Ahoy, EAA Designers,

A bit of wing flap information from YEARS ago, when I had access to an excellent 4' x 3' wind tunnel and I was designing a very conventional low wing side by side airplane. (Never built - too much sea duty). The fuselage was ~~ 44" wide (max), square corner at the trailing edge of the wing. I fastened split flaps ~~ 20% chord. Tried different span coverage. Best C/L was achieved with the flap STARTING about 9" to 12" outboard of the -- full scale -- side of the fuselage. (Very handy for a wing walkway). I no longer have any data, but the flap all across - like the Mustang II - was of a significantly lower max C/L, and much higher drag.

BTW, Split flaps are often referred to a 'drag flaps'. Not so: They are quite effective, and easy to build, much better than a simple flap ala Cessna 150, but not so good as a modern Fowler flap -- with modern CNC -- easily done.

Look at old airplanes: DC-3, SNJ, B-17. All had split flaps. Lockheed (I believe) was about the first to use Fowler flaps in production.


Enjoy /s/ Bob