In a message dated 98-07-16 09:12:19 EDT, mlowell@noclant.navy.mil writes:
<< Machinery's handbook lists the nominal yield strength of 304L stainless
steel as 30,000 psi. Using a safety factor of 1.5, that gives you a
strength of 20,000 psi for calculations. This is nowhere near the 87,000
psi strength that Texas Towers is listing for the Rohn masts, for
comparison.
Particularly in light of the fact that WA5JWU lives in a 95 MPH winspeed
zone plus he's within 100 miles of hurricane oceanline. Not the application
for a weak mast.
>> Definitely get the MARC mast strength program from Champion Radio to
determine what this mast will hold with the given properties. Not having
used it myself, I am assuming that you can plug in the size and yield data
of a custom mast (Steve, can you comment on this?). You will also want to
find out if MARC uses a built in safety factor or not to help you decide
whether to give it the full yield strength value or a reduced one. >>
Thanks for the plug. More info on MARC is available at
http://ww.championradio.com. It used Dave Leeson's (W6NL, ex-W6QHS) book,
"Physical Design of Yagi Antennas" as the source of all wisdom.
Cheers, Steve K7LXC
--
FAQ on WWW: http://www.contesting.com/towertalkfaq.html
Submissions: towertalk@contesting.com
Administrative requests: towertalk-REQUEST@contesting.com
Problems: owner-towertalk@contesting.com
Search: http://www.contesting.com/km9p/search.htm
|