Setting up the 401 gyro

Setting up the 401 is fairly simple. First you select a control horn position on the servo such that the arm length on the servo is about 17 to 20 mm. Next set the tail control rod length such that when the servo horn is orthogonal to the control rod, the heck rotor blades have an angle about 10 degrees (pushing to counter the torque when hovering). Next select the proper gyro mode for you servo (e.g. DS on for the 9253 servo). Next put the delay on the gyro to zero (in case you have a fast servo like the 9253).

Put the trim of your rudder channel in the zero position including sub trim etc. Make sure that there is no revo or any other mixing to your rudder channel!. Program you Tx such that you can control the heading hold and rate modes of your gyro (connect a channel that you can switch to the gain channel). Now put your tx in heading hold mode, and turn on your receiver and wait for the gyro to initialize (the led should go on continuously). Now switch your gyro gain channel such that the gyro goes into rate mode (led goes off). Now turn down the limit pot on your gyro. Next put the rudder stick in one of the extremes, and rotate the limit pot until there is a maximum control throw on the blades without binding (check both directions). Choose the limit such that there is no binding on either sides.

Next put the ATV or EPA values of your TX rudder channel on 100% (reasonable piro rate for now). If you ever want a faster piro, you can turn up the ATV or EPA of your rudder channel. Now control your ATV or EPA values of the gain channel in both directions to 50%. Your basic setup of the gyro is done.

Go and fly and check how she feels. You can now turn up the ATV values of the gain channel in both gyro modes for all your idle ups such there is no oscillation in your tail (wagging). You can test this best by diving the helicopter from some height. If it does not oscillate there, then it is ok. Make sure that your gain is e.g. 5% below your maximum setting for the different idle ups (less strain on your servo). After this you can adjust the piro rate to your liking by adjusting the ATV of the rudder channel.

That’s it, you’re done.