[AR] Re: What happened to the Space Shuttle?
- From: J Farmer <jfarmer@xxxxxxxxxxxxx>
- To: arocket@xxxxxxxxxxxxx
- Date: Thu, 25 Jul 2019 16:42:39 -0400
On 7/24/2019 2:16 PM, David McMillan wrote:
On 7/22/2019 11:37 AM, Henry Spencer wrote:
And hoping that, e.g., none of their materials suppliers would change
their products enough to mess things up. (It's happened.)
Or that the "critical specs" on some components don't create a time
bomb for the next poor engineer. I had that happen on a job for a
major airframer, too -- they wanted to automate inserting hi-locks
through the fuselage skin into the ribs and stringers, and installing
and torquing down the nuts on the inside. The *nuts* should have been
the *easy* part -- after all, that's what wobble sockets were invented
for, right? This is a solved problem, with multiple off-the-shelf
solutions in other industries.
One *small* problem: the customer got their nuts from three
different suppliers. And only spec'd the thread size, torque, shear
strength, and *general* outer dimensions. In production, the nuts
were randomly mixed (they bought them by the barrel, almost
literally). And it turned out that each supplier made different
choices for the *non-critical* dimensions of the nuts, which in turn
was just enough difference to make it impossible to create a securely
gripping wobble socket that could reliably hold all three varieties
I often ran into showstoppers like that back in my days analyzing and
designing computer driven factory automation systems. Many engineers,
managers, and beancounters rarely understood how flexible and
intelligence a typical worker has.
I had a potential client who wanted to lower his costs, particularly
labor driven ones. Aka, shrink his labor force... His remade rollers
used in paper presses. Had very definite standards for finished shape,
surface, and balance. The problem was incoming items. Huge pieces of
steel, with both the bearing and work surfaces worn semi-randomly. He
wanted to automate the process of inspection, prep grinding, surface
buildup (weld process), regrind new bearing and work surfaces, and then
balancing the roller.
He balked when I told him in a response letter that (in 1985 dollars),
the first step of evaluating off-the-shelf options and developing
possible preliminary high level system designs was going to cost at
least 30K. He shutdown the entire idea when we got to the part of
detailing new staffing requirements. (Cut the size of his skilled labor
group, but unskilled labor would go up, and adding several engineers and
IT types. Not to mention ongoing support and service contracts...). He
was going to invest serious money with a very stretched out ROI and
little improvement in production or customer satisfaction...
Sometimes the right answer is a trained worker with a couple of sockets
in his pouch...
John
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