Dear Owen:
As you, and others, have concluded from my descriptions, I too have mass
and force in separate bins.
I continue to be amazed at the facility with which MEs use "pounds" to
indicate just what they want it to indicate. Every time that I do a
mechanical design (or check a mechanical design), I convert to SI units with
a careful check accompanying the conversion of whether I have converted
forces or masses. Once in SI, everything is easy.

I have had discussions with some of my fellow P.E.s of the ME persuasion
about this: they contend that they always know when force and mass is
involved. I remain unconvinced.

A mass centered system (SI) is more straight forward than a force
centered system where an assumed gravitational field is used.

Here in the North, ice plus a moderate amount of wind is most often what
kills antennas having cantilevered elements.

Thanks for your comments.

73 Mac N8TT
--
J. Mc Laughlin; Michigan U.S.A.
Home:
"Owen Duffy" wrote in message
...
On Sun, 18 Jun 2006 00:31:54 -0400, "J. Mc Laughlin"
wrote:


I do not recognize the "30 Lb of ICE" specification. Most often, ice
loading is specified in terms of size such as 12 mm of ice all of the way
around each element (12 mm of radial ice).

Given the looseness of use of the unit lb to specify mass and
(incorrectly) force, it is a bit ambiguous... but he probably means
mass. 30lbf of windage from ice loading isn't much on an antenna of
that type!

(We sin in the metric system as well! If someone asks me what I weigh
(being a force) I will answer in Kg (being a mass) instead of N
(force).)

Having said that, the impact of ice on the wind forces is probably
much more significant than the gravitational force due to the mass of
the ice.

Mac, I agree, radial ice loading is a more relevant specification.

Owen
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