Differential thrust for twin engines

Does ArduPlane support differential thrust for twins? I searched the Plane category and didn’t see anything. A bunch of us flying MyTwinDream’s are starting to talk about it. Not mission critical by any means, since most guys are flying MTD’s for long distance FPV, which doesn’t involve a lot of turning. :wink:

Saw this post this morning on RCG about a Vector user who is trying something clever with the Vector flight controller and an Arduino to implement differential thrust on his twin.

Curious what’s been done or considered to date for differential thrust in ArduPlane.


Hi, you could reference this article:

yes, plane does support twin motor planes with differential thrust. To use do this:

  • setup your two motors as throttleLeft and throttleRight with the SERVOn_FUNCTION parameters. The values are 73 for left and 74 for right
  • set RUDD_DT_GAIN to the amount of differential you want. default is 10, which means 10%

When you fly you can put in differential thrust with rudder, or just let ArduPilot apply it automatically based on the KFF_RDDRMIX parameter.

Late to the party, but this is brilliant. I’m building a very large twin, and this will rid the plane of a large rudder servo.


what param can adjust the both engine thrust seperately?


@xixijoe RUDD_DT_GAIN It controls the differential speed sensitivity of the dual motors. We generally use it to control the front pull motors with different thrusts.

@dkemxr @cuav_le
Thank you for your answer.

I guess this param is in addition to the servo controlling of the yaw. What I need is to separate adjust the thrust of the both engine. As the engines may has the different thrust to make the plane not flying straight forward at the yaw direction. Tell me if I got it wrong.

What happens if I increase the value: RUDD_DT_GAIN, too high? @cuav_le