[galgot]

Supersonic heat also. Concorde was in Aluminum and at 2.1 mach it was at the very limit of what could be done in aluminum. Which required a very "tight" design, engineering marvel in fact. Go faster and one have to go for titanium, which is much more difficult to work with and manufacture.

[hinkley]

Didn't the Blackbird weep jet fuel because the seals couldn't hold when the skin was at ambient temperature?

I heard they put enough fuel in it to take off and get up to temperature and then refueled it in the air for safety reasons.