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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Does anyone know of a Website that has the parameter list and what the meanings are ?

Hi I was wondering if anyone could take a look at this log and help me out with a flyaway problem in loiter mode. Flies well in stabilize, but when I enter loiter, it changes roll to max within a second or so and flies into a tree unless I switch to stabilize. There are some vibrations but I don't think this caused it as my other two MR's are doing the same thing in loiter.

copter 3.3.3

6s, 380kv 15" props, 880mm 6lbs

Could it be the momentary gps glitch? I wasn't able to run telemetry, but here's the .bin log of the last crash where I enter loiter once, and have to go back out immediately as it seemed to take off. Then I tried it once more and it took off into a tree before I could switch to stabilize. Luckily it escaped undamaged. It shows a radio loss as the antenna broke off when it hit the tree. Or could the issue be caused by these settings I had previously made in attached photo?

Any assistance and I would be most appreciative, thanks!


Is this the list you are looking for? http://ardupilot.org/copter/docs/parameters.html

Don't look a gps glich, only look a vibe glich the two times that you switched to Loiter but I don't know why, your compass and acc all are well calibrated?

Acc is well calibrated. Compass I'm pretty sure is, I tried a few different times and flew some test flights and this last one had the lowest IMX, IMY and IMZ in ekf3. The only motor I'm 100% sure is not fake is #3 (they're sunnysky's), and pretty sure at least 1 or two are fakes. Which might be where the vibrations are from. Would it flying well in stabilize rule out vibes though?

Yes, Thank You Derek


is there a reason why you changed GPS_NAVFILTER to 3? It should remain at the default 8 for Airborne 4G.

You also changed EKF_VEL_GATE to 12 (default is 3). These are standard deviations, so you disabled the gate.

Perhaps you should try a complete reset of your Parameters.


Thanks Hubertus for your reply,

Did a reset of the parameters, recalibrated acc and compass, but loiter is still taking off horizontally.  

Here's a log of the same craft taken last year with an older firmware and loiter worked well. Maybe my larger MR isn't adjusting well to a new parameter or change in the code?

I had a similar problem once. The cause was the GPS, it was one of the ones mounted on a circuit board with out a clear way a identifying correct orientation. I was 90* off and upside down and had the symptoms you are describing.

After verifying that the ground station or aircraft compass matched a real compass in all four directions, east and west were also reverse, the machine flew correctly in loiter.

I felt really dumb when I realized it.

Compass orientation looks OK.

Do you have a log with the reset parameters?

You might be on to something. I did switch GPS units on the offseason. Its this gps http://www.readytoflyquads.com/mini-ublox-m8n-gps-w-35x35mm-mountin...

I have it mounted as shown (with the ceramic antenna up). Wires going towards the back of the MR. I recall someone saying not to do the roll180 setting as the orientation changed from the old apm days, and all new gps were actually upside down but that was considered right side up. Or has that been my problem, not putting the rotation_roll_180 in the drag down menu?

Hi attached is log with reset parameters. I see the position innovations (IPN and IPE) go bad around the time I bail out of loiter. Little strange as it seemed out of control during loiter but it shows a low IPN/IPE. Then IPN/IPE goes bad (but is flying OK in stabilize)


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