Hi all,
As being the lucky person to clean up the mess left by Owen's tower failures, I
can tell you first hand that all antenna weights, wind load specs, lengths,
etc. were passed on to Heights before Owen put them up, anyone who knows Owen
knows he goes by the book and documents!! He was told that his loading was
within spec.
I am no expert on aluminum welding but I do a fair amount about steel welding
and what I have seen is a failure of welds on his towers. Normally, a weld is
stronger than the surrounding material. If there is a failure, the weld is
intact but metal is ripped away around the weld. A sign of a good weld is a
slight cutting away of material right at the weld. This is the point where the
material starts to melt and becomes one with the welding rod material. Some of
the failed welds on his HF tower that came over first look like they just poped
off, like a cold solder joint.
His second failure, just a couple of weeks ago, occured at 36 mph as measured
by his Davis wx station and verified by the local airport which reported only a
31 mph gust. The top section failed right where it went inside the next
section. A leg buckeled in and it was all down hill from there. Once again, as
the leg that was receiving all the downward pressure (opposite the legs in the
wind) pushed inward and the Z bracing which is supposed to keep it from
collasping, didn't. I did not see the Z bracing buckle, the welds just broke.
All the discussions thus far seems to be centered around just self supporting
foldovers, not crank ups as Owen's was. I'm sure there is a difference between
the way the load is distributed down the tower.
At K8GP, we use a lot of Univeral self-supporting towers that pivot up from
atop our school buses. Our towers take a lot of abuse from being overloaded
(it's only 5 days twice a year!) and riding around on bumpy roads on top of
school buses. Our towers have survived 80+ mph winds and when we have a break,
it's usually a fatigued Z brace and NOT at a weld and we only go up 30 to 40
feet.
I'm not passing judgement on Heights towers or aluminum towers in general, just
adding to the discussion of what I saw. For most of us, a tower is a pretty
good size investment in time and money, and since my tired, old, fat butt is
climbing up, I want nice heavy, thick, galvanized STEEL under me!
Terry
-------------- Original message --------------
From: <donovanf@starpower.net>
> Hi Dick,
>
> Unlike K3CB's recent experiences with the catastrophic failure ofboth of his
> Heights crank-up towers (one in dead calm weather and the other in light 30
> MPH
> winds), the collapse of the Heights tilt-over tower was the direct result of
> an
> inexperienced tower owner significantly exceeding the maximum dead weight
> specification.
>
> I suspect he isn't alone in failing to appreciate the importance of not
> exceeding the dead weight specification for tilt-over towers.
>
> 73
> Frank
> W3LPL
>
> ---- Original message ----
> >Date: Thu, 14 Aug 2008 16:40:33 -0600
> >From: "Dick Williams"
> >Subject: Re: [TowerTalk] Heights Towers Aluminum??
> >To:
> >
> >I have seen several interesting comments on the reflector concerning Heights
> >Alum towers; and in fact, I posted a couple myself.
> >
> >As I mentioned in a previous post, I have three of them and they all tilt
> >over in the center (80 ft towers with the fold over at the 40 ft level).
> >
> >Obviously, weight is a concern, you can't put 400 lbs of antenna and
> >acessories on the top and expect it to work.
> >Alum masts certainly help; in fact I have a nice 20 ft, 1/2 inch wall one
> >sitting on the ground that I am not using right now (150 bucks picked up).
> >
> >As far as size, I have not found that to be a problem (just weight). I
> >put the antenna together (or take it down to work on with the boom parallel
> >to the ground (elements vertical). If the elements are too long, I just
> >start removing element sections as I lower it down until the boom is low
> >enough to work on.
> >
> >It is too bad that Glenn Martin Engineering does not produce the Voyager any
> >more. It is the similiar to the Hazer except it is on a external track on
> >the side of the tower. I have one on a 120 ft Rohn tower. Have a Force 12
> >Mag 620/340N on it with a M2 R2800 rotor. Works great; brings the antenna
> >right down to the ground ready to be worked on when needed. And all it
> >takes is a 1/2 inch electric drill to raise and lower it.
> >
> >All said and done, I like the Heights towers and the Voyager system for
> >"ground level" antenna work.
> >
> >Dick K8ZTT
> >
> >
> >
> >_______________________________________________
> >
> >
> >
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>
>
>
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