There are links to the RCC "erosion" problems on the main sites (see previous posts), including detailed pictures. The article posted by
ORAC contains some prime BS from Boeing in the line,
"The [Boeing] official declined to provide details, saying the company needed approval from NASA to release the information...". I suspect that the line translates
" . . and as an official spokesman for Boeing, I haven't a clue what I am talking about, so I'll pretend that it's a state secret to fob-off you journos . . ."
The 1999
Annual Report (3.6mb PDF, as per my previous) stated it quite openly and clearly. I'll quote it directly as some of you may not have beeen able / had time to view it.
"Another safety improvement the SSP implemented was additional thermal wing leading edge protection to prevent wing structure over temperature/failure and potential loss of vehicle due to a hole in the wing leading edge. Current wing leading edge capabilities permit a 1in. hole on the upper surface of any panel. But on the lower surface, no penetrations are allowed on the lower surface of panels 5-13. In these locations, a hole generated by orbital debris would allow heat from the plasma flow during entry to quickly erode the 0.004-in. thick Inconel foil of the “Incoflex” insulators. This will cause a loss of insulating properties and exposing the leading edge attach fittings and wing front spar to direct “blast” from the hot plasma.
"The upgrade to include additional insulation would allow single entry with a penetration of up to 0.25 in. diameter in the lower surface of reinforced carbon-carbon panels 9 through 12 and up to one inch on panels 5 through 8 and panel 13. The design team evaluated requirements for meeting the 0.25 in. requirement.
"A variety of design requirements also considered during the evaluation including minimum weight with no additional post-flight inspections. The implemented design solution after analysis and testing were complete was to add high-temperature Nextel 440 fabric to the Incoflex insulators with one layer for panels 5 through 7 and 11 through 13 and two fabric layers for panels 8, 9 and10 (highest heating environments).
"Overall weight increase to the orbiter was 53 lb. This hardware is currently implemented on OV-103, OV-104 and OV-105 and OV-102 during the maintenance down period ['99-01]." (My emphases)
It may or may not be relevant, but note that panels 1-4 were not included. Also, 107 launch-debris impact is believed to be on the lower surface of the LE, and only orbital, not launch, debris is considered in the above scenario despite earlier experience. No intention of insulting anyone's intelligence here but, just to clarify, due to high alpha (40º) during max re-entry heating, the lower surfaces bear the brunt.
Off to bed
