Multistage launch vehicle design with thrust profile and trajectory optimization

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Tezin Türü: Doktora

Tezin Yürütüldüğü Kurum: Orta Doğu Teknik Üniversitesi, Fen Bilimleri Enstitüsü, Fen Bilimleri Enstitüsü, Türkiye

Tezin Onay Tarihi: 2014

Öğrenci: EZGİ CİVEK COŞKUN

Danışman: MUSTAFA KEMAL ÖZGÖREN

Özet:

In the frame of this thesis, a Matlab® based design tool utilizing a general purpose optimal control solver GPOPS-II® was developed for the optimization of ascent trajectories of multistage launch vehicles. This tool can be utilized both for preliminary mission design of an existing launch vehicle and conceptual design of a new launch vehicle. In the preliminary mission design of an existing launch vehicle, maximizing payload mass is a very common performance measure. Therefore, a trajectory optimization code was developed to determine the optimal trajectory in terms of position and velocity, and the control functions corresponding to that trajectory while maximizing the payload mass. Whereas in the conceptual design of a new launch vehicle, minimization of gross lift-off mass for a specific mission is the primary objective, and staging is an effective way to reduce the vehicle gross lift-off mass. For this purpose, a staging optimization code was developed to determine the staging parameters (mass distribution between stages, propellant and structural mass of each individual stage) which minimize the gross lift-off mass. In this thesis, staging and trajectory optimization codes were integrated by two different manners, namely the decoupled and the coupled approaches, so as to determine the sizing, burn time and thrust time history of each stage together with the optimal trajectory of the launch vehicle. Thus, a quick and effective method to find optimal vehicle configurations in the early design phases was achieved.