Vortex generators

[GraemeSmith]

Carlos,

I don't have one. You would need to experiment and find out. However you might want to find some glider guys and ask them about "turbulator tape". It's a sort if VG Tape they use.

[radfordc]

You said, "A surprise for this "Hershey Bar" flat wing was how the air separated and the wing stalled in the wing
root first and the wingtips maintained airflow and aileron authority without the help of twist or washout
in the wing. "

I'm not surprised at all. Every description of stall characteristics of a rectangular wing that I've ever seen indicates that the stall progresses smoothly from the wing root to the outer portion of the wing.

https://aviation.stackexchange.com/ques ... t-the-root

[GraemeSmith]

You said, "A surprise for this "Hershey Bar" flat wing was how the air separated and the wing stalled in the wing
root first and the wingtips maintained airflow and aileron authority without the help of twist or washout
in the wing. "

I'm not surprised at all. Every description of stall characteristics of a rectangular wing that I've ever seen indicates that the stall progresses smoothly from the wing root to the outer portion of the wing.

https://aviation.stackexchange.com/ques ... t-the-root

Thanks for that. Interesting. I guess I was influenced by the wings I've flown or read about where some washout is introduced to make sure the tips stalled last.

--

Meantime - my Brother in Law - an avid model glider builder when he is not flying real gliders - suggested I explore using "Alula". He has been trying to mimic them on his models using turbulator tape

https://www.researchgate.net/publicatio ... ian_flight

[Bryan Cotton]

Article on turbulators on sailplanes:
http://www.standardcirrus.org/Turbulators.php

If I understand correctly, the zig zag tape is not to benefit stall but to reduce drag in cruise. All the glass guys had it but I don't think us "tin men" have nice enough airfoils to worry about a long run of laminar flow degrading into a separation bubble. If nothing else I bet the aft edge of the forward skin trips the flow.

Carlos, all I can say is one test is worth 1000 expert opinions. Would be interesting to see.

[Area 51%]

The publication escapes me (I'm thinking Plane and Pilot), but some years ago I remember reading an article about someone experimenting with a perforated tape along the thick portion of aerodynamic surfaces. They were testing it on the propeller, wings, and lift struts of a Cessna.

The perforations were patterned after golf ball dimples. All reports were positive at the time, but the lack of dimpled skins and propellers on today's airplanes brings into question the validity of the reports.

I did, however, have an unusually fast 172 that was otherwise stock except for light hail damage. Hmmmmmmmmmmmm?

[tx_swordguy]

Out of curiosity did any of the guys that have or tested the vgs, did it effect your cruise or top end airspeed?

[Sonex1517]

I have no data to prove this, but I don’t see any measurable or significant change in my top end cruise.

Your mileage may vary.

[509sx]

It occurs to me that a place where almost all legacy Sonex birds could use a couple of VGs is the wing root/body side junction. Here one would want to use the VGs to create co-rotating vortices to bring high-momentum air down into the corner. The VGs, then, would be angled with leading edges towards the intersection, maybe two on the fuselage and one or two on the wing. The problem is setting up so you can tuft the intersection and see the tufts. I sure am not keen on putting an expensive GoPro out there on a suction cup!

[GraemeSmith]

It occurs to me that a place where almost all legacy Sonex birds could use a couple of VGs is the wing root/body side junction. Here one would want to use the VGs to create co-rotating vortices to bring high-momentum air down into the corner. The VGs, then, would be angled with leading edges towards the intersection, maybe two on the fuselage and one or two on the wing. The problem is setting up so you can tuft the intersection and see the tufts. I sure am not keen on putting an expensive GoPro out there on a suction cup!

As I recall Mike Smith did some work on that transition area and photographed the results. Mike?

[509sx]

I watched Mike's video, and noted his trailing-edge extensions (sort of a poor man's fillet) at the trailing edge wing root. It looked like it worked (Kudos to Mike!). I noticed some VGs used to help tame a corner flow on a twin parked at my airport, and thought perhaps this could be a simpler way to clean up that intersection, reducing pressure drag due to the local flow separation. Got to work out how to get photographic evidence without risking either: A. losing an expensive camera, B. wrecking my paint job removing 300mph tape after-the-fact, or C. having to install a rivnut in my wing's upper surface as a camera mount. Obviously, a video cam with remote on/off switching would be highly desirable.

Did some slow flight and stalls recently, and it seemed fairly obvious to me that the stall "warning" largely comes from an H-tail inheriting a messy, separated flow from the wing-root area. It spoke to me through the megaphone aft fuselage!

Art 509SX Sonvair 2700 TD, Southern WA