Foam Inside Tank?

In article et,
"Greg D. Moore \(Strider\)" wrote:

Any reason why the foam cannot be *inside* the fuel tank?

Because if anything came off, for any reason, it would go into the
SSME?
I suspect that could spoil your whole day.

Liquid oxygen soaked into an organic material is an explosive.
So any internal insulation in the oxygen tank would have to
be non-organic.


In principle, you could immerse the LO2 tank in the LH2 tank, and insulate
the outside of the LO2 tank.

You know, that's an idea I don't think I've seen before. It's interesting
if nothing else.

Without insulation between the tanks LH2 would still boil off, oxygen
would freeze to the LH2 tank wall, and chunks of it could be shed into
the pumps. This also would be bad.

The right answers for reliability are, use a vehicle arrangement which
is not susceptible to its own detritus, and use a vehicle which is
entirely re-useable and therefore testable. For lower overall costs one
would also not use LH2.