Hardware Development and Testing for LOX/LCH4 Rocket Engine

Pedro Nunez, University of Texas at El Paso


The University of Texas at El Paso (UTEP) Center for Space Exploration and Technology Research (cSETR) has focused its research efforts on developing LOX/LCH4 propulsion systems. As part of the Janus Sub-orbital vehicle program, UTEP is developing a 2000 lbf throttleable rocket engine (Chrome X). The first iteration of this engine design will be geared for further optimization towards a flight engine. Components like electric motors, valves, and sealants have been selected to achieve throttle ability and sealing of the engine. These components play a crucial part on the engine to be able to have a successful firing. As part of the overall engine system integration, the components will be tested at conditions meant to simulate expected operating conditions during main engine firings. These tests will ultimately give insight regarding component performance, thereby allowing for evaluation, verification, and validation of the selected components. This work will primarily focus on the description of components selection and will present performance elevation test data meant to assess component operation. The actuation system is composed of a valve, electric motor, gearbox, thermal standoff, and frame. These components were selected and or manufactured using the requirements set for the injection. The injection requirements were the first set of requirements where every other set of requirements was derived from, for the other components. The injection requirements are chamber pressure / injection pressure, flowrates, and upstream pressure. These requirements were used to size the valve. The injections system has some other operational requirements, but the described parameters are the only set necessary to size a valve. Once a set of valves were selected, the breakup torque and response time were obtained. The breakup torque is the torque a valve requires to start moving. The response time is the time from close to open or inversely for the valve to operate. These requirements that were derived from the valves were used to select the electric motor. The electric motor comes with a gearbox, encoder and a digital controller. For the valve and motor to work together a couple of more parts needed to be spec out. The thermal standoff was designed and manufactured to serve as an insulator for the motor and be a connection between the valve and motor. This part has some special features to improve its insulating capabilities. However to be able to manufacture it under conventional methods seemed difficult because of the lattice design and titanium was the material picked for manufacturing. For these reasons, it was decided to do additive manufacturing for this part. The final component that is needed to make this system work is a frame to hold the aforementioned components together. The frame was made out of cylindrical plates where the valve and motor were mounted onto. Studs were used to connect the plates together. This whole system was built for the throttling valves that the engine needs. There are many forms a component can be inspected for verifications of design. The reaction control engine (RCE), throttling system, and the sealants went through a verification test. The reaction control engine after it was manufactured, some of its features like the injection orifices and the throat went through dimension validation. For these tasks, precision tools were obtained. After all of the dimensions were validated. A none destructive test campaign went underway to validate assumptions. This test series consisted of flowing water and monitoring the pressure, flow rate, and temperature upstream and downstream of the engine. The actuation system had a similar test as the RCE. Where a set up meant to be used with water was built and monitored the performance of the valve. Finally, the prospect sealants that would be used in the engine had a performance test. The purpose of the sealant test was to replicate the kind of environment the sealants would be in an engine fire test. From the data gathered it was determined that the gasket sealant had a better performance than the tape type.

Subject Area

Mechanical engineering

Recommended Citation

Nunez, Pedro, "Hardware Development and Testing for LOX/LCH4 Rocket Engine" (2017). ETD Collection for University of Texas, El Paso. AAI10689002.