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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Awesome! Thanks guys!!


 Can, the rc_speed to 500hz?


      You can change it to whatever you like.  Now, this won't affect the update rate of the controllers (i.e. the things checking the difference between your real attitude and your desired attitude) so after a point I wouldn't expect it to help much.  At some point your ESCs won't be happy about the rate...but different ESCs seem to be able to handle different rates.

Congratulations dev team, this release looks really great.

On the other hand last reports on Y6 where not that good.

Has Anyone flown a Y6 with 2.5 successfully??  I'm worried about last messages reporting a turning behaviour on take off... unflyable...



     We're looking into your issue.  I can definitely see that your throttle is falling immediately after you engage altitude hold..the question is why..


     So the issue is your THROTTLE_TRIM parameter is too low.  After an version upgrade all your parameters are reset to the defaults which is 350 for this parameter.  It will slowly update itself if you fly around in stabilize mode for a while and maintain a somewhat constant altitude.

     You can take a short-cut though and just go into the configuration screen of the AP Mission Planner and set it to 450 or maybe even 480.  That looks like the value you need.

Thanks Randy, will try that. Noticed when comparing params to my previous setup that the THROTTLE_TRIM parameter was 423 but is 408 on the new. (I did a full erase before loading 2.5 then did full setup but kept all default params)


Also how do I get a more direct feel with minimal lag for throttle stick?

Set it to 450 and flew for a few minutes, had about a meter drop in altitude on switch, reconnected to the MP and it is now at 466.

Quick questions: so will it change by itself until it settles on the right value? And will that value stay set or will this happen on every flight?

It saves it to the eeprom when you disarm your motors so it should be ok in future flights.


You can see the effect quite clearly in the logs by the way..if you graph the "rc3 servo_out" value from the "CTUN" messages.  this is the final output to the motors.  Other important factors that contribute to that number are the "manual boost" column which shows what the pilot's input via the throttle stick is having (there's a large deadzone but above and below that there will be an effect on the throttle going out).


Also you can see the initial throttle_trim used when ALT_HOLD is engaged, it appears in the column just to the right of the MOD, ALT_HOLD message.

Thanks to the whole team and to all users who knew how to wait!
Ehm... why the thread is under the section "ArduPlane"? :P


    Big thanks to you Marco for all the testing, feedback and helping us keep organised!

    Ooops!!  Fixed! :-)

It's a pleasure, Randy!
I hope that our efforts have brought best results, all users must confirm it.
I consider this a very reliable release (milestone), during testing I have performed over 120 flights without crashing my quad and loosing control, and during the test is not easy to obtain these results.
... but now: do not start to hang bottles to your quads, eh?! :-)



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