[Boatanchors] Guy Wire Insulator Placement

Thu Jul 25 22:09:37 EDT 2013

I have had a Heights Aluminum 14"/18" tower for over 35 years.  It has
withstood 100 MPH straight line winds several times with a Moseley S-402 40
meter beam at 72' and a Moseley CL-36 Tri-bander at 56'.  I rotate the whole
tower.  It was guyed one time at 48' via a homebrew ball bearing guy ring,
utilizing 5000 lb rated 1/4" 7 strand utility guy wire.  The entire assembly
beams and all, sustained the winds without damage.  

I surmise the negative experiences related on aluminum towers are the result
of someone's lack of planning and installation details and not recognizing
properly the real causes of the problem. 

Personally, I wouldn't have a steel tower because of my good experiences
with my 72' aluminum tower.  I have relocated it 4 times now to new QTH's.
I raise and lower it from a hinged base far easier than I ever could with
one made of steel.  

>From the base hinge as the only support, it will sustain a couple hundred
lbs at the tower top when it is in a horizontal position.  Try that with a
typical ham sized steel tower like a Rohn 25.  

It also doesn't oscillate (pendulum effect) in the wind like a steel tower
does.  Aluminum gives in the wind then returns to where it was without
vibrating.
73,
Ray, W4BYG 

-----Original Message-----
From: boatanchors-bounces at mailman.qth.net
[mailto:boatanchors-bounces at mailman.qth.net] On Behalf Of Kenneth Grimm
Sent: Thursday, July 25, 2013 6:40 PM
To: Jim Wilhite
Cc: Boatanchors Mail List
Subject: Re: [Boatanchors] Guy Wire Insulator Placement

You really should have a look at the Heights aluminum towers.  Normal towers
are rated at 70-90 mph.  I asked for a little more conservative design and
Drake was able to provide me with a 100-110 mph  72 ft fold over self
supporting aluminum tower that holds my 4 element SteppIR and a Force
12 240/230 Delta.  Last year with a derecho blowing through here at 80 mph
plus speeds, the tower didn't move...although the SteppIR elements looked
quite bowed for a while!!!  Heights provides engineering info on their web
site.  I don't recall any mention of anything as puny as being rated at 50
mph.

73,

Ken - K4XL

On Thu, Jul 25, 2013 at 4:45 PM, Jim Wilhite <w5jo at brightok.net> wrote:

> Every aluminum tower specification I have seen uses 50 mph for their 
> wind load design point.  The older steel designs used 75 or 90 mph.  
> That would make a big difference especially when we hams tend to 
> overload a tower up on top.
>
> Jim
> W5JO
>
>
> ----- Original Message -----
>
>
>  What I am using is personal experience. In each case where I know of
>> problems with an aluminum tower, the tower was installed using the 
>> manufacturer's recommended procedures. In each case the wind load on 
>> the tower was less than the maximum rating of the tower. In each 
>> case, the tower "buckled" at about the half-way point. That is, there 
>> were no problems with the base installation.
>>
>> These towers were installed in north Texas (Dallas, Texas, area) 
>> where the wind speed does, on occasion, get above 70 mph. In fact, 
>> every few years, the wind speed can go over 90 mph. These are 
>> "straight line" winds and not tornadoes. A tornado, of course, is a
completely different matter.
>>
>> Obviously, there are different manufacturers of aluminum towers and, 
>> probably, different specifications that must be met in different
countries.
>> As such, I have no idea as to if the aluminum towers sold in 
>> Australia are the same as those that were sold in this area. But, I 
>> do stand on my comments based on my experiences.
>>
>> In my professional experience as a telecommunications consultant, I 
>> have had quite a number of towers installed from less than 100-feet 
>> to over 500-feet. As such, I do believe that I do have at least a
"little"
>> experience with different tower types. Those towers ranged from guyed 
>> to self-supporting and I would never recommend using an aluminum tower!
>>
>> Glen, K9STH
>>
>>
>>
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--
Ken - K4XL
BoatAnchor Manual Archive
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