[TowerTalk] Verticals of Telescoping Aluminum

[George, W2VJN]

Dana,

A 40 foot piece of 4" irrigation tubing weighs 38 pounds.  It can
be lifted with one hand and will not bend.  I have made 80 meter
verticals by putting some smaller stuff in series up to 70 feet.
I was able to erect these by myself quite easily.   These sell
for $77 each here in Roseburg, OR new and I have them bought used
for $10 a length.  In 6" diameter it's very stiff and I bet it
could go to 90' or more.  Also, I have put 3 element tribanders
on 40 feet of 4" and had them up for years.  I used to stand on
my roof and pull the assy up by hand.

George  W2VJN


----- Original Message -----
From: Dana Roode <K6NR@ARRL.net>
To: TowerTalk <towertalk@contesting.com>
Sent: Saturday, September 09, 2000 11:29 AM
Subject: [TowerTalk] Verticals of Telescoping Aluminum


>
> Hello,
>
> I've been experimenting with verticals made out of 6063
aluminum tubing,
> which telescopes nicely in 1/8" progressive diameters.  I'm
interested in any
> pointers for determining what combinations of diameters,
section lengths, and
> guying produce a mechanically sound vertical.  I've been using
trial and
> error thus far.
>
> The first vertical was made out of 7' sections of 1 1/4"
through 5/8"
> diameter tubing with 1' section overlaps - 30' tall for 40m.
It works pretty
> well.
>
> Now I've built a 62' vertical for 80m.  It has 5 10' sections
starting at 1
> 1/2" diameter at the bottom, and 2 9' sections through 3/4"
diameter at the
> top.  I use a 1' overlap between sections.
>
> When we were putting it up we had one person telescoping it up
and 3 people
> manning the guys.  After about 40-50' it was really clear that
the weight of
> the top of the vertical, along with the flexibility of the
tubing in the
> middle, could easily make the vertical bend over on itself.  It
acted like a
> huge noodle, with about that much rigidity.
>
> We decided to try it at 45' for awhile, and its up and well
guyed (3 sets),
> and seems to be solid.  I'm debating whether to go ahead and
slide up the
> last two sections, or to start over.  If we are real careful
with the guys,
> all will be well, but one slip and I've got an upside down U
instead of a
> vertical.
>
> Any recommendations or experiences to share?  I like the
aluminum because I
> can telescope it up, no need for any rigging poles, etc.
Should I give up on
> it and use another material, or just use larger diameter
aluminum?  Is there
> a more "scientific" approach to determining the right diameter
and lengths
> for the vertical sections?
>
> Thanks in advance,
>
>    Dana, K6NR
>
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