Buffing out the inside curve on the winglet

G'Day john,

Great to see you some polishing done! Is that a tape vortex generator there in front of the aileron tape? Have you noticed any affects from it?

Ray Tolhurst

Hi Ray, yes, that is "zigzag" and is intended to trip the laminar flow slightly before it naturally trips. As the theory goes the flow should re-attach and improve the performance. The zigzag was on it when I bought it. I assume it was done at the factory since the guys who owned it before me weren't big glider enthusiasts. It needs to be in the right place for it to work. From reading the various Dick Johnson articles over the years on laminar flow, if it's too far forward it degrades performance and if it's too far behind the separation point the separation "bubble" is too high off the surface of the wing to affect it. I've never flown it without zigzag, so I don't really know if it helps. I have flown with other Ximangos, though and several have commented that mine seems to go better engine off than theirs. It's also on the bottom, but farther back than the top. This is typical for what I've seen on racing sailplanes where there is zigzag top and bottom, indicating that the attached flow goes farther aft on the bottom of the wing. That also makes me think it's factory. The way to tell where the separation bubble occurs is to oil test the wing in flight and record where the pattern in the oil shows the separation. I'm playing with that on my Europa touring bird right now on these cool, stable winter days.