Airmode not keeping quad stable for flips/rolls w/throttle low

hello! I am having an issue with Acro mode on a 5 inch quadcopter running Arducopter. I have arm/disarm set to a switch so airmode should be enabled, however when I am flying in Acro mode and pitch or roll over 90 degrees or fully inverted (flip or roll) AND I drop the throttle all the way down momentarily, the quad looses all of its authority and starts flopping around uncontrollably until throttle goes back up to around mid stick. I am used to airmode in Betaflight that keeps the quad controllable and stable at any attitude even with the throttle completely lowered. does airmode in Arducopter work the same or is this normal?

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I have not flown an Arducopter based multirotor as you are doing but my thought is to increase the ATC_THR_MIX_MAN parameter. Default is .1 so try doubling it and see how it performs.

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I think that’s one parameter I didn’t mess much with. ill give it a try tomorrow and report back.

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I’ll have to try this. I have a pretty tight tune on a 4" and 3" and have not seen any loss of control in flips or rolls. I can share my parameters if it would help

Also can you share a log with the problem? You want all logging options on apart from IMU_RAW and IMU_FAST

Also please set INS_LOG_BAT_OPT = 2 and INS_LOG_BAT_MASK = 1 so that we can see your vibes. Are you sure this is not just propwas? What is the stability like when you descend rapidly?

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Hi Billy and Andy,one thing you could do is use a mix in your transmitter that gives you say 25% throttle and play about with that setting also have it set on a switch to allow you to disable it,Andy may I have a look at your 3" parameters please many thank’s

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Gecko3-Tuned4.1.param (22.6 KB)

Thank you so much Andy

I believe this may be the best workaround until Arducopter gets airmode working properly. basically set the minimum throttle (idle up) to 20-30 percent and have it on a switch so that you can enable it after takeoff. im going to give this a shot today and will report back. thank you

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thanks for your suggestions. I am new to Arducopter so I have not done any logging yet, but I will get that set up today. should just need to throw an SD card in there and enable logging. the build is clean with very little vibration, (I checked the VIB from the HUD while flying) but I will try to collect some gyro data. it also descends pretty well with not too much prop wash. so I don’t think its that. I will get some dvr today so you can see what im talking about.

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My acro performance substantially increased when I used the harmonic notch - are you using this?

The vibe will only tell you about the accels so is more informative for EKF performance than acro (which is pretty much gyro only)

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I’ll be interested to see the results of this discussion. I’m waiting for 2 motors for my 3" seemingly on the slowest of boats.


Hi every one yea do it the way you said there Billy,and Andy which parameter is the haronic notch please

INS_HNTCH_* - but do you have ESC telemetry?

I have not tried the notch filter yet. I will give that a shot and see if it helps. thank you. also very cool that you have Arducopter running on a 3 and 4 inch. any tips for keeping interference between components to a minimum on such tight builds?

Vibration is the killer - the main thing is to use harmonic notch, preferably with ESc telemetry.

If you are not using the harmonic notch then I suspect your problem is simply that you don’t have a very tight tune and when you encounter these high noise maneovres the control loops cannot cope (or have prioritized altitude over attitude or something). You will find that the harmonic notch and a retune will substantially improve this.

Also work your way through the tuning guide if you have not done so already

Interference - big cap on the battery and make sure your video / camera are well shielded and away from the GPS

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I was able to get some video of my issue as well as try the “idle up” workaround. it kind of worked but not satisfactorily. I will try setting up the dynamic notch filter tomorrow, but I feel like the gyro just shuts off completely when the quad goes over 90 degrees and throttle is down.

We really need to see a log. I guess I’m not quite understanding - if the throttle is at zero, why would the copter be stable? There is no thrust to do anything at all with.

LOG_BITMASK = 196607 I think from Leonard’s picture

I suspect one of two things are going on here.

  1. you are still using an arming mode that shuts down stabilization on minimum throttle
  2. you have not increased ATC_THR_MIX_MAN high enough as @dkemxr (Set it to 1 if you are sure your tune is stable).

Sorry but there are so many ways to set this up.

I think he wants “Motor Interlock”.

I think he’s lowering throttle completely, and expecting the copter to still stabilize itself. And it will do that with “motor interlock” set up.


I am trying to have gyro stable flight and full authority of the quad while doing full flips and rolls and other acrobatic maneuvers where you also need to drop throttle to zero momentarily. “Air Mode” in other flight control software provides this by keeping the motors running at zero throttle enough so that the pids still give you full control. im discovering that Arducopter has an “airmode” feature but it doesn’t exactly work like it should and or the wiki documentation for setting it up is not complete because there is no mention of needing to use “motor interlock”