I have a scratch built 35% Edge 540. It is modelled after the Aeroworks Edge. I have been experimenting with CG placement and have recently moved the CG back so that it is on the leading edge of the pipe for the wings. Since I have done this I have flown it and trimmed it but once trimmed, when I roll it to the inverted position it begins to climb at a 30 to 45% angle.

No one in my club can explain this at all. Could someone please tell me why this is happening?

Thank you in advance,

Regards,

Robert

It's tail heavy. With tail heavy, you trim in down elevator to keep the tail up and the nose down. Roll inverted and the down trim now becomes up trim, plus being tail heavy!

Thanks for the answer iflyj3. Makes sense of course but why when the cg is on the wingtube? One would think that this effect would be experienced at some point behind the wingtube not when the plane is balanced on the front edge of it.

Regards,

Robert

The MAC is quite far forward on that wing design
It is easy to assume it is further aft
On all I have seen (models) - the best cg is forward the tube.
My assumption from what you say is way tailheavy for precision flying
We use this same test on our planes (No EDGES) to see how flyable the cg is placd.
climb inverted at 45 degrees and ad ruddder a bit lefr or right - i it climbs - we shift cg forward somwhat.
Frankly the cg for
3D" can be anywhere from 30%-back and as long as you can still manage it
3d is mostly vectored flying so the task is NOT the same.

Do you have any down thrust? If so, that will cause changes in trim when rolling from upright to inverted flight.