[TowerTalk] Two Killed Erecting Tower

[Michael Tope]

Hi Roy,

I wasn't suggesting that anyone put 60' of unguyed Rohn 25 into permanent
service, only that 60' would probably be safe to climb in calm conditions
(to
exceed the Rohn spec for overturning moment requires around 115 lbs of
horizontal force applied at the top of the tower). In windy conditions, its
ratings
are quickly exceeded even without the additional wind load of climbers (I
wouldn't be caught dead on top of 60' of unguyed Rohn 25G if it were windy).
As far as the base is concerned, you are correct in pointing out that a free
standing installation requires a substantially larger base, as all the
overturning
force in concentrated at that point.  I admittedly did not consider this
when
making my remarks - shame on me!

BTW, if you believe Rohn specs, a 26' free span of Rohn 25G will hold up
a Cushcraft A3 in 90MPH winds (I did these calculations for my installation
in Florida). I had no hesitation climbing it in calm conditions.

73 de Mike, W4EF........................

----- Original Message -----
From: <wa4dou@juno.com>
To: <towertalk@contesting.com>
Sent: Tuesday, March 21, 2000 9:12 PM
Subject: Re: [TowerTalk] Two Killed Erecting Tower


>
> Hi Mike,
>   I'm not sure just what the thrust of your post is.
>
>   Rohn specifies two foundations for 25G.
> 1) for guyed/bracketed towers- .5-.7 cu.yds of concrete
> 1) for self supporting towers- 2.4 cu. yds. of concrete
>
>   60 feet of unguyed application sure suggests to me, that its a self
> supporting
> application. Up to 70 mph windspeed, Rohn suggests no greater height than
> 40
> ft. Windloading is 1.5 sq. ft. allowable.
>
>   Even in a self supporting application, there is no allowance for 60 ft.
>
>
>   In guyed applications there is no allowance for 60 ft. between guy
> levels.
>
>   Perhaps you know enough to second guess Rohn and to develop your own
> standards for towers. I don't and i would suggest that unless you know
> enough to
> do so and risk your life in doing so, intelligently, then you are
> encouraging others to
> do the same. Some of them may not fully realize the consequences of doing
> so.
>
>   I don't know anyone who would climb 60 ft. of unguyed Rohn 25G. And
> i'll go on
> record as saying, "anyone who would is a fool."
>
>   I'll climb 20 ft. of unguyed 25G. I know some folks who would climb 30
> ft. of unguyed 25G.
> I know one or 2 little runts who delight in taking chances who would
> climb 4. I don't know
> anyone who would climb 5 or 6.
>
>   I'll bet Steve K7LXC would back me up on it too! :o) Ha!   73 Roy
> WA4DOU
>
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