[TowerTalk] Mast Analysis

[K7LXC@aol.com]

In a message dated 12/21/00 6:25:28 AM Pacific Standard Time, 
DAVED@ctilidar.com writes:

> I guess "yield" was the wrong word. I'm looking at
>  extending my mast so it sticks out of the top of my tower by about 10' or
>  so. Presently the rotor plate is located about 3' from the top of the tower
>  and I have a thrust bearing at the top. I want a mast that is fairly stiff
>  so I can climb up on it if I have to. So I guess a stiffness (modulus?)
>  calculation is what I'm after.

Hi, Dave --

    What do you have on the mast now? What are you planning on adding? What's 
your windspeed zone?

    Typically I'd say adding 3 feet is no big deal but without the above info 
I'll hold my opinion.    

>  By the way, is it silly to have that much mast sticking out if only 3' of 
it
>  is in the tower? 

    Maybe. As you are surmising, the lever arm can be large.

> Would a 20' mast be a lot better with 10' of it in the tower and 10' 
sticking out the top?

    Well, probably. It still depends on the above answers. If it's a medium 
to large array - yes. If it's a bunch of VHF stuff, it's not as important.

Cheers,    Steve   K7LXC
Tower Tech


--
FAQ on WWW:               http://www.contesting.com/FAQ/towertalk
Submissions:              towertalk@contesting.com
Administrative requests:  towertalk-REQUEST@contesting.com
Problems:                 owner-towertalk@contesting.com