Cannot configure swash plate servos on Blade 450

I am building a Blade 450 with Pixhawk. It’s swash plate is 180 degrees offset from the swash plate shown in the Arducopter directions and pictures for connecting the servos. The directions show Ail and Pit at the front and Ele at the back. On the Blade 450, the Ele is at the front and the Ail and Pit are at the back.

After connecting everything, the servos move correctly in the radio calibration screen. The servos move correctly in the Heli Setup screen. I have Servo 1 at position 120, servo 2 at position -120 (reversed) and servo 3 at position 0. (See attached picture). The collective, elevator and aileron all move in the correct directions with the radio.
But…when I tilt the heli right, the swash tilts further right (positive feedback and guaranteed to crash). When the tilt the heli forward the swash tilts back (as it should).

I have tried tweaking the radio servo directions (Ele and Ail) and tweaking the position of servo 1 and 2 (switch from 120 & -120 to -120 & 120). I’ve fiddled all the Heli setup servo reverse toggles.

I am tweaking in circles trying to get the correct settings. I have retraced the directions many many times but can’t find why I seem to get positive feedback when I tilt the heli to the right or left. The only thing I had to do different then the directions is reorient my swash plate settings by 180 degrees because I have a Blade 450.

Could Rob or someone please point me in the correct direction to fix this? I don’t doubt this is some step I have screwed up but after 2+ weeks of retracing my steps I am obviously blind to my own stupidity.

I will gladly supply an additional information if requested.



I am new to this to but I have a few suggestions.

Go through the radio calibration, Im sure you have 10 times. make sure up elevation is max PWM. All of the other graphs follow the stick except elevator. (stick back tward your chest is max PWM)

Reverse all of the servos in the Heli setup GUI by checking the reverse boxes opposite of what you have posted if nothing in the radio cal has changed.

Verify the automatic corrections are in the right direction first. You might have to swap the elevator and aileron servo wires in the PixHawk to make it happen if the automatic corrections are backwards.

check the compass heading on the HUD in Mission planner or APM and verify the headding of the heli is correct. It seems to matter if the heli is pointed north and the heading is south, you need to fix the compass orientation. You can run the compass calibraton and change the orientation of the compass with regards to the PickHawk board. There is a setting for this in the parameters.

re-boot the copter after changing settings with the swash plate.

I think I would swap the aileron and elevator servos and try the setup again. (servos that drive the swash mostly right and left).

I went though some pain here too, but first the automatic corrections have to be correct or it is going to end poorly.


Hi Bob, what do you mean by “reorient my swash plate settings by 180 degrees” ? Do you mean the Phase Angle “H_PHANG”? This should be set to 0 degrees. The servo position should be used set with the H_POS parameters (the one with individual angles, you have +120, -120 and 0).

I have an MSH Protos 500 set up and flying with a similar swashplate arrangement, so it is possible. You just have to get all the settings right. The code actually doesn’t know which servo is called “elevator” or “pitch” or “collective”. Those are just labels used from the days of setting up CCPM on computer radios. No servo has a discrete function in the code. They are all equal, and it’s just a bit of trigonometry that does the job. All that really matters is that you have the correct servo position associated with the correct servo angular location, and plugged into the correct RC output.

Regardless of swashplate arrangement, I have found that if collective works in the right direction, then the servo reversing is set right. If pitch works correctly, but roll works backwards, then it is because the two servos which control roll are reversed on their connections or their servo position is set backwards. Flip either the servo leads, or the angular positions, and then you’ll probably also need to reverse both of them. If the roll works in the correct direction with stick input while it works the wrong direction when you tilt the heli, then I believe it must mean that the roll input on the radio is also reversed. Typically, the roll channel on your radio, and the roll input in Arducopter should NOT be reversed, these usually “just work” in the correct direction. Same with Pitch, and Yaw. Normally the only channels which you need to look at are the collective pitch, as this is reversed by default in some radios (Futaba).

The way I set up my Protos was:

Phase Angle set to Zero.
Servo 1 is the servo in the front of the swashplate. Servo Angle 1: 0 Degrees.
Servo 2 is the servo at 4 o’clock on the swashplate. Servo Angle 2: 120 Degrees.
Servo 3 is the servo at 8 o’clock on the swashplate. Servo Angle 3: -120 Degrees.

Were you able to get this working?
I am having pretty the much same issue with my 600x build, Tx is Dx8 Rx is AR8000 w/3dr encoder.
Been chasing my tail for a week now, and came across this post.
Hopefully this will get me going in the right direction, any advice you have would be GREATLY appreciated and most FERVENTLY welcomed. :smiley:
Thank you,