Cavity behind the RCC leading edge

On Fri, 29 Aug 2003 05:12:53 +0000, Jorge R. Frank wrote:

"Chuck Stewart" wrote:

Doug Ellison wrote:

Foam that has zero mass, enormous heat resistance, is flight
qualified, will not outgas on orbit, and will make you coffee in the
morning

Aerogel!

Problem solved...

How do you get behind the panels for inspection and servicing,
then...? :-)

Er... send in the Rover after it's made the coffee?

If this was to be seriously done then the aerogel would be in
pieces that would be lifted out chunk by chunk... each chunk
individually cut to a precise specification different from every
other chunk, and requiring serious overhead in record-keeping,
handling and storage while maintanence was underway.

Not that I'd make fun of a cetain design philosophy, you
understand...

--
Chuck Stewart
"Anime-style catgirls: Threat? Menace? Or just studying algebra?"

In article ,
says...
When I looked at the video of how they simulated the foam block
colliding with the reinforced carbon carbon leading edge of the
shuttle, I noticed that behind the leading edge (which is a thin sheet
of RCC) there was nothing.

Isn't this highly irresponsible, in other words stupid? Any
homebuilder of kit airplanes knows that filling the cavity with foam
would greatly enhance the strength of the leading edge without
increasing the weight of the structure. The carbon fibers comprising
the composite sheet are strong in tension/compression but can be bent.
This lack of support from the inside was the direct cause of the hole
that the foam block punched in it.

I know several people have responded to you in a rather sneering fashion,
Zoltan, but they're correct. Not only is there not a material that
wouldn't be unreasonably heavy, the thermal issue is what kills the
concept.

The RCC panels don't just sit there at room temperature as the leading
edge of the wing rises beyond 2000 degrees Fahrenheit. The panels get
hot, first along the outside surface and slowly throughout. They don't
get as hot on the inside as the outside, but they still get very, very
hot on the inside surface.

During most of the descent, the panels aren't in contact with much of
anything that could conduct that heat into the structural members of the
wing. They only contact the bolts and fittings that hold them in place,
and those are made of inconel, which takes a long time to heat up. By
the time the inside of the wing starts getting hot, you're on the ground
and the RCC panels aren't being heated anymore.

If you fill up the space behind the RCC panels with foam or anything else
that can conduct heat, that material will get really hot, really fast.
And it will conduct the heat into the interior of the wing. This is
exactly what you're trying to prevent.

It might not make sense to you in a common-sense world, but the Shuttle
enounters temperatures and stresses, and operates in environments, with
which you don't have any common-sense experience.

--

Do not meddle in the affairs of dragons, for | Doug Van Dorn
thou art crunchy and taste good with ketchup |

"Doug Ellison" wrote in message ...
"Chuck Stewart" wrote in message
news
On Thu, 28 Aug 2003 21:23:37 +0100, Doug Ellison wrote:

"Paul F. Dietz" wrote in message
...
Doug Ellison wrote:

Really? You could fill all that space with foam with zero mass?

Foam that would tolerate being in contact with white-hot RCC
material, no less.

Forgot that bit

Foam that has zero mass, enormous heat resistance, is flight qualified,
will
not outgas on orbit, and will make you coffee in the morning

Aha!

Aerogel!

Aerogel just like those used in insulating blocks on the Mars
Sojourner Rover!

Aerogel stripped from a Rover is ust the ticket... aerogel filler
will have next-to-zero mass, heat resistance, is flight qualified,
will not outgas on orbit, and the Rover can make you coffee in the
morning.

Problem solved...


Genuine thought process I once had

"That aerogel stuff looks really cool. They should make an office toy out of
it. A paperweight or something"

LMFAO - a PAPERWEIGHT!!

:P

Still - they SHOULD make an office toy out of it :P

Doug


From reading the responses here it sounds like you guys are the same
ones that designed the leading edge without the foam filling.

Practically the foam would have no appretiable weight so that point is
mute.
The foam inside would not be exposed to the heat of the outside.
As for flight qualifying the foam thats a ridiculous burocrat's
statement. All kinds of airplanes are made using composits and there
are fire resistant foams in common use.
My original point stands.

Zoltan

Doug... wrote:



If you fill up the space behind the RCC panels with foam or anything else
that can conduct heat, that material will get really hot, really fast.
And it will conduct the heat into the interior of the wing. This is
exactly what you're trying to prevent.

It seems to me that another leading edge breach is inevitable, and
unless there is a way to mitigate the effects of heat entering the
wing structure, another loss of ship and crew is guaranteed. Reentry
heating seems to be one of the most, if not the most, important
element in an operational cycle of the shuttle. I vaguely remember
reading something about aerogel in the past, but it seems to me I
remember it having an extremely low thermal conductivity, perhaps
even less than the shuttle tiles. If that were the case, and given
the low mass, filling the leading edge cavity might buy enough time
for the ship to transition through the superheating phase of
reentry and get the ship and crew home. Another thought: What would
happen if the part of the aluminum wing structure that faces that
cavity were to be lined with shuttle tiles? Would it add a couple
of hundred pounds to the weight of the structure? So what if it
did? Even with the capacity reduced that much the Shuttle is still
the heaviest lift capable ship currently operating in the world.

Just thinking out loud...

JazzMan
--
***************************************
Please reply to jsavage"at"airmail.net.
Curse those darned bulk e-mailers!
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Jazzman wrote:

It seems to me that another leading edge breach is inevitable, and
unless there is a way to mitigate the effects of heat entering the
wing structure, another loss of ship and crew is guaranteed.

Inevitable? That's a bit much. Keep in mind that they flew 113 times before
this specific problem occurred. Something needs to be done, but since
*prevention* is better, addressing the worst of the ET foam areas and/or
addressing bonding issues there, and flying ascent at a more negative alpha
in the higher qbar regimes would almost certainly alleviate *this* problem
over the expected remaining lifetime of the shuttle. If a good repair
option becomes available (and there are promising options starting to show
up now), then the contingency would be addressed.

Jon

"Chuck Stewart" wrote in
news
On Thu, 28 Aug 2003 21:23:37 +0100, Doug Ellison wrote:

"Paul F. Dietz" wrote in message
...
Doug Ellison wrote:

Really? You could fill all that space with foam with zero mass?

Foam that would tolerate being in contact with white-hot RCC
material, no less.

Forgot that bit

Foam that has zero mass, enormous heat resistance, is flight
qualified, will not outgas on orbit, and will make you coffee in the
morning

Aha!

Aerogel!

Problem solved...

How do you get behind the panels for inspection and servicing, then...? :-)

--
JRF

Reply-to address spam-proofed - to reply by E-mail,
check "Organization" (I am not assimilated) and
think one step ahead of IBM.

"Jorge R. Frank" wrote in message
...
"Chuck Stewart" wrote in
news
On Thu, 28 Aug 2003 21:23:37 +0100, Doug Ellison wrote:

"Paul F. Dietz" wrote in message
...
Doug Ellison wrote:

Really? You could fill all that space with foam with zero mass?

Foam that would tolerate being in contact with white-hot RCC
material, no less.

Forgot that bit

Foam that has zero mass, enormous heat resistance, is flight
qualified, will not outgas on orbit, and will make you coffee in the
morning

Aha!

Aerogel!

Problem solved...

How do you get behind the panels for inspection and servicing, then...?
:-)

Just take a deep breath and... (with reference to Chuck's earlier post) g

Cameron:-)

On Fri, 29 Aug 2003 06:33:40 +0000, Paul F. Dietz wrote:

Chuck Stewart wrote:

And any "foam" behind [the RCC] would
conduct the heat even faster than the void that is currently behind
the leading edges.

It's not clear this is the case. Heat is being transmitted from
the RCC to the wing structure by radiation. Interposing an opaque
material (for example, carbon aerogel) could actually reduce this.

Hmm?... but what about heat conduction via carbon strands in
contact with both RCC and wing structure? It might not be much, but
it'd be there.

Of course aerogels, silica or carbon, weren't handy when the
orbiter was designed...

Paul

--
Chuck Stewart
"Anime-style catgirls: Threat? Menace? Or just studying algebra?"

http://www.cockeyed.com/inside/foam/foam.html

"Zoltan Szakaly" wrote in message
om...
When I looked at the video of how they simulated the foam block
colliding with the reinforced carbon carbon leading edge of the
shuttle, I noticed that behind the leading edge (which is a thin sheet
of RCC) there was nothing.

Isn't this highly irresponsible, in other words stupid? Any
homebuilder of kit airplanes knows that filling the cavity with foam
would greatly enhance the strength of the leading edge without
increasing the weight of the structure. The carbon fibers comprising
the composite sheet are strong in tension/compression but can be bent.
This lack of support from the inside was the direct cause of the hole
that the foam block punched in it.

Zoltan


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Chuck Stewart wrote:

And any "foam" behind [the RCC] would
conduct the heat even faster than the void that is currently behind
the leading edges.

It's not clear this is the case. Heat is being transmitted from
the RCC to the wing structure by radiation. Interposing an opaque
material (for example, carbon aerogel) could actually reduce this.

Paul