Design of a Test Facility for Propulsion System for CubeSats

The trend of recent years shows a growing interest in small satellites. In particular, a platform that is gaining importance in the international satellite market is CubeSat. Born for educational purposes, nowadays CubeSats market is expanding also for scientific and commercial purposes. To ensure that the prospects for use of CubeSats increase, it is therefore necessary to develop a propulsion system that is reliable, performing and at the same time with limited costs: this is the origin of the CHIPS project. In the frame of the CubeSat HTP Innovative Propulsion System (CHIPS) project, a chemical monopropellant propulsion system was developed. The final design results in a propulsion system powered by hydrogen peroxide capable of providing a thrust of about 0.5 N, occupying only 1.5U in volume, respecting the mission requirements in terms of costs, mass, volumes and performance. Particular attention was paid to the development of a storage system capable of maximizing the volume available within a CubeSat, proposing an innovative design that involves the creation of a cubic-shaped bladder tank. Maintaining a dry mass of less than 1 kg, the tank is able to occupy all the space available in 1U, bringing inside a volume of hydrogen peroxide of about 0.5 l. In this thesis work, a trade-off analysis is mainly presented where it is possible to evaluate all the steps of the mechanical design of the pressurized tank. Through CAD models and structural simulations, we focused on the key points of the design, observing the behavior of the structure at the variation of critical elements such as shape, materials and installation of propellant ejection systems. In parallel with the study of the propulsion system and its components, a thrust balance has been developed in order to evaluate the proposed propulsion system performance. In fact, observing a lack of commercial products of this type, a custom solution was designed that can mainly satisfy the requirements imposed by the propulsion system in question, but at the same time present a valid option for further systems. The realization of this thrust balance is in fact based on a simple, reliable and extremely adaptable design where the possibility of studying not only chemical but also electrical propulsion systems, of different sizes and functions, has been taken into account. A hanging double pendulum thrust balance has been developed to characterize a wide range of 1D axial thrust both in static and dynamic mode. The propulsion system under investigation is mounted on a pendulum platform, which is suspended from the support structure using stainless steel flexures. The thrust profile is directly measure by a load cell and the obtained results will be post-processed to completely define the performance of the propulsion system under exam. The behavior of the thrust balance was studied using an algorithm developed on Simulink, where the trend of the thrust over time generated by our propulsion system, was established and compared with the response measured by the load cell. These theoretical results will then be compared in an experimental test campaign where the performance provided by the propulsion system will be measured both in the atmosphere and in the vacuum conditions