Futaba GY240 w/ Futaba 9C
Gyro How-to

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Mount the Gyro on the back plate behind the main shaft. Yes, the tape that comes with the gyro is not very cushiony, but that's the way it needs to be. The cushioning is done inside the gyro. The tape works great, use it. I recommend mounting on the platform behind the main shaft as this will be the least damage area in a crash.
  Make the connections just as shown in the manual. This is very simple, nothing special here, just connect the rudder servo to the female connector. Connect the male connector to the rudder channel 4 on the receiver.
radio setup Note: For this gyro you do not use the gyro menu in the radio. That menu is only used for controlling the gain and mode remotely. This gyro does not have a remote gain/mode plug. You have to set these things directly on the gyro.
zero out anything that would effect the rudder In the advanced menu go to 'REVO MIX'. Select Mix and set to 'INH'.
zero center position Go to the 'Sub-trim' menu and set 'RUD' and 'GER' to 0.
Also make sure the trims are centered.
set pirouette speed Go to the 'E. POINT' menu and set 'RUD' to 70%. Hold the rudder stick to the left and set the value to 70%, hold the rudder stick to the right and set it to 70%. This will set how fast the helicopter rotates. You may want it faster or slower so change the value appropiately.
Gyro setup First set the switch on the gyro labeled AVCS to OFF. And set the gain to 75%.
servo direction Check the servo direction. Move the rudder stick to the right and watch the servo arm. It should move the servo clockwise which thereby should pull the rudder control link forward. This will make the nose of the helicopter rotate to the right. If not, then go to the 'REVERSE' menu and change channel 4.
gyro direction Rotate the helicopter so the nose goes to the left and watch the rudder servo. The servo needs to rotate clockwise. If not, then flip the reverse switch located on the top of the gyro.
With the rudder link disconnected from the servo. The first thing to do is make the link slide as free as possible. Adjust the guides to acheive the least resistance. I added a slight bent to the front section of the rod as you can see if you click on the photo to the left. I did this so as to stop the resistance the rod had on the first frame guide due to being pulled down to the servo. I also use a JR Ball link resizing tool to remove unecessary resistance from the ball links. Once you get the link as free from resistance as you can. You need to take off the rudder servo arm and install/move the ball to a position that is about 13mm from the center. This distance should work but in some cases it maybe too much or not enough, we will set that later. Next set the rudder servo arm back on the servo so that it points up with the rudder stick and rudder trim centered. The best position for tail centering is to adjust the rudder link so that you have 4.5mm between the pitch slider and the tail rotor casing (see the picture to the left). Another way to find center other then measuring 4.5mm is to visually align the control arm to be parallel with the tail shaft. Check that the front link is centered with the ball on the servo arm. If it's not, turn the link clockwise to move it toward the back or counter clockwise to move it forward. Once the center of the ball link matches with the center of the ball and you have the 4.5mm at the tail slider, then you can move to the next step.
Set the mechanical limit You should have the linkage set to center the tail at this step. Now to set the limits set 'AVCS' switch on the gyro to ON then move the rudder stick full right and see if the ball on the servo arm moves further then the link can go or if it is not enough. If the ball will travel further then the link can go then you need to move the ball in one hole toward the center. If it does not go far enough (this is only when giving a right rudder command) then you need to move the ball out one hole.
Notes about the gyro HH/Standard Rate I recommend using heading hold mode (AVCS) so keep the switch in the ON position.
Flying adjustments To get the tail to move faster or slower, adjust the rudder channel travel. Go to the 'E. POINT' menu and set 'RUD' left and right. A higher value will make the heli pirouette faster and a lower value will make the tail slower.

Gain, set the gain so that it is just below so high that the tail wags.

Symptom Cause
Gain values have to be set low to stop any tail wagging. 1. The helicopter is out of balance. Vibration is the cause of low gain settings. Check the blades, check for bent main shaft, spindle shaft, tail shaft, out of balance tail blades, etc.
2. I found that a sticky clutch caused me to have to turn down my gain by 20%. Check the
engine/start shaft alignment and look for a broke shoe.
3. The ball on the rudder servo is too far away from the center.
HH doesn't hold good 1. The RPM's should be 1850 to 1950 for 3D flight. It's also important that your engine is running good. If your engine loads up a lot then you won't be able to keep a consistent RPM. Remember that a few hundred rpm drop on the head is several hundred rpm drop on the tail.