Sounds like you are on the right track. If you have not already, give the heli a good once over. Just follow through the building manual and make sure everything is setup and tightened as they suggest.

In regards to your specific tail rotor problem…

- Check to see that the long tail rotor servo pushrod is moving in the correct direction. It should move forward when you give the transmitter right rudder.

- Check to see that the control horn on the tail rotor servo is oriented as per the instructions. They suggest a 20 degree offset for some differential throw and this will work well with your Arlton gyro. The picture in the manual illustrates this well.

- Check to see that the bell crank on the tail rotor gearbox is at 90 degrees to the tail boom with the transmitter stick (and trim) centered. If not, screw the clevis on the end of the long tail rotor servo pushrod in and out until the bell crank lines up.

- Check to see that the tail rotor blades are set close to “neutral” once you have the above steps taken care of. With the rudder stick centered and trim set to center, the square base of the blade roots should be flat and lined up with each other. This will get you very close to where you need to be, but some trim adjustments will always be necessary later.

- Check the full throw of the tail rotor servo in each direction. Once you have everything setup as above, try giving full left and right rudder on your transmitter. Ideally you want the tail rotor blades to rotate through the maximum possible deflection in each direction without binding the servo. Servo bind will occur shortly before the slider hits the tail rotor hub (~ 1mm) and near the same deflection in the opposite direction. Proper setup will most likely involve choosing different servo arm holes, tail rotor bellcrank holes, locking collar and gyro pivot mount position, or perhaps a little of everything. If your radio has adjustable servo travel of some sort or another, this process goes very quickly. Just make sure when you are all done that the tail rotor blades return to the “neutral” position when the rudder stick is centered. Also don’t forget to use tread lock on the gyro pivot mount setscrew.

- Check the gyro setup. The setscrew on the gyro pivot mount should be pointing straight up. If you have the “dual gain” gyro version, the manual recommends the high gain mode with the spider slider pin through the upper hole in the gyro spindle. Make sure the gyro paddles are angled aproximatly10 degrees and evenly with everything on the gyro centered. Again the manual has great pictures of this. Finally, the entire gyro mechanism should move very very freely. If there is any binding, grabbing, slop, or roughness in the gyro’s movement determine the cause of the problem and correct it.


It sounds to me like you simply need to get the tail rotor blades closer to their “neutral” position with the radio gear properly setup. Once you have everything straightened up just like the manual says, give it another try. You should be able to counteract any remaining drift with the rudder trim quite easily. Keep in mind that as you throttle up and down, some rudder stick input will be required on your part to keep the nose pointing in the same direction. This is especially true if there is any wind. With everything set up well and the gyro working well, it should be possible to easily make these small corrections with the rudder stick. Figuring out how much and when is the fun of learning to fly a heli

For what it is worth,
Spiro