Vortex Generator position VG

[DesertFox4]

Great video Bryan.

The larger elevator would be a good mod to increase elevator authority in the flair.

[jrthomas]

I installed Stolspeed vg's yesterday and thought some of you might be interested. I installed mine about 2 and a half inches from the leading edge. I used the 90mm spacing except for the 24 inches from the wingtip where I used the 60mm spacing. My flight testing was not under ideal conditions since it was mid day, well into the 90's and thermals making things pretty bumpy but the results seem to be pretty impressive so far. Stall with zero flaperons went from 45 mph to 40. There was a tremendous increase in angle of attack before stall with the vg's, especially with flaperons, so obviously they're working. I don't have any exact stall numbers with flaperons down because of the thermals and the wind changing directions. I was into the mid to upper 30's but I'd like to try it again in more calm air before giving any exact numbers. It's just amazing how it hangs in the air at that speed and AOA. Oh, I'm flying a Model 4/1200, 912ul, long wing but with all the Speedster options so it's a little heavier than some. James Thomas

[Hockeystud87]

Great info! I was thinking about VG's at some point as well... Lowering your stall is never a bad thing!

Any issues on the top end? Speed decrease?

[jrthomas]

I plan on flying tomorrow so we'll see how it does and maybe post my results tomorrow night.

[David47]

Did you put any vg’s on the stab. Lower surface as well ?. This should increase overall tailplane effectiveness ...

[jrthomas]

Not yet and not really planning to at this point though that was my plan before I flew it. Slow flight AOA is so extreme that I can't imagine needing more elevator. A full stall landing, stick all the way back would cause the tailwheel to touch long before the mains as is.

[skyguy04]

Just chiming in here with another report on the Stolspeed VGs. jrthomas helped me install the Stolspeed VGs on my Model 4 Speedster. We installed them at the same location (about 2" back from leading edge). Basically we just put the nose of the VG on the leading edge tape line. We did not stagger them, and we used the 60mm spacing. My Speedster has the short wing and it worked out to exactly 60 vg's per side.

First flight test showed very noticeable difference. No flaps p/off stall went from 47 to 43, full flaps from 41 to 37-38ish. Also the stall characterics improved. It used to buffet/shake when it stalled and now it just hangs. Very smooth/solid feel as the nose just bobs. P/on stall is ridiculous. The AoA feels like i'm standing on the tail and it stalls in the low 20's. If I am ever in that situation on takeoff, i've got much more to worry about than stalling.