As the concept of my pet airplane design keeps changing and getting refined, I'm pretty confident that it'll end up as a tandem wing. Out of a desire to improve takeoff and landing distances from a somewhat small total wing area (<60sq ft), I'd like to incorporate some high lift devices. Before leaning towards a tandem, I was playing with the idea of a canard with biplane main wings (to keep each wing roughly 2'x8'), in which case LE slots in the main wings may have been a suitable solution as long as the elevator had sufficient low speed pitch authority.
I don't see why that can't be done on a tandem as well, but it requires something that I'm trying to avoid; using different airfoils for the the fwd and aft wings. The reason for that is simplicity (or at least the perception of it), and thus that propagates to the control surfaces as well, which leans towards elevons in the form of junkers-style flaperons. That ended up leading to the next idea, and the purpose of this thread, as it's something I'm having a little trouble wrapping my head around.
If possible, I'd like to use the junkers-type control surfaces as a flap+elevator+aileron. The way I'm envisioning this is that each wing has this "flapevon", with the wings on a given side being linked together where the the aft wing's flapevon direction is the same, but the deflection angle is proportionally less than the fwd's. In my mind, having these controls surfaces on both sets of wings allows them to operate as flaps (simply by pulling back on the stick). The proportional deflection angles being necessary to accommodates the higher fwd wing loading, allow for pitch control, and (by my understanding) make the fwd wing to stall first, along with some other benefits. It would also be easy enough to implement a flapevon ratio changer if necessary, but I haven't been able to wrap my head around if it is (most likely yes if there's a CG change depending on loading).
Can anyone think of any dealbreakers, or at least non-insignificant flaws in my reasoning, or does this sound plausible?
I don't see why that can't be done on a tandem as well, but it requires something that I'm trying to avoid; using different airfoils for the the fwd and aft wings. The reason for that is simplicity (or at least the perception of it), and thus that propagates to the control surfaces as well, which leans towards elevons in the form of junkers-style flaperons. That ended up leading to the next idea, and the purpose of this thread, as it's something I'm having a little trouble wrapping my head around.
If possible, I'd like to use the junkers-type control surfaces as a flap+elevator+aileron. The way I'm envisioning this is that each wing has this "flapevon", with the wings on a given side being linked together where the the aft wing's flapevon direction is the same, but the deflection angle is proportionally less than the fwd's. In my mind, having these controls surfaces on both sets of wings allows them to operate as flaps (simply by pulling back on the stick). The proportional deflection angles being necessary to accommodates the higher fwd wing loading, allow for pitch control, and (by my understanding) make the fwd wing to stall first, along with some other benefits. It would also be easy enough to implement a flapevon ratio changer if necessary, but I haven't been able to wrap my head around if it is (most likely yes if there's a CG change depending on loading).
Can anyone think of any dealbreakers, or at least non-insignificant flaws in my reasoning, or does this sound plausible?
