Set expo for roll/pitch/yaw in ArduCopter rather than on TX?

You can obviously set up expo for roll, pitch and yaw on your TX but I was wondering if it’s possible to set it up in ArduCopter with Mission Planner?

It doesn’t make a big difference whether you set it on the TX or in the flight controller software but it would seem to make slightly more sense to handle it in the flight controller software as handling it on the TX will result in some loss of resolution (if you think about how it has to map stick positions to the range of PPM values).

Flight controller software like Cleanflight and Betaflight do allow for setting expo via their respective configurators, e.g. here’s how it looks in the Cleanflight configurator:

I see there is an expo related parameter called ACRO_EXPO but that’s just relevant for the acro flight mode.

If setting expo were available as a general stick adjustment then I’d have expected to find it under Radio Calibration in Mission Planner or perhaps under Basic Tuning but there’s nothing obvious in either location.

Is it omitted for some deep reason, e.g. ArduCopter already applies some kind of expo values for all flight modes and doesn’t consider it appropriate to make these adjustable by end users? Or perhaps ArduCopter thinks expo setting is bad (some people seem to feel you should just learn to fly your sticks as they are)?

Or is it simply that ArduCopter feels expo setting is best handled on the TX and there’s no need to reproduce this functionality and add complexity within ArduCopter itself?

@ ghawkins

Hi George, did you go further on this topic? I’m asking since I’m struggling in the same thoughts.


Hi Sergio –

ArduCopter does not support setting expo - you must set this on the transmitter. At least that was the case back in 2017 and I don’t believe things have changed since then.

I did some calculations and I don’t think the loss of precision involved in setting expo on the transmitter is worth being concerned about. If you set an expo of 25 then at worst you end up with just 16 PPM values per degree of movement versus 20 without expo. I doubt anyone can really notice the difference between the two and I suspect Betaflight provides this feature simply because it’s convenient to be able to set expo in the Betaflight configurator rather than because it overcomes a noticeable loss of precision issue.


Hi George,
sorry for my late reply.
Thanks a lot for having shared your thoughts with me.
Indeed I guess that the new release of Copter can manage expo, but I need to investigate more.


ACRO_RP_EXPO and ACRO_Y_EXPO have been in there for a long time now if anybody comes by this.

Hi Leonard

Doe these expo rates have an effect when flying in Loiter mode?


Only in yaw rate. The lean angles do not have an expo variable.