Development of a Lightweight Thrust Chamber Assembly Utilizing In-Situ Reinforced Silicon Nitride

The paper describes the status of the Light Weight Thrust Chamber Assembly (LWTCA) program currently underway at Boeing Rocketdyne Propulsion and Power, under contract with the US Air Force Research Laboratory. The goal of the program is to demonstrate technology which will lead to a 40% reduction in weight (including the nozzle), a 50% reduction in cost, a 75% reduction in part count and a 3% increase in specific impulse on a full scale, 400 klbf thrust LOX/hydrogen booster engine. The demonstration will be performed through the use of manufacturing technology demonstrator hardware and 60 klbf thrust hot-fire tests. The primary means to achieving these goals is by using in-situ reinforced silicon nitride for structural components. Silicon nitride is an advanced ceramic material that has high specific strength and fracture toughness, and can be cast to near- net part shape. Tests to validate the material properties of in-situ reinforced silicon nitride are discussed, along with the resulting changes to traditional thrust chamber design as a result of the improved properties. The progress towards manufacturing and hot-fire testing a thrust chamber assembly from the material is also described. Pres: 35th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit, 20-24 Jun 1999, Los Angeles, CA.