Question about C.G.

[Wingin' Wayne]

I've read plenty of threads about finding the correct C.G. location. Thanks to this forum I know for a fully symetrical wing, 30% of the M.A.C. is a good starting point. Could someone please tell me is that with or without ailerons? I tried the search feature, but there was just too much to wade thru. Thanks a lot.

[slipstick]

The chord always incudes the ailerons.

Steve

[fhhuber506771]

If you fail to include the ailerons in the MAC... you simply end up with a forward CG, which is flyable, even if with somewhat less than desireable performance.

And its not really a question of if the wing has a symetrical airfoil or not... The flat bottom airfoil trainer designs usually do well at 30% MAC. The 30% starting CG is for a "conventional" configuration where the main wing is much larger than the horizontal tailplane (and a horizontal or V tail exists) and the separation between the main wing and the tailplane is at least 1 chord of the main wing.
(A fancy way of saying it looks a lot like a Trainer, 747 or Extra 300 in overhead or "plan" view)

[Ollie]

There is no "correct" CG position. CG position depends on lots of data and lots of understanding. It depends on what you wanted for stability. It depends on mass distribution. It depends on lift distribution. It depends on your flying skills. It depends the purpose of the plane. Etc.

Your funny planform is complex! You can't get concrete advise so, just try your funny ideas.

[Sparky Paul]

For the really "funny" shapes, a balsa toss-glider can give you an idea as to where the c.g. should be... or even if the thing is practical at all.
You can derive information about the lateral and directional axes also this way.