flaperons

[Flybyjim]

What is the reason for the flaperons separated form the wing. Seams this is not the norm on most planes, must be an advantage/disadvantage?

[jiott]

I don't know all the reasons why, but I understand that the separated flaperon helps the airflow to stay attached at high AOA. When airflow starts to detach it begins at the trailing edge of a wing. The separated flaperon acts like a small independent wing. It also adds to the total wing chord (area) and gives high roll rate as an aileron because it is full span and high drag as a flap for the same reason. It is also quite simple to build compared to trying to incorporate it as part of the main wing trailing edge.

I believe it has some disadvantages compared to conventional flaps, but maybe someone else can explain what and why.

[FoxBob]

I'm not an engineer, but I have read about this. The Junkers (pronounced yoonkers)-style aileron has advantages and disadvantages, like everything else in engineering. In the case of the flaperon, the roll rate is not as enhanced as you might think, as the inner part does not exert as much leverage on the wing as does the outer part. The separation from the wing does keep air flow attached longer for lower stall speed and better control at higher angle of attack, but the cost is increased drag, because the gap between wing and flaperon forces air to accelerate, and this always creates drag. Works great on a relatively low-speed wing, though! My understanding is that the Kitfox flaperon generates a great deal of lift, but not-so-much drag.

[N981MS]

Another difference side is increased adverse yaw with flaps extended.

Not really a big deal and it reinforces the need to keep your feet on the pedals and use the rudder appropriately.