A systems study of very small launch vehicles

Abstract

Motivated by the continuing miniaturization of small satellites and ballistic payloads, this thesis studies the perform&ace and feasibility of very small launch vehicles (15 kg- 2000 kg liftoff mass). Gross payload performance for several vehicles was calculated with a commercial three degree of freedom trajectory code. The significance of aerodynamic drag on small vehicles is discussed. Both the options of air and ground-launched vehicles were examined as well as composite configurations with existing motor stages. Parametric analyses were carried out, examining the impact of varying propellant mass fraction, stack fraction, launch conditions (velocity and altitude), and vacuum specific impulse. All vehicles are based on a version of the MIT microrocket engine, a micro-scale rocket engine fabricated in silicon, and weighing 2 g. The engines use nitrogen tetroxide and hydrazine as propellants which are pump-fed to the engine using micro turbopumps. Following the performance study, a 77 kg vehicle (w/o gross payload) was carried through a preliminary design. Various subsystems were analyzed, focusing on: vehicle structure, propellant tank design, and propellant pressurization and delivery. The mass of the various vehicle components were analyzed and compared with initial inert mass estimations used to determine gross payload performance.