Space Forum / Shuttle / July 2005

I have an idea, almost certainly been considered before, but has anyone
considered spraying the foam on the *inside* of the tank instead, where it
can't break loose and damage the tiles?

The foam shouldn't disintegrate inside because of the pressure in the tank
shouldn't fall too much (I can only guess what the pressure profile is in
the tank during ascent). If any foam does break up if the bubbles expand it
would either fall onto or float to the surface of the liquid propellant, and
not pose any danger to flight, assuming that the feed to the rocket motors
is at the bottom of the tank!

Helium bubbles in the foam should maintain insulation properties, unless
maybe the pressure in the tank is too high. (I wonder if bubbles can be
formed and 'filled' with a vacuum then sealed.) The physical requirements of
the foam might not be so stringent if inside the tank.

I'm just wondering how the temperature gradient across foam on the inside
might vary compared to being on the outside of the tank.

Should also reduce air resistance, and might even reduce weight.

Has this been considered by the engineers, and if so, why was it rejected?
If not, is this worth investigating?

Perhaps another solution could be to have foam that is just so physically
weak that it just falls off at launch, or just unzips and pulled off like
actors suits...

Andy.
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