[TowerTalk] adding up wind loads

[Jeff Kinzli]

So I know that wind load at the top of the tower is much different
than wind load 10 feet up from the top of the tower, and that towers
are wind load rated at the top of the tower.

I'm trying to understand how this fits together in terms of stacking
yagis. My plan is to use a 4el Steppir and a 2 el Cushcraft 40M about
10 feet above that. With the roughly 10sqft for the Steppir, and 6
sqft for the Cushcraft, that's 16 sqft total, but I'm sure it's quite
a bit more than that given the stack, and ratings for towers looking
at the wind load at the top of the tower rather than 10' above the
tower.

Are there calculations that I can do to figure out how much tower I
need to support this? Or would that be something a civil engineer
would do (or my architect) before I get the permit for the tower (and
buy the tower).

Thanks for any ideas...

-J