I've read and since reading have always set CG on my models from 25% to 30% of the root cord, and had success with that. I have just finished rebuilding my Cub (great planes kit # CUB4P03) and after setting up everything I wanted to double check my CG. the wing has an 11 inch cord, so in my calculations the CG should be at 2.75 inches from the LE. I looked in the manual, and it says 4 inches from the LE. that is about 36% of the cord. in my experience that would be extremely tail heavy and possibly not flyable. is there something about a cub that the 25% rule doesn't apply? is the book wrong or what?

I'm going to be taking this plane out tomorrow, I've gone though all the advice in setup I've picked up on in here and would really like to bring it home in the same condition it left in. I thought the CG would be a no brainer but thats what I get for thinking again

sportrider,
You're right about 25% to 30%. The 30% or 33% would be better, if you haven't been flying very long. True center of gravity is perfect at 37% of the wing chord. The full size Ceesna 206 the center of gravity is 12%, but don't get too slow. I would set the c of g at 30% fly it. Make sure you have plenty of elevator authority. I have a 1/4 scale Sig clipped wing Cub and have my c of g set at 37% and it flyies beautifully.
Good luck,
Darrolair

Set it 7.5 inches back from le, and you will be golden. I think.

The 25 - 30% "rule" is very safe for almost any design, but many designs fly fine with the CG further back; 25 - 30% is very conservative and not necessarily good. It depends on the length of the tail moment, the proportion of stab to wing area, and wing chord. There is a well-known formula that I and others have given in other threads. If 37% works for a 1/4 scale Cub it will work for a Cub in any other scale. I do not find that forward CGs are easier to fly. As long as a plane is not unstable in pitch, having the CG farther back has a lot of advantages. It's a good thing to experiment with and see what you like.

Jim

He is a buddy of mine, And i am pulling his chain.

let me guess??? and then run a pusher prop too right?

I have it set at 3.75 inches which calcs out to 34%. I guess I'll try it there and make adjustments if it survives the second flight curse.

No put a motor on the the elevator faced up to hold the tail down.