Hi John, Twin contra-rotating coaxial rotors do not need teetering for stability. Stability is acheived through contra-rotation. Build twin rotors with preset coning angles, use reasonable vertical fin and rudder, and it should turn easily with rudder-only steering. Keep the rotors light for EZ spinup and to prevent unwanted forces building up in the sys tem. Be sure that thrust line goes through or near vertical CG. Look on You Tube under Contratwirl for a video of a twin 4-bladed coaxial rotor autogyro. Flys great on 3-channel (rudder, elevator, throttle). Hope this info helps. Charlie