Chapter 38. CMC Body Flaps for the X-38 Experimental Space Vehicle

Summary

A pair of body flaps, made entirely of coated high performance ceramic composite, was manufactured for NASA's X-38 experimental re-entry vehicle V201. This vehicle is being built as a prototype of the Crew Return Vehicle, the “lifeboat” for the International Space Station. The body flaps were developed within the framework of the German space program TETRA. Each body flap is built up from four boxes with integral transverse stiffeners and flanges to bear the covers. They are joined with C/SiC screws. The size of one flap is approximately 1.6 m by 1.6 m. The forward ends have a precise cylindrical shape to engage with a ceramic fiber seal that prevents the hot air flow to the leeward side of the flaps. Each flap is attached to the vehicle structure with two ceramic hinge bearings. The actuator for the flap movements is attached to a bearing near the flap center. C/SiC with a wall thickness up to 19 mm was manufactured for these parts. A complete qualification body flap has been ground tested with a sequence of vibrational, thermal and pressure loads to simulate launch and re-entry. The results have demonstrated the component's capability for safe function up to 1600°C under high mechanical load. The C/SiC body flaps provide a considerable weight reduction compared to insulated metallic structures and -due to their high heat resistance - extended flexibility and safety margins for reusable re-entry vehicles and trajectories. The flight test is to verify these benefits.