[TowerTalk] Tri-Ex HS 588

[Dan Hearn]

Chuck you were very wise to ask your questions before starting down a path
with certain failure at the end. I am not familiar with the particular tower
you have but I am reasonably sure it is similar to other crankups used by
hams. Without applying numbers to your proposed design I can tell you that
you are not exceeding the strength of the parts you propose by a little but
by a lot.
1. Guying a crank up tower to try and increase its wind load capability adds
vertical force when the wind blows.
2. The tower sections are supported by the lift cables and the load on them
increases by this action,
3. You propose a vertical load of 250 pounds which will add further to the
vertical load on the tower and cables.
4. Schedule 40 pipe is made of steel which is rather soft and has a strength
rating of less than half that of the masts normally used by hams.
5. Mounting the blade assembly higher than the top of the tower adds
additional horizontal force to the tower and reduces its wind load rating a
lot.
6. The blade assembly will put an even greater horizontal force on the mast
and tower.

My advice is sell the tower and get a much stronger one designed to be
guyed. This is severe service compared to what most ham installations see.

73, Dan, N5AR

-----Original Message-----
From: towertalk-bounces at contesting.com
[mailto:towertalk-bounces at contesting.com]On Behalf Of charles mcneil
Sent: Tuesday, January 30, 2007 5:21 AM
To: towertalk at contesting.com
Subject: [TowerTalk] Tri-Ex HS 588


    I am building a wind generator and have bought a Tri-Ex HS 588 tower
from a neighbor. This was evidently a three section 58' crank-up tower but
the top section was missing.
    I want to weld in some support plates in the top and install a 12' piece
of schedule 40 pipe to set my generator on. the generator will weigh about
250 lbs with blades.
    The local building inspector tells me I will have to have an engineering
report saying the tower can be used for the purpose. I plan to guy the tower
at 20' and again at about 40' but have no idea how guying a self supporting
tower affects it's wind load capacity.
    Does anyone have any specs on this tower? Anyone have any suggestions on
how to deal with this problem? I have looked into new towers but quickly
found out that I would have more money in the tower than I could ever get
out of Renewable Energy.
    Thanks for your thoughts and time, CHUCK
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