Executive Summary

The sponsor of this project is a student rocketry organization on the UC San Diego campus known as SEDS UCSD. This team of students is currently working on a self-landing rocket named Riptide, which uses their Nephas engine to fly to 1,000 feet and land back on the ground propulsively. Using this vehicle and engine, SEDS will be competing in the Collegiate Propulsive Lander Challenge (CPLC). The first milestone of the CPLC challenge is to demonstrate a gimballed engine fire using a thrust-vector control (TVC) system. Therefore, the SEDS team has commissioned the project of building a TVC module that can be used with the Nephas engine to meet the requirements of the CPLC milestone.

A TVC system is essential to propulsive landing rockets such as Riptide since it provides the main method of attitude control for the rocket during landing. TVC works in conjunction with the throttle system of the engine, which controls altitude, to guide the vehicle to a designated landing pad. By gimbaling the engine, the vehicle can fly in different directions, whereas by throttling the engine, the vehicle can move up or down. Having both systems working in conjunction is critical to a successful landing on target, and the TVC is especially significant since the final stage of the CPLC competition requires landing within a 10-meter circle designated by the competition organizers.

The goal of the project is to deliver a fully integrated TVC module that will be mounted between the engine and the lander and will use the two linear actuators provided by the sponsor. The functional requirements include moving the engine at least 7° from its central axis in every direction (or in a 360° circle) and being able to withstand the 2000 lbf thrust load from the engine throughout 30 seconds of movement. The system will be manufactured and assembled in-house on campus. Verification tests will be conducted both without and with the final engine, contingent on SEDS timelines.

The TVC module consists of a rod end gimbal, mounted on top of the injector face of the engine assembly, which then leads into the thrust structure which is designed to connect the gimbal to the lander and to support the thrust force coming from the engine. The linear actuators are attached to the thrust structure and then point down towards the engine where they are attached using rod ends to a pair of clevis mounts which are attached to the side of the engine at a right angle relative to one another to allow control in the x and y directions. The size and geometries of each part of the TVC (except for the linear actuators) had to be constrained to the shapes that would ensure that the engine could be moved to 7 degrees off of the central axis of the lander