Mechanical Design of a Hybrid Navigation System for the Reusability Launch Vehicle Technology Demonstrator: ReFEx

Abstract

Space missions are always cost depended and one of the effective ways for cost control is to reuse the launch system completely or partially. DLR, the German Aerospace Center, is currently developing a flight experiment called Reusability Flight Experiment (ReFEx), which is a winged re-entry launch system. One of the main features of this vehicle is its Hybrid Navigation System (HNS), an autonomous navigation system that is vital to vehicle re-entry. The main goal of this thesis is to develop a highly integrated, compact, and self-contained mechanical enclosure to accommodate all the components of the hybrid navigation system, except the external sensors and antenna. The enclosure is to be integrated within the ReFEx, close to the Guidance and Control system. The mechanical design is considered based on the different requirements of the HNS components, like, the orientation, the accessibility for electrical connections and reconnections, and ease of integration. Based on the component and system requirements, an initial outline of the HNS box (HNS dummy) is created. The HNS components are then designed and included into the HNS dummy. Following this, different configurations are studied for the HNS components’ accommodation in the box. A final flight accommodation configuration is chosen based on the structural rigidity and accessibility to different components. Based on the configuration chosen, an initial design is generated through various design iterations using CATIA V5, with proper component supports. This is followed by the preliminary enclosure design, considering the different loads that are subjected to it during flight. This design is checked with the ReFEx outer structure to ensure proper mechanical clearance margins. After finalizing the design of the HNS enclosure, a detail enclosure design is generated where the individual enclosure parts are defined. This enclosure model is then integrated with the HNS sensors and electronic component models to produce a detailed HNS mechanical model. The mechanical fitting and physical attributes of the detailed HNS model is tested by producing a prototype though 3D printing technology. The enclosure prototype is assembled in house with all the HNS components using different mechanical fasteners. Based on the observations from the prototype, a HNS production model was created. The production model was used to generate subsequent part drawings for the mechanical production processes. An assembly process flow for the HNS integration is developed based on the prototype assembly for the flight model. The developed HNS model and the corresponding part drawings would be used for the HNS development. The HNS assembly and integration would be according to the assembly process plan developed.