Possible Solution to Foam Problem on Shuttle

It's looking good.
I find it incredible they didn't think of this before.

See
http://homepage.ntlworld.com/s.slee/durexcovery.htm

--
Gareth Slee

"Gareth Slee" wrote in message
m...
It's looking good.
I find it incredible they didn't think of this before.

See
http://homepage.ntlworld.com/s.slee/durexcovery.htm
- Gareth Slee

Just paint it white ... probably hold better than other solutions ...

Am Fri, 29 Jul 2005 17:59:58 +0100 schrieb "Gareth Slee":

It's looking good.
I find it incredible they didn't think of this before.

Think the other way: The insulation is only needed while on ground;
during the 8 minutes of flight it isn't needed anymore.

So what about shedding all insulation foam by design (maybe except
that on the nose cone) just at the moment of liftoff - like Ariane-4
did (and some other launchers still do) with success on its upper
stage LH2 tank? The delta-V isn't large enough then to cause harm,
especially if you design sheddable insulation panels for the right
size and form and maybe "steer" the shedding pattern by a
thought-through shedding scheme. And that all in the view of history
of American LOX-LH2 driven launcher stages - external insulation on
Centaur, carried aloft, caused many hassles and (if I remember right)
even a couple of launch failures during development phase of that
stage; OTOH internal insulation like used in the Saturn launcher
family has an absolutely clean record...

The original decision to make the ETs how they are now was simply
based on a very high projected flight frequency, where the ETs were
planned to be produced cheap - like sausages, storable, with
insulation in place - just attach, fly, throw away, one a week,
minimizing VAB and/or pad preparation time. With actual low flight
frequencies we have now, the idea of shedded-by-design insulation
(that can be attached while mating the stack) should be given a second
thought (or maybe a third or even more). And btw: it would increase
the payload capacity, because every "dead" weight, that has NOT to be
carried to almost orbital speed, will be a benefit for available
orbital payload capacity :-)

cu, ZiLi aka HKZL (Heinrich Zinndorf-Linker)
--
"Abusus non tollit usum" - Latin: Abuse is no argument against proper use.

mailto: http://zili.de

"gb" wrote in message
...
"Gareth Slee" wrote in message
m...
It's looking good.
I find it incredible they didn't think of this before.

See
http://homepage.ntlworld.com/s.slee/durexcovery.htm
- Gareth Slee

Just paint it white ... probably hold better than other solutions ...

As has been said repeatedly, paint has little to no mechanical strength, so
painting the ET (again) wouldn't help the foam shedding issue. In fact,
there was foam loss and tile damage on the first flights, which used painted
tanks.

Jeff
--
Remove icky phrase from email address to get a valid address.

"Heinrich Zinndorf-Linker (zili@home)" wrote in message
...
Am Fri, 29 Jul 2005 17:59:58 +0100 schrieb "Gareth Slee":

It's looking good.
I find it incredible they didn't think of this before.

Think the other way: The insulation is only needed while on ground;
during the 8 minutes of flight it isn't needed anymore.

This is false. The insulation also protects the ET from aerodynamic heating
during launch.

Jeff
--
Remove icky phrase from email address to get a valid address.

Am Mon, 1 Aug 2005 13:35:17 -0400 schrieb "Jeff Findley":


"Heinrich Zinndorf-Linker (zili@home)" wrote in message
...
Am Fri, 29 Jul 2005 17:59:58 +0100 schrieb "Gareth Slee":

It's looking good.
I find it incredible they didn't think of this before.

Think the other way: The insulation is only needed while on ground;
during the 8 minutes of flight it isn't needed anymore.

This is false. The insulation also protects the ET from aerodynamic heating
during launch.

Yep - This was only one of my messages about ET insulation concepts -
a very abbreviated one, where I omitted some thoughts - I CANNOT
repeat ALL in EVERY message. But for your pleasure (I hope so) I will
re-write all once again...

The LOX tank insulation is surely necessary (as you say, because of
aerodynamic heating, but not more necessarily for LOX cooling during
that eight minutes), the actual LH2 tank insulation seems to bear no
real problem and can remain, too, but the intertank area is the area
with foam shedding and popcorning (and as we know well, the PAL ramp
area, too). These are the areas, where the foam is machined down after
curing, so its surface is not more "native" like after spraying. Look
for the on-orbit ET photos made this launch just after ET separation.

And I say, the one (shedding/popcorning) HAS a direct dependance on
the other (machining), because there seem to be NO shedding/popcorning
problems in areas NOT machined down, as I believe to know.

IF I am right, there are a couple of possible solutions for that
problem:
a) Simply leave the foam there away (maybe use insulation plates
on-pad, to be removed shortly before launch). The PAL ramp may be made
as a 'monolithic' somehow bolted to the tank structure.
b) Leave it "as is" after spraying, WITHOUT machining it down and
destroying its surface.
c) Use a "re-bonding" technique as an alternative to re-densify the
machined-down surface, if and where machining down is really
necessary.
d) ...(some solutions not mentioned or just not thought about).

So "painting simply white" seems to be not the worst idea at all - if
the right paint is chosen (I guess, PU lacquer will bond best with PU
foam) - that would resemble 'my' solution c) ...




cu, ZiLi aka HKZL (Heinrich Zinndorf-Linker)
--
"Abusus non tollit usum" - Latin: Abuse is no argument against proper use.

mailto: http://zili.de