Non-heading hold Gyro How-to
|In general the gyro goes between the receiver
and the rudder servo. By this I mean the gyro will
connect to channel 4 (or whatever the rudder channel is
on you receiver) and then the rudder servo will connect
to the gyro. I will provide a few examples to help you
figure it out for your gyro: RC Vision 2000 - the plug
labeled 'RX' goes to channel 4 on the receiver and the
rudder servo plugs into the connector on the gyro labeled
'servo', CSM 400 - connect the 'Rud In' to channel 4 and
'Servo' to the rudder servo. Futaba GY401 - connect the
male plug with 3 wires into channel 4 on the receiver and
the female plug to the rudder servo.
Now your gyro may have an additional connector. This is used to control the gain. This will be plugged into the receiver. The channel you plug it into will depend on the radio. Most of the time it will be plugged into channel 5 (the gear channel). If your radio has a gyro function in the menu then it is usually connected to channel 5. BTW: There is a misprint in the Futaba 8U Super manual, you do connect to channel 5. Often times JR upper end radios use Aux2, but you will need to look in the manual to find out. If you are not sure just email me the radio you have and I will let you know. For radios without a gyro menu, you still connect to channel 5 then will use the ATV for channel 5 to control the gain.
Note: If you don't have a gain plug, then you should have a control on the gyro that you turn to adjust the gain. The remote gain is nice because you don't have to stop the helicopter and use a small screwdriver to adjust it.
Note: If you are connecting a Futaba plug into another brand receiver then in most cases you have to remove the flat 'key' on the side to the plug.
|Mount the Gyro on the back plate behind the main shaft. Use the double sided foam tape that came with the gyro. Some gyros use thick foam and others use thin. It all depends on if the gyro has internal dampening. If you put too much dampening this can cause a resonance problem.|
|radio setup||Disconnect the rudder link from the servo. Turn on the radio and receiver.|
|zero center position||In the radio, set the servo centering to zero (CNT=rd6000, SubTrim=JR radios). Make sure the rudder trim is centered.|
|set limits to 100%||Set the rudder end limits (EPA=rd6000, ATV=JR radios) to 100% both directions|
|dual rates to 100%||Set the Dual rates to 100%|
|set the gain||If you don't have remote gain, then use the
control on the gyro. Turn it to about 70 to 80%.
For remote gain use the gyro menu in the radio to set it. Now some radios list the range from 0 to 100 and others go from -100 to +100. A good value to start with either is +75. You can later fine tune this to get the best hold.
For radios that don't have a gyro menu (like the Futaba 8u non-super) then go to the menu for servo end point limits (ATV's/EPA/Travel adjust) and adjust the end point for channel 5. Set to 75%. Note: If you are using another channel so you can use a different switch, then you will need to adjust the end point for that channel instead of channel 5).
PS: If you do have a gyro menu then make sure you adjusting the gain for the flight mode you want.
|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 channel reverse menu on your radio and change the direction of 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 back of the gyro sensor box.|
|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 used 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, turn on the radio and receiver. Most piezo gyros need to initialize so don't move the helicopter until the gyro is ready. Most gyros will move the rudder servo a little to let you know it's ready. Set the rudder servo arm so that it points straight 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 Note: make sure the collective stick centered up/down and left/right. Check that the front link is centered with 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 arm and you have the 4.5mm at the tail slider, then you can move to the next step.|
|Hold the tail rotor stick full right and pull the control rod all the way forward. Hold the link over the servo arm to see which hole it will align with and install the ball in that hole. This will usually be around 10mm from the center. You want to use the one that is furthest from center that does not allow the servo to mechanically bind. After you mount the ball, confirm that it does not try to pull the link further than it can mechanically go either right or left. Now you can snap the link on the ball.|
Adjust the rudder link so the helicopter does not rotate at hover.
You want to increase the gain until you see the nose of the helicopter wag (oscillate back and forth), then back off the gain. That will be the highest you can set the gain.
|Revolution Mixing||Note: If you later get a heading hold gyro
you need to zero out the revolution mixing!
Initial setup - (helicopter not running of course) move the throttle/collective all the way up. Now set the 'up' revolution mix so that you have more pitch in the tail blades. How much will be determined later, but for now set it to 20%.
Move the throttle/collective all the way and set the 'down' revo mix to give less tail pitch, for now set to 10% Note: this may need to be a negative value, whatever it needs to be less pitch then when set to 0%.
In flight adjustment: Do a climb out and adjust the 'up' mix so the helicopter remains straight. Then do a descent and adjust the 'down' mix to also keep the helicopter straight.
|Gain values are low.||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 electronic boards inside the sensor box could be vibrating. Use small rubber foam pieces inside to cushion the circuit boards.
4. The ball on the rudder servo is too far away from the center.
|Gyro 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.|