[TowerTalk] antenna/mast height above tower

[Doug Faunt N6TQS +1-510-655-8604]

Thanks, I've now seen that number a couple of places, also a figure of
32.4 pounds per square foot at 90 MPH for wind force.  Since Glen
Martin rates my tower at 12 square feet of antenna at 87MPH, I just
used those numbers to get a rating of 384 foot/pounds.  Using a 9 foot
mast with 3 feet in the tower means that the rating is for a maximum
sideways force of 64 pounds at the top of the mast.  That's just about
2 square feet (ignoring the wind load of the mast itself).  I'm glad
that I'm in a protected location.

And that gives me a feeling for how much sideways force I can safely
apply when I'm working on the tower.  Enough, but I'll really try for
a calm day to do much work high up.

You can use some of thee numbers to work out some of the forces at
work when you're climbing your mast.  Note that mast steps would add
to the wind load of the mast, if you leave them in place.

And a question- we've all seen photos of towers that have bent or
broken- how many examples do people know of the MAST bending or
breaking?

And have I gotten anything wrong in my analysis?

73, doug

   Message: 9
   Date: Mon, 23 Jul 2007 12:36:18 -0500
   From: "Larry & Karen" <k0is at iowatelecom.net>

   I know that US Tower says something about one foot above the thrust
   bearing for what it's worth.

   Larry  K0IS