APM:Plane 3.3.0 released

The ardupilot development team is proud to announce the release of version 3.3.0 of APM:Plane. This is a major release with a lot of changes. Please read the release notes carefully!

The last stable release was 3 months ago, and since that time we have applied over 1200 changes to the code. It has been a period of very rapid development for ArduPilot. Explaining all of the changes that have been made would take far too long, so I've chosen some key changes to explain in detail, and listed the most important secondary changes in a short form. Please ask for details if there is a change you see listed that you want some more information on.

Arming Changes

This is the first release of APM:Plane where ARMING_CHECK and ARMING_REQUIRE both default to enabled. That means when you upgrade if you didn't previously have arming enabled you will need to learn about arming your plane.

Please see this page for more information on arming:


I know many users will be tempted to disable the arming checks, but please don't do that without careful thought. The arming checks are an important part of ensuring the aircraft is ready to fly, and a common cause of flight problems is to takeoff before ArduPilot is ready.

Re-do Accelerometer Calibration

Due to a change in the maximum accelerometer range on the Pixhawk all users must re-do their accelerometer calibration for this release. If you don't then your plane will fail to arm with a message saying that you have not calibrated the accelerometers.

Only 3D accel calibration

The old "1D" accelerometer calibration method has now been removed, so you must use the 3D accelerometer calibration method. The old method was removed because a significant number of users had poor flights due to scaling and offset errors on their accelerometers when they used the 1D method. My apologies for people with very large aircraft who find the 3D method difficult.

Note that you can do the accelerometer calibration with the autopilot outside the aircraft which can make things easier for large aircraft.


After an auto-landing the autopilot will now by default disarm after LAND_DISARMDELAY seconds (with a default of 20 seconds). This feature is to prevent the motor from spinning up unexpectedly on the ground
after a landing.

HIL_MODE parameter

It is now possible to configure your autopilot for hardware in the loop simulation without loading a special firmware. Just set the parameter HIL_MODE to 1 and this will enable HIL for any autopilot. This is designed to make it easier for users to try HIL without having to find a HIL firmware.

SITL on Windows

The SITL software in the loop simulation system has been completely rewritten for this release. A major change is to make it possible to run SITL on native windows without needing a Linux virtual machine. There should be a release of MissionPlanner for Windows soon which will make it easy to launch a SITL instance.

The SITL changes also include new backends, including the CRRCSim flight simulator. This gives us a much wider range of aircraft we can use for SITL. See http://dev.ardupilot.com/wiki/simulation-2/ for more information.

Throttle control on takeoff

A number of users had problems with pitch control on auto-takeoff, and with the aircraft exceeding its target speed during takeoff. The auto-takeoff code has now been changed to use the normal TECS throttle control which should solve this problem.

Rudder only support

There is a new RUDDER_ONLY parameter for aircraft without ailerons, where roll is controlled by the rudder. Please see the documentation for more information on flying with a rudder only aircraft:

http://plane.ardupilot.com/wiki/ardupla ... udder_only

APM1/APM2 Support

We have managed to keep support for the APM1 and APM2 in this release, but in order to fit it in the limited flash space we had to disable some more features when building for those boards. For this release the AP_Mount code for controlling camera mounts is disabled on APM1/APM2.

At some point soon it will become impractical to keep supporting the APM1/APM2 for planes. Please consider moving to a 32 bit autopilot soon if you are still using an APM1 or APM2.

New INS code

There have been a lot of changes to the gyro and accelerometer handling for this release. The accelerometer range on the Pixhawk has been changed to 16g from 8g to prevent clipping on high vibration aircraft, and the sampling rate on the lsm303d has been increased to 1600Hz.

An important bug has also been fixed which caused aliasing in the sampling process from the accelerometers. That bug could cause attitude errors in high vibration environments.

Numerous Landing Changes

Once again there have been a lot of improvements to the automatic landing support. Perhaps most important is the introduction of a smooth transition from landing approach to the flare, which reduces the tendency to pitch up too much on flare.

There is also a new parameter TECS_LAND_PMAX which controls the maximum pitch during landing. This defaults to 10 degrees, but for many aircraft a smaller value may be appropriate. Reduce it to 5 degrees if you find you still get too much pitch up during the flare.

Other secondary changes in this release include:

  • a new SerialManager library which gives much more flexible management of serial port assignment
  • changed the default FS_LONG_TIMEOUT to 5 seconds
  • raised default IMAX for roll/pitch to 3000
  • lowered default L1 navigation period to 20
  • new BRD_SBUS_OUT parameter to enable SBUS output on Pixhawk
  • large improvements to the internals of PX4Firmware/PX4NuttX for better performance
  • auto-formatting of microSD cards if they can't be mounted on boot (PX4/Pixhawk only)
  • a new PWM based driver for the PulsedLight Lidar to avoid issues with the I2C interface
  • fixed throttle forcing to zero when disarmed
  • only reset mission on disarm if not in AUTO mode
  • much better handling of steep landings
  • added smooth transition in landing flare
  • added HIL_MODE parameter for HIL without a special firmware
  • lowered default FS_LONG_TIMEOUT to 5 seconds
  • mark old ELEVON_MIXING mode as deprecated
  • fixed 50Hz MAVLink support
  • support DO_SET_HOME MAVLink command
  • fixed larger values of TKOFF_THR_DELAY
  • allow PulsedLight Lidar to be disabled at a given height
  • fixed bungee launch (long throttle delay)
  • fixed a bug handling entering AUTO mode before we have GPS lock
  • added CLI_ENABLED parameter
  • removed 1D accel calibration
  • added EKF_STATUS_REPORT MAVLink message
  • added INITIAL_MODE parameter
  • added TRIM_RC_AT_START parameter
  • added auto-disarm after landing (LAND_DISARMDELAY)
  • added LOCAL_POSITION_NED MAVLink message
  • avoid triggering a fence breach in final stage of landing
  • rebuild glide slope if we are above it and climbing
  • use TECS to control throttle on takeoff
  • added RUDDER_ONLY parameter to better support planes with no ailerons
  • updated Piksi RTK GPS driver
  • improved support for GPS data injection (for Piksi RTK GPS)
  • added NAV_LOITER_TO_ALT mission item
  • fixed landing approach without an airspeed sensor
  • support RTL_AUTOLAND=2 for landing without coming to home first
  • disabled camera mount support on APM1/APM2
  • added support for SToRM32 and Alexmos camera gimbals
  • added support for Jaimes mavlink enabled gimbal
  • improved EKF default tuning for planes
  • updated support for NavIO and NavIO+ boards
  • updated support for VRBrain boards
  • fixes for realtime threads on Linux
  • added simulated sensor lag for baro and mag in SITL
  • made it possible to build SITL for native Windows
  • switched to faster accel sampling on Pixhawk
  • added coning corrections on Pixhawk
  • set ARMING_CHECK to 1 by default
  • disable NMEA and SiRF GPS on APM1/APM2
  • support MPU9255 IMU on Linux
  • updates to BBBMINI port for Linux
  • added TECS_LAND_PMAX parameter
  • switched to synthetic clock in SITL
  • support CRRCSim FDM backend in SITL
  • new general purpose replay parsing code
  • switched to 16g accel range in Pixhawk
  • added FENCE_AUTOENABLE=2 for disabling just fence floor
  • added POS dataflash log message
  • changed GUIDED behaviour to match copter
  • added support for a 4th MAVLink channel
  • support setting AHRS_TRIM in preflight calibration
  • fixed a PX4 mixer out of range error

Many thanks to everyone who contributed to this release. We have a lot of new developers contributing which is really great to see! Also, apologies for those who have contributed a pull request but not yet had it incorporated (or had feedback on the change). We will be trying to get to as many PRs as we can soon.

Best wishes to all APM:Plane users from the dev team, and happy flying!

Views: 15542

Comment by Graham Dyer on June 20, 2015 at 7:50am

We've had to revert to v3.2.1 due to the following problem: https://github.com/diydrones/ardupilot/issues/2368, would like to use the new firmware obviously to take advantage of the other improvements but this is a show stopper. Is there any other reason perhaps why RC7_OUT would stop responding to RC7_IN?

Comment by Grant Morphett on June 20, 2015 at 2:58pm

@Graham, I added a comment to your issue.

Thanks, Grant.

Comment by Chris on July 23, 2015 at 4:29am

Hi Guys,

I have been building a flying wing running a Pixhawk. Up until today, I have been very successful with the build and tuning. The machine has been operating well in all modes and both auto takeoff and landing work well. I have followed the online guidance religiously (Zener diode, ESC/BEC for rail power) and modified the power module or use with 6s. All testing has been done without a camera until today. The wings have small digital servos (one in each) and analogue servos for the flaps (one in each). All current draw ratings are below the BEC MAX.

I and using a Sony A6000 with a stratosnapper v2 as the trigger. The camera wifi is off. During an Auto takeoff, as soon as the machine left my hand it held the requested pitch angle of 15 degrees for about half a second, then did a 180 degree roll and crashed. I rebuilt the machine, changed the servo's over, thinking it may have been the compass as I did not do a compass calibration before takeoff. My last compass cal was done about 50Km from this site.

Today I did another launch in MANUAL mode, without the camera. The stratosnapper was plugged in to the pixhawk and external BEC. The aircraft performed flawlessly. We conducted a manual landing.

We put the camera in again and performed a MANUAL takeoff. The same crash happened again, this time to the left. 

I think it could be the stratosnapper, or the way it has been wired. Currently I have only a signal and earth wire on RC port 10 on the pixhawk which connects to SERVO 1 on the SS. The SS then has an external BEC on SERVO 2 providing it with 5.1 Volts. The Sony is then connect on the WIRE port of the SS.

Looking at my data logs for the flight, the Vcc looks to be ok, fluctuating between 5.05 and 4.87.

During both crashes, the CH1 In and CH 1 out appear to be momentarily reversing (going in the wrong direction). The CH1 in and Ch1 Out in other datalogs vary in opposite directions on the graph, but in the two crashes they vary in the same direction momentarily.

I have rewired the SS to be powered by the pixhawk, thus removing the BEC from the SS Servo port 2. I am thinking that this may fix the issue, as this is the way the tutorial suggest it should be wired, I interpreted it incorrectly.

Has anyone had this issue before? Have I overlooked something?

Any help much appreciated

Comment by Grant Morphett on July 23, 2015 at 3:51pm

Hi Chris.  This should probably be in a support forum post on its own as its not really 3.3.0 release related :-)

Sorry but I've never used the stratosnapper. 

If you could post a dataflash log of the flight during the crash that would help us to be able to diagnose the issue.

Thanks, Grant

Comment by Chris on July 23, 2015 at 4:39pm
Hi Grant,

Ok no worries, I have created a discussion and attached the data logs. Here is a link to it: http://diydrones.com/m/discussion?id=705844%3ATopic%3A2053949

Comment by Grant Morphett on July 23, 2015 at 5:05pm

Thanks Chris.  We will have a look.

Thanks, Grant.

Comment by Chris on July 23, 2015 at 11:42pm
Thanks Grant, let me know if you need any more info.
Comment by Leon DeBell on July 24, 2015 at 11:08am

Does anyone know if the geofence function is broken in Arduplane 3.3? I'm using Mission Planner and have also tried APM 2.0 but neither of these seem to let me set a geofence. I can set a rally point, define a separate polygon, but can't then specify that polygon as a geofence. I've also tried setting waypoints but I can't define those as a geofence. Either I'm doing something wrong (likely), the Wiki hasn't been updated to instruct correctly or there's something amiss? Geofencing in Arducopter is simple and straightforward, but it's anything but in Arduplane..

Comment by Grant Morphett on July 27, 2015 at 1:41am

Hi Leon.  I have tested and yes its working fine.  I have updated the documentation at


and I hope this makes it clearer how it works.  Remember to set FENCE_ACTION to 1 to get the plane to return to the fence return point you have set.

Thanks, Grant.

Comment by Leon DeBell on July 27, 2015 at 4:31am

Grant, thank you!

I've just read through the wiki and it makes perfect sense, I can see why my fence polygon points weren't being recorded in MP now.

Thanks again, Leon.


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