[TowerTalk] W6NL 40m Moxon (again)

[john at kk9a.com]

Yes, a 3" mast using 1026 DOM blows away a 2" Chrome Moly mast.  I have not
used a 2" mast in well over a decade. To quote VE7RF " Whoever standardized
the 2.0 OD mast was fubar" 

John KK9A

To:	towertalk at contesting.com
Subject:	Re: [TowerTalk] W6NL 40m Moxon (again)
From:	Kevin Stover <kevin.stover at mediacombb.net>
Date:	Wed, 20 Apr 2016 19:56:19 -0500

Ken,

Thanks for all of the help.

I just stuffed your number in the ARRL mast calculator.
I will have an Optibeam 11-5 one foot above the top (15.7 sqft - 71ft), the
Moxon 11 feet above that (7 sqft - 82ft) plus 5 sqft of mast and a 3 sqft 6m
beam at the top.

I get mast survival, three inch, 0.25 wall, 87Kpsi material, of 130 mph.
Over 900lbs of wind force. Looks like the thrust bearing is pretty
important.

The tower will take that load to 110 mph, the antennas start coming apart at
100 mph. So...when the F1 tornado comes dancing through the neighborhood the
tower will stay up, the mast won't bend and every roof for 100 yards radius
will be gone.

That mast calculator really opened my eyes. Everybody using two inch masts
needs to see just how overloaded they may be. My proposed antenna's on a two
inch mast of 87K 1026 DOM material fails at 88 mph. Switching to 4130 and
110K material gets you another 11 mph to 99. Diameter is everything.

The calculator is fun to play with.