I never got mine to fly with flat bottoms. I'm running plastic symmetricals. They're a little hard on the spindle and main rotor shaft though if you impact anything and if you land too hard...you're replacing the tail boom. I've done carbon fiber symme's. They are nice but expensive. The plastic blades are difficult to balance out also. I'm still flying the same plastic blades after several strikes but I got a new set on order...these are spent but they still fly.