[TowerTalk] FW: Tri-Ex W-51

[maflukey at gmail.com]

Hi Don,

I have a fabrication shop drawing for a Triex W-51 dated January 1967.  I
don't have the installation manual.  The shop drawing shows the two upper
section legs are 1" x .065" tubing with 5/16" tie rods.   The bottom section
is 1.25" x .093" tubing with 1" x .065" reinforcement tubing inserts in the
lower 10' and 3/8" tie rods.   The tube steel specification was ASTM A245
(now obsolete) and did not specify grade.   The spec on the tie rods was SAE
1020 with 50 ksi yield strength.   

I have performed a finite element structural analysis of a W-51 which
indicated the weakest point on the tower under load is in the bottom portion
of the middle section - just above the overlap region.   I have photos of a
W-51 folded over from wind overload at this exact location.

The WT-51 upgrades the middle section legs to 1.25" x ?? tubing and upgrades
the lower section tie rods to 7/16".    My guess is that the middle section
upgrade may have been to address the weakness in that section mentioned
above, and the lower section tie rod upgrade may have negated the need for
the inserted stiffener in the lower section allowing more economical
fabrication.

In any event, my W51 has held up for 55 years and formerly supported ~13 sf
of antenna load.   The tower is still in use today.   It have been re-cabled
once and the winch rebuilt once.  I can't recall if I replaced the pulley
bearings or just reconditioned them.   On the last install I fabricated an
adjustable fold over mounting plate which was I found to be a worthwhile
improvement.

Hope this helps and good luck.

73
Matt
KM5VI




-----Original Message-----
From: TowerTalk <towertalk-bounces at contesting.com> On Behalf Of Don Tucker
Sent: Saturday, July 30, 2022 1:10 PM
To: Towertalk <towertalk at contesting.com>
Subject: [TowerTalk] Tri-Ex W-51

Does anyone know what the difference is between the W-51 tower of old and
the later nomenclated WT-51 - or - is it just that, a renomenclated tower
with no physical changes?

I have a W-51 (on saw-horses) I was given a few decades back I'm looking at
possibly using as a second tower, but the owner had no documentation (except
for the mounting base and hole details).

All of the manuals I find on-line are WT-51.

Don W7WLL
_______________________________________________



_______________________________________________
TowerTalk mailing list
TowerTalk at contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk