[TowerTalk] Tower calculator software?

[Jim Lux]

At 10:12 PM 7/20/2007, Kurt Andress wrote:
>Hi All,
>
>I would never recommend that anyone not already intimately familiar 
>with FEA go try and do what I did!
>FEA is not a program one just fires up and runs to find out how to 
>build their tower, it is another profession one needs to learn and 
>become proficient enough with to even start thinking they have 
>enough valid information to make informed decisions!
>
>If you want to become your own tower designer, you will be best 
>serviced by starting with something more like 
>this............http://www.risatech.com/risatower.asp
>
>73, Kurt, K7NV

I would echo Kurt's comments. Just from the process of doing the 
analysis,  structural FEM (e.g. GRAPE, etc.) is probably an order of 
magnitude more complex/difficult than electromagnetic FEM (e.g. NEC). 
For instance, theres's more degrees of freedom at each node in 
structural FEM.  There's also the issue that if you screw up your NEC 
model nobody dies, the antenna just doesn't work like you 
expected.  If you screw up your structural FEM model, the potential 
for disaster is much greater.

In both cases, there's also an "art" to making simplifying 
assumptions (how long can the segments be, do I model every little 
detail to a gnat's eyelash, etc.) which come from experience and 
training.  Then, there's the whole material properties thing.  At 
least, from an electrical standpoint, all aluminum is pretty much the 
same. This is definitely not true of steel, cable, welding, and bolts 
in the structural area.

Jim, W6RMK