Re: Foam and rescue possibilities

Jeff Findley wrote:

Even if you could overcome those problems (some previous rocket stages used
internal insulation), you've got to increase the mass of the
aluminum/lithium alloy so that it will be strong enough at the higher
temperatures it would see with internal insulation.

I'm not sure when peak loading is but I suspect its fairly early in the
flight - probably when the SRB's burn out.

Anyone who understands a bit about structural engineering or materials
science knows that the strength of a metal (or metal alloy) generally
decreases with increasing temperature.

Though its brittleness decreases with falling temperature, and this
effectively reduces its performance. Metals tend to work very well at
room temperature. Go much below zero, and you can have a problem. Given
the metal is inside the insulation, and next to the cryogenics, I
suspect being too cold is more of a problem than being too hot.

With external insulation, the ET's
aluminum/lithium alloy is cold enough that this effect was taken advantage
of when the tank was designed.

I still think with some redesign the foam could be removed just before
launch. This might need a dual walled metal ET skin - say a thin ***
of (hot) titanium on the outside and a thin *** of cold aluminium on
the inside.

.

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