Modeling dispersions in initial conditions for air-launched rockets and their effect on vehicle performance

Growing interest in air-launched rockets as a method for lofting satellites into orbit motivates the need to investigate the unique challenges that air launch presents. This thesis explores how uncertainties in an air-launched rocket's state at ignition can affect system performance and investigates a reference trajectory strategy to mitigate performance loss. First, representative vehicle configurations for a generic air-launch system are presented. Mass properties, propulsion characteristics, and vehicle aerodynamics are estimated for the generic rocket configuration. A six-degree-of-freedom (6-DOF) simulation models the vehicle's behavior during the uncontrolled drop phase prior to rocket ignition. The results of 1000 Monte Carlo runs with various initial conditions produce a statistical representation of the expected dispersions in vehicle state at ignition. A 6-DOF Simulink simulation of the rocket's first stage bum is used to quantify the vehicle's performance. The simulation is run for a variety of ignition states, reference trajectories, and constraints on the rocket's control system. The results indicate that for a highly responsive thrust vector control (TVC) system, the rocket experiences negligible performance losses due to dispersions in ignition conditions. However, for a rocket with a less responsive TVC system, dispersions will result in significant performance loss by the end of first stage burn. Finally, the thesis illustrates how selection of a reference trajectory that is optimized for a given dispersed ignition state can significantly reduce the system's performance loss due to dispersions..

Department dc:contributor.department

Massachusetts Institute of Technology. Department of Aeronautics and Astronautics.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2013

Author dc:creator

• Beerer, Ingrid Mary

Advisor dc:contributor.advisor

• Phillip D. Hattis and Kerri Cahoy.

• Aeronautics and Astronautics.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/86865

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/86865