The results of the tests show that the thin 2-ply composites performed essentially as predicted by the trade study and similar to 8-ply materials fabricated using similar procedures. The only exception to this was the low and widely scattered tensile strength and modulus values.This may reflect the specifics of the C-C composite lay-up and the geometry of the tensile test and not reflect a true difference in tensile strength between the projectd value and the measured value.
The radiator panel constructed using the C-C facesheets with the aluminum honeycomb core also performed well, with the insert pullout strengths being well above that required for the application. Based on the trade study, and the mechanical and thermal properties measured in this study the carbon-carbon composite radiator panel design was found to be more than adequate for the EO-1 bay four radiator panel.
The flight radiator and backup radiator were delivered to NASA Goddard and have successfully completed thermal/vacuum and vibration testing (not described in this paper). The panels were delivered to the EO-1 spacecraft integrator, Swales Aerospace, on May 19, 1998.
The final point to be made regarding the suitability of C-C radiators for use on future spacecraft concerns cost and availability. Table VII shows the approximate cost associated with the design, fabrication, and ground testing of the three panels for the EO-1 spacecraft. The tasks include non-recurring costs that would not need to be repeated for future radiators if a similar design were used. The radiator integration task includes approximately $22 K of non-recurring costs. The time for total production was about 10 months but could be optimized to 6 months using current production technoloty. It is predicted that the cost would be $283K for an additional set of C-C radiator panels using the EO-1 design.
Table VII.-CSRP EO-1 C-C radiator cost summary