Design and Test of a Student Hybrid Rocket Engine with an External Carbon Fiber Composite Structure

The development of hybrid rockets offers excellent opportunities for the practical education of students at universities due to the high safety and relatively low complexity of the rocket propulsion system. During the German educational program Studentische Experimental-Raketen (STERN), students of the Technische Universität Braunschweig obtain the possibility to design and launch a sounding rocket with a hybrid engine. The design of the engine HYDRA 4X (HYbridDemonstrations-RaketenAntrieb) is presented, and the results of the first engine tests are discussed. The results for measured regression rates are compared to the results from the literature. Furthermore, the impact of the lightweight casing material carbon fiber-reinforced plastic (CFRP) on the hybrid engine mass and flight apogee altitude is examined for rockets with different total impulse classes (10 to 50 kNs). It is shown that the benefit of a lightweight casing material on engine mass decreases with an increasing total impulse. However, a higher gain on apogee altitude, especially for bigger rockets with a comparable high total impulse, is shown.