I've read up many articles abou7t KF ... 2, 3 and 4 .... and TBH - they all say same - the benefits can be easily out done by losses ... but one thing for sure - it can stiffen a foam wing.
Studies have shown that it has a very poor speed range for effectiveness ... How think a wing ? I have a couple of models with KF ... but the main one that comes to mind is my RC Eagle. This is a variation on the KF3 type. Instead of having centre sheet and then a KF either side to create the 3 layers ... BOTH KF are placed on top of the wing to create the 'feather pattern' .... The main wing base is 6mm and then the KF are 3mm each ... and only has a single span CF spar instead of two as I would think needed without that KF. The wing is stiff. I would suggest that as thickness increases - the need to create a rounded L/E would increase. If a blunt slab L/E is left with a thick KF setup - then the L/E would be highly critical of Angle of Attack. Rounding it - would create a smoother transition.
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