[Top] [All Lists]

Re: [TowerTalk] kt34xa torque balancing

To: "TowerTalk" <>
Subject: Re: [TowerTalk] kt34xa torque balancing
From: W0UN -- John Brosnahan <>
Date: Sat, 08 Jan 2005 18:10:23 -0600
List-post: <>
Unfortunately, Jim, you are making the same mistake that amateur antenna
manufacturers and Dr. Dave Leeson (who is ALMOST perfect) made!

See below-->

>A computer program will not estimate drag from the complex
>shape of the kt34 traps any better than a seat-of-the-pants
>Without a doubt, the program which W0UN suggests will do much
>of what one needs, and more....but I doubt it will estimate the
>effective windload of sequential tubes, like the kt34 traps.
>Turbulence is complex to model.
>And so, I rest my case..

You need to read my original posting on this topic from late Friday night.
I'll send it again to you privately -- so as not to waste more reflector BW.
And it would be very useful if you locate the original pubs by Dick Weber
that are cited in my first note.

The elements make no difference as long as they are symmetrical.
Any wind force on an element half on one side of the boom, complex
traps and all, is balanced by an equal and opposite force of the element
half on the other side of the boom.  The cross flow principle is what is
used and it is the correct answer.

The only important part is the boom and the boom hardware asymmetries--
at least to first order.  (There is a bit of shadowing of the downwind
element half due to boom turbulence but it is very minor and has a very
short moment arm.)

It is a lot easier to explain with a drawing, but I will not bother.  The
original references are more complete than I could ever be.  Once you
get a "handle" on the concept it seems obvious, until then, the old way
seems to make sense--but is wrong.

73--John W0UN


See: for "Self Supporting Towers", "Wireless Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions and ask for Sherman, W2FLA.

TowerTalk mailing list

<Prev in Thread] Current Thread [Next in Thread>