I HAVE A OLD DIRTY BIRDY WING THAT I WAS GOING TO USE ON A SCRATCH BUILT FUESLAGE. AFTER LOOKING AT THE PLANS I NOTICED THE CG IS BACK QUITE AWAYS. DOES ANYONE KNOW THE REASON FOR THIS???

I would think that the Dirty Birdy would fly better with the CG back about 32-40%. Better rolls without excessive corrections required. We used to run our Cursor and Boxer series planes at 40-45% without any ill effects.

Peace

Mark O

Because of the swept back LE the CG at the fuselage side view seems farther back than it actually is at the MAC; it appears to be almost 50% back. However, if you measure it at the MAC it is just under 40% back. (this is based on the RCM plans)

David

rainedave nailed it. It's the sweep of the leading edge. That CG is correct and it flys beautifully there. I had to move all my radio gear into the back and put the servos under the stabilizer. Then had to move the firewall back an inch. I was using a Tower .75.