Looking for Mr. KM9P
K7LXC at aol.com
K7LXC at aol.com
Mon Feb 12 13:08:40 EST 1996
Hello, Bill --
I know you're out there but I don't know your address. Please e-mail me
if you would be so kind as I have a couple of questions for you. Tnx.
73, Steve K7LXC
>From Bill Fisher KM9P <km9p at akorn.net> Mon Feb 12 18:32:24 1996
From: Bill Fisher KM9P <km9p at akorn.net> (Bill Fisher KM9P)
Date: Mon, 12 Feb 1996 13:32:24 -0500 (EST)
Subject: 3830 Reflector
Message-ID: <Pine.BSD/.3.91.960212133024.11644C-100000 at paris.akorn.net>
On Mon, 12 Feb 1996 K7LXC at aol.com wrote:
> >I've misplaced the address of the 3830 reflector. Please send me an
> >E-mail directly with that information.
> I also am interested in the information. In addition, the callsign of the
> chap that runs it. Please someone let me know. Tnx.
Post your scores to 3830 at akorn.net. You do not have to be subscribed to
post your score.
If you want to see scores in your mail box, then subscribe to
3830-request at akorn.net. The word 'subscribe' only in the text of the
You can also review scores via the WWW at
>From Big Don <bigdon at eskimo.com> Mon Feb 12 18:47:28 1996
From: Big Don <bigdon at eskimo.com> (Big Don)
Date: Mon, 12 Feb 1996 10:47:28 -0800 (PST)
Subject: Tower Load Distribution
Message-ID: <Pine.SUN.3.91.960212103404.21567B-100000 at eskimo.com>
On Mon, 12 Feb 1996, Barry Kutner wrote:
> Big Don <bigdon at eskimo.com> writes:
> > A classic case of this is the first Tacoma Narrows bridge which was most
> > certainly designed to withstand a bumper-to-bumper traffic jam of
> > fully-loaded 18-wheelers in both directions in combination with *static
> > loads* from some peak windstorm. Yet it failed when lightly loaded in a
> > rather moderate garden-variety windstorm. For those who have never seen
> > the video of what came to be known as "Galloping Gertie," the wind set up
> > a swaying/twisting action in the main span that increased in amplitude
> > until the whole works deposited itself in Puget Sound.
> As I recall from engineering classes in college, the problem with the
> bridge was it became a resonant structure, and therefore required very
> little energy to get it swinging back and forth. It had to do with the
> type of suspension and supports used. [...]
That's exactly the point. Go watch, for example, a long boom flopping
with the gusts, or the tower twisting and untwisting when hammered by the
rotor slop stops being hit. Whatever the tower/antenna system's natural
frequencies in torsion and bending are, they will be excited by this action.
And that is what these proposed computer programs cannot begin to deal with
adequately. For example, some natural resonances will depend on the guy
tension which is a spring of sorts. This is a big unknown and rarely
stays constant. How often does anyone check that with a calibrated
measuring device, assuming they ever did during the initial
installation of the tower.
Steady-state wind load analyses don't address any of this.
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