Download a PDF file that explains How to Balance Your Blades, Rotor Head, Tail Rotor and your helicoptor itself.
"If you do all these things you will have a heli that will hover in place (Hands Off) for short periods of time and will be much easier to fly and control. This is the culmination of all my years experience working on military helicoptors applied to the micro helis we all love to fly."
- SSG Scott, author of 'Balancing your Helicopter for Incrrdibly Smooth Flight'

Balancing the Main Rotor

I prefer to balance the entire Main rotor Assembly as a unit while it is removed from the aircraft.

Balancing must be done in a room where there is no air current from heating/cooling units, etc. or from people or objects moving around.

You must first remove the Flybar and Rotor Head Assembly and the Center Hub, Spindle and Blade Grip Assembly. These can be removed as a unit by disconnecting the Paddle Control Frame Pushrods (009) from the Upper Swashplate (044). Then remove the Retaining Pin (035). Now you can remove the entire Main Rotor Assembly from the aircraft by pulling the Center Hub (008) off of the Main Shaft (050).

I use a balancing device that I made from scrap wood. Figure 1

Prior to balancing, prepare the Main Rotor Assembly by grasping each Main Blade Grip (037) in your hands and pulling them away from one another. Figure 2. This will force the head into the position it would most likely find during flight when centrifugal force acts upon it. Most Blade owners experience a certain amount of play in the Main Rotor Assembly as a result of the Spindle (016) length. To accommodate this play during balancing follow these instructions and pull the Blade Grips (037) outward.

Place the Main rotor Assembly in the balancing device as shown in Figure 3.

Place strips of tape on the light blade to achieve balance. I try to estimate the length of the tape needed and place it carefully on the light blade near the blade tip with the sticky side of the tape facing up. This way I can move the tape in or out until perfect balance is achieved. Then I flip the tape over and stick it to the light blade in the same spot it was when face up. I try to use a single piece of tape that will go from the trailing edge over the top and back underneath to the trailing edge again. This guarantees a smooth surface over the entire blade profile. Figure 4.

Continue to check and add or remove tape as needed to achieve balance.

Reinstall the Main Rotor Assembly, Install the Retaining Pin (035) and reattach the Paddle Control frame Pushrods (009) to the Upper Swashplate (044).

If you made any adjustments to the balance or are replacing blades, the track must be checked as outlined in the next section.

Exploded View

Figure 1

Figure 2

Figure 3

Figure 4

Setting Main Blade angle to zero

Another nominal setting that is beneficial under certain circumstances is Main Rotor Blade pitch set to zero degrees.

To accomplish this we must first unplug the Main and Tail Motors from the 4-in-1 Controller. Figure 5. Make sure that no battery is connected to the aircraft. Set the transmitter to the normal starting position as shown in Figure 6. Turn on the transmitter.

If you are certain that the Main and Tail Motors are disconnected from the 4-in-1 Controller, plug the battery into the aircraft and wait for the 4-in-1 to arm.

Stand clear of the aircraft and raise the throttle to 50%. Hopefully the Main and Tail Motors did not spin since they are to be unplugged from the 4-in-1.

Place the Idle Up switch in the Idle Up position (toward the face of the transmitter). Make sure that the collective/throttle is at 50%, cyclic is centered along with trim, throttle trim is in the down (off) position.

Now eye down the length of each blade comparing the bottom of the flat-bottom blade (042) to the top of the Paddle Control Frame (031). Figure 7. They should be parallel to one another. If you are using symmetrical blades use the blade centerline for comparison.

Lengthen or shorten the Pitch Control Links (006, 007) to obtain zero degrees (parallel to Paddle Control Frame).

A word to the wise: Whenever you make adjustments to the Pitch Control Links (006, 007) or the Servo Pushrod Control Links (045) make note of how many turns or half-turns you make to each. That way if you are not happy with the outcome you can always go back to where you started.

My experience has been that when starting from this point I usually need to lengthen the Pitch Control Links (045) 2 or 3 turns to achieve the proper throttle to hover ratio. I use the very crude measurement of ¾ throttle should have me hovering chest high on a fresh stock battery and 10T pinion with flat-bottom blades.

Exploded View

Figure 5

Figure 6

Figure 7

Tracking the Main Rotor

This operation requires that the Blade be run up at approximately 75% throttle. This is usually enough to cause the aircraft to lift into a hover. Therefore you must secure the aircraft against this. I just lay something heavy across the landing gear. Figure 8. The Tail Rotor will also spin during the Tracking operation. Be careful. I like to do this on a bench so that it is easier to observe the track.

Prepare the Main Rotor Blades (042) by coloring the tips in contrasting colors. I use a Sharpie brand magic-marker - one red and one black. Figure 9.

Prepare a "Tracking Flag" by folding a piece of standard writing paper in half along its length.

Prepare your transmitter by centering all of the trim sliders except for throttle which should be all the way off (down). Do this carefully - it's important. Move the collective/throttle lever all the way down. Idle Up switch in the Normal mode. Figure 6. Make sure that no battery is connected to the aircraft. Turn on the transmitter. Plug in the battery and wait for the 4-in-1 to arm.

Caution - Don't let the Main Rotor Blades (042) or the Tail Rotor Blades (057) contact anyone or anything while spinning. Serious injury or damage could result.

With the aircraft secured against lift-off and the Main and Tail Rotor areas clear, increase throttle to about 75%. Make sure that the aircraft is properly secured against movement. Hold the Tracking Flag in hand and slowly move it into the main rotor disc until the blades lightly contact the paper. Watch your fingers! Figure 10.

Reduce the throttle to zero and observe the red and black marks on the paper left from the blade tips.

If adjustment is needed, disconnect the battery and turn off the transmitter. Lengthen the Pitch Control Link (006, 007) of the low blade (the blade that made the lower mark on the paper). Do this in half-turn increments and re-check at 75% throttle. Continue until you have achieved the best track possible within the half-turn limitation of the Pitch Control Links.

Exploded View

Figure 8

Figure 9

Figure 6

Figure 10

Taken from BladeCPrepair.com