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[TowerTalk] Fwd: Mast and stacking question

To: <towertalk@contesting.com>
Subject: [TowerTalk] Fwd: Mast and stacking question
From: w7ni@teleport.com (Stan Griffiths)
Date: Sat, 3 May 1997 22:08:09 -0700 (PDT)
>I do have a question or two.  I have determined that with my three antennas I
>will need a mast capable of 65000 PSI Y.S.  It also recommends .250" wall 
>thickness.  Will it matter what the wall thickness is as long as the Y.S. is 
>at least the desired value?

Yes, it will.  The actual amount of load the mast will take is a function of
BOTH the yield strength of the material AND the cross-sectional dimesnions
(OD and wall thickness) of the mast.

  The supplier I found claims that his 4130 .250" 
>wall is rated at 100,000 PSI or better and that I probably could go with
>.188" 
>or .156" wall instead.  Any thoughts?

Your supplier is suggesting that you can trade off some wall thickness for a
material of higher yield strength.  He is correct.  You will have to do some
calculations to know if it a wise tradeoff or not.

  Where can I find data that will show 
>Y.S. based on wall thickness?

You can't find that data since Y.S. in only a function of what alloy the
mast is made of and not its dimensions.  The total load a mast will take is
a function of both Y.S. and the mast dimensions.

Hope this helps.

Stan  w7ni@teleport.com

PS  You might ask Steve for a copy of my article that I wrote years ago
telling how to make the calculations I referred to above.



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