Re: wrap Et in mesh?

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

> litnbolt@xxxxxxxxxxx wrote in
> news:1112831990.546511.279750@xxxxxxxxxxxxxxxxxxxxxxxxxxxx:
>
>> 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 @ WeBeGood@xxxxxxxxx
.

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