On 6/16/2017 11:34 PM, Kurt Andress wrote:
Hi Jim,
Thank you for you contributions to the discussion!
How you may decide to solve some problems is not necessarily how I
would chose to solve them....but that is probably not critically
important.
We are pre-assembling three 16 element tribanders and two full size
40's for a very large new rotating tower system for a client, with
several other antennas on it. I have determined what needs to be done
to the antennas to maintain wind torque & gravitational balance on all
the antennas, as they can actually be installed on the tower system,
and we have made the counterweights and compensators to do that. No
antenna builder out there is capable of doing that!
We just do it for our clients, when they decide they want things done
right....
Be mindful that even when antennas are properly torque balanced the
best they can be.....there are certain sites that produce unbalanced
wind loads on them due to the near field terrain!!!!
Rating rotators for the incorrect or correct antenna areas is totally
useless! Rotators only care about the torque developed by the antenna
system they need to control!
Jim, when you have developed the software to perform non-linear
analyses of antenna members continually inclined to different attack
angles in the increasing wind speeds, please let us know! Most of my
pro colleagues would like to have that capability, there is no
non-linear platform that can do it today....
I know how I approach that, it takes many tons of time to even
approximate it, but it can be done if one is dedicated enough to spend
the time to approximate it! If you have finite element software and
are a capable practitioner with it, you can do this, it just takes
more time than following 222-G standards......
On reflectors there are always people that say things, then there are
people that appear to know things, then there are people that actually
do the things they know......
Nothing I have ever designed from scratch has ever failed, I've had
plenty of failures trying to make things delivered/built by others
survive!
The linear analyses of EIA/TIA 222G do a pretty good job according to
the hordes of professional engineers that developed it, for us to use
as a guide to do what we do! I'm sure you have never ever even seen
it! But, you might learn something if you did........but, since this
is certified to be Amateur Experimental Radio, we all have free
license to just be Amateurs and experiment with what we think we know ;-)
How the individual parts of antennas are designed and built is up to
the designer that is responsible for that, nothing I have designed
from scratch for any clients have ever failed, because I have fully
vetted them for the loads the were expected to encounter, for the
EIA-222-G rating I certified them for. I have no knowledge of what
others have done....
There is one simple principle, that my first year engineering
professor drilled into our minds.....things only fail when they are
inadequate, there is always a reason for that, Our job is to
understand it and figure out how to not let that happen! What it takes
to do that is a bit more complicated.......
73, Kurt, K7NV
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