[TowerTalk] Mast section modulus correction

[Pete Soper]

(Toss that last "cookbook" message I sent into the bit bucket. Stan 
Griffiths was kind enough to point out that I botched the formula
description. Here is what I should have written)

For the folks that enjoy knowing how to do this stuff yourselves:
 
Section modulus(of a hollow cylinder) = pi*(D**4 - d**4)/32D

Where D is the outer diameter and d is D minus two times the wall thickness,
"*" means multiply and "**" means raise to the power of (and pi is 3.1415).

If you divide the section modulus into the inch-pounds of force on the mast
you get the bending stress which must be less than the yield strength of the
material to avoid damage.

(From pages 3-4 to 3-6 of the Leeson book)

Regards,
Pete
KS4XG

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