Wing VG's Installed - HS VG's ????

[John Bickham]

Yesterday I installed John Gilpen's Stolspeed VG's on the wings. I had the pleasure of spending a few days with John G a few years back in SE Oregon when he made his "see the USA tour". I was a Kolb driver then too.

I've done some test for take-off, landing, stalls and slow flight prior to installing the VG's. I didn't think about this being in the category of "major change" till I was putting on the second to last VG. So now I'm waiting for the "right" FAA type to return my call for notification and approval of flight test area for return to phase 1. While I wait for the FSDO to call me any second, , I'm sorting out my test data.

I'm still on the fence on installing the VG's on the Horizontal Stabilizer. I have a 4-Place Model A with the epoxied wood profiled ribs. I think I got one of the last sets of these Mark had made. My review of previous post seems like mixed reviews. I was wondering if anyone has done any evaluation of VG's on the wing first and then with the HS VG's added later? Or did most just install on both the wings and the HS and go fly. I want to bad! Two simultaneous changes are hard for me to discern the real effect.

DSCF3001.JPG
That's between the third and fourth rivet on the Model A wing, as recommended by Jonathan.

DSCF3009.JPGDSCF3007.JPGDSCF3010.JPG

and if you ain't got nothing to do, light BH porn -- https://youtu.be/VRocXsq2RQM

[Utah-Jay]

I had already watched your video… I am a subscriber

I love practicing landings

https://youtu.be/L_3bYqwdec4

[N942VT]

I had installed VG's on the horizontals on my A model 4 place but not on the wing. It was an effort to help get the tail down on touch down and it made a significant difference. They were not profiled ribs. After install it was easier to touch tail wheel first when light.

[John Bickham]

That is an interesting point. I am kinda working in the opposite direction. Since I'm working on landing on rougher and unimproved strips, I'm trying to keep the tail up for over the nose visibility and protect the tailwheel.
Thanks for that.

[Rollie]

That also translates to getting more elevator authority in slow flight/stalls. With a forward cg, before I put the vg's on the tail, I wasn't really getting to a full stall, I was just running out of elevator. I didn't really realize that until I did some stalls with weight in the back seat and my stall speed decreased by several knots.

[Bissetg]

Is anyone flying Stolspeed VGs on the Riblett wing? I’ve flown microairs on a C210 and 172, very impressed with the slow flight improvements. Curious as to how the Riblett airfoil responds. I understand they have to be mounted well forward (6%) of chord???

[Battson]

Is anyone flying Stolspeed VGs on the Riblett wing? I’ve flown microairs on a C210 and 172, very impressed with the slow flight improvements. Curious as to how the Riblett airfoil responds. I understand they have to be mounted well forward (6%) of chord???

I understand that they are best positioned so that when the wing is at the highest angle of attack, the VG is fully exposed to the oncoming airflow i.e. at the highest point of the wing. That's how I arrived at my recommended location for install, and practically it's proved a winner. You can apply the same approach with your aerofoil, all you need to know is the AOA at stall (in landing configuration). You want them at the highest point of the wing, when it's at the stall AoA.

Some guys put them too far back, i.e. 12% of chord is sometimes mentioned. This isn't ideal from what I have heard.

My understanding comes from a lot of pre-reading, watching other guys testing on Youtube, practical experience on my own plane (the modified NACA Bearhawk-A aerofoil), and discussing the Breeden's experience from testing VGs on their Cubs in AK. Bob B reached the same conclusion as I did, highest point on the aerofoil at stall AoA.

[Bissetg]

Thanks Jono, that is my understanding as well. I’ll report on my testing.