[TowerTalk] Which Vertical is More Robust ?

[Richard (Rick) Karlquist]

Recommend that you consider chain link fence "top rail" instead
of EMT.  Get the "1 7/8 inch" OD variety.  It is the same
diameter as "1 1/2 inch" water pipe.  It is actually intended
to be structural.  There is also a "1 3/8 inch" OD variety than
you can telescope.  It is the same diameter as "1 inch"
water pipe.

Rick N6RK

On 1/1/2020 8:13 AM, Gedas wrote:
> HNY to all !
> 
> I cannot think of a better time to start a new 40m phased vertical 
> project then the dead of winter with snow on the ground (as usual I 
> could not get to it during the summer or fall).
> 
> Anyway, I have drawn up two possibilities for a pair of 33' self 
> supporting verticals. Both start out with a 10' length of EMT but one 
> choice starts out with a larger dia then the other before I switch over 
> to tapering aluminum sections.
> 
> A) Starts out with a 10' length of 1-1/4" EMT followed by tapering 5' 
> sections of aluminum tubing (4' long exposed, 1' inside the previous 
> lower section) until the very top length section which will be 3/4" OD 
> dia. These will be standard DX engineering aluminum tubes.
> 
> B) Starts out with a 10' length of 1-1/2" EMT, then a 5' length of 
> 1-1/4" dia of EMT (4' long exposed, 1' inside the previous section of 
> EMT) then followed by tapering 5' sections of aluminum tubing as above. 
> The only difference being this choice would end up using 1" aluminum 
> tubing as the very top piece.
> 
> So the obvious difference between the two are that choice A) uses just 
> one length of thinner EMT and overall thinner aluminum tubing sections 
> to the top while choice B) uses 2 lengths of larger dia EMT and then 
> larger dia aluminum tubing to the very top.
> 
> I do not have the software to analyze choice A) vs. choice B) in a high 
> wind situation. I am uncertain if the stronger, larger dia tubing with 
> it's higher wind load will be a plus or a minus in the end to it's 
> overall strength. Any thoughts or comments on which one will survive 
> better during heavy wind conditions? TU
> 
> Gedas, W8BYA
> 
> Gallery at http://w8bya.com
> Light travels faster than sound....
> This is why some people appear bright until you hear them speak.
> 
> _______________________________________________
> 
> 
> 
> _______________________________________________
> TowerTalk mailing list
> TowerTalk at contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
>