Hi All,
I would like to ask if it is possible to configure Arudplane to have vertical elveons ( Rudder that consists of upper and lower part) beside horizontal elevons?
I know it is weird question but I found this configuration in “Dornier Do 335”.
I was watching this video about planes in WWII and this question popup to my mind.
That’s just a dorsal and ventral rudder, and there’s nothing stopping you from assigning rudder output to more than one servo (or just use a Y cable) to control both surfaces.
The example aircraft has no elevons, but rather a conventional horizontal tail with an elevator.
who said one servo ? 
I wanted to have two servos to the ventral rudder (same as elevons) so I can have differential move of the control surface.
This shall provide more control.
so you want to mix roll into the rudder?
Yes exactly!
The rudder move is right , left and roll
im not sure if it could be done without a lua script. another option is just to plug the rudders into a vtail mixer to mix them with roll.
I think you’ll find that aft surfaces so close to the longitudinal axis will act more like speed brakes than they will provide a rolling moment when actuated asymmetrically. But @geofrancis has the right idea for mixing them if you really want to do that.
I don’t think the example airplane used its dual rudder the way you are picturing it…
yes, I think its just a 2 piece rudder, I dont think the parts were independent.
I have done a split elevator by converting it to elevons to help with roll control but that was with a skyhunder twin boom plane with the elevator in the prop wash. because of the thrust directly over the tail it gave it pitch and roll control at zero air speed.
can you please clarify more? what is exactly lua script ?
its a script that can run on the flight controller to get custom actions.
https://ardupilot.org/copter/docs/common-lua-scripts.html
Many thanks for the support.
From the first glance, it doesn’t look as easy as I expected.
I will give it more study.
Aerodynamically, it’s also not super simple.
Consider the case where a 2 channel glider has only rudder and pitch control (or picture sitting in a traditionally configured aircraft and skidding all the turns with rudder only/neutral aileron).
The rudder is typically mounted above the longitudinal axis, and this thus you might guess that the rolling moment caused by rudder input would induce a roll opposite the pedal pushed (i.e., left rudder, right roll).
In reality (and over-simplified) the left yaw pushes the right wing faster into the slipstream, overcoming any minimal roll moment from the rudder surface, causing more lift on the right wing, and thus a left bank.
As such, a very docile, positively stable design can be successfully controlled with only pitch and yaw control.
Extrapolating that concept to your proposed design…I’m not confident at all that it will work that way you guess it might, and again, you might just end up with a what amounts to a squirrelly speed brake rather than effective roll control, particularly if you expect to achieve coordinated turns with these tail surfaces alone.
Now a big rudder surface can certainly make for some fun flying. Consider the rather poorly named “3D aerobatic” class of RC airplanes (or the Extra 300 / Yak 55, among others). Often a huge rudder surface is used as a surrogate elevator during knife edge passes. So a crossed tail design like that (without the fancy mixing) might make for some interesting aerobatic characteristics given a high thrust to weight ratio.