Matthias... little did you expect to get your plane back. Have you flown it since its been repaired? I hope you'll have many more great flights with this aircraft. The KF airfoil concept continues to grow. Did you ever get to see Dave Powers "KF Airfoil Testing" on YouTube. It turns out that the KFm4 is faster than the other versions. Maybe its because 50% of this airfoil is air against air, thus no direct friction or drag. Be well.Dick Kline
ApachePilot is now working on a KF5 wing that will include some slats on the leading edge. His flying wing Divinity has two steps on top and one on the bottom. View his video here: http://www.vimeo.com/3654017
The steps should be just deep enough to trap a vortex to the wing as an attachment which prevents separation. Think of it this way. The KFm4, which has a step on the top and bottom @ 50%, means that 50% of this airfoil produces no direct friction or drag because it is air against air. That is why it flies faster than the other KFm airfoils. The KFm3, top steps on top, is a heavy lifter and good for camera work. Here is an example of the nice groove this plane flies in. http://www.rcgroups.com/forums/showthread.php?t=1017445
In my opinion, simple paper airplanes also have an airfoil like this KF. So the advantages are that the wing structure is lighter and there's no need for any extra turbulators after the leading edge?
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The steps should be just deep enough to trap a vortex to the wing as an attachment which prevents separation. Think of it this way. The KFm4, which has a step on the top and bottom @ 50%, means that 50% of this airfoil produces no direct friction or drag because it is air against air. That is why it flies faster than the other KFm airfoils. The KFm3, top steps on top, is a heavy lifter and good for camera work. Here is an example of the nice groove this plane flies in. http://www.rcgroups.com/forums/showthread.php?t=1017445
In my opinion, simple paper airplanes also have an airfoil like this KF. So the advantages are that the wing structure is lighter and there's no need for any extra turbulators after the leading edge?