STS-133 LH2 and ET Problems

Underlying metal cracks found on Discovery's tank
http://www.spaceflightnow.com/shuttl...3/101110crack/

Cracked foam insulation on the shuttle Discovery's external tank was
cut away overnight, revealing serpentine cracks in an underlying
structural rib, or stringer.
...
Overnight, engineers at pad 39A cut away the foam insulation in the area
of the crack, revealing underlying cracks in a structural stringer that
is part of the vertical ribbing that makes up the intertank section. The
cracks appear to run in a wavy line from bolt to bolt in the stringer.

It is not yet clear what caused the underlying cracks. They presumably
could have been triggered by temperature-induced stress as the tank was
loaded with supercold liquid oxygen and hydrogen rocket fuel. But a
similar crack was found in ET-138, scheduled for use by the shuttle
Atlantis next summer, and that tank has not yet been subjected to
cryogenic temperatures. The cracks may be related to the use of
lightweight materials in the latest generation of tanks.
...
Whether Discovery's launch team can complete the leak repair and fix
the crack damage in time for a Nov. 30 liftoff is not yet known, but
engineers are cautiously optimistic. The schedule is considered "success
oriented," however, and there is little margin for error.


In other words, they created a new ET design/modifiaction/improvement. One
of the new ETs faild by its own weight. The other during fueling. But
they hope after a repair of the obvious cracks that thing will survive the
loads of the Mach 10+ hypersonic environment.

I hope they will be lucky. But why introduced this idiots a new ET type
at all? Since 2005 they had no mission the old ET could not accomplish.
No need for any weight reduction till retirement.

Besides this metal cracks in a new ET the leak in the hydrogen vent line
system is similar appaling. Such LH2 systems are an engineering challange.
But it was alraedy solved in the 1960 before and during Apollo - and for
most of the time till now. That they have such trouble now to fix it
makes me think they have retired or fired a few guys to much. This
broken part of NASA will now design a new rocket in the class of the
Saturn V?



## CrossPoint v3.12d R ##

This
broken part of NASA will now design a new rocket in the class of the
Saturn V?

This part of NASA was already broken as Constellation was just beginning.
There were numerous articles on NASA engineers visiting Apollo displays in
museums to study the actual hardware and re-establish lessons that were
learned on Apollo. The Saturn documentation is mostly gone and much of the
original design crew is also gone. But I do believe you're right as the crew
is dispersed they don't really realize that undocumented skills or processes
are being lost. There was an article some time ago by an architect that was
hired to design a space habitat. She asked for data on past manned units -
much of which was not readily available. The excuse was that as projects
end - members are assigned to different teams - and the bulk of the
paperwork isn't archived in an orderly fashion. After the initial design was
complete they conviened a review board of engineers with experience fron
past programs which resulted in a major redesign effort.

I was in one meeting where an engineer presented a newer more efficient
design they were using on a terrestrial program - one of the more senior
NASA guys raised his hand and stated - we tried that - it doesn't work in
space, along with a here's why.


Val Kraut

On 11 Nov 2010 21:05:00 +0200, wrote:

But a
similar crack was found in ET-138, scheduled for use by the shuttle
Atlantis next summer, and that tank has not yet been subjected to
cryogenic temperatures. The cracks may be related to the use of
lightweight materials in the latest generation of tanks.

In other words, they created a new ET design/modifiaction/improvement.

This was in the 1990s, to make up for the performance shortfall to
Space Station missions created by cancellation of the Advanced Solid
Rocket Motor. The new SLWT design first flew on STS-91 in 1998.

I hope they will be lucky. But why introduced this idiots a new ET type
at all? Since 2005 they had no mission the old ET could not accomplish.
No need for any weight reduction till retirement.

The weight reduction program referred to is the Super Lightweight Tank
introduced in 1998. The cracks seem to be related to the use of
Aluminum-Lithium allow in the stringers on the Intertank. Such cracks
have been seen before and repaired at Michoud before delivery.

Besides this metal cracks in a new ET the leak in the hydrogen vent line
system is similar appaling.

Cracks? The vent line leak was due to a seal misalignment, not a
crack.

Such LH2 systems are an engineering challange.
But it was alraedy solved in the 1960 before and during Apollo - and for
most of the time till now.

My bet is that these problems (the GUCP leaks, the stringer/foam
cracks, and the 2005-06 ECO sensor failures) have always been with the
Shuttle program, but only came to light with the increased safety
vigilance post-Columbia.

That they have such trouble now to fix it
makes me think they have retired or fired a few guys to much. This
broken part of NASA will now design a new rocket in the class of the
Saturn V?

No, Ares V was cancelled on February 1st. A new vehicle, tentatively
called SLS (Space Launch System) is to be closely derived from the
Shuttle External Tank, among other Shuttle heritage The cracked
stringer issue seems easily enough solved by going back to straight
aluminum instead of the lighter but more brittle Al-Li for SLS, at
least for that vehicle's intertank.

Brian

But a
similar crack was found in ET-138, scheduled for use by the shuttle
Atlantis next summer, and that tank has not yet been subjected to
cryogenic temperatures. The cracks may be related to the use of
lightweight materials in the latest generation of tanks.

In other words, they created a new ET design/modifiaction/improvement.

This was in the 1990s, to make up for the performance shortfall to
Space Station missions created by cancellation of the Advanced Solid
Rocket Motor. The new SLWT design first flew on STS-91 in 1998.

I hope they will be lucky. But why introduced this idiots a new ET type
at all? Since 2005 they had no mission the old ET could not accomplish.
No need for any weight reduction till retirement.

The weight reduction program referred to is the Super Lightweight Tank
introduced in 1998. The cracks seem to be related to the use of
Aluminum-Lithium allow in the stringers on the Intertank. Such cracks
have been seen before and repaired at Michoud before delivery.

I know this program of the 1990s. After the first tank of it was
launched in 1998 I thought it was running out and the design
frozen. From another article:

In a statement posted on NASA's web site Thursday, the agency said the
cracks may be the result of using a lightweight aluminum-lithium alloy
in the latest generation of external tanks.

This ref to "the latest generation of external tanks." can not mean
the program closed 10 years ago. The "similar crack was found in ET-138,
scheduled for use by the shuttle Atlantis next summer," points to
something new going on. I read the CAIB and I dont remember any ref
to stringer cracks in the ET. It would be most interesting in the
relation to the foam cracks. Would open a whole new perspective.

I cant imagined they hide stringer cracks from CAIB. So this seems
a new development. It sounds like this program thought closed 10
years ago is still running.

Such LH2 systems are an engineering challange.
But it was alraedy solved in the 1960 before and during Apollo - and for
most of the time till now.

My bet is that these problems (the GUCP leaks, the stringer/foam
cracks, and the 2005-06 ECO sensor failures) have always been with the
Shuttle program, but only came to light with the increased safety
vigilance post-Columbia.

No, no. Such worse the Shuttle program cant be than. Otherwise they
would have lost more Shuttles. The present GUCP leak was beyond the
sensor limit of 6%, safety limit was 4%. Any start would looked like the
Delta Heavy launch few years ago.

The ECO sensor problem was not the sensor but a faild connector in
its wire line. This connector was in the LH2 environment and faild
at low temperatures. I suspect they changed something on the connector
design before. Because that problem was solved at least 30 years ago.

There is no need for such "improvements" and the whole program design
should have been frozen after the CAIB implementations.




## CrossPoint v3.12d R ##

On 13 Nov 2010 16:14:00 +0200, wrote:


But a
similar crack was found in ET-138, scheduled for use by the shuttle
Atlantis next summer, and that tank has not yet been subjected to
cryogenic temperatures. The cracks may be related to the use of
lightweight materials in the latest generation of tanks.

In other words, they created a new ET design/modifiaction/improvement.

This was in the 1990s, to make up for the performance shortfall to
Space Station missions created by cancellation of the Advanced Solid
Rocket Motor. The new SLWT design first flew on STS-91 in 1998.

I hope they will be lucky. But why introduced this idiots a new ET type
at all? Since 2005 they had no mission the old ET could not accomplish.
No need for any weight reduction till retirement.

The weight reduction program referred to is the Super Lightweight Tank
introduced in 1998. The cracks seem to be related to the use of
Aluminum-Lithium allow in the stringers on the Intertank. Such cracks
have been seen before and repaired at Michoud before delivery.

I know this program of the 1990s. After the first tank of it was
launched in 1998 I thought it was running out and the design
frozen. From another article:

In a statement posted on NASA's web site Thursday, the agency said the
cracks may be the result of using a lightweight aluminum-lithium alloy
in the latest generation of external tanks.

They're referring to Super Light Weight Tank, which is made of
Aluminum-Lithium. Discovery's tank was not built differently than any
of the other SLWTs built since Columbia. "Latest generation" simply
means third generation, after the original Standard Weight Tank and
then the Light Weight Tank.

This ref to "the latest generation of external tanks." can not mean
the program closed 10 years ago.

It didn't close. SLWT has been in use since 1998, except for STS-107
which used one of the last two older LWTs. This might be a language
problem? "Latest" doesn't necessarily mean "recent" in English.

My bet is that these problems (the GUCP leaks, the stringer/foam
cracks, and the 2005-06 ECO sensor failures) have always been with the
Shuttle program, but only came to light with the increased safety
vigilance post-Columbia.

No, no. Such worse the Shuttle program cant be than. Otherwise they
would have lost more Shuttles. The present GUCP leak was beyond the
sensor limit of 6%, safety limit was 4%. Any start would looked like the
Delta Heavy launch few years ago.

Not necessarily. The GUCP is high up on the pad, where any leak could
be dissipated by winds, and the Delta IV phenomenon at the base of the
vehicle is an order of magnitude greater than the GUCP leaks.

The ECO sensor problem was not the sensor but a faild connector in
its wire line. This connector was in the LH2 environment and faild
at low temperatures. I suspect they changed something on the connector
design before. Because that problem was solved at least 30 years ago.

No, they just never noticed the ECO sensor problem before. It was
discovered because NASA began using stricter safety protocols after
Columbia.

There is no need for such "improvements" and the whole program design
should have been frozen after the CAIB implementations.

It wasn't. NASA has never stopped trying to fix problems and prevent
others. The External Tank foam, most prominently, has been a "work in
progress" ever since Columbia.

Brian

On 11/13/2010 8:16 AM, Brian Thorn wrote:

They're referring to Super Light Weight Tank, which is made of
Aluminum-Lithium. Discovery's tank was not built differently than any
of the other SLWTs built since Columbia. "Latest generation" simply
means third generation, after the original Standard Weight Tank and
then the Light Weight Tank.

Aluminum-Lithium has real problems with developing hairline cracks when
drilled; Boeing was originally going to use a lot of it in the 777 to
save weight, but couldn't figure out how to fix the cracking problem
before production started.
And here comes crack #3:
http://www.wftv.com/countybycounty/25784443/detail.html
The disturbing thing is that if the insulating foam hadn't fractured
over the crack, allowing the ice team to see the anomaly, and if there
hadn't been that hydrogen leak...then they would have launched Discovery
with a defective ET attached to it.

Pat

This ref to "the latest generation of external tanks." can not mean
the program closed 10 years ago.

It didn't close. SLWT has been in use since 1998, except for STS-107

I meant the development program, not the production after it. Of course
they build it for 12 years now. But is there still development on
the structural parts?

There is no need for such "improvements" and the whole program design
should have been frozen after the CAIB implementations.

It wasn't. NASA has never stopped trying to fix problems and prevent
others. The External Tank foam, most prominently, has been a "work in
progress" ever since Columbia.

Brian

For the foam, ok. But now we have a problem with the structure. I do not
remember any stringer cracks till CAIB. This cracks seem to happen only
in the last 2 years. (The "" are not from me):

ET-138, the last "new" tank to be produced by MAF also suffered from
a cracked stringer during production, prior to undergoing a repair.

http://www.nasaspaceflight.com/2010/...und-on-et-137/

During production a handling failure can often cause a crack. No news.
But now on the pad there is no evidence for any handling failure. The
structure simply seems too weak. I see it related to the word "new" and
nobody so far explained what this "new" means. I dont buy that it refers
to a 12 years old development.



## CrossPoint v3.12d R ##

On Nov 14, 9:04*am, wrote:
This ref to "the latest generation of external tanks." can not mean
the program closed 10 years ago.

It didn't close. SLWT has been in use since 1998, except for STS-107

I meant the development program, not the production after it. Of course
they build it for 12 years now. But is there still development on
the structural parts?

There is no need for such "improvements" and the whole program design
should have been frozen after the CAIB implementations.

It wasn't. NASA has never stopped trying to fix problems and prevent
others. The External Tank foam, most prominently, has been a "work in
progress" ever since Columbia.

Brian

For the foam, ok. But now we have a problem with the structure. I do not
remember any stringer cracks till CAIB. This cracks seem to happen only
in the last 2 years. (The "" are not from me):

* ET-138, the last "new" tank to be produced by MAF also suffered from
* a cracked stringer during production, prior to undergoing a repair.

http://www.nasaspaceflight.com/2010/...al-defectcrack...

During production a handling failure can often cause a crack. No news.
But now on the pad there is no evidence for any handling failure. The
structure simply seems too weak. I see it related to the word "new" and
nobody so far explained what this "new" means. I dont buy that it refers
to a 12 years old development.

## CrossPoint v3.12d R ##

launch without understanding 100% is risking the end of the program
with another preventable lost vehicle and crew

better to ground the program permanetely and use the flawed tanks for
display purposes...

or take a year safety standdown and do it right....

please dont kill any more crews...

"please dont kill any more crews"

Moral of a story on Rec.models.scale - "You don't die for a lost cause"

and at this point in time the shuttle program is essentially there, there's
nothing left to learn, we know the basic layout was more dangerous than a
linear stack, and the ISS isn't providing Earth shattering results, if
there's any safety of flight doubt at all we shouldn't risk another crew.
NASA lofted the space station into orbit, quit while we're ahead - let
Europe and Russia run the milk runs from here on.


Val Kraut

On 11/14/2010 11:34 AM, Val Kraut wrote:
"please dont kill any more crews"

Moral of a story on Rec.models.scale - "You don't die for a lost cause"

and at this point in time the shuttle program is essentially there, there's
nothing left to learn, we know the basic layout was more dangerous than a
linear stack, and the ISS isn't providing Earth shattering results, if
there's any safety of flight doubt at all we shouldn't risk another crew.
NASA lofted the space station into orbit, quit while we're ahead - let
Europe and Russia run the milk runs from here on.


We did learn a lot about the concept of reusable launch vehicles though
from the Shuttle experience...primarily "Don't ever do it that way
again, and maybe don't ever try it again at all, at least with existing
technology*."
If you were to try to build something like the Shuttle again today, the
technology hasn't changed all that much, so it would end up looking a
lot like what NASA came up with, with the exception of probably having
liquid rather than solid boosters on it for safety's sake.
Between the vehicle's inherent complexity leading to launch delays due
to malfunctions, the frequent weather delays to scheduled launch and
landing dates, and the high cost of inspection and refurbishment to the
orbiter and its engines between flights, it turned out to be anything
but that "Pickup truck to orbit" that NASA sold it as. It was more like
a Indy 500 racer pulling a U-Haul trailer, and about as safe and
economical to operate.

*You develop some sort of high thrust rocket engine with a isp of around
1,500 and the whole equation changes markedly, as now you can make a
big, robust SSTO vehicle that can afford to carry a heavier and tougher
TPS on it, so that it doesn't need all the TPS inspection between flights.
But we've gone just about as far as traditional chemical propulsion can
take us in that regard with out resorting to very exotic (and toxic)
propellant combos.

Pat