I have previously made two "safe" attempts at addressing these seemly draggy locations and both failed. One was to cover the top hole with a thin aluminum plate that moved up with the aileron at the wing tip and the other was to flush plug the recesses in the ends of the flaps and ailerons. I have rationalized a cause for the failures similar to holding a bottomless cup into the wind out of a car window compared to the same cup with a bottom in it. In both cases the inlet was unaltered but the outlet was closed or choked down. There is rational thought that says they should have worked but experiments and testing showed otherwise.
I don't know how much can be gained in this area but I'm convinced if there is anything it is on the inlet and shape of the structure on the bottom of the wing. This is a worrisome area because the constantly moving roll control surface is right there adjacent to the possible drag area. I have seen this addressed with fiberglass fairings on a very fast RV-8 and the well known owner who shall remain nameless told me they weren't worth much. Still, I don't have anything better to look at at the moment and I have three weeks until the next race. Yesterday, I got under the right wing especially the outboard end of the aileron with some 0.016" 2024-T3 aluminum and some tools and fashioned a square edged fairing that would cover the back slanting mount and the width of the opening and could be mounted with screws to make it serviceable. It looked neat but it occurred to me that the resulting ramp would be several times wider than the mount. I could rivet a rounded solid leading edge to this and I ordered a couple of feet of bar stock just in case I decide to go this way. There is a more wedge shaped fairing possibility but this could change the direction of the air flow and actually force more of it into the gaps for control movement - vertical parallel side walls seem best. I can still put on the modeling clay and give fiberglass a shot as well. Ice and improperly mounted fairings in this area could cause serious problems.
Just thinking at this point.
Bob Axsom
I don't know how much can be gained in this area but I'm convinced if there is anything it is on the inlet and shape of the structure on the bottom of the wing. This is a worrisome area because the constantly moving roll control surface is right there adjacent to the possible drag area. I have seen this addressed with fiberglass fairings on a very fast RV-8 and the well known owner who shall remain nameless told me they weren't worth much. Still, I don't have anything better to look at at the moment and I have three weeks until the next race. Yesterday, I got under the right wing especially the outboard end of the aileron with some 0.016" 2024-T3 aluminum and some tools and fashioned a square edged fairing that would cover the back slanting mount and the width of the opening and could be mounted with screws to make it serviceable. It looked neat but it occurred to me that the resulting ramp would be several times wider than the mount. I could rivet a rounded solid leading edge to this and I ordered a couple of feet of bar stock just in case I decide to go this way. There is a more wedge shaped fairing possibility but this could change the direction of the air flow and actually force more of it into the gaps for control movement - vertical parallel side walls seem best. I can still put on the modeling clay and give fiberglass a shot as well. Ice and improperly mounted fairings in this area could cause serious problems.
Just thinking at this point.
Bob Axsom
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