The Dev team have been hard at work and have now released the best ever version of arducopter!

ArduCopter 2.9 is now in the mission planner and the downloads area!

The major improvement is we use inertial navigation to improve altitude hold.  This increased reliance on the accelerometers means you must do some additional set-up before flying:

Arducopter 2.8.1 is now in the mission planner and in the downloads area! Remember to do your MP configuration again after loading this code, since it erases your EEPROM and sets it to the new defaults. 

Note: Issues with APM1 user's level feature not working are now resolved.  If you installed 2.8 we highly recommend you upgrade to 2.8.1 as 430 extra bytes of RAM have been freed up which reduces the chance of memory corruption (although we haven't seen any cases of this on the APM2 at least) .

Note #2: this release has not gone out for Traditional Helicopters until they can be tested fully.  Flip and Toy mode have also not been fully tested.

Improvements over 2.7.3:

• Improved ACRO mode (Leonard Hall)
• Improved stability patch to reduce "climb-on-yaw" problem (Leonard, Rob Lefebvre, Randy)
• Rate controller targets moved to body frames (yaw control now works properly when copter is inverted) (Leonard/Randy)
• Less bouncy Stabilize yaw control (Leonard)
• OpticalFlow sensor support for APM2.5 (Randy)
• DMP works again by adding "#define DMP_ENABLED ENABLED" to APM_Config.h You can also log DMP vs DCM to the dataflash by adding "#define SECONDARY_DMP_ENABLED ENABLED" (Randy)
• Watch dog added to shutdown motors if main loop feezes for 2 seconds (Randy)
• Thrust curve added to linearize pwm->thrust. Removes deadzone found above 90% throttle in most ESC/motors (Randy)
• More timing improvements (main loop is now tied to MPU6000s interrupt) (Randy)
• GPS NMEA bug fix (Alexey Kozin)
• Logging improvements (log I terms, dump all settings at head of dataflash log) (Jason)

Bug Fixes / Parameter changes:

• fixed skipping of last waypoint (Jason)
• resolved twitching when no GPS attached (Tridge)
• fixed loss of altitude if alt hold is engaged before first GPS lock (Randy/Jason)
• moved Roll-Pitch I terms from Stabilize controllers to Rate controllers
• TILT_COMPENSATION param tuned for TradHeli (Rob)

Code Cleanup:

• HAL changes for platform portability (Pat Hickey)
• Removed INSTANT_PWM (Randy)

As per usual PIDs are optimised for the 3DR quad with 850 motors and 10" props. If you're using more powerful motors/props and are seeing bad flight behaviour in stabilize, start by turning down Rate Roll P in 25% steps.

Please note that on this release we've moved the Roll and Pitch I terms from the Stabilize controller to the Rate controller. There's some evidence that says this can lead to flips on take-off if you move the roll or pitch sticks around as you take-off so we recommend you leave these sticks in the middle until you're in the air.

Please feel free to report issues you find in the discussion below and/or add them to the issues list.

Thanks and enjoy!

This guide will walk you through the construction for your Arducopter 3DR frame and Power Distribution board.

Functional Improvements over 2.7.1:

• Fast waypoints (Jason) - if the turn angle between two waypoint the copter is less than 60 degrees it does not slow down
• Navigation improvements and logging including switching to filtered location for distance calculations (jason)
• Flip improvements - more aggressive and flexible flip code based on attitude instead of timing (Jason)
• Improved camera control - you can now control any axis (roll, tilt, pan) with any rc channel.  it probably makes most sense that you will use 6 but others are possible too.  Unfortunately these changes required we change the set-up procedure so the mission planner gimbal set-up screen needs to be modified again.  Please refer to the AC_Camera wiki page for how to manually set-up the gimbal (Amilcar)
• Flybar acro mode for TradHeli (Robert)
• "Fast gains" - allows strong correction of attitude using accelerometers while the quad is stationary on the ground but relies more on gyros while flying (Tridge, Jason)
• Baro filtering improvements (Tridge)

Bug Fixes:

• DMP timing fix (Randy) - the MPU6000's dmp unit was inadvertantly turned on and caused timing delays in the main loop- xbee bricking issue (Craig / Tridge)
• Dataflash fixes (Jason)
• Engine ticking - was a combination of roll/pitch rate D term being too high and the dmp timing fix above (Randy, Emile)
• Faster heading correction on start-up - resolves issue with simple mode getting incorrect heading if you took off very soon after start-up (Tridge)

Code Cleanup:

• Increased maximum number parameters (Tridge)
• Formatting changes to code (Pat)
• Replaced "int" with "int16_t" everywhere (Randy)

As per usual PIDs are optimised for the 3DR/Jdrones quad with 850 motors and 10" props. If you're using more powerful motors/props and are seeing bad flight behaviour in stabilize, start by turning down Rate Roll P in 25% steps.

There is still some question on whether the default Roll/Pitch Rate P (0.175) is high enough (it was 0.185 in 2.7.1) and also some people feel the Throttle Rate should be higher (currently 0.300 but some say 0.330 or even much higher would be better).

Please feel free to report issues you find in the discussion below and/or add them to the issues list.

Thanks and enjoy!

This Hexa frame is based off the Arducopter 3DR Quadcopter, but includes 2 extra motors for added lift and stability in windy conditions.  This guide will show you how to assemble the kit

New and Improved:

• NEW: 3-axis camera stabilization
• NEW: AP_Limits library: Altitude limits and geofencing.
• NEW: Automatic Flip (Roll axis) is now enabled on Channel 
• NEW: GPS lag estimator
• Better altitude control in ALT_HOLD and better altitude transitions
• Better loiter, especially with the new 3DR uBlox GPS. Check out the video from Marco above!
• Better yaw control
• Better DCM implementation, resulting in noticeably smoother flight
• Better velocity control in Auto missions
• Etc

Bugfixes:

• Fix to dataflash erasing, which should resolve an issue some users were having
• Fix some MAVLink commands
• Fix Circle command
• Fix some units
• Etc

Notes:

No more 1280 support (out of program space)
AP_Limits documentation
Jason's explanation of several improvements

This guide will show you how to build the SIX600 Hexacopter frame.

This hexacopter frame is essentially the same as the X600 quadcopter frame, but has an extra 2 arms to make it into a hexacopter.  This frame also comes with high landing gear so you can easily mount a camera underneath the frame.

This will guide will walk you through the assembly process of the X600 Quadcopter frame.

The X600 quadcopter frame is an affordable quadframe that is great for anyone starting out, or for someone who wants a great test platform for trying new moves, or custom code.

Here are two comparison videos of loiter mode for a tricopter fling the latest arducopter 2.6 code, compared to the previous v2.5.5 code.

Thanks to Dean for sharing the videos

Version 2.6 of the ArduCopter code is now available in the AP Mission Planner and in the downloads area!

Updates to MavLink 1.0 means you will need to use "ArdupilotMegaPlanner10.exe" to connect.  If you've updated your mission planner recently you should find this executable in the directory where the mission planner is installed.

The above video is done using a prototype 3dr ublox GPS which seems to have better accuracy than the standard mediatek.

Improvements over 2.5.5 include:
     - MavLink 1.0 support (use with ArdupilotMegaPlanner10.exe) [Tridge, Craig]
     - Stability improvements especially during level hover [Jason]
     - throttle range improvement (higher min and max) [Jason]
     - improved standard Loiter PIDs [Alan, Heino, Jason, Angel]
     - dataflash erase speed up ('+' messages removed but it only takes 6 seconds now) [Tridge]
     - Copter LEDs [Robert Lefebvre]
     - RTL loiter stage target set to home to improve final landing position [Jason]
     - flip & acro improvements [Jason]
     - circle mode target improvement for ground station [Jason]
     - Auto Approach [Adam Rivera / Marco]

Tuning:
PIDs are optimised for the stock Arducopter quad kit with 850 motors and 10" props.  If you're using more powerful motors/props and are seeing bad flight behaviour in stabilize, start by turning down Rate Roll P in 25% steps.

This time we spent some time optimising the loiter PIDs.  Tuning loiter can be tricky so please refer to the discussions which will appear below for more community feedback on what parameters work best.
 
All feedback welcome below.  Enhancement requests and bug reports can be put into the arducopter issues list.  When possible please include logs (tlog and/or dataflash) and tell us whether you're using APM1 or APM2 and what version of the software you're using (presumably 2.6 but tell us anyway!).

Happy flying!