wrap Et in mesh?

With all this info about foam still going to fall of, was there any
consideration to putting a tight mesh "net" around the ET to contain
any loose debris?

yes

wrote in message
oups.com...
With all this info about foam still going to fall of, was there any
consideration to putting a tight mesh "net" around the ET to contain
any loose debris?




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Seriously, per the many briefings yesterday a spokeperson was referring to
suggestions of embedded fibres and nets and said something along the lines
it would create more problems than not. Did not elaborate....



wrote in message
oups.com...
With all this info about foam still going to fall of, was there any
consideration to putting a tight mesh "net" around the ET to contain
any loose debris?




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wrote in
oups.com:

With all this info about foam still going to fall of, was there any
consideration to putting a tight mesh "net" around the ET to contain
any loose debris?

Some consideration. It adds a lot of weight and, considering that some of
the foam "popcorns" off with considerable force, isn't guaranteed to fix
the problem.


--
JRF

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check "Organization" (I am not assimilated) and
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wrote in message
oups.com...
With all this info about foam still going to fall of, was there any
consideration to putting a tight mesh "net" around the ET to contain
any loose debris?


Yes, as I recall from one press conf i heard, but the mesh would have had to
be very close knit and rather heavy and the decided it was not feasible as I
recall.

I'm sure others have a more definitive answer.


I'm more intrigued by the airflow patters which can create impacts in the
first place, though.

Brian

--

Brian Gaff....Note, this account does not accept Bcc: email.
graphics are great, but the blind can't hear them
Email:
__________________________________________________ __________________________________________________ __________

On Thu, 07 Apr 2005 03:22:13 +0000, Jorge R. Frank wrote:

wrote in
oups.com:

With all this info about foam still going to fall of, was there any
consideration to putting a tight mesh "net" around the ET to contain
any loose debris?

Some consideration. It adds a lot of weight and, considering that some
of the foam "popcorns" off with considerable force, isn't guaranteed to
fix the problem.

How much consideration?

A 1/8 inch net made with a single fiber of Kevlar (or carbon) embedded in the
last layer of foam might top out at a couple of kilograms or so.

8 fibers/inch * 2 dimensions * 36 inches/yard = 576 yards of
fiber/square yard of net.

http://www.syntheticthread.com/kevtech.htm

Size A filament 20,000 yards/lb at 6 lbs breaking strength. Giving 6*8*2 =
96 lbs/sq inch, or an even 100 psi protection

20,000 (yards/lbs) / 576 (yards of thread/yrd^2 of mesh) = 35 sq yards mesh/lb.

Estimate of ET surface area next to Orbiter 10x50 square yards = 500 square yards

Weight of net = 500/35 = 14 lbs of net to cover the ET area of interest.

Hummm, maybe size B filament 28lbs and 200 psi of protection.

Or, size F filament at 56 lbs and 400 psi of protection.

The guy at:
http://www.sedakayak.com/shared/construction.html
seems to think,
"A single strand of KEVLAR will cut your fingers if you try to pull it
apart. It will not break."

At least when the popcorn blasts it's way thru the Kevlar, it would be cut
into 1/8 inch little pieces. So exactly how is NASA insuring the size of
the popcorn meets it's new ET debris criteria?

The expensive part would be the recertification, since they just completed
redesigning and recertification of the tank without an embedded tread net.

--
Craig Fink
Courtesy E-Mail Welcome @

On Wed, 06 Apr 2005 20:14:22 -0400, Lynndel Humphreys wrote:

Seriously, per the many briefings yesterday a spokeperson was referring to
suggestions of embedded fibres and nets and said something along the lines
it would create more problems than not. Did not elaborate....


It's not weight, it's not strength, makes me wonder what problems?

--
Craig Fink
Courtesy E-Mail Welcome @

Seriously, per the many briefings yesterday a spokeperson was referring
to
suggestions of embedded fibres and nets and said something along the
lines
it would create more problems than not. Did not elaborate....


It's not weight, it's not strength, makes me wonder what problems?

Possibly aerodynamic drag.

Possibly the mesh would somehow interfere with thermodynamics already
designed into the E.T.


JD

Craig Fink wrote:
On Wed, 06 Apr 2005 20:14:22 -0400, Lynndel Humphreys wrote:


Seriously, per the many briefings yesterday a spokeperson was referring to
suggestions of embedded fibres and nets and said something along the lines
it would create more problems than not. Did not elaborate....



It's not weight, it's not strength, makes me wonder what problems?


AIUI, The ETs are coated with the foam, which is then "machined" into
its final aerodynamic shape after the foam has solidified. Given that,
here are some problems that might have to be solved:

If fiber/mesh is applied before foam solidifies:

* how do you place the fiber/mesh at the correct distance from the tank
wall so that it'll end up at the outer surface of the foam?

* if the fiber/mesh is embedded in the foam (not at the surface), what
is the effect on the tendency of the foam to break loose? You're
essentially building-in a separation plane in the foam...

* how well does the foam adhere to a useful fiber/mesh?

If fiber/mesh is applied after the solidified foam is machined:

* how do you guarantee that the fiber/mesh remains attached to the ET
surface, particularly considering the aerodynamic & radiant heating that
occurs during flight?

* how do you apply the fiber/mesh to the machined tank, accounting for
the LOX feed pipe, intertank access hatch, LH2 umbilical interface, and
other protuberances?

--
Reed Snellenberger
GPG KeyID: 5A978843
rsnellenberger-at-houston.rr.com

Is the foam sprayed on in straight lines or applied in specific patterns
like a checker board cake?


"Reed Snellenberger" wrote in message
...
Craig Fink wrote:
On Wed, 06 Apr 2005 20:14:22 -0400, Lynndel Humphreys wrote:


Seriously, per the many briefings yesterday a spokeperson was referring
to
suggestions of embedded fibres and nets and said something along the
lines
it would create more problems than not. Did not elaborate....



It's not weight, it's not strength, makes me wonder what problems?


AIUI, The ETs are coated with the foam, which is then "machined" into
its final aerodynamic shape after the foam has solidified. Given that,
here are some problems that might have to be solved:

If fiber/mesh is applied before foam solidifies:

* how do you place the fiber/mesh at the correct distance from the tank
wall so that it'll end up at the outer surface of the foam?

* if the fiber/mesh is embedded in the foam (not at the surface), what
is the effect on the tendency of the foam to break loose? You're
essentially building-in a separation plane in the foam...

* how well does the foam adhere to a useful fiber/mesh?

If fiber/mesh is applied after the solidified foam is machined:

* how do you guarantee that the fiber/mesh remains attached to the ET
surface, particularly considering the aerodynamic & radiant heating that
occurs during flight?

* how do you apply the fiber/mesh to the machined tank, accounting for
the LOX feed pipe, intertank access hatch, LH2 umbilical interface, and
other protuberances?

--
Reed Snellenberger
GPG KeyID: 5A978843
rsnellenberger-at-houston.rr.com



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