I debated whether to send this to you but off times you say my (meaning
your) experience is better that engineering. This is the best explanation of
why it isn't that I've ever seen. I hope you don't take offence at least not
too much offence anyway.
Julio
-----Original Message-----
From: towertalk-bounces@contesting.com
[mailto:towertalk-bounces@contesting.com] On Behalf Of jimlux
Sent: Saturday, January 16, 2010 4:43 PM
To: Tower and HF antenna construction topics.
Cc: brahmangou@aol.com
Subject: Re: [TowerTalk] Guying a tower....Heresy to follow..... True
statement!
Doug Renwick wrote:
> Marty, I welcome your true life experience. So here is one of the many
> problems with this reflector ... you get beat up posting your real life
> experience which trumps any theory any day.
Nope... real life experience is an anecdote, not engineering data. It
predicts only the past for that one case. There's no way that anecdote
trumps analysis, particularly if the analysis is based on test data in
controlled circumstances.
That's the big difference between craft and engineering. With craft it's
"do it like we've done it before, and it works ok, and we don't care
why". With engineering, you can predict what happens before it happens,
so you can go beyond just duplicating something before, and more to the
point, you don't have to worry about whether what worked before happened
to be just about to fail.
Back in pre-engineering days (or even today, if you can't calculate with
sufficient certainty), you can do "proof testing" (that is, test it with
a load that is greater than you expect to see in use). This is what we
do with spacecraft (which are so complex that you can't calculate all
the failure probabilities..): we test at some multiple of the maximum
expected load or temperature or whathaveyou.
--- that said, a lot depends on the consequences of failure. Craft may
work just fine, if the consequences are small or unlikely or immaterial.
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