At 10:35 AM 2/5/1999 EST, K7LXC@aol.com wrote:
>>
> Rohn specs allow 1.5 sq.ft. of 25G @ 70 MPH (20 psf wind force) for a
>height of free-standing 40 feet. The inference is that at little or no wind
>the tower has MORE than adequate ability to hold a climber or two during
>construction at that height.
>
> Yes, there is some 'pucker factor' involved. It's like climbing a
mast -
>it's the ability to do these tasks that separate the 'professionals' from the
>'amateurs'.
>
> Not very many people are comfortable doing these kinds of tasks.
Climbing
>and working on a tower is 90% mental. If you're psyched out and uncomfortable
>- that's fine, you know where your limit is.
>
> This isn't too confuse professional capability with 'crazy', though.
>I've heard of non-professionals doing some pretty crazy stuff that NO
>professionnal would touch.
My problem with this way of looking at things is that Rohn's spec -- or for
that matter Kurt's analysis -- assume that the tower sections are in good,
nominal condition -- no metallurgical changes or damage to the joining
sections of tower legs, no broken or weakened welds, etc. My astronaut
friends used to have a saying -- "When its my pink body that's on the line,
I want to feel REAL confident."
I'm almost totally without acrophobia, so I don't think that's the issue.
I'm sure that once you've done 50 different towers, your sense of what's
insecure is a lot more accurate than somebody who's done one or two. If
that's what Steve means by "professional", then I agree. But when I
envision 200 lbs at the end of a 40-foot Rohn 25 lever arm, not static but
moving around, and then add 20 mph of wind pressure on the 4-5 square feet
of area I might represent, I can't help harboring a little uncertainty. If
temporary guys rigged with big grips, properly used, can add some margin,
then I think it's probably worth the extra time.
73, Pete N4ZR
Loud is good
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