MS Defense by Havva Irem Caglar

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Havva Irem Caglar
(Advisor: Prof. Dimitri Mavris]

will defend a master’s thesis entitled,


A Methodology for Conducting Design Trades for A Small

Launch Vehicle with Hybrid Rocket Propulsion


Tuesday, April 6 at 11:00 a.m.


The commercial space industry has seen a paradigm shift recently related to launch of a small satellite to Low Earth Orbit. In the past, a small satellite was launched as a secondary payload with a large launch vehicle where the primary payload placed a constraint on the orbit and schedule. Today, a dedicated launch of a small launch vehicle is the main operational concept to launch a small payload. To improve the launch services, many small vehicles have been under development by commercial space industry in recent years. Despite these efforts, the specific prices per launch are still high and reduction of the prices further remains a challenge. One of the promising technology candidates to reduce costs for small launch vehicles is hybrid rocket propulsion which has matured recently with some cost and safety advantages. With this motivation, a methodology to conduct the design trades of a small launch vehicle with hybrid rocket propulsion was presented in this thesis.  The vehicle concept investigated is an expendable launch vehicle with varying number of stages and number of hybrid motors at each stage.

A physics-based conceptual design approach was followed in this study since small launch vehicles are new concepts without any historical performance data. First, a physics-based modeling and simulation environment was constructed with three core disciplines: trajectory analysis, aerodynamics, and propulsion.  Such an environment can be computationally expensive depending on the trajectory optimization method and fidelity levels of each discipline. This expense poses a difficulty to perform a trade-off study for hundreds of vehicle design alternatives under schedule limits in conceptual design phase. To solve this problem, a specific mechanical energy-based design trade-off methodology was developed using a probabilistic approach. With this approach, trajectory optimization is left out of the design trade-off process to speed up the design process. Moreover, some design of experiment and surrogate modeling methods were investigated to approximate the environment to enable a rapid design space exploration. Finally, with an extended design study, this methodology was demonstrated to enable a system designer to design some feasible vehicles rapidly and accurately where these vehicle candidates can step to the next design phase for further comparison, analysis, and design.



  • Prof. Dimitri Mavris – School of Aerospace Engineering (advisor)
  • Dr. Michael J. Steffens – School of Aerospace Engineering
  • Dr. Bradford E. Robertson– School of Aerospace Engineering


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    Tatianna Richardson
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    Tatianna Richardson
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