JR 662 & Revolution PZ-200 Gyro How-to
|This gyro does not have remote gain so the connections are very simple. Basically you should only have two plugs, the male plug will go to channel 4 (rudder) on the receiver and the female plug will connect to the plug from the rudder servo.|
|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. Go to 'SB-TRIM' and select 'RUD'. Set this to zero. Also make sure the rudder trim is centered (use the rudder digital trim to set the value to zero.|
|set limits to 100%||Set the rudder end limits. Go to 'TRV ADJ' and select 'RUD'. Move the rudder stick left and set to 100%, then move the stick right and set this to 100%.|
|set the gain||To set the gain you adjust the pot on the gyro. I would start out at 80%, so if it is labeled one to ten then set at 8.|
|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 'REV-NORM' and select 'RUD' then change the value.|
|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.|
|set 'neu'||To set the neutral pot, adjust it so you have equal servo travel both directions (full left rudder to full right rudder).|
|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 (in or out) 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 'MIX RVU' 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 'MIX RVD' 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.|