courierguy wrote:The increased elevator authority goes hand in hand with the better and slower low speed handling on my S-7S, when at that last possible high AOA just keeping it in the air speed, and they (Micro's) really help out in off airport type landings. I can however see that if someone just flew the plane like they always had, they might not think they work, or at least not notice much of a difference. In my case it wasn't until I started really pushing things that I noticed I could get now away with it.... Blunt LE, thick airfoil.

I agree. Even though I have a different rans wing, I had very similar results. The lowered stall really starts to shine at higher aoa's (or at least that seems to be the case). The plane is very forgiving at high aoa which is very nice! But as mentioned different results to be expected on different wings etc.

dougs wrote: So you guys that dont like vgs would you tell me how you figured out that you had them placed in the right spot fore or aft on the wing where they actually were in position to work???....

Since I was installing them on a certificated airplane, I went with an STC'd product.
The Micro Aero kit includes templates to ensure that the VG's are installed as the designer intended.
I've seen VG's offered for homebuilts, but you might be on your own as far as determining just where to place the VG blades.
(There's a reason they call them "experimental".)

Landshorter VG's offers kits for homebuilts.
From their website (landshorter.com):

 " On most sport type planes you will see NO difference in your cruise speed if you place your VG's on the "sweet spot" of the airfoil.  We include all the instructions and templates you need to find this spot and since we've sold nearly 2000 sets of VGs we've got the installation location really dialed in."

and

" Our eight page manual and complete set of computer generated templates give you the information you need to install your Landshorter! vortex generators.  Most likely you will end up placing them around the 10% chord line for your wing and spacing them at about 50 per wing (close to 1% of span).  If you decide to use them on the underside of your horizontal stabilizer to improve your flare then you will place them about 1" apart and just in front of the elevator.  In all cases the VG's are placed at a precise angle to the airstream and are aligned and spaced with the included templates."

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85 hp champ @ 2000 rpm very little rudder input,220lb driver, ~18 gallons fuel level flight and bouncing off 20 indicated

Oh yeah and micro airs[emoji39]


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That's pretty good, but I can show 0 mph on the ASI in my S7-S! Point being, pitot error at high AOA pretty much makes those super low numbers not mean much, but I get it, the Champ flies real slow! My first VG kit from Micro was for a Champ, and I used it's placement guide as a starting point for my S-7S.

I use my snowboarding speed and bike riding speed to sort of calibrate my planes landing speed, meaning I board and ride faster then I land by a fair bit, most landings below 25 MPH near as I can tell, with a little help from "upslope ground effect", my invented aeronautical term for how slow I can get when landing on the steeper slopes. Some of those are "get out and walk speed", or so it seems, damn slow.

Yesterday I had a crane job to check on, a work site 25 miles away and I needed to eyeball the site to see if the crew had showed yet, and if so who, as it would tell me when I needed to arrive there. I had lost the foremans cell #, and didn't want to get there in the crane too early. I put it in a 45 mph bank with half flaps and settled in to circle, at 3 or 400', with the job site perfectly centered in my lift strut V. At 2.7 GPH, I could have maintained that aerial post for a bit over 8 hours with the fuel I had onboard, not sure if VG's helped much for that but they sure don't hurt when getting bumped around by hitting your own vortices.

Yeah I hear ya. Wish I had flaps. I think on the ground I was showing 45 or so. Vg's are worth every penny as far as I'm concerned. The ol 170 needed full rudder dancing on the pedals before the vg's were on it to stay out of a spin. After the vg's it was a different plane.


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So do you want your vg,s to be effective with full power, half power, idle, landing, taking off, flaps down , flaps up, no flaps at all. this all makes a difference on placement to be efficient.

I installed a set of Micro VGs on my Cessna 170, equipped with 180 hp engine, otherwise stock. At the time I installed them (in accordance with the manufacturers instructions), I had over 600 hours in that plane. I would NEVER do that again. The VGs didn't change the stall speed more than MAYBE one mph.

The VGs did mellow the stall a tiny bit, if the plane was held in a full stall.....but it was never difficult to maintain wings level in that configuration before the VGs were installed.

VGs seem to be more effective on some wings than others, which I suppose shouldn't be a surprise.

I have a higher opinion of the BLR kits than the Micro kits, in any case.

MTV

For the guys who love 'em, how do they affect your crosswind takeoffs and landings? What is the maximum crosswind you've landed or taken off with 'em? I understand the benifits of going slow by reducing stall speeds. What's the rest of the story? Can you get a VG equipped, low stall speed aircraft to "stick" in a moderate (10-15 kt) or stronger crosswind? How about a safety-never-in-doubt takeoff as crosswinds become stronger (how much stronger)??

Dunno about the others, but I believe that Micro Aero first produced VG kits for twins, designed to lower the single-engine minimum controllable airspeed (Vmac). They then moved on to producing them for singles. I think that one of the design goals, perhaps the most important one, is not a lower stall speed-- instead, it's improved control effectiveness at low speed. That's why Micro's kits include VG's not only for the top of the wings, but in most cases also for either the vertical stabilizer and/or the bottom of the horizontal stabilizer.
Here's a quote from the how-do-they-work page of the MicroAero website ( https://microaero.com/ ):

"How do Micro VGs Work?
Micro Vortex Generators are placed in a spanwise line two to fifteen percent aft of the leading edge of the wing. They control airflow over the upper surface of the wing and the tail surfaces by creating vortices that energize the boundary layer. This results in improved performance and control authority at low airspeeds up to the critical angle of attack.
A Micro Vortex Generator creates a tiny vortex in the airstream over an airfoil. This vortex energizes the normally stagnant boundary layer of air on the wing and tail surfaces. An energized boundary layer is more resistant to flow separation than a stagnant boundary layer. The result is that airflow "sticks" to the wing and control surfaces better, providing greater lift, which results in greater control in flight at slower airspeeds such as take-off and landing."