promising results were achieved however this work did not include the requirement for the vehicle to be pitch trimmed, which is an important aspect which must be addressed.The purpose of the investigation described in this thesis was to gain a better understanding of the impact that the second stage vehicle's planform has on the pitch trim of the vehicle. This was addressed through a numerical study utilising and expanding on the capabilities of the MDO system developed by Jazra (2010) by: i) Defining a more realistic mission of delivering small satellites up to 500 kg into a Sun Synchronous Orbit of 566.89 km altitude suitable for several earth science missions.ii) Increasing the fidelity of the MDO system to enable an accurate estimate of the trim drag. This included refining the vehicle mass model and aerodynamic module updates such as introducing a 2-D aft body exhaust expansion model plus elevon force and pitching moment inclusions.

No abstract

No abstract