Thread: Build Log twin edf- micro DC9 project
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Old Dec 25, 2012, 08:47 AM
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Paris (France)
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Calculating the optimal balance point

Ok, i have made the wing attachement system. It woks ok, but the dihedral is a little bit too much. We'll see later.
It adds 1,5g but it makes the plane easier to transport.

I've calculated with a program, that the COG is 8 cm after the leading edge of the wing.

In fact, the optimal balance point is backward because of the stabilisator's area and the great lever.

René Jossien proposed a formula that takes in account these parameters + the kind of airfoil, etc...

Read this instructive article:

http://jmquetin.free.fr/1indoor/tips8e.htm

With Rene Jossien's formula, i find a balance point at around 9,1 cm behind the Leading edge.

This result sems to be confirmed by the glide tests.

This would mean that i don't really need to put the AR6400 so much frontward to balance the plane.

I can probably shorten the piece of depron which supports the brick, and still balance the plane with two190 mA.h batteries (10g) installed a little frontward.

More to come...
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Last edited by indoor_fr; Aug 04, 2015 at 08:06 AM.
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