Version 2.5 of the ArduCopter code is now available in the AP Mission Planner and in the downloads area!



  1. The first ArduCopter code release optimized for the APM 2.  Leans and drift should be much reduced or even eliminated for most users.  This was accomplished through a number of core improvements to the DCM implementation by Tridge like this one and this one.
  2. Loiter and waypoint following should be improved due to a D term bug fix, some tuning and the improved DCM performance mentioned above.
  3. On start-up, the yaw heading is updated with first successful mag read (so you should no longer see the slow rotation from north to your actual heading).
  4. Increased output rate to ESCs to 490hz.  This update rate is also user selectable using the new RC_SPEED parameter.
  5. hexa copter stability patch bug fix (should resolve slight flattening when pitching forward and accelerating very rapidly).
  6. improved baro filtering
  7. fix to dataflash logging of Mag heading
  8. addition of H1 swash plate type and bug fix for proactive yaw compensation for collective pitch changes for TradHelis.



The default PIDs are optimized for a 3DR/Jdrones quad with 850 motors and 10" props. If you're using more powerful motors/props, start by turning down Rate Roll P in 25% steps.

While some testers have reported very good flights with the default PIDs, some have reported that this release is a little "sharper" due to the DCM improvements and have found they needed to:

     reduce stabilize P by 10% (i.e. 4.5 -> 4.2)

     reduce stabilize D by 30% (i.e. 0.15 -> 0.10)

     increase rate D from 0 to 0.001

Tuning loiter can be tricky.  Refer to the discussions which will appear below for more community feedback on what parameters work best.


Please post your feedback in this discussion.  For enhancement requests  and bug report, please add them to the arducopter issues list.  When possible please include logs (tlog and/or dataflash) and tell us whether you're using APM1 or APM2 and what version of the software you're using (presumably 2.5 but tell us anyway!).


Thanks for this release go to the developers (both in the core team but also those who have provided bug fixes through the issues list) and also the community members who participated in the previous release thread and provided some great detailed information in the form of issue reports and logs which allowed us to nail some bugs!


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Question about the version 2.5/2.5.1: have you noticed differences with APM1 and accuracy of the yaw?
I mean compared to version 2.4 or earlier (like 2.1), in keeping the position with compass.
Give me your impressions, it is important, thanks!

This is EXACTLY the behaviour I'm getting. It is stable one moment - for a moment - then nicks violently to the side, or does a wobble. Sometimes it responds instantly to input and sometimes it "builds" something inside and tries to fight me for a while. I thought it was me fighting some I-terms, but even with all I=0 I get the same result. It flies better with some Is for Rate because my CG is a little off when hauling a camera (though I'd expect the I to be need in Stabilize - but it does only harm there). Another issue is when II do a fast translation it would yaw (not always), sometimes even when just hovering.

At one point I had it so carefully tuned it stayed in one place like it was loitering (even with slight wind), and then run amok in an instant.

Multiwii also works for me but I don't like how it flies compared to when APM works, but at least there's no sudden erratic behaviour - It's just consistently less stable :) 

I'm really surprised most people here like how 2.5 flies - it must be something specific to us, like sensor placement or motor layout (but flyduspider is extremely precise in CG and does not vibrate nearly as much as F450 f.e.). I really have the feeling most people getting problems are on flat hexas.

How is your controller mounted on the flyduspider? Directly above the plate, or do you have a skyscraper in there like me? :-)

I have noticed a tendency to not be as "locked-in" on Yaw when compared to the previous versions that I have flown. It seems to drift slightly 5-15 degrees with no yaw input.  I will try to pull some logs later. I am not ruling out my hardware and motor alignment (numerous crashes survived :)), but it's definitely more noticeable than before.  I am a bit confused on the declination setup these days as well, if I should do it manually or automatically.

Oops this is with APM 2.0, not APM1.  Well, hopefully that helps anyways.

Hi Marco,

Last week I reported Yaw issue on my Quad when testing 2.4.2 beta. Last weekend the issue getting worsen, I thought it because of Vibration, cause I change the way I mount my APM2 and I though may be the changes I made causing more vibration and affecting the yaw, the quad fly very stable btw.

I did all things I can think of regarding the mounting but still the yaw issue exist and worser than last week issue, at some point the quad rotate CCW (look from top) by it self.

Until I saw one of the arm on my quad that was broken few months back, I did not replace the arm, I just "patch" it. I look at carefully the arm (back-left arm) and it seems the motor is not perpendicular, it slightlly lean to the right side. So i tried to bend it so its perpendicular, and voila it flyes very stable and no yaw issue at all. Its super stable.

Back-Left arm that broken is CCW motor, and since its a bit lean to the right it gave more boost for CCW yaw and causing drag for CW yaw, this explains why its hard for me to rotate CW and its easier to rotate CCW.

Botom line, for those who has yaw issue, check again the angle of the motors.




Forgot to mention that I also did magnetic interference test and the result is good. My compas pointing the same direction regardless the throttle inputs.

As i see, uve a Mega. I speak about the APM. ;)

As u can see on the pic, my APM is mounted on 5mm rubber stands, so its not vibrating. (U can see this in the logs).

Sorry for intruding (and for repeating myself in regards for this version), feel free to disregard this since I'm not on original APM, but I have been flying every version possible since 2.0.49. My board uses mostly the same sensors and core code (like DCM) is untouched, It might have a longer cycle time than original APM but so far my experience with the code has been consistent with the original APM users in every case

My setup is Flat Hexa X.

My experience:

Yaw is behaving reasonably well with 2.0.49, with newer versions (I can confirm 2.4+) it is randomly yawing (but keeping the new orientation, would interference do that?). Mission planner shows correct (new) orientation - but I don't give it any yaw input to start with.

It also yaws differently to left/right. Left is always good. Right requires higher Ps. With low Ps and right yaw it does nothing but starts rotating left to "counter" the nonexisting rotation as soon as I release the stick. The same goes for yaw left - it tries to rotate back slightly and I haven't been able to get rid of that. My motors are fairly straight and running consistently, so IMO not a hardware error. I tried two different motor sets with the same result.

Using any I-term for Yaw (stabilize or rate) makes it more pronounced, the error is present even with I=0. I tried wildly different Rate P and Stabilize P  combinations (low/high, high/low) for Yaw with little difference to the actual behaviour.

I know, but it's almost the same ;) I wanted to see it because I was wondering how APM fits on the frame and I want to get the original APM myself - but I'll likely wait for the ARM version - tarduino make me want to vomit the more I know about it - like the rest of the last millenium RC stuff it makes me think about steam engines :-P pun intended :)

Your motors are KDA 20-26M or something like that? I still plan on making larger arms and putting some more powerful motors with 10" props on that. Paul said most spiders are <1kg - mine is 1.5kg and still climbing as I add stuff so it's gonna need some overclocking soon. I wish Paul made a larger spider instead of the FCP :(

No rig will be perfect after a few crashes so that still makes it a software error IMO - that's why the yaw hold is here, to correct for unwanted yaw. If everything was perfect we'd need no compass for that :-)

Just to be sure I am looking at the correct number - as I said, new to this :-) 

This is the TRIM_THROTTLE value?

If so, mine is now 683

yeah, something's not right there, star the issue if you see the same problem, hopefully a fix can be found soon.

Just saw v2.5.1 beta is up.  What's changed since v2.5, and is it recommended to use this version over v2.5? Thanks

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