Micro AeroDynamics VG Installation

[stewartb]

Probably not enough air flowing there to do much. Venting the flap LE ala Rev 3 would work better.

Maybe you could get Carbon Concepts to build you some slats?

[courierguy]

One thing at a time, and preferably easy on and off, for experimental purposes. Still not quite ready to invest in slats, time and labor wise, and any speed hit. Which also means less range and duration, least we forget! Besides, any enhanced flap action may only compliment any future slat install.

[stewartb]

Replicate your flaps but extend the chord?

[courierguy]

That's been done, by S-7 guru Joel Milloway, with good effect, no decrease in cruise near as he can tell, and more effective flapping. But he also made them wider span, and went deeper chord on the ailerons also. In other words, he had to fabricate 4 new control surfaces, including the ribs for them, then cover and finish them. Something to keep in mind if I wreck mine and need to re-build it, but way more of a mod then I want to mess with as a minor add on. I also know some (Hal Stockman) have extended the chord by attaching brake formed aluminum trailing edges, right over the fabric, to the flaps and ailerons, again with good effect. Both methods add a bit of weight though, and Joel was the one who wants me to try the VG's as an alternative. So at least I'll have someone to blame if they don't work! I'm calling Micro today to see about pricing for a few, as a multiple time buyer of complete kits I'm hoping for a fair deal from them on a dozen or so of the same size I have on the wings.

I am in no screaming need of doing anything at all, the plane flies great as is, lands real slow with good control, etc., etc. I'm just being greedy, like we all are when it comes to STOL, I want just a little more. Last weekend pic, two different sites 8 K+, the new ultralight Airstreaks at 3.5 psi handle the sharp rocks just fine.

[courierguy]

last pic

[skywagon8a]

....and Joel was the one who wants me to try the VG's as an alternative. So at least I'll have someone to blame if they don't work! I'm calling Micro today to see about pricing for a few, as a multiple time buyer of complete kits I'm hoping for a fair deal from them on a dozen or so of the same size I have on the wings.

I am in no screaming need of doing anything at all, the plane flies great as is, lands real slow with good control, etc., etc. I'm just being greedy, like we all are when it comes to STOL, I want just a little more.

courierguy, Notice what is happening to the streamlines over the trailing edge starting at about 1:07. See how the one closest to the upper surface has moved away from the wing. This indicates that the boundary layer flow has moved some distance above the wing at high angles of attack when you are looking for your VGs to help the flaps. This means that VGs will likely have no effect at all for your experiment. Do not be disappointed if nothing happens. If you can prove me wrong good, I will have learned something.



Here is another using yarn demonstrating the same result.

[phdigger123]

The RANS S-7 has what I believe is properly referred to as "plain" flaps. Not to be confused with plane flaps. They hinge at the trailing edge in such a way that is simple, light, and easy to manufacture. They are effective also, and the thing lands plenty slow, but it has occurred to a few of us that just possibly, VG's on the upper surface of the wing's trailing edge, about 2 " or so from where the flap is hinged, may help keep the airflow attached to the upper surface of the flap when it's deployed. This assumes the ones already in place on the wings LE are too far away to directly energize the flap surface. Similar to what they do on the hor stab/elevator.

I am sick of reading about the double slotted P flaps advantages you Cub guys can bolt on by simply writing out a check, (and I don't want to take on the task of engineering something similar for the S-7, that's beyond my ability most likely and I'm too busy anyway) and I'd have a set of those tomorrow if I had a Cub. BUT, I can ably layout and install VG's, using double sided carpet tape for experimental purposes. What you think, been done before, a waste of time? I don't want my plane to be laughed at! BTW, I landed three new 8K plus sites the other day, it does alright as is, but a bit more drag and/or more lift at certain flap settings would not be a bad thing.

I think your idea is valid. If I had an experimental I would try it in a heartbeat. I can’t see a down side to giving it a go.

[courierguy]

I'm tapping out, before I start. Anne at Micro got me lined out, turns out there is a reason why you don't see this done.....my vortices are perfectly fine as is, even way back there, extra aft VG's would just mess things up. Then she got technical, something about the wing stalling from the back first, and halfway through that explanation I told her I was going to hang up, we were done! I'm smart enough to usually know when I have a stupid idea and just move on, this one qualifies. Chuck White still checks in daily, MR. VG, but at 92 the ladies answer the phone, as his hearing is like mine, I asked her to tell him I said hi. She claimed she would be happy to take my money, but was knowledgeable and honest enough to dissuade me. No pain,no gain. I'll spend the money on more mo gas.

[Gordon Misch]

Gotta love it when a vendor recommends that you not buy their product. Seems to me that's the ultimate in honesty.