ArduCopter 2.5 released!

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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  • Moderator

    Guys I am really getting frustrated these days with tuning. And honestly, I'm about ready to go buy a skywalker and set that up instead. My copter used to fly like the above video from the above previous post or better. My hexacopter is running the latest version from the mission planner. I am having a few different issues and would love some opinions on them:

    1. My aileron and elevator channels responds abnormally with it being very numb around the center but when it does move it is very abrupt. It takes quite a bit of stick deflection to get it to pitch forward and then when it does it is extremely abrupt resulting in massive stick deflection in the opposite direction to try and keep it from rocketing away. I had upped the stabilize_P value from 4.5 to 4.9 and then 5.0 and it seemed things got a bit better (still no oscillations). 4.0 was completely unstable. I moved the Stab_D value down to .020 as I read it might have worked on another similar setup and I think it helped. I'm honestly tuning blindly. Making random changes it seems and hoping for the best. I've read all of the tuning guides but nothing really seems to be working. All the motors are calibrated correctly.

    I tried playing with the dampening values but could not really get them to work. I'd rather set my expo values in my radio personally if that is what it refers to.

    2. My sonar was working half decently and tests fine in the terminal. When I switch to alt hold while flying ,with my sonar enabled, the copter now wants to slowly rise or fall without any signs of stopping.Is this because the copter is rising or falling when I engage it?

    3. I'd like you guys to see the below video to see my setup. I was flying the below setup minus the landing gear, floating camera plate and fpv gear very well around the 2.0.46-2.0.49 time period. I was out of the game for a while while I was planning a rebuild after a crash and did not have time to commit to fixing it. Now that I have reloaded and tested everything, I am having just utter shit flight qualities. It seems like the copter is always wanting to drift and it seems like my compass is always adding on about 5-10 degrees to the left after I stop yawing with the stick.

    So I am wondering if the landing gear is creating any major issues with the sensors from a pendulum effect? Does that have any bearing or should I be compensating in the tuning values somehow? I would mount the batteries above the APM if it helped.

  • Hi all, I'd like to show you how my hexa flies :-)

  • Yesterday my hexacopter, APM2 and 2.5.5 finally were allowed to collaborate in their native element, Free Space!

    I dared to take off and I could touch down on my local airfield. 

    Thanks for support



  • HELP!!!! Please!!!!  

    How I must programm the 3DR 20A ESCs with the original 850KV motors an APM2??  

    Battery type??

    Cut Off mode??

    Cutoff thresold??

    start mode??


  • Moderator

    O.K here is some vids of 2.5.5 using a homebuilt Tri made from large chopsticks, cable-ties and some fiberglass basically a load of old junk...

    If this can fly as well as this.. Although it`s taken a while to tune, and it`s still not as I want it? but what can be expected from cheap 6 pound motors and 4 pound esc`s, some pine sticks, cable ties and a bit of superglue?

  •   I am following the APM2 S/W releases forum & blogs, nice progress.


    Configurations supported <?> Tri-rotor with 2 servo, an Enhancement request -

      I have interest for a Tri Y config with two forward rotors using servos for tilt-rotor improved performance.  Is there an interest in APM2 to support this type platform?.  Ard Paris board, and Aussie Scarab are flying this config, with good success.

    reference flight video, here:

    Servo mix with ESC for different flight attitudes, requires new dev & flight regime testing, I believe.  I do not believe that it is straight-forward, unless you have a servo configured tri-rotor platform for tests to get mix ratios.

     Regards - john h., Calif.

  • Today I finally was able to test 2.5.5 on my hexa. Setup: Jakub's hexa frame, KDA 20-22 924kv, SS 18-20A ESC & 10x4.5 APC props.  Settings: all standard, rate_KP on CH6 for tuning (0.11 adjustable to 0.14 max and 0.08 min)


    Stabilize was flying fine.  The yaw now and then lost direction a little bit but it got corrected in the end.  Although the correction was not as fast as I would have liked.

    Alt hold: wasn't able to mount my dome (forgot straps at home), probably because of that wind was causing a jojo-effect of about 4 meters.  Will have to test again with dome.  Correction in altitude were very agressive.  Would like to have a quicker response without the response being too agressive.

    Positioin hold: complete disaster: big circles and sometimes very agressive correction. Didn't trust it at all...

    Loiter: didn't try because I could't get a good position hold.


    Which standard parameters do I need to adjust to get better results in alt hold and pos hold?

  • I tried other firmware in the Mediatek GPS:

    MTK3329_A1.5E_20110118_10Hz_115200.bin; FMP04_Camled_010327_A1.5E_20110118_10Hz_115200.bin and AXN1.50_2366_3329_96.1151100.1.bin work with minigps but not with apm1.

    AXN1.30_2389_3329_384.1151100.1_v16.bin is ok but I can't change defaut value (1HZ 38400b). Maybye GPS must works with APM1 at 38400b?.

  • Moderator

    I think that I may be having an issue with the 2.5.5 code. When I was out testing this morning I noticed that when I switched into Alt Hold mode (Sonar enabled and tested fine) that the copter slowly lands on its own at a consistent rate. If this were a autoland feature, then it works flawlessly in terms of throttle control. Is this a flaw or something that I might have setup incorrectly? I tested the modes and I'm using loiter, alt-hold and RTL. Still tuning PIDS right now.

    Let me state it. I despise dampening. Is this basically a APM expo setting? It seems like it is not consistent with pitch which remains open to stick input.

  • Hi Guys could someone have a look at my video and suggest any tuning tips, the Hexa seems a bit wobbly.  Maybe my Rate P is a bit too high.

    Xaircraft Hexa frame KDA 20-22L motors, Apm 1 Code 2.5.4

    Stabilise P 4.2 I 0.1 D0.140 Rate P 0.19 I 0 D0.001

    All other settings standard.

    Any help would be most appreciated.


    Regards Pete

This reply was deleted.


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Aug 25