Motors 1&2 Offset Between 3&4 - Suggestions Please

Quad is an IRIS+, running latest version. The RCOU values for motors 1 and 2 are
essentially superimposed, and above them are motors 3&4, also superimposed.
I recall that all four should be superimposed…any suggestions welcome!

The attached .bin RCOU reflects the above. This .bin also reflects notch filters being
analyzed…should be don’t care.

I recently changed motor #1 with an exact replacement IRIS NOS motor.

Copter 4.2.1
MP Ver.1.3.77 build 1.3.8110.38294
3DR IRIS+ quad, fmuv2

The .bin:

without looking at the log:

  • either twisted arms, or
  • the CW props have different efficiency from the CCW props.

Thanks! I was giving some thought to taking it apart (again!) and replacing the new motor on #1 with the original. The #1 arm was replaced; it came with motor installed.
Will check for any twist in the new one. Your response is appreciated.

Just to be clear, in Quad X configuration

  • Bias to 1 and 3 or 1 and 4 or 2 and 4 or 2 and 3 is a weight/COG imbalance - this may be expected or easily fixed
  • Bias to 3 and 4 or 1 and 2 is a twisted motor mount or arm (CW versus CCW) and needs fixing before it affects reliability/stability


It’s easy to translate logs to other multirotor configurations

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