Converting V-tail???

[Newtron]

Hi... so what happens when you use v-tail controls on a split elevator / rigid rudder setup... both elevators up = pitch up... both elevators down = pitch down... right elevator up / left elevator down = yaw to right???... left elevator up / right elevator down = yaw to left???... I have the servo card and TX from an Aerobird Challenger... can anything be done with it other than another V-tail setup?... thanks... Tim

[stu78]

Im sure you will get more informed responses, but this is mine:

If your elevator is flat (i.e. not a V) there will be no direct yaw from the elevator halves moving in opposite direction as there is with a v-tail. Instead you will get roll (like ailerons, but much less responsive because they are more inboard) so it may work, but I'm pretty sure the deflections will have to be opposite to a normal v-tail (i.e. for left, left surface up, right surface down).

You could probably use the gear on a flying wing with elevons, as elevon mixing is very similar to v-tail mixing.

Stuart

[Sparky Paul]

You would get a modest rolling effect with a v-tail system on a flat horizontal.
Nothing to fly a plane with as a primary control.

[John O'Sullivan]

On a normal V-tail, Right surface up and Left surface down produces a Left yaw (and also a minimal Right roll effect).

Right surface down and Left surface up will give a Right yaw (and a minimal Left roll effect - "adverse roll") . (think of the effect if you rotated each surface to the vertical)
The roll force is much less, but acts Opposite to the yaw force.

With an inverted V tail Right side up and Left side down gives a Right yaw and also a minimal Right roll ("proverse roll"). This is more coordinated aerodynamically and is the reason that many UAVs use this layout.

John O'Sullivan

[HELModels]

That explains alot! I experienced the right roll, left yaw effect with my v-tail. Every once in a while in steep stall turns, it will start to roll opposite to input. The main wing must be fully stalled and as soon as the wing starts to recover, the apparent reversal goes away. I guessed that it had something to do with the v-tail not being stalled while the wing was, and the v-tail being a bit larger than really necessary. It still mystifies me when I see it.

BTW, Mr. O'Sullivan, I also get the pusher tendency to turn under high power. You mentioned a long time ago that one of your pushers required full left rudder under full power. I chalked mine up to asymmetric alignment of the motor, but it never went away completely after that was corrected, although it improved.