I'm building a Ziroli 'Stuka' and wondering about the location of the various control surfaces. The plans show the LE of the ailerons, and flaps, even with the TE of the wing. I'm wondering what, if any, changes in control are obtained by changing that configuration-even slightly? The question goes more to what if I'm off by a small bit in making up the surfaces? Getting the split flaps to move precisely in unison proves to be more of a challenge than I expected. The Junkers style control surfaces don't appear to have been used very much, at least not to my knowledge. Any thoughts? Bill

There is a simple reason that the Junkers type control surfaces went the way of the DODO bird.....

They create a lot of extra drag with no benefit when they're doing nothing, much less when they're deflected.

When conventional surfaces are "at rest" they create no extra drag. Ailerons that're in a conventional wing are simply part of that wing when they're not working. With Junkers ailerons or flaps, they're extra drag that wouldn't be there when they're doing no extra work. After all, the Junkers wing is simply a conventional wing with "unmovable ailerons" isn't it. But with another entire little wing stuck under it's trailing edge.

An airplane with Junkers type control surfaces is slower and uses more fuel and weighs more than that airplane would be with conventional surfaces. You'll notice that the Germans didn't produce any airplanes with that style surface after the few that used them.

If you consider the wing with it's "Junkers" junk as if it were a biplane, some ideas stand out.

There is interference between biplane wings that reduces the effectiveness of both wings. To solve that requires separating the two biplane wings quite a bit. The amount of separation needed is something like the chord of the widest wing. Quite a bit, right. So considering that concept, if the wing of the Stuka is the top wing of a biplane, if only half it's chord would be needed to free the "lower wing" of interference, how far would the ailerons/flaps have to be to be out in the clear? so...............

Assuming the ailerons/flaps are in disturbed air, it's probable that their positioning won't matter much. I would think that any differences that evolve from different positioning will be minute and probably impossible for an RC flyer to feel.

I like the biplane comparison, makes sense. I was concerned about the airflow over the top at the TE of the wing colliding with the LE of the ailerons/flaps and how that might affect control, if I had the control surfaces to far aft. But, supposedly the Ziroli Stuka is a good flier. Thanks again.