ArduPlane 4.0 Twin Engine Servo Output Mapping

I’m running a twin engine setup and so I have Throttle Left and Throttle Right as servos 1 and 2, ailerons as servos 3 and 4, and an elevator on servo 5.

My RC is mapped as Channel 1 Throttle, Channel 2 Yaw, Channel 3 Roll and Channel 4 Pitch.

When I connect my RC and move the sticks around, Channel 3 on the RC is able to move the ailerons, but nothing I move alter servos 1, 2 or 5. For example, pushing the left stick up moves Channel 1 up, but there is no output on servos 1 or 2.

How do I map a channel to a servo? The only way I’ve been able to see a servo connection is by using an RC pass-through instead of a servo function… which kinda ruins the whole point.

I apologize for a silly question…but just in case.
Do you have the motors armed?
What mode are you in? FBWA would be a good start.

If worse comes to worse and you’re still stuck…I’d suggest reverting (at least temporarily) to a default config. I’m pretty sure a default load for plane does AETR in order. Use that and a single motor to be the T output. After you get it working, you can start substituting your unique assignments…changing the input order and then the output order and doing the left/right motor assignment.


i would start in Manual mode and can you post your param file so i can look at it i have 2 twin engine planes
you can put the the control surface in any servo output as long as you tell it what to do

Sounds like it could be the safety switch.

I am not arming yet - I am simply looking at the response of each servo in Mission Planner. Now 3, 4 and 5 respond accordingly to RC controls, but 1 and 2 are not doing anything. I’ve mapped them correctly and all, I just seem to be missing something.

can you post your .param file so we can look at it

I just did a brief test on one of my planes to verify behavior.

Even after actuating the hardware safety switch, you won’t get any motor outputs until the motors are armed.

Since you are doing basic testing, you should have the props removed! As long as they are removed, you can safely arm the motors. Until you arm the motors, the motor outputs will not work.


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I’ve confirmed that this is indeed the case.

After removing all safety switches and arming (no props obviously - really only testing on servos at this point) - throttle is received and outputs to Left and Right with appropriate differential thrust perfectly.

Thanks for your input!