Thrust tests: Motor Thrust Scaling in Motor Tests? In Motor Tests: CTUN.ThO == Throttle?

Hi everyone!

I want to determine the function that describes what thrust is produced at which throttle, for my particular UAV.
Therefore I set the UAV to perform a certain throttle, and measure the thrust it produces. For now, I used the Motor Test of MissionPlanner. The curve I got so far is highly non-linear (regression: thrust / N = 0.001032 * (throttle / 100%)^2.302). As motor thrust scaling ( is performed with MOT_THST_EXPO == 0.5, my gut tells me the curve should not be that non-linear. So my first question is:

  1. If MissionPlanner’s Motor Test routine is performed, does ArduCopter apply Motor Thrust Scaling?

An alternative approach would be to arm the UAV and put it into STABILIZE mode. Then I would slowly increase the throttle and measure it.
Hence my other two questions:

  1. Is there a way to immediately show the actual throttle value at MissionPlanner’s HUD?
  2. Is the log entry CTUN.ThO the throttle value I’m looking for (the value after motor thrust scaling)?


PS: I have a quadcopter (X-configuration), ArduCopter 3.6.11, MissionPlanner 1.3.68

Here is a graph of my existing test data. Perhaps this is a bit more demonstrative, than the formula alone :wink: The blue values (label “FALSE”) are the relevant ones.


Hi there @peterst
I know it’s been year ago, but I’ve found your post asking whether CTUN-tho is the throttle value in Misson Planer, did you have any luck solving this issue?

I am wondering if this Motor Scaling is still relevant where I have not seen a small-size motor that can fulfil the idea. I tried and notice only industrial-grade motors can manage to fulfil it, such as T-Motor U10II, Hobbywing X6rotor, etc.