[TowerTalk] Tower "DROP ZONE" or "DROP RADIUS" for Rohn 25G &Trylon Titan?

Jerry Keller - K3BZ k3bz at arrl.net
Thu Jan 13 12:15:31 EST 2005


John...I'm no engineer, but I doubt that anyone could accurately provide such a figure, other than 
as a maximum, which would likely be the length of the tower. I think that's why it's not on Rohn's 
drawings or any other I've ever seen.

Your Building Inspector would likely want the specs to show that the installation will meet the 
town's code requirements. The requirements may be something like my town's, for example, which says 
the tower base must be a minimum of the tower height plus 10 feet from the nearest property line.

73, Jerry K3BZ

----- Original Message ----- 
From: "John WA2GO" <xnewyorka at hotmail.com>
To: <towertalk at contesting.com>
Sent: Thursday, January 13, 2005 7:53 AM
Subject: [TowerTalk] Tower "DROP ZONE" or "DROP RADIUS" for Rohn 25G &Trylon Titan?


> The Building Inspector is requiring my engineering drawings to specify what he is calling the 
> "drop zone" or "drop radius" of the tower.  He wants to see what is the radius of the circle it 
> will all land inside when it all comes crashing down.  (perish the thought!)
>
> I couldn't find this figure in the Rohn catalog anywhere. The one engineer I talked to didn't seem 
> to know about it either.
>
> In case anybody here knows about these, here are some possibly relevant figures for each tower I 
> need this figure for:
>
> 1) A 98' Rohn 25G, guyed for 90 mph at 95', 63' and 32' at a guy radius of 80', with 33' boom on 
> top antenna.)
>
> 2) A 108' Rohn 25G guyed for 90 mph at 105', 70', 35' at a guy radius of 88', with 24' boom on top 
> antenna.)
>
> In both cases, assume 7 sq. ft. of wind load at top of tower plus 4 sq. ft. of wind load at 2/3 
> tower height and 4 sq. ft. of wind load at 1/2 tower height.
>
> 3) A 96' Trylon Titan freestanding with 4.5 sq. ft. at 97' on a 23' boom, 4.5 sq. ft. at 67', and 
> 4.5 sq. ft. at 37', plus 3.1 sq. ft. at 77' and 3.1 sq. ft. at 47'.
>
> If someone can tell me what the values are for the figures I need, or where I can look to find 
> these figures, or how to calculate them myself, I would be very grateful!
>
> John
> WA2GO
>
>
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>
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