Towertalk
[Top] [All Lists]

Re: [TowerTalk] Philly installation

To: n4zr@contesting.com
Subject: Re: [TowerTalk] Philly installation
From: "Roger (K8RI)" <K8RI-on-TowerTalk@tm.net>
Date: Tue, 01 Sep 2009 12:58:00 -0400
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>

Pete Smith wrote:
> This assumes that elongation of the Phillystran for a given load is the 
> same as EHS.  In fact, according to K7NV 
> <http://wiki.contesting.com/index.php/Guy_cable_data> 6700-lb Philly 
> elongates about twice as much as 3/16" EHS and almost 4 times as much as 
> 1/4" EHS which is rated for the same breaking strength.
>   
But the elongation/stretch of either is pretty much meaningless except 
for precision positioning and even then takes place with the initial 
tensioning. It's doubtful there is much elongation associated with wind 
load unless the tower is overloaded and/or the winds are very strong as 
in approaching the system limits.  In practice there is probably (I've 
never measured it but I have seen the movement) more give in the 
catenary with EHS than there is with the catenary AND elongation of 
Phillystran. EHS has almost no elongation. What's 4 times almost 
nothing? OTOH the *give* in both is slight unless someone runs into your 
guy system with a tractor while you are up there. I know it's 
substantial with EHS at 90 feet.(been there, done that, didn't like it 
at all)  I'll leave it up to some one else to test the Phillystran via 
that method <:-))

Both are good, both have little give, and both are acceptable methods of 
guying and even in 30 MPH winds you will not feel the tower move. Been 
there and done that too. It was a much more pleasurable (or at least far 
less stressful) than having the tractor test run on the guy system.<:-))

73

Roger (K8RI)
> I have 6700-lb Philly on my top guy set, with steel below, tensioned at 
> 400 lb and the tower feels very steady.  YMMV.
>
> 73, Pete N4ZR
> New Articles Daily - the Contesting Compendium at http://wiki.contesting.com
> The World Contest Station Database, updated daily at www.conteststations.com
> The Reverse Beacon Network at http://reversebeacon.net  
>
>
>
> Roger (K8RI) wrote:
>   
>> ...
>> Yes it's true you do not have a weight of EHS or the massive catenary.  
>> There is so little catenary in the 4000 and 6000# test Phillystran you 
>> really have to look to see it when sighting down the cable. However that 
>> means the guys are less likely to be able to cushion shock.
>>   
>>     
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
>
>   
_______________________________________________



_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk

<Prev in Thread] Current Thread [Next in Thread>