I recently received my Ardupilot mega, but I could not find instructions on how to get it working on airframes like Twinstar, which have separate servos for each aileron. One related blog post here in diydrones mentioned, that feature is being implemented (although I did not find an open issue about it) but I was too impatient to wait for proper fix.
Here's my ugly fix for this:
1. Disable aileron mixing from transmitter and make connections to ardupilot as you would do on 1-servo aileron case.
2. Connect 2nd aileron servo to ardupilot output 5
3. Open ardupilot sketch in arduino ide and open "Attitude" file
4. Insert these two lines to place marked in picture:
g.rc_5.radio_out = g.channel_roll.radio_max.get() + ( -1 * (g.channel_roll.radio_out - g.channel_roll.radio_min.get()));
APM_RC.OutputCh(CH_5, g.rc_5.radio_out); // send to Servos
5. Compile and upload
Remove "-1 *" part, if 2nd servo does not need to be reversed compared to 1st servo.
Since failsafe mux only operates on first four channels, on event of failure, 2nd aileron can't be moved.
I hope this feature will be implemented properly in the near future, but this should do at least for now and at least for me. Hope this helps others too!
One thing to keep in mind, Historicly, the reason we were keeping aileron support to one channel, was keeping the first 4 channels (mux passthrough) was allowing for primary rc control, in case of APM failure.
Flapperon support takes primary navigation out to a non-muxed channel. This causes a configuration that could fail if the apm failed and couldnt support a hardware manual mode.
Now that being said, that was early on...
Today; a quad copter (ACM) will never be flyable with hardware manual, (thats why they avoid ch8...)
so whats the huge issue with having a non-flyable config if apm goes on the blink?
(apm may glide, acm will plummit)
I feel it could to be added to the APM3 wish list, as enhanced speed control options with flapperon and potentialy airbrake support.
Yes it would be nice to have proper flaperon support. And that is something you can not get with Y-cable, nor with reversed Y-cable.
And BTW can someone add a "flaperon" tag to the blog post ? (added by moderator)