[TowerTalk] Rohn RSL tower - slightly off topic

[terry burge]

Guys, I really got to wonder about this. It seems to me IF your antenna load on the tower is a concern, why not just add some guy wires. A guyed tower can handle the wind forces so much better and you can sleep well at night knowing that. I personally have wondered about the integrity of free standing towers over time. Sure, they may look nicer (maybe) and have a smaller footprint outside the concrete base, but knowing how us hams always want bigger and better antennas, why not just guy a tower to make sure it will stand up to the wind forces. Maybe won't handle a tornado but then what tower would?

Just my $.02 worth.

Terry
KI7M

> On June 6, 2019 at 1:30 PM Steve Maki <lists at oakcom.org> wrote:
> 
> 
> Seems like if the wind is in-line with the booms, there will be a small 
> amount of torque even if the antennas are perfectly wind balanced (if 
> they share the same side of the mast).
> 
> And that small torque will be somewhat canceled if they are on opposite 
> sides of the mast.
> 
> -Steve K8LX
> 
> On 6/6/2019 4:11 PM, George Dubovsky wrote:
> 
> > I'm with you, Chuck. The torque is additive regardless of which side of the
> > mast the antenna(s) are on.
> 
> > On Thu, Jun 6, 2019 at 1:32 PM Chuck Dietz <w5prchuck at gmail.com> wrote:
> > 
> >> Maybe I’m dense, but I don’t see how this does anything (much). If the
> >> back of both antennas has a larger wind area than the front, the torque on
> >> the mast is going to twist the mast in the same direction no matter to
> >> which side it is attached.
> 
> >> From: k7lxc--- via TowerTalk
> >> Sent: Thursday, June 6, 2019 11:38 AM
> >> To: towertalk at contesting.com; bjtatum1 at att.net
> >> Subject: Re: [TowerTalk] Rohn RSL tower - slightly off topic
> >>
> >>
> >>>   Hello-? ? I was at a friend's QTH recently viewing his new Rohn
> >> RSL100L10, a 100' self supporter put together with 10' sections R-10H
> >> through R-1. It is rated for 25 ft/2 wind load at 90 MPH, dropping back to
> >> 11 ft2 at 100 MPH. We were discussing his planned installation of a KT-36
> >> and M2 3 ele 40 meter yagi. He wishes to have the KT-36 about 15' above the
> >> tower top plate with the 40 meter yagi approx. 1' or 2' above tower top.
> >> Both antennas are fairly close in weight (approx. 95#), boom length (36')
> >> and wind load (10 ft2). ? I wanted to get opinions of folks experienced
> >> with large antennas and self supporting towers if this planned installation
> >> is OK for this tower.
> >> Hiya, Byron --
> >>      The proposed configuration sounds good to me but I'm not offering an
> >> answer to your question. What I am offering is a tower technique that I
> >> highly recommend.
> >>
> >>      Install the antennas on opposite sides of the mast. That way many of
> >> the wind vectors cancel each other out. This was determined by Dick Weber,
> >> K5IU, a PE and the article appeared in QEX years ago. Anything you can do
> >> to reduce the wind induced torque on a mast is a good thing. Did I mention
> >> this is highly recommended?
> >> Cheers.Steve    K7LXCTOWER TECH
> >>
> 
> 
> _______________________________________________
> 
> 
> 
> _______________________________________________
> TowerTalk mailing list
> TowerTalk at contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk