what are the pros/cons of barn door ailerons vs full length?

The main reason most kits have strip ailerons is that by extending the aileron to the root of the wing you are close to the fuselage which allows a single servo to drive both ailerons. Using barndoor ailerons requires installing either two servos or a complex mechanical linkage if only one servo is to be used. I don't know what the aerodynamic considerations are, if any.

Dave Segal

With full length ailerons, the tip half of the aileron length produces about three times as much rolling moment as the root half. The thing that saves full span ailerons is that the narrow chord of the full span aileron is almost as effective as a wide chord aileron. The ideal aileron chord ia about 20 to 25% of the wing chord and the ideal location is in the outer half of the wing.

The big disadvantage of wide chord control surfaces is the very high load that they put on the servo and linkages.

thanks guys. I suppose from your answers there is no aerodynamic advantage to strip ailerons, and no disadvantage to barn door type other than need for extra servo? I'm finishing up a Slow Poke 40 with barn door ailerons. Would I realize any benefit to enabling the flap function on my computer radio for a wing with this much area 1076 sq in len 61" cord 14", or will it just float anyway?

If you arrange the flaps so that they deploy about 70 to 90 degrees, they will produce lots of drag, lots of lift and a nose up pitch. If you mix in some down elevator with the flap deployment you can have any slow, power-glide angle you want. The slow power-glide may be nose down so you may have to time the flair so that you touch down with a slight nose up attitude. With a little wind you should be able to bring it in almost vertically over the spot that you pick. All this assumes that the engine idle RPM and prop pitch combination is such that little or no thrust is being produced in the slow power-glide. A low RPM idle and a low pitch prop can even produce drag rather than thrust at a moderately high airspeed. An engine with at least five to one maximum to minimum RPM ratio is what works best in this application.

G-H....Couple of things....With the "barn-door" arrangement you'll find less travel required for ailerons to have same roll effect as full length ailerons...but as Ollie mentioned more servo strength is required to move that surface(big surface elevons...aileron function and elevator function mixed together were employed on the F117 Stealth Fighter to reduce surface movement for maximum roll inputs to reduce Radar attenuation....helping keep its slick stealth profile...)...with a plane such as yours you could also mix in alittle aileron droop( aileron droop is a "trick" employed on large commercial aircraft to get all the lift possible for takeoff and landing) during flap extension to increase lift and also adds some stability with flaps extended....have fun....Bill....