[TowerTalk] Rohn 55 vs. Rohn 45

[K8RI on Tower Talk]

Don't forget there are ROHN 45s and there are ROHN 45s, then there are 55s 
and there are 55s. IE, not all 45s or 55s are created equal.  Both are, or 
at least were available in hollow and solid leg forms with a fair difference 
in ratings.

>
> OK, here's a toss up that should generate some real discussion:
>
> Rohn 45 and Rohn 55 have essentially the same face width and
> the same cross bracing.  The Rohn 55 has slightly thicker wall
> side rails -- the center to center spacing of the side rails
> is only 1/4" more (about 1.5% larger) than that of Rohn 45.

Look at the difference in seight per section.

>
> I am confused when comparing the Rohn 45 and 55 catalog specs
> for 100' at 110 MPH.  The 45 design uses 1/4" EHS at the top and
> 3/16" for the intermediate guys ... it is rated for 7.9 sq. ft.
> The 55 design uses 5/16" EHS at the top, 1/4" EHS in the middle
> and 3/16" EHS at the bottom ... it is rated for 15 sq. ft.  The
> guy anchors for the 55 design have about 25% more concrete (.84
> cu yd vs. .67 cu yd).
>
> I can't imagine the difference in rated capacity is explained by
> the modestly larger side rails. Does this indicate that Rohn 45

What do you mean by side rails? Legs?
If you mean legs, then even a 1/16" of an inch makes a substantial 
difference.

> could safely be loaded more heavily if the guy wires were upgraded
> (e.g., to the Rohn 55 design or by using TA45 "star" guy brackets
> and double guys at each level)?  I also know that many users have
> significantly overloaded towers when compared to Rohn's catalog
> designs and gotten away with it.

I don't think any of us are going to agree if it's not in the book.
>
> Is the added cost (about 25%) for Rohn 55 "worthwhile" -- is it
> really that much stronger or is Rohn 45 "as good" when guyed the
> same way as 55?

Again, what is the difference in weight?  The 55 is supposedly stronger by a 
good margin.
>


Roger Halstead (K8RI, EN73 & ARRL Life Member)
N833R, World's Oldest Debonair (S# CD-2)
www.rogerhalstead.com
> 73,
>
>   ... Joe, K4IK
>
>
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