Portions from a personal email from Tom, n4kg,
(small portions of prior posts removed to save bandwidth)
On Mon, 28 May 2001 19:39:15 -0400 Frank Norton <franknorton@home.com>
writes:
> Hello everyone,
>
> I have followed with great interest the discussion about using a Yaesu
> G1000. I am unclear as to the use of foot-pounds in
> expressing the K factor Yaesu has calculated for safe use of it's
> rotors. It is confusing for those who cannot convert easily, and each
> added step adds a factor of uncertainty.
>
> According to the Yaesu rotor manual "K" is calculated by the
multiplication of the
> turning radius of the antenna (in meters) by the weight of the antenna (in
> Kg), and the weight of the mast (in Kg)
>In addition to this calculation one must ensure the square meters of wind
> surface area do not exceed 2.2 m2. My brother, who is a mechanicalengineer
>ran several calculations on the G1000 and believes it easily capable........
NOTE: 1st para refers to post about 6-8 wks ago but is self explanatory
in the discussion that follows.
I messed up that post about my confusion about calculating "K" tremendously
by not putting in the source of my confusion--> The Yaesu web site, and the
Texas Tower web site both leave out the mast in the calculation of the "K"
factor , made sense to me. So I purchased my G1000DXA and waited for the
UPS truck to bring my shiny new rotator, which I purchased with this new
"scientific system" to assure my "safety freak" side all factors are
covered. But when I open the box and read the manual there it is--> A half
page explanation (with diagrams) that suddenly includes the weight of the
mast in calculating the "K" factor. I didn't understand why--so I started
making phone calls. I called Texas Towers and they didn't know for sure
which was correct, next I tried Vertex and had no luck getting anyone but
marketing who him-hawed around really not knowing what to do.
My brother is a C.P.E. but not a ham, he felt that in engineering a
structure he would not consider the mast, but since he did not have access
to the engineering information on the rotor he could not say whether the
vertical loading should be included in the "K" factor or not. Yaesu's own
literature contradicted itself. I still have not received a reply to my
letter from Vertex/Yaesu.
I would like to feel completely comfortable with my decision to leave the
mast out of the calculation, but if something happens and the rotator
clamshell fails, and the antennas fall damaging part of my home......what
will the insurance company determine? God forbid what if someone were hurt,
or killed! The safety freak inside me has not been sleeping well waiting
for an answer from Vertex/Yaesu (now 6 weeks overdue).
Thanks for your email at least I know there is someone else who feels that
the concentric force of the mast is insignificant compared to the eccentric
torque of the antennae when calculating "K".
At 10:31 AM 7/10/2001 -0600, N4KGwrote:
Hi Frank,
I have never understood why weight of the mast is a factor since
it has such a small radius. Also, the K factor is not a "real"
moment but a ficticous number that "sort of" indicates rotor
capability. The actual moments depend on WHERE the weight
is distributed. Empirical evidence is still the best criteria for
rotor selection, unfortunately.
Tom N4KG
73 de Frank, kb8xu
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