Integrate Kevlar netting within layer of foam

If the foam is sprayed on to the tank during assembly, then maybe a
sub-surface Kevlar netting that is integrated into the application of
the foam would help. The netting would be below the surface of the
foam layer (thus eliminating any aerodynamic issues), and it would be
able to help 'hold together' the foam.

I'm not sure if the thermal coefficients would match up between the
materials, or if they could be engineered so that they do, but I think
the concept might be worth exploring. I'm also not sure if the added
weight would be prohibitive (I read elsewhere that even the weight of
paint on the external tank was too much, so they discontinued using
it).

-Randy

Randy MacKenna wrote:

If the foam is sprayed on to the tank during assembly, then maybe a
sub-surface Kevlar netting that is integrated into the application of
the foam would help. The netting would be below the surface of the
foam layer (thus eliminating any aerodynamic issues), and it would be
able to help 'hold together' the foam.

I guess it depends on why the foam breaks off to begin with. At those speeds,
if the foam breaks off, the netting may not be anywhere near strong enough to
keep the foam piece from being blown away.

My gut tells me they need to find some more flexible material that doesn't
crack when bent/vibrated.

"John Doe" wrote in message
...
Randy MacKenna wrote:

If the foam is sprayed on to the tank during assembly, then maybe a
sub-surface Kevlar netting that is integrated into the application of
the foam would help. The netting would be below the surface of the
foam layer (thus eliminating any aerodynamic issues), and it would be
able to help 'hold together' the foam.

I guess it depends on why the foam breaks off to begin with. At those
speeds,
if the foam breaks off, the netting may not be anywhere near strong
enough to
keep the foam piece from being blown away.

My gut tells me they need to find some more flexible material that
doesn't
crack when bent/vibrated.

Have they ever tested this material when it was undergoing strong
vibration, such as it would experience from the SRBs during launch? Have
they ever tested it under such vibration conditions when it is going
supersonic (well, now that I think about it, I guess they have since they
put it on the ET and then launch it in space)? I'm referring to simulated
launch conditions, of course. One thing I noticed from the ET video is
that it appeared that the ET shell was flexing quite a bit. Did anyone
else notice this?

" George" wrote in
news:1baGe.218054$xm3.77711@attbi_s21:

One thing I
noticed from the ET video is that it appeared that the ET shell was
flexing quite a bit. Did anyone else notice this?

I didn't. I *did* notice that the LOX feedline that the ET camera was
mounted to was flexing quite a bit, but the tank under it seemed stable.

--
JRF

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

George wrote:

I'm referring to simulated launch conditions, of course. One
thing I noticed from the ET video is that it appeared that the
ET shell was flexing quite a bit. Did anyone else notice this?

You evidently saw the normal twang caused by the side-mounted main
engines. After an extensive standdown such as this one, it's been SOP
for KSC to conduct a Flight Readiness Firing (FRF) prior to launch.
This flexes the tank in advance, to a large extent.

Speaking of the (non-FRF) approach taken this time, after the launch
Griffen told the media that we owe "this team" a "large debt of
appreciation" for its "sheer gall." Bill Readdy, Griffen's deputy,
immediately chimed in with "Amen!"

I think the sheer gall belongs to Readdy, Griffen, and Bush. However, I
wouldn't want to influence anyone who hasn't the time to look further
than the media reporting by the likes of Bill Harwood and Jay Barbree
at the Cape.

Challenger's Ghost

" wrote in message
ups.com...
George wrote:

I'm referring to simulated launch conditions, of course. One
thing I noticed from the ET video is that it appeared that the
ET shell was flexing quite a bit. Did anyone else notice this?

You evidently saw the normal twang caused by the side-mounted main
engines. After an extensive standdown such as this one, it's been SOP
for KSC to conduct a Flight Readiness Firing (FRF) prior to launch.
This flexes the tank in advance, to a large extent.

What is a "normal Twang"? Is that a New NASA term for flexing metal? lol.
Where I saw flexure and shaking was directly beneath the orbiter on the
wall of the ET nearly in front ot the camera. I realize that it may be
caused by the vibration of the SRB, but that was my point.

George wrote:

What is a "normal Twang"?

Twang normally begins a few seconds prior to SRB ignition and ends a
few seconds afterward. You were apparently referring to a later time,
and probably a different camera. I was picking up on your reference to
sumulation, since the FRF tests such things without any SRB ignition.

Challenger's Ghost

" wrote in message
ups.com...
George wrote:

What is a "normal Twang"?

Twang normally begins a few seconds prior to SRB ignition and ends a
few seconds afterward. You were apparently referring to a later time,
and probably a different camera. I was picking up on your reference to
sumulation, since the FRF tests such things without any SRB ignition.

Challenger's Ghost

No, I was referring to before SRB separation, and the view of the ET from
the ET tank camera.

George wrote:

No, I was referring to before SRB separation, and the view of the ET from
the ET tank camera.

Okay, I may have seen something like that on video myself -- live. Did
you see it live, or in a rerun? If you did see that, it could help
explain things which happened at SRB sep and subs.

Challenger's Ghost

" wrote in message
ups.com...
George wrote:

No, I was referring to before SRB separation, and the view of the ET
from
the ET tank camera.

Okay, I may have seen something like that on video myself -- live. Did
you see it live, or in a rerun? If you did see that, it could help
explain things which happened at SRB sep and subs.

Challenger's Ghost

Both, but I didn't notice what appeared ot be flexing to the tank surface
until after I watched it again in a re-play. Unfortunately, I didn't
capture the video onto my computer at the time of the launch, and for some
reason when I go to the NASA return to flight page, the video will not play
in the version of media player that they provide through Yahoo (that really
****es me off. It was fine the way they had it before). And I don't have
real player because I don't like it.