[TowerTalk] Question on R-TA-45 Torque Bracket
Bob Shohet, KQ2M
kq2m at kq2m.com
Mon Jun 17 13:37:10 EDT 2019
All yagis should definitely be torque balanced, preferably right at the clamp where it bolts to the mast. Having said that, a significant issue is that local topography and wx cndx can combine to insure that all booms can be broadside to the wind. Aside from tornadic events in which the winds clearly swirl, there are lots of other wx phenomena where swirling winds can be experienced and are not expected.
In the Macroburst wind event in Newtown, CT last year on May 15, with 110 mph gusts, there were violently swirling winds which appeared to be tornadic in nature, responsible for literally tearing off massive limbs on hundreds of trees with piles of branches at the bases of trees at sharp angles to the direction of the winds. There was no rotation of the clouds but there was some rotation of the winds, which was likely due to the direction of the storm movement as impacted by local hills, valleys and other terrain effects . You can have a tower properly guyed and it may not matter if the swirl is strong enough and rapid enough and it can be a major problem on some hilltops or in some valleys.
All of this increases the likelihood of failure even if the actual wind speeds are within spec., and points out how important it is to anticipate and plan for potential failure points beyond the levels that are considered “normal” for your area.
From: Jim Thomson
Sent: Monday, June 17, 2019 1:14 PM
To: towertalk at contesting.com
Subject: [TowerTalk] Question on R-TA-45 Torque Bracket
Date: Sun, 16 Jun 2019 19:22:26 -0000
From: <john at kk9a.com>
To: <towertalk at contesting.com>
Subject: Re: [TowerTalk] Question on R-TA-45 Torque Bracket
<That is my concern too with rotating towers however there are many out
## with a plane jane tubular mast, you just alternate sides of the mast, for each yagi.
## EACH yagi needs to be TORQUE BALANCED ! Thats most of folks issues right there.
Its dead simple to tq balance any yagi.
## Problem with the rotating tower concept is..... the tower is 3 sided.... so ALL the yagis,
end up on the same tower face. The issue starts when all booms pointed into the wind.
You still end up with a tq imbalance.
## with all booms broadside to the wind, the yagis are then again tq balanced.... which is... the fix.
## Think of a rotating tower as a 100 to 200 ft long drive shaft.
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