Sorry, Joe - 'twarn't me, 'twere Roger who wrote that. I, in fact,
referenced Kurt's work also.
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
On 9/1/2009 3:53 PM, Joe Subich, W4TV wrote:
> Pete wrote:
>
>
>> 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.
>>
>
> Sorry, Pete - elongation/stretch makes a big difference. Please
> review the tower studies by K7NV on his web site ...
> http://k7nv.com/notebook/towerstudy/towerstudy1.html
>
> Pay particular attention to "Configuration Variation #5" is which
> 3/16" and 1/4" EHS is replaced by HPTG6700 in a stock 100' tall
> Rohn 45 design with 20 sq ft. at the top. Also note that spreading
> the 20 sq ft of windload down the tower results in greater stress
> at the base of the tower (due to elongation of the lower guys)
> than shown in the base case (all 20 sq ft at the top).
>
> Kurt's take away for aramid (Phillystran) cables is:
>
>
>> These are very strong and lighter than the steel cables. They
>> exhibit higher elongation than comparable strength steel guys.
>> Since, some guyed towers can be sensitive to cable elongation,
>> replacement of steel guys with aramid cannot be only done based
>> on strength alone.
>>
>> Guy elongation must be considered.
>>
>
> 73,
>
> ... Joe, W4TV
>
>
>
>
>
>
>> -----Original Message-----
>> From: towertalk-bounces@contesting.com
>> [mailto:towertalk-bounces@contesting.com] On Behalf Of Roger (K8RI)
>> Sent: Tuesday, September 01, 2009 12:58 PM
>> To: n4zr@contesting.com
>> Cc: TowerTalk
>> Subject: Re: [TowerTalk] Philly installation
>>
>>
>>
>>
>> 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.
>>>>
>>>>
>>>>
>>> _______________________________________________
>>>
>>>
>>>
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>>>
>>>
>>>
>> _______________________________________________
>>
>>
>>
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>
>
>
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