[TowerTalk] Choice of aluminum

[Richard (Rick) Karlquist]

If you can possibly obtain 3" aluminum irrigation pipe in your area,
you will be much happier with it and probably save a lot of money.
Stiffness is proportional to the cube of the diameter, so you really
need the 3 inch diameter.  You can't fix this problem by using
thicker wall small diameter tubing, because the weight increases
as fast as the wall thickness, so the stiffness to weight ratio,
and thus sag, is constant at a given diameter.  Irrigation pipe is
made of a cheaper alloy than 6061, and therefore will take a set
more easily.  But again, the large diameter trumps alloy selection.
The exception to this is the completely different philosophy used
in the Titanex verticals, where they bend like a fishing pole and then
spring back.  The alloy they are made of seems to be unobtainium
AFAIK.  Has anyone successfully purchased from Titanex recently?

Rick N6RK


On 10/13/2012 2:09 PM, Rudy Bakalov wrote:
> I was wondering if anyone can help me select the right material for full-size 80m verticals. My questions are as follows:
>
> 1) metalsupermarkets.com offers 6061-T6 aluminum, but not T8. Is there a difference between T6 and T8 for my purpose?
> 2) Should go for the 0.125 or 0.065 wall thickness?
> 3) Is 1" tubing OK for the topmost segment? Too stiff for the wind at 70'? Not strong enough?
>
>
> I am aware that many ham stores offer 6061-T8 tubing, but I do want to buy it local in VE3, close to my QTH, in 12' lengths (instead of 6') and avoid shipping complications due to length or clearing customs.
>
> 73 Rudy N2WQ
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