Originally Posted by TrumpetRhapsody
Wow that video is awesome! Can't wait to get mine built. I'm especially glad I picked this plane now that I saw that video. This is exactly what I wanted for my first foamie build. High angle low speed passes down the runway, slow acrobatics and such.
I was at the field today, and I've been informed that apparently we have a hobby town and that they carry foam safe CA, so I'll be going by there tomorrow to get some. Awhile back somebody else told me they closed down in our city a year or two ago, but apparently not.
So what is the whole theory behind the KF step wing? I was explaining the design of the regal to a foamie guy at the field today, and got to the part about the KF step (he had never heard of it), and couldn't fully explain how it worked. Does it just give the wing more contour as opposed to the normal flat sheet of bluecore, or is there something special about the sharpness of the step?
Trumpet, I've attached a PDF file that I hope explains what I believe is happening with this airfoil shape. There's a whole thread devoted to the KF- Kline-Fogelman
flying wing. If you read that thread, you'll get a bunch of information to wade through on the KF 'foil, and how different people think it works. The attached PDF drawing is my crude attempt to generally explain what I think is happening. I believe there's much more actually going on with the wing than the drawing depicts. Since the airfoil shape is completed by "air", I believe that the airfoil dynamically changes shape as the speed of the aircraft or angle of attack changes. This is possible because the rotating vortex is free to increase or decrease in size. Since this airfoil dynamically changes automatically, you're always flying with the best possible airfoil shape based upon your wingspan, chord, and step location/height. If the theory I hold is correct, it explains why the airfoil can fly extremely well, both very fast, or very slow. Remember, this is the theory I have, and is by no means proven or necessarily exclusive.
I hope you find it useful.