Quique Somenzini a few years back showed how to accomplish this on his Beast biplane using the JR 12X. He used the 4-Aileron wing type and swapped the left and right aileron on one wing while leaving them in their conventional locations on the other wing. If you download the 100cc Beast manual and look under the Crow setup, you’ll see how he did it.
His scheme works because all servos rotate in the same direction with an aileron command if none of the channels are reversed. So it makes no difference whether a particular servo is located on the upper or lower wings or on the left or right side as long as all the servo arms point away from or toward the fuselage and all the control horns are on the same side of the ailerons. With this standard setup the ailerons will always respond correctly regardless where they are put. However, with a flaperon command the left and right servos rotate in opposite directions. So if you swap the left and right aileron servos in either the upper or lower wing, a flaperon command will deflect its ailerons in the opposite direction of the other wing ailerons.
So all you have to do is:
(1) Set up a 4-Aileron wing type.
(2) Make sure the FLAP [OUT] in the DEVICE SELECT is set to SYS
(3) Set up a SPS that is on with low throttle.
(4) Set up the FLAP SYSTEM menu in the Function List.
(5) Set up a program mix of FLAP > FPRN. Include the FLAP SYS in the master FLAP channel. Set the POS0 rates to zero. Set the POS1 rates to 100%. Set three switches in the SW SEL to ON: the SPS, AND, and the FLAP SW position for the crow to take place.
(6) Swap the left and right aileron servos on one wing.
In Quique’s setup, the crow is activated by a switch. To have it come on when you idle back makes it more complicated and riskier. I would assume you wouldn’t want it to occur every time you throttle back. That could be disastrous on a landing approach! While the steps above ANDed the FLAP SW and the stick position switch, it is still risky. It is too easy to forget to disengage the crow by flipping off the FLAP SW after you pull out of a dive because the throttle had been advanced enough to turn it off .
I would recommend you scrap the idea of activating the crow with a stick position switch and just used the FLAP SW to turn it on and off. That isn’t fool proof but it would be safer than tying the crow to your throttle.
Allan