More cracked ribs on Discovery ET

Four new cracks on the other side of the tank from the first ones:
http://spaceflightnow.com/shuttle/sts133/101230cracks/
I note that the original and newly found cracks seem to be about equally
spaced to either side of the port SRB; was that involved in their
formation by stresses on the intertank structure during assembling the
launch stack or from something slightly shifting while it sat on the pad?

Pat

On 1/01/2011 4:31 AM, Pat Flannery wrote:
Four new cracks on the other side of the tank from the first ones:
http://spaceflightnow.com/shuttle/sts133/101230cracks/
I note that the original and newly found cracks seem to be about equally
spaced to either side of the port SRB; was that involved in their
formation by stresses on the intertank structure during assembling the
launch stack or from something slightly shifting while it sat on the pad?

Pat

Cracked ribs? I thought it was the insulation that was the problem.
Thanks for the correction.

On 1/01/2011 4:31 AM, Pat Flannery wrote:
Four new cracks on the other side of the tank from the first ones:
http://spaceflightnow.com/shuttle/sts133/101230cracks/
I note that the original and newly found cracks seem to be about equally
spaced to either side of the port SRB; was that involved in their
formation by stresses on the intertank structure during assembling the
launch stack or from something slightly shifting while it sat on the pad?

Pat

Makes one wonder whether this is the first time such cracks have
ocurred, or merely the first time they've been detected (something which
is probably unknowable). It seems incredible that in the run up to
program termination, tanks still cannot be built reliably.

Sylvia.

* I'm still trying to figure out what they mean by that; either the
launch is necessary, in which case they should either fix the tank or
swap it with another one ASAP, or the launch isn't necessary, in which
case they should just cancel the last two flights and save a lot of
time, effort, and money.

Pat

how many would volunteer to end their jobs early espically in this
economy?

volunteers please?

On 1/1/2011 5:44 PM, Alan Erskine wrote:
On 1/01/2011 4:31 AM, Pat Flannery wrote:
Four new cracks on the other side of the tank from the first ones:
http://spaceflightnow.com/shuttle/sts133/101230cracks/
I note that the original and newly found cracks seem to be about equally
spaced to either side of the port SRB; was that involved in their
formation by stresses on the intertank structure during assembling the
launch stack or from something slightly shifting while it sat on the pad?

Pat

Cracked ribs? I thought it was the insulation that was the problem.
Thanks for the correction.

The insulation cracked over the first set of cracks...which is pretty
lucky, as that's what led them to examine the damage and find the first
set of cracked ribs.
If the foam hadn't cracked, they would have just fixed the hydrogen
fueling system leak and launched several days later, never knowing about
the cracks.
On the other hand, they only spotted the cracked foam as they were
de-fueling the ET after the launch was scrubbed by the hydrogen leak, so
if the hydrogen leak hadn't occurred, would they have spotted it, or
have launched with the cracked ribs and foam? That could have led to a
major foam shedding incident at the least, and possibly a structural
failure of the ET intertank structure at the worst.

Pat

On Sun, 02 Jan 2011 08:03:52 -0800, Pat Flannery
wrote:


* I'm still trying to figure out what they mean by that; either the
launch is necessary, in which case they should either fix the tank or
swap it with another one ASAP, or the launch isn't necessary, in which
case they should just cancel the last two flights and save a lot of
time, effort, and money.

Not exactly like there are other tanks sitting around which might be
used.

On 1/2/2011 4:39 AM, Sylvia Else wrote:
Makes one wonder whether this is the first time such cracks have
ocurred, or merely the first time they've been detected (something which
is probably unknowable).

That's exactly what I thought; for all we know, we've been launching
aluminum-lithium ETs with cracked ribs on them from the beginning, and
since the foam covering them didn't crack when fueling started, they
went undetected.
Apparently, NASA employees have been spotted wearing T-shirts with
"WWED?" emblazoned on them, this standing for "What Would Elon Do?" (a
parody of "What Would Buffy Do?") and probably a reference to the ET
crack problems and the lengthy "launch rational"* description of what's
going on in regards to it, versus Musk's team cutting the back of the
Merlin engine nozzle off around a day or two after cracks were found in
it:
http://www.latimes.com/news/nationwo...,2011017.story

* I'm still trying to figure out what they mean by that; either the
launch is necessary, in which case they should either fix the tank or
swap it with another one ASAP, or the launch isn't necessary, in which
case they should just cancel the last two flights and save a lot of
time, effort, and money.

Pat

On Jan 2, 10:59*am, me wrote:
On Sun, 02 Jan 2011 08:03:52 -0800, Pat Flannery
wrote:

* I'm still trying to figure out what they mean by that; either the
launch is necessary, in which case they should either fix the tank or
swap it with another one ASAP, or the launch isn't necessary, in which
case they should just cancel the last two flights and save a lot of
time, effort, and money.

Not exactly like there are other tanks sitting around which might be
used.

and the next tank already has at least one crack, its been a ongoing
issue, but this was the first seen at the pad after fueling

"What Would Elon Do?" - Musk's team cutting the back of the
Merlin engine nozzle off around a day or two after cracks were found in

My undertanding from the News articles is, this was a piece of engine bell
that gave better performance in vacuum - essentially a nice to have. OK so
they trimmed it to stop the crack from propagating further. On the shuttle
we have a piece of structure in a region where a similar failure caused the
loss of vehicle. Seems a bit of irrational grasping at straws to compare the
two situations.

Val
Kraut

On 1/2/2011 7:59 AM, me wrote:
On Sun, 02 Jan 2011 08:03:52 -0800, Pat
wrote:


* I'm still trying to figure out what they mean by that; either the
launch is necessary, in which case they should either fix the tank or
swap it with another one ASAP, or the launch isn't necessary, in which
case they should just cancel the last two flights and save a lot of
time, effort, and money.

Not exactly like there are other tanks sitting around which might be
used.

There are two other ET's built and ready to go down at the Cape; the
last planned flight is to use the ET that was damaged in the hurricane
and repaired, and there is a brand new ET that is being held in reserve
in case the last planned flight suffers a problem that leaves it
stranded in orbit or at the ISS. I imagine both of those would get a
pretty close inspection via X-rays to see if there are any cracks in
them before being swapped with the damaged ET.

Pat