NASA - National Aeronautics and Space Administration

The NESC Composite Crew Module (CCM) team is chartered to develop a Crew Module (CM) design tailored to composites and to characterize the design drivers such as geometry, mass, manufacturability, inspectability, repairability, damage tolerance, crashworthiness, micro-meteoroid and orbital debris, and radiation shielding. The CCM team has constrained their scope to retain the reference design outer mold line, maintain the inner mold line within 1.5 inch of the reference design, and to maintain the interface points at the Launch Abort System and the Service Module.



Composite Crew Members pictured above going over presentation materials are (left to right): Dr. Ivatury S. Raju, Technical Fellow for Structures, Sotirios Kellas, Paul W. Roberts, NESC Back-up Principal Engineer, and Michael T, Kirsch, NESC Principal Engineer and Team Lead for the CCM Team.

This team has developed three concepts: geometrically stiffened laminate, stiffened sandwich (utilizing the aluminum-lithium aeroshell) and monocoque, design analysis, and sizing iterations, but none were optimized with respect to mass or manufacturability. Each concept had a different level of design maturity, and all three had less definition than the reference Crew Exploration Vehicle Project aluminum-lithium design. Comparing estimated mass values at this stage yield rough order of magnitude values at best. The design did not include analysis of landing or dynamic loads, reusability, thermal loads, subsystem packaging and integration, or development costs and schedule implications of incorporating a composite solution.

The NESC has contracted to perform manufacturing assessment and although preliminary, all concepts were deemed manufacturable and could be performed using an automated fiber placement process. During the manufacturing assessments, it was noted that manufacturing cost was a key decision driver for the composites industry in determining metallic versus composite fabrication with mass being a secondary benefit.

The NESC composite team has conducted micro-meteoroid and orbital debris impact assessments. Additionally, ground-based inspectability and repairability of the composite solutions were evaluated through literature searches. Based on these searches, it was determined that all three designs can be inspected and repaired with commercial equipment and techniques. However, the geometrically stiffened laminate was preferred due to accessibility.

Other areas of review include a quantitative radiation shielding assessment that was performed on all three composite concepts and the reference design for solar particle events and galactic cosmic rays. Crashworthiness of composite and metallic airframes was conducted, but the evaluation was limited to demonstrating that techniques are sufficiently understood for considering crashworthiness of composites. Damage tolerance design methodologies were evaluated for composite and metallic systems that showed tolerance in composite systems and this was not deemed to preclude the considerations of composite CM concepts.

The NESC composite CM team has recommended that NASA continue the composite CM structural design and include fabrication manufacturing and tooling expertise in a collaborated environment.