[TowerTalk] sag--->length in guy wires

[K4OJ]

wow - K6LL is way too technical for this QCAO!

too techie for me, ain't this stuff plumbers delight...not Civil Engineers
delight ????????


Pete,

How are you tensioning the guys?  Assuming you are using a pork chop (that's
southern for a "Chicago grip") your lengths should not have to be much
longer than the calculated lengths...I always allow a slop factor just in
case the point where you attach the guy to the leg ends up being a little
higher than planned due to trying to grab the diagonal brace leg
intersection at the weld, etc...

The most important consideration here is not to be silly...cutting it just
right could mean it ends up too short - at what savings...at a couple of
bucks tops per piece "extra" you could have several feet wild and no ulcers
worrying about being "too short"....

That wild end can be very handy as well...we pass it through the heart of
the turnbuckle, which will prevent the turnbuckle from spinning and
loosening!


73,

Jim, K4OJ
k4oj@arrl.net

Proud member of the Florida Contest Group, visit our website at:
http://www.qsl.net/fcg

The Florida Contest Group thanks K1ZZ and the ARRL for the opportunity to
host W1AW/4 in the 2000 IARU HF Championship.



----- Original Message -----
From: <k6ll@juno.com>
To: <towertalk@contesting.com>
Sent: Thursday, June 15, 2000 5:02 PM
Subject: Re: [TowerTalk] sag--->length in guy wires


>
>
>
> On Thu, 15 Jun 2000 20:51:33 +0000 Pete Smith <n4zr@contesting.com>
> writes:
> >
> > Is there a good rule of thumb for how much additional length is
> > required in
> > 3/16 EHS to account for sag, as compared with the pure mathematical
> > right
> > triangle length?  Put another way, if a guy station is at 95 feet
> > above
> > ground, and the guy anchor is 85 feet from the tower base,
> > Pythagoras says
> > the guy is 127.5 feet long.  How much should you add in length to be
> > safe
> > when pre-cutting guys?
>
> For horizontal wires, there is a nomograph in the ARRL Antenna
> Book that will give you sag as a function of span (1/2 the
> distance between the supports), tension, and
> wire weight.
>
> For vertical wires, there is no sag.
>
> I would take the horizontal nomograph sag and multiply it by the
> cosine of the guy elevation angle, with 90 degrees being straight
> up.
>
> For your example:
> span = 63.75 feet
> tension = 400 pounds
> wire weight = 73 pounds per 1000 feet
> cosine of the guy angle = .67 (85/127.5)
>
> Nomograph sag for horizontal wire =  0.4 foot
> Nomograph sag x cosine of guy angle = .27 foot (.4 x .67), or about
> 3.25 inches.
>
> The nomograph in the antenna book is not optimized for short spans
> and high tensions, so the sag scale goes from 0.5 feet to 50 feet.
> I had to extrapolate a little to get to the 0.4 reading.
>
> Caution! This mechanical engineering data was generated by an
> Electrical Engineer.
>
> Dave Hachadorian, K6LL
> Yuma, AZ
> K6LL@juno.com
>
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