ArduPlane 2.73 released

I've just released ArduPlane 2.73 as a bug fix release for several important bugs in 2.72

The main reasons for this release are:

  • fixed a noise and scaling problem with airspeed sensors
  • fixed a potential flyaway problem with the L1 navigation controller
  • improved handling of poor GPS velocity for attitude correction

This release does not contain the new attitude controllers that I previously said would be in 2.73. Paul and I decided that it would be better to hold those over to the next release, and get this release out with just the above critical bug fixes.

The airspeed problem stemmed from a changed introduced in 2.72 to make ArduPlane automatically scale analog inputs with board voltage. That change was good for voltage and current sensing, but it added a lot of noise to airspeed sensing as the 3DR airspeed sensor is ratiometric (the sensor output scales with the supply voltage). The fix was to add support for ratiometric analog inputs. This release also fixes a bug in the airspeed ratio handling. To confirm the fix I have been driving around in my car with an APM2 and PX4 logging airspeed and GPS speed - that test confirmed the airspeed sensing is now accurate.

The flyaway bug in L1 was caused by an unusual situation where the previous waypoint was equal to the next waypoint, which can happen when a mission is interrupted and restarted. The L1 controller would then level the wings and fly straight ahead until the operator intervened. The bug fix was to make the L1 controller detect this situation and track directly to the next waypoint. I don't think many users would have seen this bug, but it definitely could happen and warranted a bug fix release.

The GPS handling bug was related to the MTK GPS, which can be very slow to report loss of GPS lock, which could lead to very poor attitude from DCM and even a crash if the plane tries to turn while the GPS is reporting incorrect velocity information. The fix was to watch the satellite count, and stop using the GPS velocity for accelerometer correction when it had less than 6 satellites. This is selectable with the new AHRS_GPS_MINSATS option.

Other changes

While this release doesn't have the new attitude controllers I decided to leave in some other smaller changes that have been made since the 2.72 release that I consider to be low risk, including:

  • fix the PX4 barometer driver to run at full rate
  • fixed handling of a saturated compass on PX4
  • added COMPASS_ORIENT option to support external compasses
  • fixed the compass in HIL simulation
  • added GCS messages to flash logs
  • allow 3D accel calibration over MAVLink
  • Added new ELEVON_OUTPUT option
  • removed MANUAL_LEVEL option (manual level is now always on)
  • improved pitch handling when inverted

Of these, perhaps the most useful is the ELEVON_OUTPUT option. That makes it possible to setup your transmitter with normal aileron/elevator and get the APM to do a software elevon mixer on output. That gives better control in FBWA mode than the previous elevon options.

I recommend that all users of 2.72 upgrade to 2.73. Happy flying!

Cheers, Tridge




You need to be a member of diydrones to add comments!

Join diydrones

Email me when people reply –


  • why did you remove manual level.

  • Hey Andrew.. When you guys do new software do you guys do any QA behind the scenes? I have someone asking me. They're concerned the software is being thrown out to the modelers to test on their own. Feel free to pvt me if you wish. 

  • I am still only getting 30 degrees bank in FBW with the max bank set to 60 degrees. Auto mode is giving me the full 60 degrees and is working great. I have recalibrated the controls. Any ideas what I can try?
  • Developer

    For those of you struggling with the new ELEVON_OUTPUT option, I have added some docs here:

  • What is considered acceptable vibration levels for arduplane?
  • Moderator
    Hi. First flights with 2.73 in APM 2 on an X5
    The new eleven system is many times better than the old version. The setup is more work but so worth it. Still needs a bit of fine tuning but 90% correct and flyable on first flight. Good auto tracking, even survived a line wind at over 50mph as it passed through! Time to fit the camera. Thanks Tridge for a great system .
    L1 set at 22, still testing
  • Flew my X8 with the 2.73 firmware yesterday.

    This navigation control is excellent.

    The aircraft now loiters in a perfect circle with the default settings whereas with the prior version it loitered in a square.

    It hits every way point exactly and the throttle management in auto seems much improved for some reason.

    All in all a fantastic upgrade experience.

    Did not try the new elevon output option though.

  • I was doing the last check in my house before test the 2.73 release and  I have noticed in MP that there was problem with the level.


    I connect the APM with MP and the level moves until it keep in the following position although the plane was in the correct position.

    (roll level moves to right along until this position)

    (See the image attached)

    I re loaded  the 2.65 release and everything come back to normal situation.

    I installed  2.73 release again and got the same issue.


    Do you have any comment or suggestion…


  • The L1 controller is one of the best things to happen to Ardupilot. I love it. My plane stays on the flight path, and guided is a perfect circle. Way to go!

  • SO far Im loving the new L1 nav controller. I am wondering however, what value I should adjust to get the plane to tighten up its turn at the waypoint and get back on track to the next, since xtrack seems to be greyed out now.


    The plane tracks very well once its on the line between waypoints, but swings wide after it makes the turn off the waypoint and eases back onto the line. I would like it to get back on quicker.


This reply was deleted.