Copter-3.3 beta testing

Warning #1: an issue has been found with Tower's Pause button which can cause the vehicle to fly to an old position if the vehicle has not sent a position update to Tower in some time.

Warning #2: Copter-3.3.2 fixes a bug found in Copter-3.3.1's desired climb rate initialisation which could lead to a sudden momentary drop when switching from Stabilize or Acro to AltHold, Loiter or PosHold.

Warning #3: Copter-3.3.2 fixes an issue found in Copter-3.3.1 which could lead to hard landings in RTL or AUTO if the WPNAV_SPEED_DN was set too high (i.e. >400 or 4m/s) and/or the WPNAV_ACCEL_Z was set too low (i.e. <100 or 1m/s/s).

Warning #4: a bug was found in Copter-3.3 which could cause a sudden crash if you abort a Take-off initiated from a ground station.  Video description is here.  The bug is fixed in Copter-3.3.1 so we recommend upgrading.

Note #1: AC3.3-rc8 corrected a long standing bug in the HDOP reporting.  HDOP values will appear about 40% lower than previously but this does not actually mean the GPS position is better than before.
Note #2: if upgrading from AC3.2.1 the vehicle's accelerometer calibration needs to be done again.
Note #3: set SERIAL2_PROTOCOL to "3" and reboot the board to enable FrSky telemetry like in previous versions.
Note #4: the wiki will be updated over the next few weeks to explain how to use the new features

Copter-3.3.1 is available through the mission planner.  The full list of changes vs AC3.2.1 can be see in the ReleaseNotes and below are the most recent changes since AC3.3.

Sadly this version (and all future versions) will not run on the APM2.x boards due to CPU speed, flash and RAM restrictions.

Changes from 3.3:

1) Bug fix to prevent potential crash if Follow-Me is used after an aborted takeoff

2) compiler upgraded to 4.9.3 (runs slightly faster than 4.7.2 which was used previously)

Changes from 3.3-rc11:

1) EKF recovers from pre-arm "Compass variance" failure if compasses are consistent

Changes from 3.3-rc10:

1) PreArm "Need 3D Fix" message replaced with detailed reason from EKF

Changes from 3.3-rc9
1) EKF improvements:
    a) simpler optical flow takeoff check
2) Bug Fixes/Minor enhancements:
    a) fix INS3_USE parameter eeprom location
    b) fix SToRM32 serial protocol driver to work with recent versions
    c) increase motor pwm->thrust conversion (aka MOT_THST_EXPO) to 0.65 (was 0.50)
    d) Firmware version sent to GCS in AUTOPILOT_VERSION message
3) Safety:
    a) pre-arm check of compass variance if arming in Loiter, PosHold, Guided
    b) always check GPS before arming in Loiter (previously could be disabled if ARMING_CHECK=0)
    c) sanity check locations received from GCS for follow-me, do-set-home, do-set-ROI
    d) fix optical flow failsafe (was not always triggering LAND when optical flow failed)
    e) failsafe RTL vs LAND decision based on hardcoded 5m from home check (previously used WPNAV_RADIUS parameter)

Thanks for your testing!

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      • yea i have a micro pixhawk called pixfalcon micro from hobby king on a 250 i uploaded rc11 and everything went nuts on mission planner the horizon thing was spinning around in circles everything was on acid... went back to 3.2.1 everything was fine  weird.. rc11 3.3 is just well nuts

        • I have deinstalled MP and re-installed ( running the MSI as administrator with a registry tweak ) trying to get the beta releases I still get a 403 from the servers when trying to download the update. Can anyone point me to the beta builds of the files that I can use or a list of files that comprise the beta upgrades.

        • T3


          hell of a lot of nuts around...

          I am pretty sure that AC3.3rc11 is not to blame if AC 3.2.1 is running fine. Your copter should fly better with AC3.3rc11

          But, have you gone through all the calibration steps again?

          Best regards,



          • um no rc11 is to blame.. didnt do it on 3.2.1 the official release.. when i went back it was fine so it was the beta... dont forget im a captain and been flying helis for 20years now.. but this new tech is all software based.. to many sensors to many things to mess up.. before you had to actually know how to fly with this stuff its point and click..

            • Moderator


              Where exactly do you think AC 3.2.1 came from, another planet perhaps? It came from the same developers working on this release.

              What Thorsten was asking you, which by the way you didn't answer, was if you had followed all the directions at the top of the page, you know the ones in bold red type warning you of impending doom if you don't do certain things like re-calibrate your accelerometers when upgrading from AC3.2.1? If you didn't then go back and follow the directions. I think you will find it makes a world of difference.

              Live long and prosper,

              Nathaniel ~KD2DEY

              • spock calibrated it for me... yes of course i did.. but for some reason it seemed like a drunk uncle that just got bad news that nascar isnt going to be around no more and his favorite beer is going outta business.. 

                but seriously once i went back to the stable release no problems...

      • ian,

        Make sure you are in the "Administrator" account when you do the MP upgrade. You may also need to turn off your virus checker when upgrading to the MP Beta release, others have problems with it. See this link:

        • +1 on that advice - On Windows machines, always right-click and 'run as administrator' as well as suspend / disable any real-time virus scanning.

          • Thanks Phil, Kurt. Unfortunately that didn't fix it. I'm getting a 403 error from the server during the download of the dll.

  • I was wondering if this a new change that was meant to be there. In 3.2.1 using tower you could switch to Auto and without moving the throttle the copter would take off and fly its mission with out touching the R/C controller. I am trying 3.3RC11 and now in tower I switch to auto in Tower and I need to move the throttle to make the copter fly. Is this a setting I need to change or is this the way it is suppose to be for now? 

    Thanks and Great work. Very smooth....

This reply was deleted.


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