Thanks Bob for taking the time to set us straight. This info is timely
because I'm interested in purchasing one of the HT soon.
----- Original Message -----
From: "W5LT" <W5LT@verizon.net>
To: <email@example.com>; <firstname.lastname@example.org>
Sent: Thursday, August 14, 2008 6:33 PM
Subject: Re: [TowerTalk] Heights Towers Aluminum??
> There must have been more at work here than the marginal addition of some
> Heliax. I designed the fold-over mechanism for the Heights new tower
> a few years ago, in accordance with the Aluminum Association
> and the Uniform Building Code, which include industry accepted design
> margins. I am assuming the tower that failed was one of the newer design
> (post 1995) units. The pre-1995 units were substantially over rated.
> The tower sections have two parameters: a moment rating and a shear
> Both must be considered in the tower design for wind and also the
> case. For a typical Yagi antenna and associated rotor & mast, the forces
> generated during fold-over are much less than (typically around 1/2) those
> that would be experienced during a rated wind load event. For example, my
> HTS tower is rated for 36 sq-ft projected area at 80 ft in my 70mph wind
> zone, which yields a wind pressure at the top of the tower of about
> That force generates a shear force at the apex the top section of that
> magnitude, and a moment of 700 lbs x 8 ft = 2800 ft-lbs at the bottom of
> section. The top tower section must be chosen to carry those loads to the
> next lower section, in addition to the loads from the wind area (or
> self-weight) of the section itself. As the design progresses down the
> both the total moment and shear load grow and each tower section must be
> selected to carry both. The fold-over case loads are derived similarly.
> Analysis of the fold-over case for my tower shows that the shear and
> loads are well balanced, that is, the actual load to the maximum design
> ratios are about equal for each section, and are less than half the
> corresponding section rating.
> It would be very unusual for a properly designed tower supporting its
> wind load to fail in shear during the folding operation. The only way I
> think that could happen is that, as Frank suggests, the user added some
> wind resistance dead weight to the tower that exceeded the shear rating by
> significant margin. Perhaps a several hundred pound lead ball at the top?
> The engineering ratings of the Heights tower sections are provided on
> website, along with the methods to engineer you own tower configuration.
> Bob, W5LT
> -----Original Message-----
> From: email@example.com [mailto:firstname.lastname@example.org]
> Sent: Thursday, August 14, 2008 9:11 AM
> To: email@example.com
> Subject: Re: [TowerTalk] Heights Towers Aluminum??
> Don't forget that you must comply with the dead weight capacity of your
> tilt-over tower. This is important, a nearby ham failed to comply with
> dead weight specification and his Heights fold-over tower collapsed as he
> tilted it up. His mistake? He forgot to count the weight of his Heliax
> Everything you add to your tower must be counted against the dead weight
> specification, including all cables, masts, rotators and other
> Give serious consideration to using an aluminum mast and light weight
> antennas, feedlines and control cables.
> Its especially important to minimize every pound of weight above the top
> the tower (i.e., mast and antennas and feedlines). Every pound above the
> top of the tower adds very significantly to the moment on the lower tower
> sections and the tilting base.
> ---- Original message ----
>>Date: Thu, 14 Aug 2008 5:11:25 -0700
>>From: Dennis <firstname.lastname@example.org>
>>Subject: Re: [TowerTalk] Heights Towers Aluminum??
>>To: W3OA <email@example.com>, firstname.lastname@example.org
>>Thanks for taking the time to respond Dick.
>>Very good input on some of the issues I would be faced with. How do you
> rotate the antenna at 40' or is it stationaly? Isn't there some kind of
> ring assembly for rotating antennas on the sides of towers?
>>Thanks Dick, Dennis, k0eoo
>>---- W3OA <email@example.com> wrote:
>>> Hi Dennis -
>>> I have a 60' Heights tower with a fold-over kit and 10 feet of mast out
>>> the top.
>>> It's been up for 5 years now and I'm very happy with it.
>>> You do need to watch how big an antenna you put on it. If the antenna
>>> is too large you won't be able to lower the tower far enough to work on
>>> most of the antenna from the ground. I suppose that's obvious but it's
>>> a trade I thought about for a long time before I decide to get a
>>> fold-over tower. I ended up with two Force 12 C-4s, one at 40 feet and
>>> one at 70 feet. I can reach the feed points using an 8 foot step
>>> Another gotcha I found out through experience is that rotor brakes that
>>> hold an antenna just fine when the tower is up may not hold the antenna
>>> in position as the tower rotates down. The antenna, of course, wants to
>>> rotate so its heavy end is pointed down and the break may not hold it in
>>> any other position. This can be an even bigger problem with side
>>> mounted antennas.
>>> I'd do it again 'cause I don't want to climb a tower.
>>> Good Luck - Dick, W3OA
>>> Message: 6
>>> Date: Mon, 11 Aug 2008 20:46:23 -0500
>>> From: "Dennis Petrich" <firstname.lastname@example.org>
>>> Subject: [TowerTalk] Heights Towers Aluminum??
>>> To: <email@example.com>
>>> Message-ID: <A577548AEF344F668DEB831F901180B9@D5V7GZF1>
>>> Content-Type: text/plain; format=flowed; charset="iso-8859-1";
>>> Hello all who have aluminum towers.
>>> I am thinking of putting up the tilt-over self supporting aluminum tower
>>> from Heights Towers. This one is 69' with the tilt-over kit and is
>>> 21sq' at 80mph. and will take a 12' mast. I will be putting up 15sq' of
>>> Anyone of you have experence with such a thing?? The whole tower tilts
>>> so you can work on the antenna from the ground, an idea I like very
>>> You can see it on their web page.
>>> Thanks in advance for your comments
>>> Dennis, k0eoo
>>> TowerTalk mailing list
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