> In the pre-TIA/EIA-222, UBC, et al. days, there wasn't much in the way
>of standardization for structures and wind forces. Since then, many
>standards, including the aforementioned ones, have been adopted. Many of the
>crankups were designed before the current standards. And like antenna
>manufacturers, crankup tower manufacturers sometimes play games with figures.
The density of the air hasn't really changed, and the wind speed is still
the wind speed.
> In order to upgrade the towers to a 70 MPH minimum would require: 1)
>recalculating all of these towers (it would be expensive and no manufacturer
>is really interested in doing it again since they've already spent the
>engineering expense once);
Yea, like *I*'m in a better position to perform these calculations, even
if I were a PE (which I'm not).
> 2) down-rating ALL of the above towers to comply
>with the (as you pointed out) MUCH larger wind pressures;
How is this down-rating? They would merely publish the ratings for the
designs as they currently ARE. They aren't changing the ratings, just
stating them more correctly.
> 3) investing in
>design and tooling for towers that really ARE capable of complying with the
>these forces and loads.
This would be for larger (more capable) towers.
> Do you think that amateur radio operators (a bunch of widely recognized
>cheap bastards) would be willing to pay for these more expensive towers? I
>don't think so; they complain enough about the cost of anything as it is.
> Everything gets back to manufacturing cost so the manufacturers are
>unwilling to increase the cost of their products unless absolutely forced
OK, so where does that leave us?
I just want to put a tribander up on a modest height of 45-49 feet. Guyed
towers aren't practical in my lot, and crank-ups offer advantages to the
neighbors. Tubular crank-ups especially so. But, if my 50 mph tower falls
in 70 mph winds, my insurance company may decide they aren't going to
cover it, since it was underrated for the conditions.
If the manufacturers aren't willing to rate their wares effectively, and
insurance requires it, doesn't it open them up for potential liability?
Bill Coleman, AA4LR Mail: email@example.com
Quote: "Not in a thousand years will man ever fly!"
-- Wilbur Wright, 1901
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