Hello Rob

Sounds like the guys here don't go much on co-axial design.

Mine flew superbly and was the most stable and easy to fly gyro I have ever built. Maybe I was just lucky ??

Anyway, here are the images of it. Both upper and lower rotors are of the same dimensions with just the fixed dihedral/cone angle being different. It was actually an experiment with an old fuselage I had and it worked well except it needed more hang angle really. Blades were of flat bottom section set at about -1 degree measured on the flat underside. I double checked and the dihedral angles were 7 degrees each side for the lower rotor and 14 each side for the upper. Even though it was easy to fly and very stable I still managed to destroy it one fine day when I made a stupid mistake........I won't bore you with the details except to say it was 100% pilot error/stupidity.

Currently I am building a small co-axial of similar design for a .09 engine.

Have fun

Sean