Loosen up the split gear on a Raptor 50

The Raptor 50 V2 uses a split gear to have a driven tail during autorotations. However, the gear needs to be loosened up before installation. If you do that, you loose less energy when going to throttle hold to enter the autorotation.

The original white gear moves very difficult over the aluminum autorotation hub. It is designed this way to give the white tail gear some support since it is pulled towards the back of the heli by the tail belt. It is supposed to wear in over time, but this takes way too long. The method described below, will wear in the tail gear so that it rotates freely, and is still properly supported by the aluminium autorotation hub.

Just put the main shaft in a drilling machine, and attach the autorotation hub with the grey gear and the white tail gear to the main shaft as shown in the picture below.



Now hold the grey gear as shown, and slowly start the drilling machine. Now increase the speed of the drilling machine, and keep it rotating until the white gear starts to spin freely. Let it cool down for a couple of seconds, and feel if it rotates freely. If not, repeat this a couple of times. This will perfectly match the new white gear to your aluminum autorotation hub so that it rotates as it should, and that it is still properly supported by the autorotation hub.

This fix will only take a couple of minutes and is much easier than grinding or sanding the white gear! Furthermore, this way guarantees a perfect round fit with good support.

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.