[TowerTalk] Trylon self supporting tower 80 ft fall report

[Jim Thomson]

Date: Thu, 31 Jan 2013 09:07:17 -0600 (CST)
From: Gene Smar <ersmar at verizon.net>
To: k4vud at hotmail.com, towertalk at 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 at 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 at 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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