Just look at the physics of it. Whipping of the elements represents
stored energy, just as in a spring. If that energy is released at the
end of travel it adds to the momentum of the elements that would
otherwise be due only to their mass. I'm not saying that aluminum
elements don't whip, but any antenna with lots of whip is going to put
more stress on a rotator than an antenna with less whip ... assuming the
masses are equivalent.
By the way, given the material properties of fiberglass versus aluminum,
and without knowing the exact figures, I wouldn't be surprised to learn
that fiberglass elements also have more mass than comparable aluminum
elements.
73,
Dave AB7E
On 6/27/2013 9:38 AM, Steve Dyer wrote:
Any large beam, fiberglass tube or aluminum is going to potentially whip in
wind. I've never seen any compelling evidence a SteppIR causes any more forces
at the rotator than an *equivalently* sized Al beam.
73,
Steve
________________________________
From: Joe Nuccio <k4nyy@yahoo.com>
To: Chris Pinholster <k4win@mac.com>
Cc: "towertalk@contesting.com" <towertalk@contesting.com>
Sent: Thursday, June 27, 2013 5:29 AM
Subject: Re: [TowerTalk] What rotor should I use
Hi Chris,
Thanks for the input and your experience.
The concern seems to that the 36' elements on the SeppIR start 'whipping' back
and
forth while the antenna is being rotated which puts a lot of stress on the
gears when it
comes to a stop. Apparently, this 'whipping' action is not of a concern on
large beams
made out of aluminum.
73, Joe K4NYY
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