The Propulsion sub-system is in control of the rocket’s propulsion system. It is therefore involved in the development of code for simulating both the motor’s as well as the rocket’s performance, the manufacturing of solid propellant and, lastly, the design and manufacturing of rocket motors.
In the pursuit of reaching a given altitude with great accuracy, the need of having the optimal motor emerged. This led to the development of a Matlab-based optimization tool with a Graphical User Interface (GUI) implementation. This tool combines the rocket’s flight performance with the performance of many different motors, so as to select the optimal one corresponding to the rocket’s requirements. In addition, the sub-system has developed a code in order to design and optimize the motor nozzle. This is achieved in conjunction with the computational study of the combustion of the solid propellant, during the necessary data for the dimensioning of the nozzle are obtained. The aim is to maximize its performance, while also minimizing its weight. A further study of this is carried out using a CFD commercial code.
The sub-system has so far acquired technical expertise in regards to the manufacturing procedure of solid propellants used in its motors. A significant factor ensuring the motor’s optimal performance is its proper construction. That’s the reason why specific stirring equipment has been constructed to achieve a proper homogenization of the oxidizer with the fuel, before it is heated and introduced into the mold for the manufacturing of the grains. Another factor is the experimental study of its combustion. In particular, several propellant experiments have been carried out in parallel with the static tests of the motors. As a result, useful data is obtained for the design of future motors, such as the effect of pressure on the propellant burning rate.
So far, the sub-system has successfully designed and built a Class G solid propellant motor (read more here: https://asat.gr/2019/03/29/rocketry-propulsion-sub-team/). The experience gained from the static testing of this motor and its use in Rocketry Project’s H1 and H2 rocket launches (read more here: https://asat.gr/2019/04/16/1291/), helped the sub-system design a Class I motor, with the aim of achieving an overall thrust with the greatest possible accuracy.
The I-class motor is a subscale model of the full-scale motor we’re currently designing, which will have a Total Impulse of 9500Ns. Static tests are expected to be carried out in the near future, in order to verify theoretical performance, have repeatability of the performance and make sure that this motor is reliable for use on a rocket. In particular, the static tests will measure the motor’s thrust and pressure, as well as the external temperature of the combustion chamber and nozzle.