What was the biggest problem for each of the 2 destroyed US space shuttles?

In article ,
says...
Brian Thorn wrote:

On Wed, 1 Sep 2004 17:53:29 -0600, "Jay Windley"
wrote:
It's unfair to say they were "ignored".

"My, God, Thiokol... when *do* you want us to launch... April?"

When you launch over the strong and continued objections of the lead engineers
and the Director of the Space Shuttle Solid Rocket Motor Project I would say
that it's very fair to say that they were in fact "ignored."

Yep. But while the management clearly made a major mistake in ignoring
those objections, it is worth noting that Lead Engineers and a Director
*should* have been able to present the supporting data for those
objections in a way that is understandable to management. Explaining
things to non-engineers is part of what distinguishes a Lead Engineer,
much less Director, from a Junior Engineer or non-techinical manager.

I've said this befo In Visual Explanations, Edward Tufte makes the
case that (in part) the inability of the engineers to present the
available data in a comprehensible fashion doomed the Challenger. Given
the charts that the engineers presented to their management, there is no
obvious elation ship between temperature and O-ring erosion, so the
management had no reason to delay the launch.
--
Kevin Willoughby lid

Imagine that, a FROG ON-OFF switch, hardly the work
for test pilots. -- Mike Collins

In article , says...
A truly useful launch vehicle would be manufactured in runs of hundreds
or thousands, not five, and would have a market large enough to justify
that production. Pranging two of them would not shut down the program.

Is the number of shuttles built significantly different from the number
of any particular type of aircraft carrier? How many Queen Mary-type
steamships were constructed?


Your point about the shuttle being "too marginal" is significant. The
number of units produced is really not that important.
--
Kevin Willoughby lid

Imagine that, a FROG ON-OFF switch, hardly the work
for test pilots. -- Mike Collins

"rk" wrote in message
...
|
| When you launch over the strong and continued objections of
| the lead engineers and the Director of the Space Shuttle Solid
| Rocket Motor Project I would say that it's very fair to say that
| they were in fact "ignored."

Well, these engineers were the same people who, since 1978, had said time
after time after time, "The joints are safe to fly; don't worry about it;
we've got it covered." What had been "strong" and "continous" up to that
point was the recommendation to fly mission after mission. Every time
something new came up in a joint, they'd go back into the laboratory and
shoot flames through test joints, and then come back and say, "Okay, we
figured out what happened and it's no big deal." And they genuinely
believed that -- both Thiokol and NASA.

Then on one instance Thiokol changed their minds. And naturally NASA said,
"Do you have any hard data for this sudden change of opinion?" And, sadly,
it turns out they didn't. Why? Because the one time cold weather had been
suspected in O-ring erosion -- the previous winter -- was determined too
freakishly atypical to be repeated. So on that point the engineers didn't
bother going to the lab to determine exhaustively how cold an O-ring could
get and still work. They essentially thought, "We don't need to know in
great detail how the O-rings work at cold temperatures because we're never
going to get those temperatures again."

Everyone wants to look only at what happened on the eve of the launch. All
of the interesting stuff happened in the months and years the preceded that
night, and that's where the real problem -- in my opinion -- lies.

The SRB had been cleared to fly by the elaborate flight review process that
included a launch constraint *requiring* a review of the SRB joint problems
to date. Thiokol all of a sudden, the night before the launch, wanted to
rescind that clearance. This wasn't quite the shift of burden of proof that
has been suggested. The contractor had already cleared it for flight
according to a lengthy rationale. And the process of clearing or
constraining a flight is not just a bunch of guys sratching the backs of
their necks and saying, "Well, shoot, I just don't know. Guess we'd better
not fly." It's much more formal than that, and it has to be.

The flight review process looks at issues that are properly brought to
everyone's attention, properly recorded, and properly reviewed at the
various appropriate levels. That degree of organization is absolutely
necessary when you're dealing with something as complicated as a spacecraft.
The temperature issue had been dealt with in the spring of 1985 and was
considered a "closed" issue.

From NASA's point of view, Thiokol was trying to change the flight readiness
criteria on the fly, contrary to the entire process NASA and its contractors
had put into place to avoid chaos in flight readiness reviews. NASA
considered it irregular, but consented to let Thiokol present its case.
Unfortunately the case wasn't there. Everyone knows that elastomers get
harder when they get cold. But that's an abstract fact; it doesn't
necessarily describe how the actual O-rings function on the actual space
shuttle. When you look at *that* data, it turns out there's no experiential
correlation between pre-launch temperature and O-ring erosion or blow-by at
ignition.

So NASA listened, but Thiokol -- for various reasons -- could not make a
convincing case. NASA consented to let Thiokol add cold-soaking as a new
launch constraint. NASA consented to let Thiokol try to make a case that
the joints wouldn't work when it got cold, according to that new constraint.
But Thiokol lacked the "hard data" to back up their case. Every other
launch issue has to be looked at in terms of "hard data". The contractor's
ability to call off a launch doesn't include just getting cold feet. Common
sense might say it should, but if you start letting hunches stand on equal
footing with formal rationales, then you reduce the whole process to
subjectivity.

I don't believe the engineers and/or managers made their mistake on the eve
of the launch. I believe the mistakes were made far earlier than that, in
gradually accepting the behavior of the joint as normal. That goes for both
NASA and Thiokol.

--
|
The universe is not required to conform | Jay Windley
to the expectations of the ignorant. | webmaster @ clavius.org

"Jay Windley" wrote:
The flight review process looks at issues that are properly brought to
everyone's attention, properly recorded, and properly reviewed at the
various appropriate levels. That degree of organization is absolutely
necessary when you're dealing with something as complicated as a
spacecraft.

Nah. We've routinely operated nuclear submarines for decades without
anything really resembling a flight readiness review.

D.
--
Touch-twice life. Eat. Drink. Laugh.

"Jay Windley" wrote:

Needless to say you can't pin the Challenger disaster on one person or class
of people. Plenty of blame to go around.

The same is true, in a general sense, of the Challenger accident.

D.
--
Touch-twice life. Eat. Drink. Laugh.

On Fri, 03 Sep 2004 04:30:40 GMT, (Derek Lyons)
wrote:

Nah. We've routinely operated nuclear submarines for decades without
anything really resembling a flight readiness review.

....And that's because the DoD wouldn't fund Flying Sub development,
natch.

OM

--

"No ******* ever won a war by dying for | http://www.io.com/~o_m
his country. He won it by making the other | Sergeant-At-Arms
poor dumb ******* die for his country." | Human O-Ring Society

- General George S. Patton, Jr

On Thu, 2 Sep 2004 18:47:04 -0600, "Jay Windley"
wrote:

I don't want to turn this into a long thesis. I write too many of those.

....Yeah, of late, you have.

Oh, wait...you said "thesis" and not "feces"...

OM

--

"No ******* ever won a war by dying for | http://www.io.com/~o_m
his country. He won it by making the other | Sergeant-At-Arms
poor dumb ******* die for his country." | Human O-Ring Society

- General George S. Patton, Jr

Kevin Willoughby wrote:

A truly useful launch vehicle would be manufactured in runs of hundreds
or thousands, not five, and would have a market large enough to justify
that production. Pranging two of them would not shut down the program.


Is the number of shuttles built significantly different from the number
of any particular type of aircraft carrier? How many Queen Mary-type
steamships were constructed?

Ships have large numbers of very similar predecessors, so they're
depending on that accumulated experience. They also don't have a ~1% per
trip risk of being lost, since they are operating in an inherently
more forgiving environment and are built with much larger margins.

Paul

"Kevin Willoughby" wrote in message
...
In article , says...
A truly useful launch vehicle would be manufactured in runs of hundreds
or thousands, not five, and would have a market large enough to justify
that production. Pranging two of them would not shut down the program.

Is the number of shuttles built significantly different from the number
of any particular type of aircraft carrier? How many Queen Mary-type
steamships were constructed?


Your point about the shuttle being "too marginal" is significant. The
number of units produced is really not that important.

The bigger issue is arguably flight rate and flight duration. Aircraft
carriers don't sit idle in port as much as the shuttles sit on the ground.
Space shuttles spend very little of their "operational lifetime" actually
flying. If they're lucky, they'll fly two missions in a year of a week or
two in duration. If they're in "maintenance down time" or the fleet is
grounded, they may not fly any missions in a year.

Jeff
--
Remove icky phrase from email address to get a valid address.

"Paul F. Dietz" wrote:

Kevin Willoughby wrote:

A truly useful launch vehicle would be manufactured in runs of hundreds
or thousands, not five, and would have a market large enough to justify
that production. Pranging two of them would not shut down the program.


Is the number of shuttles built significantly different from the number
of any particular type of aircraft carrier? How many Queen Mary-type
steamships were constructed?

Ships have large numbers of very similar predecessors, so they're
depending on that accumulated experience. They also don't have a ~1% per
trip risk of being lost, since they are operating in an inherently
more forgiving environment and are built with much larger margins.

Ships *now* don't have a ~1% trip risk of being lost, but historically
speaking, thats a recent change. Even so, that does not support your
contention that a truly useful vehicle is built in large production
runs.

D.
--
Touch-twice life. Eat. Drink. Laugh.