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## Masts and stacking considerations

 To: Masts and stacking considerations w7ni@teleport.com (Stan Griffiths) Sat, 15 Jun 1996 00:53:26 -0700 (PDT)
 ```>K7LXC@aol.com writes: > >> If you go to a rotator with a clamshell type of mast clamp, a 3 inch is >> no problem because it'll self-center. Correct me if I'm wrong, but going >> from 2 inch to 3 inch isn't necessarily going to save you any money because >> it doesn't significantly increase the strength of the mast. Besides, the >> forces remain the same. >> > > >Steve - I believe you are wrong. I don't have the formula handy for >calculating tensile strength of a round member, but diameter is the >single-most important factor, as it is exponential, not linear. I have >the formula at home somewhere, and can dig it out, if there is interest, >and nobody else has it handy... 73 Barry > >-- >======================================================================= >Barry N. Kutner, W2UP Internet: barry@w2up.wells.com >Newtown, PA Packet Radio: W2UP @ WB3JOE.#EPA.PA.USA.NA > Packet Cluster: W2UP >WB2R (FRC) >....................................................................... I think the formula you are looking for is in my article on mast strength that was published in NCJ a few years back. Unfortunately, I have not been following this thread, but most of the time people are interested in the bending strength of a mast with a stack on it and not the tensile strength. The bending strength of a mast is proportional to the "yield strength" which is a function of the type of metal and alloy the mast is made of. It is also a function of the "moment of inertia" of the mast which is determined by its shape, usually a round cylindar, and the actual dimensions of the mast. Ouside diameter is VERY important to mast strength. A three inch mast is a LOT stronger than a 2 inch mast, all else being equal. BTW, "tensile strength" usually refers to how much "stretching" a member can take like pulling on a rope or cable. It is true that when bending a mast, one side of the mast is in tension while the other side is in compression so tensile strength alone does not give enough information to know the whole story. stan w7ni@teleport.com ```
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