CEV to gain more Shuttle systems

I have just found this article:

http://www.flightglobal.com/Articles...e+systems.html

I am surprised about NASA thinking on using Shuttle TPS for the CEV.

"Rand Simberg" wrote in message
...
On 25 Feb 2006 06:55:06 -0800, in a place far, far away, "apozo"
made the phosphor on my monitor glow in such a way as
to indicate that:

I have just found this article:


http://www.flightglobal.com/Articles...0/204825/CEV+t
o+gain+more+Shuttle+systems.html

I am surprised about NASA thinking on using Shuttle TPS for the CEV.

It's actually not an reasonable choice (though I think they're still
trading it against an ablator). Part of the reason that the TPS is so

I suspect you mean unreasonable?


bad for Shuttle is that (a) it's exposed to debris at launch and (b)
the Orbiter has a large and varied surface area, making almost every
tile unique. Neither of these is true for the CEV CM, since it's on
top of the stack and the heat shield is hidden at launch, and it's an
axisymmetric body with much less surface area, so maintenance will be
much more streamlined.

On 25 Feb 2006 06:55:06 -0800, in a place far, far away, "apozo"
made the phosphor on my monitor glow in such a way as
to indicate that:

I have just found this article:

http://www.flightglobal.com/Articles...e+systems.html

I am surprised about NASA thinking on using Shuttle TPS for the CEV.

It's actually not an reasonable choice (though I think they're still
trading it against an ablator). Part of the reason that the TPS is so
bad for Shuttle is that (a) it's exposed to debris at launch and (b)
the Orbiter has a large and varied surface area, making almost every
tile unique. Neither of these is true for the CEV CM, since it's on
top of the stack and the heat shield is hidden at launch, and it's an
axisymmetric body with much less surface area, so maintenance will be
much more streamlined.

On Sat, 25 Feb 2006 15:08:49 GMT, in a place far, far away, "Greg D.
Moore \(Strider\)" made the phosphor
on my monitor glow in such a way as to indicate that:


"Rand Simberg" wrote in message
...
On 25 Feb 2006 06:55:06 -0800, in a place far, far away, "apozo"
made the phosphor on my monitor glow in such a way as
to indicate that:

I have just found this article:


http://www.flightglobal.com/Articles...0/204825/CEV+t
o+gain+more+Shuttle+systems.html

I am surprised about NASA thinking on using Shuttle TPS for the CEV.

It's actually not an reasonable choice (though I think they're still
trading it against an ablator). Part of the reason that the TPS is so

I suspect you mean unreasonable?

Right. I originally wrote that it was a reasonable choice, then
decided to soften it (because it is still being traded), and forgot to
double the negative.

h (Rand Simberg) :

On 25 Feb 2006 06:55:06 -0800, in a place far, far away, "apozo"
made the phosphor on my monitor glow in such a way as
to indicate that:

I have just found this article:


http://www.flightglobal.com/Articles...e+systems.html

I am surprised about NASA thinking on using Shuttle TPS for the CEV.

It's actually not an reasonable choice (though I think they're still
trading it against an ablator). Part of the reason that the TPS is so
bad for Shuttle is that (a) it's exposed to debris at launch and (b)
the Orbiter has a large and varied surface area, making almost every
tile unique. Neither of these is true for the CEV CM, since it's on
top of the stack and the heat shield is hidden at launch, and it's an
axisymmetric body with much less surface area, so maintenance will be
much more streamlined.

I consider (b) to be a huge factor. With the original shuttle design when
you need to do repairs quickly you must either have a huge stock of tiles
(most of them that you will never use) or have equipment ready to custom
cut/shape a material that is very hard to work with. In comparison for an
axisymmetric design only a relativily few shapes are needed. Maintaining a
repair stock pile becomes a lot cheaper.

Earl Colby Pottinger

--
Cruising, building a Catamaran, Rebuilding Cabin, New Peroxide Still Design,
Writting SF, Programming FOSS - What happened to the time?

apozo wrote:
I have just found this article:

http://www.flightglobal.com/Articles...e+systems.html

I am surprised about NASA thinking on using Shuttle TPS for the CEV.

Why the surprise?. The mass savings could be substantial,
meaning more payload.

- Ed Kyle

Why not simply use Ariane? The cost per kg is half that of the shuttle.

Earl Colby Pottinger wrote:

I consider (b) to be a huge factor. With the original shuttle design when
you need to do repairs quickly you must either have a huge stock of tiles
(most of them that you will never use) or have equipment ready to custom
cut/shape a material that is very hard to work with. In comparison for an
axisymmetric design only a relativily few shapes are needed. Maintaining a
repair stock pile becomes a lot cheaper.

Another thing in favor of the capsule: while you can't mould an entire
space shuttle in one tile, it should not be impossible to make a single
tile that can cover the entire bottom of the CEV.

Whether this is desirable or not I'll leave up to the experts to
decide. Tiles might be easier to deal with if the heat shield has to be
replaced or touched up often.

Jon Acheson

wrote:
Why not simply use Ariane? The cost per kg is half that of the shuttle.

Then why not use Proton? It costs less than Ariane.

- Ed Kyle