Looking For W&B Using Arm Instead of Moment

Recent readings revealed folks referencing balance by arm instead of
moment - something I'm not used to doing or reading. It raised the question
in my mind whether there are charts that use weight/arm instead of
weight/moment.


Yes, such charts exist.

I take it you are referring to the "envelope" into which you n eed to fit.
I've seen it with weight plotted against CG (arm), which I prefer as it makes
the envelope fit better on the page, and I've seen it with weight plotted
against moment, (which makes a skinny sloping envelope) There are other ways
to represent the envelope too, but in all cases you need some term involving
weight plotted against some term involving arm. The "arm" term could be arm
(CG) itself, or moment, which is just armxweight. Whichever is used, I'll call
it "balance".

To get the final point, you still need to figure out the contribution to total
weight and total balance due to each factor (pilot, passenger, fuel, etc).
This is a simple multiplication, but a multplication can be represnted on
another graph by a sloping line. This is just the old algebra y=mx+b rearing
its friendly head again. The charts are designed to be compatible, so there's
a minimum of arithmetic involved.

It is actually possible to plot the contributions from each station as
gridlines on the same graph as the envelope, but the lines are curved if you
use arm for balance, and they are hard to distinguish from each other if you
use moment for balance. I did actually set a few up that way; it allows one to
figure out the weight and balance with no math whatsoever. But before I
finished the program to do that, I found CoPilot for the Palm, and that was
that.

Jose



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