No rudder control

Hi fellow pilots,

I have a strange issue with my rudder servo. When I move the yaw stick the rudder servo is not moving. The swash servos do move when I move the yaw stick.

All other controls are correct. When I move throttle and cyclic controls the correct servos move. Also the swash is corrected in the expected direction when I tilt the helicopter. When I turn the helicopter the APM should correct this by giving yaw control but it is not doing that.

In MP all controls are correct at the radio calibration screen I.E. when I move the yaw stick the rudder input bar is moving in the correct way. However, the rudder servo is not moving.

There is no mixing done by the radio.

What could the issue be?


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  • Could be your yaw PID settings.  You'd really need to post your parameter file so we can help.

    • Never thought of the params file. I have attached it. Please see if this helps.


      • Ok, so the problem is that your Rate_Yaw parameters are basically zero.  P and FF are zero, and I is very small.

        Also, I noticed that your Rate Roll and Pitch FF terms are probably much too big.  You have 4 and 5.  These should probably be more like 0.04 and 0.05.

        • Hi Ron,

          That was it! Thanks. Now I have to do refinements because the heli drifts very slowly backwards. Lets say 7 o' clock. I think I have to make mechanical adjustments to the swash rods. Make the elevator a bit longer so the bird will not be pulled back.

        • Hi Rob,

          Thanks for your excellent reply. I will try that. I got these settings from the internet because it has not flown yet :-(

          Hopefully these settings make the bird fly so I can start from there.

          I must say the HK450 is my first helicopter and also my first experience with APM. Getting this bird in the air has proven to be a very steep and slow learning curve. But one step at a time I will get there.

          Thanks Rob, your help is much appreciated.

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