CSM400 Gyro How-to
Using the Airtronics RD6000

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  Connect the 'Rud In' plug on the gyro to channel 4 on the receiver. Next run the 'Servo' wire to the plug of the rudder servo. Next run the 'Gain' wire to channel 5 on the receiver.
  Mount the Gyro on the back plate behind the main shaft. Use the mounting tape that comes with the gyro. Apply one strip on the left and one on the right of the bottom of the gyro. Make sure you clean both mounting surfaces so the tape sticks good.
  Before we continue it helps to understand the characteristics of heading hold gyros. They all have to initailize. This one takes about 5 seconds. Don't move the helicopter during the first 5 seconds after you turn it on.
Common misconception of all heading hold gyros Another thing that a lot of people don't understand is that the rudder travel adjust (EPA's) does not adjust how far the servo moves. You cannot use this to prevent linkage binding. This adjustment only effects how fast the tail moves (your pirouette rate).
radio setup Disconnect the rudder link from the servo. Turn on the radio and receiver. Wait 5 seconds for the gyro to initialize.
zero revolution mixing Go to 'Ru' and down to 'RV.H'. Use the f.mode button and set all modes to zero. Do the same for 'RV.M' and 'RV.L'
zero center position In the radio, go to the rudder 'Ru' menu and down to CNT and set it to zero. Next go to the trim for the rudder channel 'TRM' and set it to zero.
set limits to 90% Set the 'Ru' rudder end limits (EPA) to 90% both directions
dual rates to 100% Set the rudder 'Ru' Dual rates 'D/R' to 100% for each flight mode (use the f.mode button on the keypad).
set gyro ch. Set the gyro channel. For the Airtronics RD6000 go to 'G' on the menu and down to 'GYR'. Use the flight mode button to select 'N' and set it to +60, then select '1' and set to +60, then '2' and set to +60.
set to normal mode Move the rudder stick to the right, then back to center, if the servo does the same then you are in normal mode. If the servo moves to one direction but does not move back to center then you are in heading hold mode. If the gyro is in heading hold then you can go to 'G' on the menu and down to 'REV' and change the value.
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.
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. Wait 5 seconds for the gyro to initialize. 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 with 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.
set to heading hold mode In a previous step you used the servo reverse function to put the gyro in non- heading hold mode so go back and set it to heading hold now. Go to 'G' on the menu and down to 'REV' and change the value.
Install the ball on the servo arm Mount the ball on the rudder servo arm so that it is 14mm from the center of the screw that holds the arm to the servo.
Flight adjustments
without independent
normal/HH trims
If you don't have the radio setup so that it has independent trims for normal and heading hold modes, then you have to trim out the HH first, then mechanically adjust the rudder link to make the normal rate hold still. The reason for this is that HH requires a the radio to constantly send a 'center position' signal to it. Anything off of center will tell the HH mode to move. So if in normal rate mode you move the trim (sub-trim or trim knob) to the right to stop any drift, then when you switch to HH, the heli will rotate to the right. So set the trim to make HH still, then adjust the rudder link on the helicopter so that normal mode does not drift.

Gain settings:
For normal mode 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. Do the same for HH.

CSM400 auto setup mode With the helicopter off, turn it on and before the gyro initializes, toggle the reverse setting in the 'G' menu a couple of times. The gyro will verify setup mode by moving the rudder servo back and forth a couple of times before going to center. During this time make sure the rudder trim is centered and you do not move the rudder stick. The gyro is remembering center position at this point. Now to set the gyro reversing you first check that the yellow "REV" LED turns on and off as you move the rudder stick full left and full right. Now move the rudder stick to the left and release it back to the middle. This will set the gyro direction. Toggle the 'G' 'REV' value to move to the next step. The gyro will 'zip' the servo back and forth in acknowledgement and again park the servo in the middle. The next step is to set the travel limits. After you just got through toggling the 'G' 'REV' value you should have noticed the rudder servo moved all the way to the first travel limit. Use the rudder stick to adjust this position. Toggle the 'G' 'REV' value and now set the other side of the travel limit the same way. Toggle the 'G' 'REV' value again and you should see the rudder servo move back and forth twice then go to center. The auto setup is now complete. For the setup changes to take effect you have to turn the helicopter off then back on.
How to: configure a switch
on the RD6000 to toggle HH
and normal gyro rate.
First go to the gyro menu 'G' and down to 'GYR'. Use the flight mode button to select 'N' and set it to +60, then select '1' and set to +60, then '2' and set to +60. Next go to 'etc' on the menu and down to 'MAS 1' and set to 'gy'. Go down to 'SLV 1' and set to 'gy'. Go down to 'g->g 1' to -150. This will let you use the cmix 1 switch on the top/front/left of the radio to toggle between heading hold and normal.
Adjustment Example: Lets say we notice the gain in normal mode is too high. Go to 'G' and down to 'GYR'. Use the flight mode button to select 'N' and decrease the value. Next, because of this type of configuration, we have to make all other flight modes the same. So use the flight mode button to select '1' and set to the same value you had in 'N' mode. Do the same for mode '2'.
Adjustment Example: Lets say the gain is too high in heading hold. Go to 'etc' and down to 'g->g 1' and 'increase' the value. If you have the value at '-150' then try a higher value like '-130'.
Disadvantages to this configuration:
1. It uses up one of the mixes. I use both mixes for my cyclic to throttle for 3D flight.
2. Everytime you adjust the normal rate gain in the gyro menu 'gyr', this will also slightly effect the HH gain.
3. Everytime you adjust the normal rate gain, you have to set that same value in the other two flight modes.
4. You have to use the 'etc' menu to get to the mix 1 to set the heading hold gain.
Symptom Cause
Gain values for Normal and HH 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.
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.