Random thought...
Butterfly or V-tails can be elegant and attractive, but the one-up and one-down ruddervator movement for left or right rudder application causes adverse aileron roll as the ruddervators try to twist the plane wrong way. Inverting the V-tail solves that problem, so the twist is in the right direction, but tend to have ground clearance issues unless carried on the end of twin booms. So here's my idea....
What about putting two separate control surfaces canted inwards 45 degrees on the end of a relatively narrow-chord horizontal surface, basically an H-tail but with the verticals now canted? The horizontal surface would be fixed, really more of a faired strut, but it would add a little pitch stability and might be a good location for a trim tab. All the pitch and yaw control would come from the canted surfaces, like the two "wings" of an inverted V-tail but separated. The horizontal separation would actually magnify the beneficial roll effect with rudder.
I have this in mind for a simple, two-axis machine along the lines of a Sky Pup but looking more like an Ercoupe, but this could certainly work for a conventional three-axis machine as well.
What do you think?
Butterfly or V-tails can be elegant and attractive, but the one-up and one-down ruddervator movement for left or right rudder application causes adverse aileron roll as the ruddervators try to twist the plane wrong way. Inverting the V-tail solves that problem, so the twist is in the right direction, but tend to have ground clearance issues unless carried on the end of twin booms. So here's my idea....
What about putting two separate control surfaces canted inwards 45 degrees on the end of a relatively narrow-chord horizontal surface, basically an H-tail but with the verticals now canted? The horizontal surface would be fixed, really more of a faired strut, but it would add a little pitch stability and might be a good location for a trim tab. All the pitch and yaw control would come from the canted surfaces, like the two "wings" of an inverted V-tail but separated. The horizontal separation would actually magnify the beneficial roll effect with rudder.
I have this in mind for a simple, two-axis machine along the lines of a Sky Pup but looking more like an Ercoupe, but this could certainly work for a conventional three-axis machine as well.
What do you think?
