APM automatic flap deployment ready for testing.


I have uploaded a new revision of APM to the trunk repository (r3665) with automatic flap functionality. I am really pressed for time so am hoping some community members can do some flight testing on it and report back.


Flap functionality can be assigned to channel 5 or 6, using the rc_5_funct and rc_6_funct parameters (similar to setting up differential ailerons).  The value to assign for automatic flaps is RC_6_FUNCT_FLAP_AUTO (in your config file) or 2 in the GCS parameter.


Flaps will function manually in flight modes of MANUAL through FLY_BY_WIRE_B, and will be set automatically for flight modes of FLY_BY_WIRE_C and higher.  If you want to know what FLY_BY_WIRE_C is, you'll have to wait a couple more days ;)


Automatic flap deployment is based on desired speed.  Desired speed is the current value of airspeed_cruise, which can be set with mission commands, or on the fly by changing the parameter value.  If you do not have an airspeed sensor flap deployment is based on the current value of throttle_cruise.  Four parameters have been added that can be set through your configuration file or through the ground station with MAVLink.  These are two speed values and two flap positions.  If the speed setpoint is above flap_1_speed then the flap position will be 0%.  If the speed setpoint is between flap_1_speed and flap_2_speed then the flap position shall be flap_1_percent.  If the speed setpoint is below flap_2_speed then the flap position shall be flap_2_percent.


The flap range is set up with the normal radio calibration procedure.  A flap value of 0% corresponds to the minimum value on the flap channel and a flap value of 100% corresponds to the maximum value on the flap channel.


Modest flap deployment should be useful for AP applications where you need to fly at a slow speed.  Higher flap deployment will be useful for even slower airspeeds with increased descent rates for landing approaches.


Have fun with it and please let me know how it goes.



Views: 2179

Comment by Anthony Bee on August 27, 2011 at 6:23pm
That's such a smart idea!
Comment by Tom in NOVA on August 28, 2011 at 8:48am

Pefect!  I am bit behind with building and programming, but this would certainly help with proceeding ahead. Thank you Doug for keeping the flaps option in your sights and coming up with such a great solution..

Comment by Ahmed Rehan on August 28, 2011 at 11:52am

Will auto flaps work in auto takeoff or auto landing mode?

if it can work deep stall landing will be possiable and flaps deployment during takeoff has advantage for hand launch planes with more weight and less power long endurance type .

Good work. will test as soon as apm arrives.


Comment by Doug Weibel on August 28, 2011 at 1:12pm

Hello Ahmed,


Yes, it will work for all navigation commands in Auto mode (including takeoff and landing).  If you are going to use flaps during takeoff be sure you know what an appropriate takeoff flap setting for your airframe is.  Too much flaps during takeoff is bad.

Comment by dusl on August 28, 2011 at 11:31pm
that's great
Comment by Tom in NOVA on May 20, 2012 at 12:43pm

Does (auto) Flap deployment speed matter?  Wonder, if the flaps deploy too fast 50% and later 100% that APM2 can't keep up with stabilizing.  Should I slow down the flap servo or it doesn't matter?

Comment by Philip on February 25, 2013 at 11:05pm

Hi All

   Is auto flaps working?

I am in ground testing with this at the moment and have a servo connected to ch5 and ch6, I have both of these set to Auto_flap. (in auto mode, loiter, RTL, nothing appears to work)

I have tried multiple settings on the flap speeds and percentages and assume something should happen when I blow into the Pitot tube... but nothing... running arduplane 2.7 at the moment, on a 3DR APM2.5.

Comment by Doug Weibel on February 26, 2013 at 7:39am

Yes, auto flap is working.  The functionality has nothing to do with the actual airspeed or the pitot tube.  Auto flaps works only in the fully autonomous modes and is based on the current airspeed setpoint.  You can test your setup by disconnecting your motor (to keep the prop from spinning up), putting in a mission with a few waypoints, and putting the AP into Auto mode.  Then set FLAP_1_SPEED to some speed and FLAP_1_PERCNT to 100, and change the TRIM_ARSPD_CM parameter to be above and below FLAP_1_SPEED.

To use auto flaps in a mission use the change speed command...

Comment by Philip on February 26, 2013 at 2:07pm
Thanks for that, that now makes sense :) will try it today, I am being extra careful on this UAV as my last one only lasted 5 seconds after the dodgy HK AIO board failed after takeoff. Running genuine hardware and latest firmware now :)
Comment by Eduardo Romero on March 3, 2013 at 8:09pm

What are the units for flap_1_speed? cm/s or m/s?


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