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




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Great work.. I will be giving it a try this week end in my Ardu-Raven sUAS. When do you foresee the release of the new attitude controller. I am looking forward to this next feature to make setting up an airframe simpler.

Thanks, Tridge. Looking forward to trying out the new Elevon controller. 

Andrew thanks for the quick turn around on a bug fix. I'll load up the firmware later on today and give it a whirl! 

Hi Joseph,

I am currently thinking the new attitude controller may be released in a couple of weeks, but it depends on testing results, and time to do testing.

Cheers, Tridge

Thanks for the update... I am loving the direction the Adrupilot is going. Great work...

Andrew, when are you going to enable gimbal control? And GRIDv2 not filling in the polygon. You had to have seen my many posts about this...

It seems like 90% of people just use Arduplane for flying waypoints. But those wanting to map are plagued with bugs and no help. We are the minority but we still want a working product. I cant even use this for mapping because of the lack of gimbal control through DO commands, and the problem with GRIDv2, which I need for camera triggers...

 I don't understand how to beg harder than I already have for some assistance.



Hi Matt,

The first thing to do is to create an issue in our issue tracker. I tend to check that list before releases and try to fix as many issues as I can.

Regarding GRIDv2, we'd need to work out if this is a MissionPlanner issue or a ArduPlane issue. My first guess is it is probably a MP issue, but that would need to be confirmed by examining the interaction between the APM code and MP when a grid is created. I don't use the GRIDv2 feature myself, so perhaps you can tell me if it has worked in the past and is now broken, or if it has never worked? Does it work on ArduCopter?

I apologize that these issues haven't been addressed previously. I don't read all the forum postings (I'd need a lot more hours in the day to do that!), so I rely on users creating issues and then I use the issues list as a todo list.

Cheers, Tridge

Tridge -- thank you, you rock! This was a great move.

I had some fly aways happen in 2.7.2 and thought it might have to do with WP telemetry data transfer errors but I never experienced that before 2.7.2. It always failed and gave an error or worked flawlessly in previous versions. 

I would like to also continue testing the 2.7.3 beta (now 2.7.4beta?) with the new attitude controllers and happy to provide feedback. 

Great work! I look forward to testing the new 2.7.3 production firmware.


Thanks for the link, Ill add future bugs there. Gridv2 has never worked for me since I purchased the unit last year. Not sure on arducopter.

Heres an open issue that someone created for me 2 months ago, addressing the DO Mount issue, and its still open:


Thank you for the bug fixing.before you release the 2.73,I fly my skywlker(1680)and it appears the two cases(airspeed sensor,L1 algorithm).Now I use the 2.73 firmware,thank you for your hardworking.

Hi again Matt,

I just had a go with GRIDv2 for the first time. It really is a nice feature!

I found it worked for me as long as the total number of mission items doesn't exceed the mission item limit in ArduPlane (which is currently 176 items).

Can you tell me:

  • what version of MP you are testing with
  • how big an area you are drawing the grid on
  • how closely spaced the lines are
  • if you have enabled shutter triggers
  • how closely spaced you put waypoints on the lines
  • how many mission items in total you end up generating

Also tell me if the grid does get generated in the planner and the problem is with the upload, or if it doesn't get generated in the planner. If it is generated in the planner screen, can you save the resulting mission and attach it in a reply?

I notice that Randy has closed your issue request and asked you to move it to the MissionPlanner issues list. That may mean Randy has already looked into this and knows it is a MP problem.

Cheers, Tridge

Well here's my test results from this afternoon. Mission in full auto from start to finish. 


Complete with a video flyby 


I should probably go in there and do a bit of PID tuning for the Skyhunter with the new firmware. So far I'm using 16 and 0.75 for my NAV1 settings. Anything outside that and the plane looks like a roller coaster. 

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