[TowerTalk] TX-455 versus LM-354 tower

[K7LXC at aol.com]

In a message dated 1/26/2008 9:02:51 A.M. Pacific Standard Time,  
towertalk-request at contesting.com writes:

>  Looking at the specs for the Universal Towers  TX-455
versus the Tashijian LM-354 tower they are very
similar.   Same height, same weight, etc.  However the
LM-354 is rated at 23 sqft  load at 85mph while the
TX-455 is rated at only 12.3 sqft at 70mph.  

>  I wonder if there is a good reason the LM-354 is  rated
higher or if it may be exagerating its limits?  


        Boy, this is a good one.  Before the TIA-222 and other building codes 
were so prevalent, crank-ups used to  be rated at 50 MPH windspeeds. Nowadays 
it's not even a wind until it reaches 70  MPH - the lowest windspeed rating 
in the US. Very few, if any of them, could  meet the 70 MPH spec. 
 
        Both of those towers were  originally designed by the same guy - Lou 
Tristao - so they are reasonably  similar structures. The difference is that 
one has a #3 top section (the 354)  and the other (the 455) has a #4 top 
section. Since the 455 is known to conform  to current codes, I'd say that its 
capacity is realistic. And in that vein, I'd  say that the 354 is incredibly 
generous in its capacity rating. I don't think  I've ever seen ANY crank-up tower 
that could take 23 sq.ft. @ 85 MPH. Karl is a  PE so I'm assuming he knows what 
he's talking about but I'm very skeptical. 
 
Cheers,
Steve     K7LXC
TOWER TECH n-
Professional tower services for hams
Cell: 206-890-4188 



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