Arducopter Pitches Forward During Takeoff (Channel Order Help!)

ArduCopter Copter 4.5
1

Hello all! I would appreciate some help diagnosing strange behavior.

Context: I had crashed a quad (my fault) and did some stack overhaul. Added a Skystars H7 HD flight controller and ESC and changed the RC to @olliw42 's excellent mLRS system.

I’m experiencing an issue I can’t seem to fix: the quad pitches forward when I increase throttle and will eventually flip if I don’t disarm. Before it flips, the quad does not respond to my stick input as expected (eg: yaw doesn’t produce a yaw and so on and so forth)

  1. RC is a Radiomaster Boxer with channel order AETR, mLRS RX channel output is AETR, and my RC channel order in AP is AETR
  2. I am flying X Frame, Betaflight X motor order and the props direction and motor spin order are good
  3. I’m only trying to takeoff and confirm the basic tune in order to go into my autotune steps.

I believe that this is a channel order problem, but considering I set everything to AETR and the Radio Calibration tab of Mission Planner shows the desired outputs, I’m not sure what I’m missing.

Attached are 3 logs exhibiting the same behavior

Log #3: Fresh 4.5.1 Install

Logs 1 and #2 are 4.6 from yesterday.

2

To me that sounds like a motor ordering or AHRS_ORIENTATION problem rather than an RC channel problem.

Look here for motor orders.

Then remove your props, go to the motor test page in Mission Planner and test if your motors spin in the correct order.

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3

Thanks for the reply @Janno .

Prior to posting I confirmed my frame layout params, conducted a motor test, and also checked the artificial horizon in Mission Planner to validate AHRS_ORIENTATION. All of these params as well as the ESC settings look good.

That’s why I believe something with mLRS channel order is involved. Hoping it’s something else I’ve overlooked!

4

I think the issue is the RC2_TRIM has been set to 1001 which is the same as RC2_MIN.

It looks like ARMING_CHECK = 128 so nearly all pre-arm checks have been disabled including the one that checks for exactly this configuration error.

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5

How embarrassing :man_facepalming:

This was it! Hopefully this post can serve as a reminder for others in the future to check trim.

I suppose that CH2 was trimmed down to a throttle 0 position when I had an incorrect channel order in an earlier setup and this was never corrected.

Thanks for looking into this :pray:

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