[TowerTalk] {SPAM} Re: hazer comments

[TexasRF at aol.com]

Your math looks ok; but this is without any wind blowing on the  structure!
 
What will the forces be with 70mph winds?
 
73/k5gw
 
 
 
 
In a message dated 7/30/2008 11:18:00 P.M. Central Daylight Time,  
K8RI-on-TowerTalk at tm.net writes:

Dan  Hearn wrote:
> Dennis: You will find different opinions here on many  subjects however I
> believe there is almost uniform opinion on guying  crankup towers. Don't do
> it. That puts additional stress on the  lifting cables when horizontal force
> is applied to the tower.   73. Dan, N5AR
>
>   
(If I did the math  correctly)
Think of it this way.  Each 1/4" guy wire at 440#  tension  (10% of 4400# 
strength) and 60 degrees  at the anchor =  30 degrees angle at the 
tower.  Neglecting the weight of the guy =  440*Cos(30) = 381#. There are 
three guys per level so that would be 1143#  vertical load added to the 
tower and on the raising cables.
Say a  second set at 45 degrees = 440#*Cos(45)= 311# or 933# vertical 
load added,  so adding just two sets of 1/4" guys properly tensioned will 
add 2076#  vertical load to the tower and cables. IOW adding guys to just 
two levels  that move adds over a ton of load on the cables. Using steel 
guys would  also add additional weight from the cables as would larger, 
stronger  guys.

The strength of wire rope varies over a very wide range which  makes the 
selection of the cables a primary consideration and pretty much  
eliminates what you find at the corner hardware, or big box store  
although the hardware store could likely order it to spec.  This is  also 
why it's important not to oversize the guys on a tower.  

73

Roger (K8RI - ARRL Life  Member)
www.rogerhalstead.com
N833R (World's oldest  Debonair)

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