The Bell Hiller mixer mod

The Bell-Hiller mixer mod is quite simple and best of all it is free! It increases your available pitch window to +/- 12 degrees and increases direct swashplate input, increasing roll rate and pitch rate. It can be accomplished as follows:

1. Remove Bell-Hiller mixer arm, and disconnect attached control rod.
2. Drill a new hole for it 3 mm from the tip of the grip. Tap it for a 2mm screw if necessary.
3. Replace mixer arm, but turn it as shown in the picture. Be sure it looks exactly like it does in the photo! Keep tightening the screw ¼ turn until you can feel the friction in the arm, and then loosen it back out a ¼ turn.
4. Replace connecting rods. The long end of the arm now connects to the flybar, and the short end connects to the swashplate.

This mod increases the amount of direct input from the swashplate at the expense of some stability input from the flybar. It does this by switching the ratio, which is equal to the ratio of the distances from the pivot point to the ball joints. With a high RPM and heavy blades, this produces a stable and maneuverable helicopter with almost no pitch up tendency in forward flight, a must for smooth and aggressive aerobatics.