Video of VG's on top of wing

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Video of VG's on top of wing

Postby av8rps » Fri Nov 18, 2011 12:39 pm

I found these cool videos of tuft testing a Kitfox Model II wing (uses same airfoil we do) before and after VG's installed on top of wing. I hate having to admit I was wrong before, (thinking VG's on top of the standard wing didn't do much), but I obviously was wrong. These two videos prove it.

I think my Highlander and my Kitfox are going to get VG's :oops:




No VG's installed; My Kitfox Model 2 with wool tufts on the upper wing surface to test the stall characteristics before installing vortex generators. Stall progresses out the wing from root to tip as designed although it's hard to get the tip to finally stall. Sequence is takeoff, climbout, the stalls including a deeper one where the tip finally stalls and the plane falls off in roll before recovery, followed by a flyby of my hangar and then approach/landing. Notice how fabric appears loose and flutters/oil cans, especially toward the wing root. Couldn't tell if this was just loose fabric, bad turbulence at the boundary layer, or natural flexing of the wing. See followup vid with vortex generators installed for more on this problem.



After VG's installed; A second vid now with vortex generators installed along the leading edge upper surface of the wing, 7% cord aft of the leading edge on my Kitfox 2. Sequence is takeoff, climbout, accelerate to cruise airspeed, then a sequence of stalls. Main difference from previous vid is that I can't get the stall to progress out to the tip with vg's installed and it occurs 5 mph slower (30 vs 35 mph). Also, the flexing of the fabric noted on the first vid doesn't appear here. I did tighten the fabric a little with a heat gun but think most of this is due to smoothing of the boundary layer caused by the vg's.
av8rps
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