[TowerTalk] Guy breakup at tower...

[donovanf at starpower.net]

Gary,

Phillystran cuts easily with a sharp knife, bolt cutter or hacksaw. As
with all Preforms, the thimble  M U S T  be the heavy duty type. 

Philly is an excellent but expensive solution when you include the
cost of the two preforms, one heavy duty thimble and articulating
attachment hardware (e.g., shackles) for each guy.

The guy attachment to your rotating tower must allow articulation of
the attachment hardware.  In other words, the rotational stresses
must be taken up in hardware that is intended to articulate (e.g.,
shackles).  

You do not want the rotational forces to be taken up at
the interface of the Phillystran to end of the Preform.  That will
cause the Phillystran to wear, potentially resulting in catastrophic
failure.

The need to use articulating guy attachment hardware is often not considered by hams, especially on rotating towers where these forces
can be very significant when starting and stopping rotation.

If you observe commercial tower installation practice, articulating guy attachment hardware (e.g., shackles) is always used.

73!
Frank
W3LPL

---- Original message ----
>Date: Wed, 14 Feb 2007 10:21:11 -0700
>From: "StellarCAT" <RXDesign at ssvecnet.com>  
>Subject: [TowerTalk] Guy breakup at tower...  
>To: "tower" <towertalk at contesting.com>
>
>Re: my previous post on having interaction with the 6' lengths 
>of EHS at the tower (through the tower it is actually ~13.5') 
>... it does interact with BOTH 10 and 15 - probably slightly 
>more on 15 than 10. Frank had suggested some robust shackles and 
>another 502 insulator... but I am not sure how i would then 
>connect to the tower...
>
>
>the alternative I am considering is simply replacing this 6' 
>piece with phillystran. I was looking at the 11200 which is 
>0.44" thick and rated at 11200#.
>
>how does one cut this stuff?
>
>If i go this way am I simply looking at 2 preforms and the one 
>6' length? Nothing else?
>
>Does one use a standard metal galvanized thimble for this (at 
>the tower) - no concerns about it "wearing" over time as the 
>metal galvanization is often pretty rough.
>
>the down side of this method is it requires a separate temporary 
>guy line to be run vs. Frank's idea would be doable by simply 
>adding another (temporary) preform just past the insulator 
>preform and then using a come-along to this point to temporarily 
>take the pressure allowing the new insulator shackles to be 
>installed... in reality this may not be so easy either.
>
>Hindsight says I should have listened to the call for using 
>Philly or Fiber. I wanted something that would not stretch and 
>K7NV's notebook shows philly to stretch way too much... not sure 
>where the descrepancy is between the analysis and real life but 
>many have used philly with no problems...
>
>
>g.
>
>
>
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