Air Launch versus Ground Launch: a Multidisciplinary Design Optimization Study

Air Launch versus Ground Launch: a Multidisciplinary Design Optimization Study of Expendable Launch Vehicles on Cost and Performance
TU Delft, November 18th, 2013
http://repository.tudelft.nl/view/ir/uuid%3A16093448-e5bf-4ee7-a895-67168fc9e2c2/

This work reports a thesis research done in the field of air launch at TU Delft’s faculty of Aerospace Engineering. During the entire era of space flight air launch is seen as a very promising concept. Despite its claimed advantages, air launch is up till now only a marginal success with the Pegasus launch vehicle from Orbital Sciences. In this study is investigated for which conditions expendable air launched vehicles can achieve a performance gain compared with expendable ground launched vehicles. The scope of this study is limited to near-term feasible concepts. Therefore, only existing carrier aircraft that require minimum modifications are evaluated. Solid propelled rockets are more promising for air launch than liquid rockets, therefore, only solid propelled rockets are considered during this study. Potential markets for launch vehicles with a 10 kg and 2,000 kg payload capability to low earth orbit are identified. The influences of different launch parameters and the presence of a wing on the potential performance gain of air launch are investigated.

A Multidisciplinary Design Optimization (MDO) is deemed the most suitable approach for the comparison between air launch and ground launch. In earlier thesis work performed at the TU Delft an MDO tool in the Tudat framework is developed by Jan Vandamme. This tool is used as a starting point for this work but is heavily modified and expanded. For the typical disciplines of launch vehicle design models are developed and validated. The Multidisciplinary Design Analysis (MDA) and MDO validation tested the ability of the tool to model the design and the trajectory of launch vehicles. During the MDA validation it is shown that the tool is capable to do this for the design as well as for the trajectory. From the MDO validation it can be concluded that the optimized designs have realistic configurations and a lower cost per flight than the designs for the MDA validation.