DX 7 Differential Programming

The DIFFERENTIAL function only goes "positive". Which means if you aren't getting the DIFFERENTIAL way you NEED to, you have to exchange/swap the servos between AILERON and FLAP (plug what was the LEFT wing into the RIGHT wing RX connector, etc., then tweak directions, and ATV's as needed).

From the manual: (Setting WING TYPE)

Press the Increase or Decrease key until the desired wing type appears on screen: NORMAL, FLAPERON, DELTA WING

NOTE: When Flaperon or Delta Wing type is selected, the travel adjustment is used to adjust the individual servo throw; while the combined aileron travel is adjusted with the aileron dual rate. It is also possible to set aileron differential. Reverse switches are applicable for each servo. Neutral adjustments of each servo are made by the Sub-Trim Function Flaperon Wing Type Connections AILE servo port (right aileron) AUX1 servo port (left aileron) Delta Wing Type Connections ELEV servo port (right aileron) AILE servo port (left aileron)

Translating this means they have programmatically-bound the Differential function to the configuration of AILERON and FLAP channels as specified in the "setup" instructions in the manual.

IF that is your configuration [Right aileron plugged into AILE, Left aileron plugged into AUX1], then positive differential means "Less Down than Up aileron travel", and it will affect both channels properly by reducing the DOWN aileron travel, even though the display indicates a + (positive) value!!!.

IF you need "reverse" differential, the only solution is to configure your AILERON and FLAP channels OPPOSITE to the instructions.  To spell it out, for "normal" differential, plug Right Aileron into AILE, Left into FLAP.  For "reverse" differential (more Down than Up), plug Right Aileron into FLAP, and Left Aileron into AILE.

I have tested this.  It is so.  Weird discovery, but true.

Thanks to "The boys Back" on RCU for asking about this, and helping us discover it!

(Weird though it may be)