On 7/10/2022 11:15 PM, Craig Williams wrote:
Thanks, that seems more reasonable. So the center of the tank is used for the
arm I would assume. After all it's essentially a rectangle. I did find a pic
on Marks website (http://www.flykr2s.com/wing.html) so measuring between the
spar faces also should give me the number I need. So far my rough numbers are
putting me at the aft edge of the envelope. So I am looking for any problems
with the ARM's I am using.
Craig
N886MJ (N51CW)
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
You can't use the numbers from anyone else with any certainty. The
method Chris posted is the only sure way to know what is right for your
airplane. For example, my wing tanks are long and narrow, only 10
inches behind the froward spar to eliminate CG problems so they won't be
correct for your airplane.
With the airplane level, tanks empty, determine the CG location. Add
fuel to both tanks, I'd suggest 3 to 5 gallon minimum, Do weight and
Balance again. Divide the difference in the "moment" number by the
difference in the "weight" and that is the "arm" for the fuel. That's
the only way to get correct numbers for your aircraft for any item on
the list, pilot, fuel, baggage, etc. You can then add the weight for
full fuel X the arm to determine the CG location for full fuel. Once
the "arm" of an item is determined everything else can be done with
pencil and paper.
Larry Flesner
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