Text 1978, 207 rader
Skriven 2005-08-14 22:14:52 av WAYNE CHIRNSIDE (1:123/140)
     Kommentar till en text av MARK LEWIS
Ärende: NASA, shuttle, anyone?
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-> -> ->  CA> Have been a bit surprised at the lack of interest in 
-> -> ->  CA> this echo of the sloppiness of the recent space 
-> -> ->  CA> shuttle launch?

-> -> -> sloppiness??

-> ->  WC> Yup.
-> ->  WC> Rules stated no launch without all four tank fuel sensors
-> ->  WC> working.

-> -> ok... all four were working when they tested and launched...

->  WC> All four worked intermittently, 

-> not according to what i've seen... it was the backup sensor to the backup
-> sensor that failed in the testing done during the launch countdown... they
were
-> unable to reproduce the failure during later testing after going into the
-> system to try to track down the failure...     

Every sensor is the backup for the other three and that's a fact.

->  WC> one of the hardest sorts of faults to track down from my
personal
->  WC> electronic experience. 

-> yes, mine too...

->  WC> Had the sensors failed again as they had before as nothing had been
->  WC> done to fix them it's possible the sensors would have indicated
->  WC> fuel it was running out.

->  WC> This would lead to the flame from the engine nozzels being sucked
->  WC> back into the combution chambers, BOOM.

-> wrong... the indication of lack of fuel would shut down the engines and they
-> would not have made it to orbit... 
   
I expressed myself poorly.
Had the sensors indicated fuel when there was none the shutdown signal
would not be sent and the situation I described could have occured.
It's why those sensors exist in the first place, or so said a NASA
engineer.

-> the failure was a "no fuel" indication when
-> the tanks had fuel... not an indication of fuel when there was none...

Any intermittent failure is unpredictable and with a half million 
gallons of liquid hydrogen and oxygen there's little room for error.

The chief Morton Thiokol engineer had authority to stop the
shuttle Challenger from flying due to his expressed concerns about the
cold's effects onthe o ring seals in the SRB's.

He was overruled and the shuttle Challenger blew up.
Being an embarrassment for telling the truth he was fired shortly
thereafter.

Engineers, quite a few of them, expressed deep concern about the deris
that hit the Columbia's wing after liftoff.
The lower rank engineers had no avenue to express their concernes to
flight managers.
Later their e-mails all came out reveasling their concerns very early
on after the liftoff.
Another shuttle lost by ignoring evidence at hand :-(

->  WC> This is generally considered a bad thing.

->  WC> Also a repair to a dent in the shuttle's tank was repaired after
->  WC> the foam was removed. Foam was replaced but it was deemed 
->  WC> unnecessary to inspect the affected area.

->  WC> As it happens foam from this area detached during launch to orbit. 

-> i have the video and pictures... the problem i have with what you are saying
is
-> that the same thing happened on the other side of the tank where the other
SRB
-> was mounted... so that's two foam detachments... not just one... methinks
that
-> some are confusing some things...                       

There were FIVE foam detachments, one was just over a pound
and had it struck the orbiter earlier in denser air it could have
disabled it for a sucessful landing.

-> ->  WC> Shuttle not rolled back but delayed.

-> -> so... don't have to rollback to fix a problem...               

->  WC> Don't worry they didn't. 

-> i'm not worried... i was saying that there does not have to be a rollback to
-> fix a problem... i left off the word "you" in front of "don't"...

You do if you want to go inside the tank where the fuel sensors
are and actually diagnose what's wrong with them, or so said NASA.
They flew on a wing and a prayer instead.


->  WC> They flew the shuttle without a clue as to what had caused the
->  WC> problem. 

-> ->  WC> Intermittent problem with the faulty fuel sensor never pinned down
-> ->  WC> it happened to be working when they launched after deciding to
-> ->  WC> override their own safety rules.

-> -> when did they decide to override their rules? i don't recall that 
-> -> and i watched and recorded most all of the NASA TV broadcasts...     

->  WC> It was repeatedly announced after the initial delay and after they
->  WC> failed to pin down the intermittent fuel sensor problem,

-> it was announced that they were overridding their safety rules?? i
definitely
-> do not remember that specific wording... 

They said they would fly with three operating sensors in direct
violation of safety regulations requriring all four be working.

->  WC> It just happpened the sensor didn't fail during the runup to
->  WC> launch, very fortuitous.

-> are you positive that it was a sensor failure? they aren't...

they were getting a false reading intermittently and they checked the
wiring and swapped the wires from differing sensors never finding the
source of the failure.

Let me tell you about an intermittent failure I had in Tenneessee
around 1980.                               
I'd had the failure a numer of times, couldn't find it as it was
intermittent but no major probem... until.

I was driving to Florida on a mountain road out of the Rocky mountains
in an area where there were no barricades to prevent driving off the
mountain as is or was comon in 1980 in rural Tenneessee.
It was a moonless night.
There was no street lighting of any sort.
I was too far from a city to even have that light.
I was driving on high beams in a 72 maroon Gran Torino.
Without warning the lights went out with neither high nor low beams 
available,
I could see nothing at all but slowed while estimating my existing turn
where the road had showed before loghts out.

It gets worse.
Right about then I see headlights in my trear view mirror.
Well a maroon car is virtuallly invisable at night until you're right on
top of it and it's too late.
I threw it in reverse, guessed where the gully on the high side of the
mountain was trying to dump the car into it to avoid
collision.
I got lucky  and landed in the gully where intended thougyh it was all
done in the blind.
The other car never saw me at all passing a few feet to my right.
Now this is a mere car with an intermittent and it nearly killed 
me twice in a matter of 90 seconds, the shuttle is a bit more
complicated than a Ford.  

I finally found the ground fault, it was in the high - low beam selector
button on the floor and a new one cured the problem.

-> ->  WC> Now the tank's burned up returning to Earth we'll never know why
-> ->  WC> the sensor malfunctioned.

-> -> one suggestion was a ground problem because the problem never
-> -> happened after the initial discovery... could also have been a 
-> -> loose connection... either way, they apparently fixed it while 
-> -> getting to it and studying it...              

Could have been this, could have been that, could have been anything.
Know what blew up Apollo 13's service module that nearly killed the crew
and aborted their moon landing?

There was a heated in one of the oxygen tanks to vaporize the liquid
O2 to fuel the fuel cells in the cold of space.
That heater was specified to be 24 volts, it wasn't.
It was spec'd 12 volts. An astronaut following standard procedure  
turned on the heater and a moment later the stirrer,
Seconds later the oxygen tank expoded taking much of the despirately
needed service module with it.
Astronauts lived in the LEM lander sick and cold in that craft not
designed for the job to save what kittle was left of the capsule for the
last monments of re-entry.


->  WC> Ground problems are FAR from trivial as an electrical _circuit_
->  WC> requires a return to function. In my personal experience ground 
->  WC> problems are actually the worst sort of problem.

-> yes, they can be... i've done my fair share of them over the years ;)

They can kill you rather quickly even here on Earth.

->  WC> I spent months tracking down an intermittent ground problem in  a
->  WC> stereo amplifier once.

-> -> what else was sloppy??

->  WC> See above.

-> besides that...

They launched in spite of the known problems.
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