DaveD
Well-Known Member
I'm looking at using Frise ailerons on my Project-Ex design and on reading Hoerner's Fluid Dynamic Lift, I've come up with some quieries:
The pic on the left is actually a "slotted" type which appears to just be a Frise Aileron but tweaked to encourage flow through the slot... So does this mean that a 'real' Frise aileron should be designed to try and limit the flow through the slot as much as possible? from the 'real' Frise aileron pic (on the right) it looks like you would get some flow through the slot with the aileron deflected up (i.e. anticlockwise), but much less with it deflected down - does this help by adding to the drag of an up deflected aileron? Has anyone seen a Frise Aileron with a sealed gap?
What's everyones opinion on the relative merits of the middle and right pictures compared? Having the surface pivot in line with the wing is probably easier to construct, but what is the effect of the gap in the top surface? Would you get a standing vortex in the 'hole' energising the boundary layer and reducing separation on the control surface... or is that just wishful thinking?
The pic on the left is actually a "slotted" type which appears to just be a Frise Aileron but tweaked to encourage flow through the slot... So does this mean that a 'real' Frise aileron should be designed to try and limit the flow through the slot as much as possible? from the 'real' Frise aileron pic (on the right) it looks like you would get some flow through the slot with the aileron deflected up (i.e. anticlockwise), but much less with it deflected down - does this help by adding to the drag of an up deflected aileron? Has anyone seen a Frise Aileron with a sealed gap?
What's everyones opinion on the relative merits of the middle and right pictures compared? Having the surface pivot in line with the wing is probably easier to construct, but what is the effect of the gap in the top surface? Would you get a standing vortex in the 'hole' energising the boundary layer and reducing separation on the control surface... or is that just wishful thinking?
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