[TowerTalk] Windload calculation query

[Dick Dievendorff]

I know I'm going to need a PE's formal plan before I really construct this
thing.

 

I have tower specifications that describe a tower's windload capacity, which
I take to mean the capacity if all the antenna were installed at exactly the
top of the tower.

 

However, I plan to install a couple of antennas on a mast that extends from
the top of the tower.  

 

Is there a basic calculation that I could perform (say, with some Excel
spread sheet formulae) that would help me plan the tower capacity?

 

I have the windload numbers for each of two antennas.

 

I'm planning for a 20'  mast (2 or 3" in diameter), with about 10' sticking
out of the top of the tower.

 

One antenna is going to be mounted very near the top of the mast.

 

One is going to be at the bottom of  the mast, just inches above the top of
the tower.

 

I know I have to add the windload of the mast itself, which increases the
surface area of the part that sticks down as well as up.

 

Thanks!

 

Dick, K6KR