Date: Thu, 31 Jan 2013 09:07:17 -0600 (CST)
From: Gene Smar <ersmar@verizon.net>
To: k4vud@hotmail.com, towertalk@contesting.com
Subject: Re: [TowerTalk] Trylon self supporting tower 80 ft fall
report
Charles:
Sorry to learn of your Trylon problems. Of course, you know it was overloaded.
Based on your estimate that the top was 12 inches across you probably have a
Titan T-300-80
http://www.trylon.com/lightdutytowers/pdfs/80ft%20Titan%20Profiles.pdf . If you
look at the specs
http://www.championradio.com/T300-80-Trylon-Self-Support-Tower.52 it's really a
light duty tower. At 85 mph winds it is rated to support only 6 sqft of anenna,
and that's within two feet of the top shelf. My T-500-64 Trylon holds only a
Skyhawk tribander, D40 dipole and GP-15 V?UHF vertical. I calculated that I
could add a long-boom VHF and UHF Yagi and that's it.
The design of Titan towers virtually guarantees that they will fold in half as
you experienced. The upper sections' legs and cross bracing are made from
thinner gauge steel than the lower sections. If you use Trylon's design tool
http://www.trylon.com/lightdutytowers/towercalc.asp you will see that the mid
sections have the least safety margin. They will fail first upon overloading.
73 de
Gene Smar AD3F
### That tower was beyond grossly overloaded ! What on earth were you thinking
of. You also had a whopping 17 feet of mast above the top of the tower. You
effectively just added two full tower sections !! Your 6 sq foot rating just
dropped to well below ZERO. Even the T-400-80 with it’s 15” C-C wide top
and 45” C-C wide base would still be overloaded. The 80’ tower is only 76’
8” due to the 4.5” section overlaps. Toss in the 17’ of mast above the
tower, and you
are now sitting at 93’ 8” . A better tower would have been the T-500-72
..with a 18” C-C top and 45” C-C base. The T-500-72 is 69’ tall.....and 86’
with your 17’ mast. Even that is pushing your luck. The T-600-64 would
have been the ideal
ticket. 21” C-C top and 45” C-C base. It would be 61’ tall..then add 17’
of mast = 78’.
## The weak point is 38’ above the ground on these towers. IE: Junction of
5th + 6th section. They are designed that way so they fold in the
middle....and not full length at the base. The HDX-689 by UST is similar.
It’s a 5 section tower,and the
weak section is the 3rd one up from the bottom.
## These wind ratings for these Trylons is only 2’ above the top... NOT 17’ .
On a UST tower it’s only 1’ above the top.
## Think of the tower as a giant torque wrench. Your 94’ tall torque
wrench won’t handle the strain. Simple math exercise really. Watch out on
the trylon towers. They are as streamlined as a brick. At 100 mph the wind
rating will fall through the floor.
Even the T-500-72 is only good for 6 sq feet (2’ above tower top) in a 100 mph
gust. And none of that factors in ICE.
## Trylon does make heavy duty freestanding towers...in 10’ sections..that
will handle huge loads..and are rated for 1 inch of ice. ( that’s 1 inch of ice
on each side). AN wireless makes a similar heavy duty tower.
If you want to put big windloads on tall free standing tower’s, they have to
be engineered for those loads. Then you also have to factor adding in a tall
mast.
Jim VE7RF
On 01/31/13, Charles Harpole<k4vud@hotmail.com> wrote:
I put up a used Trylon self supporting 80ft tower that I do not have the Model
number of. It was about 36 inches from leg to leg at the base and tapered to
about 12 inches at the top, each section nesting inside the next larger one,
forming one shipping package. The cross members were angle iron galv. steel and
the uprunning three legs were U channel, not tubular. It was loaded, or over
loaded, with one each 20m 5 el, 15m 5el, and 10m 5el HyGain yagi in the HyGain
Christmas Tree pattern with a very heavy (I could not lift it) 23ft chrom molly
mast, six feet down inside the tower with two thrust bearings and the T2X rotor
below. All the bolts throughout were replaced with new galv correct sized bolts
and it had no rust. Mounted in a six by six solid concrete base. Four years
after installation, I noticed two bowed cross members next to each other on
horiz. at about the 40ft level and one bowed at about the 70ft level, all of
which were replaced with similar steel angle iro
n, bolted as the original. After seven and a half years, a very powerful
straight line wind with near horiz rain for about five minutes caused the tower
to fold over at about the 40 foot point, the lower sections standing ok, and
only the one bent section destroyed. All yagi sustained total loss of front
half of each, with the ten getting more bending. Rotor and mast were ok. The
break point showed about 30 degrees of twisting. Seventy feet away is a 70ft US
Tower crank up free standing with a two el 40m quad and inside elements for 30
17 12, made by Cubex, T2X rotor. This tower was cranked to full height and
sustained no damage. My conclusion is that the Trylon was very loaded and that
its weakness was to twisting forces, which it hinted at earlier and showed
conclusively upon it folding over. Because it failed, I also concluded that "it
was high enough." Replaced it all this week with new tower and rebuilt yagis.
73,
Charles Harpole
k4vud@hotmail.com PS... if you have never dis assembled a T2X rotor, be
POSITIVE to read hams reports of how to do that prior to opening the bell.
Those in the know are now smiling.
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