In sci.physics, jabara
on Sun, 31 Jul 2005 21:50:43 -0500
> "Sam Wormley" <swormley1@xxxxxxxxx> wrote in message
>> Posted on Sun, Jul. 31, 2005
>> Ref: http://www.contracostatimes.com/mld/cctimes/news/nation/12269385.htm
>> Old maxim didn't apply to NASA's foam problem
>> By John Schwartz
>> NEW YORK TIMES
>> "We are ready to fly."
> Think about it.
> You have to spray a tank with foam that insulates and hardens at sea level.
> It is then exposed to severe vibration and less pressure, so the foam both
> expands and cracks.
> Bad design?
> Bad Foam, or could any Foam ever do the job?
I suspect no foam will ever work. Foam, after all, is
substance + air. Air is under pressure (this is proven
in a number of ways). The pressure goes down outside,
the foam expands inside.
If the bubble skin is thin enough, it might work --
however, if not, well...
(There is the remote possibility of placing the entire
tank in a near-vacuum, or perhaps using steam to apply the
foam, allowing the water vapor to fill the bubbles, which
collapse when the steam cools sufficiently. The former
looks highly impractical; the latter has the problem that
the steam condenses to water, which may, given the wrong
conditions, form a skin between foam and tank, ready
I'm beginning to wonder if they'll have to eschew the
foam and fabricate a gigantic heating coil underneath the
shuttle (between the bimounts). The main problem with
that is that the heating element might break away too,
in flight -- but it might beat being hit with chunks of ice,
especially if the element is sprayed with some sort of
epoxy or superglue.
> [Old Saying in rocket/aerospace industry, "FIFI" =>F*ck It, Fly It.]
Then die in it, apparently. It's admittedly an interesting
tradeoff: how much is an astronaut's life worth?
(Considering that we get about 20 deaths in Iraq *per day*
because of operations there, 17 deaths in the span of
over 30 years isn't all that bad. But it's still 17 deaths.)
It's still legal to go .sigless.