12.2. Balancing the main rotor blades using the KSJ-528 blade balancer

Balancing the blades will minimize vibration which will make hovering easier, and it will give the heli more power because less energy is wasted shaking the heli. Also the heading hold gyros will work much better with less vibration because they gradually accumulate yaw error with every little motion. Reducing vibruation will minimize the "gyro drift" where the heli slowly starts to turn. Therefore, balancing the main rotor blades is very, very impoortant.

There are multiple ways to balance the blades, but this method works best for me so far. It minimizes the amount of tape used and we avoid disrupting the airflow where the blades generate the most lift by putting most of the tape near the bolt holes and the CG.

Be sure to use ELECTRICAL tape to balance the blades. Regular transparent tape is not heavy enough. Electrical tape weighs about 0.1 gram per 2.5cm (1 inch).

12.2.1. Step one: Matching the CG

  1. Remove the blade holder posts from the balancing tray of the KSJ-528.

  2. Make sure the balancing tray balances evenly when nothing is on the tray. If necessary, use the setscrews to balance the tray.

  3. Place one blade in the KSJ-528 tray and delicately shift the blade left or right across the balancing tray until the blade balances.

  4. Mark this point with a felt tip pen.

  5. Repeat for the other blade.

  6. Stack the rotor blades, then put a bolt through the hole to align the blades perfectly. Check if the CG of the blades match within 1/16th of an inch (1.5mm).

  7. If the CGs are close enough, go to Step two: Matching weight

  8. Determine which blade has CG farthest away from the mounting bolt hole.

  9. Move the CG of this blade closer to the bolt hole by placing placing 1-2 inches of electrical tape on the underside of the blade next to the leading edge near the bolt hole.

  10. Measure the CG on this blade again and mark it.

  11. Go to step 6

12.2.2. Step two: Matching the weight

  1. Determine which of the blade holder posts fit your blades, then mount them on the balancing tray.

  2. Make sure the balancing tray balances evenly when nothing is on the tray. If necessary, use the setscrews to balance the tray.

  3. Mount the blades on the blade holder posts and make sure both blades balance and are perfectly horizontal.

  4. If the blades do not balance, put a small strip of electrical tape on the underside of the lighter blade at the CG point next to the leading edge of the blade.

  5. Add or remove tape on the lighter blade at the CG point until the blades balance.

12.2.3. Step three: Optimizing tape usage (optional)

  1. If only one blade has tape or you used less than seven inches of tape in steps one and two, you can skip this step.

  2. If one blade has a lot of tape near the bolt hole and the other blade has a lot of tape on the CG, then you should definitely perform this step.

  3. On the blade with tape near the bolt hole, remove all the the tape.

  4. On the blade with tape at the CG, remove the tape and discard half of the tape. Reapply the other half of the tape to the blade but at a point halfway between the CG and the tip.

  5. Go back to step one and rebalance. The blades should require less tape to balance this time.