🚀 go-pugleaf

Uwe Hercksen <hercksen@mew.uni-erlangen.de> wrote in 
news:a8f6c7Ffo3U1@mid.dfncis.de:

> 
> 
> Jon Kirwan schrieb:
> 
>> Of all those single points of failure, the ones that worried
>> me the most were the pyros. You can test a lot of things --
>> like the 65,000 pounds of force the parachute had to bear.
>> But you can't test the ACTUAL pyros you will use. No matter
>> what you do, the ones you place in there can't have been
>> tested. We know how to make explosives of great uniformity,
>> of course. But all of that has to go into a system and it
>> must fire exactly correctly, under buffeting circumstances,
>> without a single point of failure in a single pyro. Just one
>> and that is it. Not that the rest wasn't also difficult. But
>> some of the things, since as the novel use of an imbalance in
>> weight distribution in order to permit direction control
>> during entry, can have errors in one part of the software be
>> compensated by the outer control loop in another part. So
>> even there, there is a backup hope. But the pyros either
>> work, or don't. That's what I was watching mostly for, though
>> the rest was also sincerely knuckle-whitening as well.
> 
> Hello,
> 
> pyros have been used for more than five decades in space missions and 
> they were critical for each mission. They were used for stage 
> separation, four or more for each stage and all should work perfect.
> But it is possible to test the cabling and the fuse of the pyro by 
> measuring the resistance without blowing them. I guess there were more 
> than twenty pyros necessary for this mission.
> If hundred pyros were built within one lot, you may test fifty or more 
> and use only the rest if all tests were perfect. You may even test some 
> just before the start, if one fails all pyros of this type and lot have 
> to be replaced. Not cheap, but a failing pyro is much more expensive.
> 
> Bye
> 
> Bye
> 
> 

Heh,testing of the pyros reminds me of a "tech" at TEK-Indianapolis that 
had a scope in for repair that blew it's line fuse,and he went and got all 
the fuses from bench stock,and one by one,put them in and each time tried 
powering up the scope,never first finding where the excess load was,or 
using a Variac to bring up the power slowly and measuing the DC supplies.

Only after blowing ALL the fuses in stock of that value did he ask another 
tech what he should do....

He never did work out as a repair tech. He didn't want to learn.
But he was sure good at avoiding work.

-- 
Jim Yanik
jyanik
at
localnet
dot com