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Old February 4th 17, 02:32 AM posted to sci.space.history
Fred J. McCall[_3_]
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Default The Space Race was about Power Projection - Miles O'Brien

Stuf4 wrote:

From Fred McCall:
Jeff Findley wrote:

In article ,
says...

On Saturday, January 28, 2017 at 5:39:54 PM UTC-6, Stuf4 wrote:

snip
As it was, the only shuttles that were disintegrated happened
as a result of lack of care, rather than anything intentional.

Correct, they were management failures, not technological failures.

To be fair, middle level shuttle managers were put in a bad spot by the
higher ups. They had to manage what amounted to an experimental program
and pretend it was an "operational" program after five test flights.
The higher ups put a huge amount of pressure on middle management to
increase the flight rate. This created the management culture of "if
we're going to ground it, you have to prove to me it will fail", which
doomed the Challenger crew.

Middle managers were also forced to do this with a budget which was
smaller than it should have been. An example of this was right before
Challenger there was a distinct lack of spare parts. They were pulling
parts from recently returned orbiters so they could be installed on
another orbiter which was being prepared to fly. Imagine if you had two
cars and had to pull the cylinder head from one and install it on the
other when you wanted to use it. Insane, right?

To begin with, the SRBs ought to have been replaced with reusable liquid
boosters, but that would have been *quite* expensive to develop (which
is why SLS is still using solids). Other improvements, like non-toxic
OMS/RCS propellants and replacing the APUs and hydraulics with
electrically operated actuators would have improved the turn-around time
and reduced the risks to ground crews.

Unfortunately, SLS/Orion seems to have given up on reuse which creates a
vicious cycle of low flight rates and high launch costs. The very low
flight rate is bad for safety for a variety of reasons. Imagine a job
where every task you perform has to be done perfectly, but you only do
each task every other year, so you are assigned hundreds of tasks to
perform for each mission. You'd have little chance to get better at
your tasks, since by the time you have to repeat a task, you will have
forgotten most of what you learned from doing it the last time.


There are times when I think Usenet needs a 'Like' button...


I myself see a lot to be in wanting in Jeff's post.


JF: Imagine if you had two cars and had to pull the cylinder head from one and install it on the other when you wanted to use it. Insane, right?"

That is called "cannibalization", and a very common practice in high performance aerospace vehicles. Hardly ideal, but a cost-effective approach to maintenance.


No, it's not 'cost effective' at all. The 'cost effective' thing to
do is to have spares and maintain all your vehicles. We had them
until they were used up in order to build Endeavour on the cheap. What
do you get for the cost of moving parts from vehicle to vehicle to
vehicle? More costs, that's what.


JF: "the SRBs ought to have been replaced with reusable liquid boosters"

A fact that so many people are willing to ignore is that the SRBs performed totally adequately for 24 straight missions. They never failed a single time. So that's 48 SRB successes in a row. 144 field joints did their job.


Well, no, they didn't, unless your definition of 'adequate' equals
"didn't catastrophically fail". There were many cases of O-ring burn
and leakage. 'Luck' shouldn't be a part of 'adequate' performance.
Math in public is hard. There are six joints PER SRB and two SRBs per
launch, so 24 launches equals 288 joints.


The only time they failed was when NASA decided to launch with temps WAY OUT OF LIMITS. Here is an exact quote from Thiokol's Bob Ebeling:

"[W]e're only qualified to 40 degrees ...'what business does anyone even have thinking about 18 degrees, we're in no man's land.'"
(https://www.nasaspaceflight.com/2007...of-challenger/)

THAT is the one and only proximate cause of the Challenger disaster.


Except that that launch was not the only one to show evidence of hot
gas escaping through the O-ring. In point of fact, the joints had
been on the critical failure list since 1982, but NASA waived their
own safety requirements in order to keep flying.


SRB field joints had a batting average of 1000. 144 successes with 144 at bats.

Not a perfect design, to be sure. But it worked when established limits were respected.


So why did the Rogers Commission describe them as "a faulty design
unacceptably sensitive to a number of factors"? *I* know why, but you
don't seem to.

Look at the failure modes for segmented solid boosters. Now look at
the failure modes for liquid boosters. Add in the inability to
terminate thrust once the solids are lit and any sane human being will
arrive at the conclusion that putting people on solid rockets is a
very bad idea.


--
"Insisting on perfect safety is for people who don't have the balls to
live in the real world."
-- Mary Shafer, NASA Dryden