[TowerTalk] Opposing boom to mast plates?

[Chuck Dietz]

Ok, I was thinking of broadside to the booms. That’s the ten meter thinking
coming out in me. Small element wind areas.

Thanks for the clarification.

Chuck W5PR

On Mon, Sep 18, 2023 at 1:33 PM Steve Maki <lists at oakcom.org> wrote:

> That's what I used to think, but when shown how the vectors all cancel
> out when the elements AND boom are mounted at their exact centers, I
> became convinced otherwise. Of course boom to mast clamps are often not
> at the boom center, so that throws things off a bit.
>
> -Steve K8LX
>
> On 09/18/23 1:28 PM, Gene Smar via TowerTalk wrote:
> > The balancing to which I referred (and which I should have defined) is
> wind coming onto the Yagis broadside to the radiating elements, not
> broadside to the boom.
> > 73 de Gene Smar AD3F
> >
> > Sent from my Radio Shack TRS-80 model 100 laptop
> >
> >    On Mon, Sep 18, 2023 at 1:21 PM, Chuck Dietz<w5prchuck at gmail.com>
> wrote:   I don’t understand the physics of how that works. If I imagine
> that I am
> > looking straight down from over the mast and I have a Yagi that has more
> > wind area in the front than the back, then it will exert a twisting force
> > on the mast trying to turn the mast to the left no matter which side of
> the
> > mast it is clamped to.
> >
> > Chuck W5PR
> >
> > On Mon, Sep 18, 2023 at 12:14 PM Gene Smar<ersmar at verizon.net>  wrote:
> >
> >> I believe the problem that's looking for a solution here is balancing
> the
> >> twisting torque imparted on the rotator, not bending moment exerted on
> the
> >> mast. Mounting hf Yagis on opposite or alternating sides of the mast
> will
> >> reduce the twisting torque versus having them on the same side.
> >>
> >> 73 de
> >> Gene Smar AD3F
> >>
> >>
> >> Sent from my Radio Shack TRS-80 model 100 laptop
> >>
> >> On Sun, Sep 17, 2023 at 8:33 PM, Stan Stockton
> >> <wa5rtg at gmail.com>  wrote:
> >> Seems to me if you really believe mounting antennas on opposite sides of
> >> the mast is going to make a difference in whether the mast bends you
> >> already have a problem regardless of how you mount the antennas. I would
> >> think mounting the top antenna just a few inches lower would make more
> >> difference.
> >>
> >> 73…Stan, K5GO
> >>
> >>> On Sep 17, 2023, at 7:22 PM, Chuck Dietz<w5prchuck at gmail.com>  wrote:
> >>>
> >>> Well my masts are very heavy. Weight of the antennas is not a real
> >> factor.
> >>> And saying someone is not an engineer doesn’t help either.
> >>> I believe It is a fact that the wind forces on Yagi antennas pointing
> in
> >>> the same direction are transmitted to the mast in the exact same manner
> >>> regardless of which side of the mast they are clamped to. It is a
> fallacy
> >>> to think that they would exert force in the opposite directions and
> >> cancel.
> >>> Chuck W5PR
> >>>
> >>> On Sun, Sep 17, 2023 at 4:03 PM<k7lxc at aol.com>  wrote:
> >>>
> >>>>> They were minimizing eccentric loads off the vertical centerline by
> >>>> putting one on either side. It won't do anything for reducing turning
> >>>> torque or wind loading, of course.
> >>>>
> >>>>      Looks like you're not a Professional Engineer.
> >>>>
> >>>> Cheers,
> >>>> Steve      K7LXC
> >>>> TOWER TECH
> >>>>
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