VGs ... specifically, the flight characteristics

Factoids:
I fly floats & skis only.
Am currently refurbishing the wings.
I think I want to install VGs (before paint).
I realize that VGs affect slow & higher AOA flight.

Question:
How (specifically) will my flight characteristics change when near the stall? My plane currently won't shudder or break, it just mushes & loses altitude. It's a bit of an exersise to keep it balanced (level), but not tough to do.

Will VGs let me slow down enough that I'll get a nasty surprise when she does get below MCA?
Should I install VGs or just leave well enough alone?
(Try to be helpful George)

Logano-

You might want to tell about current mods to your wings......

The wings have been squared off, so there's 2 (closer spaced) full ribs past the ailerons outboard, and have droop tips.
I made flap extensions to inboard 'em to the fuselage.

That's it.
What'll it be?

why install before paint? if dopes & paint is done well and prep for vgs is done well they stick good,

I would think you would make runs/sags near them from paint sucking to them..like ?capilary action(wrong word, kinda same effect though at an edge/overlap)

Understand what'cha mean Mike. Good point. I kinda figgered the paint would fuse everything together better.

I just rebuilt a wing for my PA11 and installed the VG's after paint. I use Polytone on the wings and painted the VG's first with Aerothane. Just stuck them on tape, hung them up and painted them.
The VG's will give you lot more aileron control at low speed. I use to loose aileron control at stall, but now never loose aileron control. Try em, you'll like em.

Well VGs were the best safety mod I did to my plane. It will stepdrop your nose, when you are at 2000# full backtrim, backelevator and full flaps. But it takes a while to do so, but than really gentle. At first it mushes down, after that it starts stepdropping the nose! You are on floats, so I do not believe that in your normal operations you'll have your nose that steep up to encounter that attitude. Skiflying is a bit different and 31" Bushwheels makes the real differents !!!!
Glue the VGs to the fabric!!!!!!!!!!!!!!!!! No nitro or dope will be so sturdy to have the same bonding like the VG-glue to the fabric! My own experience when linepoeple refueled my plane. And even that will brake off, when some stupids shave the hose over the VGs. But mostly the fins will simply bend.
C-V

Be advised when using the templates that come with Micro's vg's: I also used Polytone for my finish paint, and the adhesive template, while only in place for a couple of hours (inside/no sun) left gooey residue when I pulled it up. No biggie I thought, hours later I was cursing it, and using progressively more aggresive thinners, to the point where the paint was coming off, or at least thinning somewhat. I did not have this problem on other aircraft, also when using Polytone, so I don't know what the deal was but it was a real bitch getting that goo off. Even so, I'd do it again, the vg's are that good for slow flight. I left them unpainted, they are anodized and I like the look.

Thanks Roger, looks like I should be doing 'em! Was wondering if they did anything besides slow controlability. Is there ANY drawback??

C_V, what the H is "stepdropping"? Never heard that term before.
No way does anyone but me put fuel in. (but then, I don't 'do' airports)

C-Guy, I'd guess that the template is a spacing thingie, right? So can I lay a strip of masking tape & then put the template on that?
Unpainted would be good too ... maybe.

Thanks guys, you're OK no matter WHAT SJ says about you!

Here is one way to hold onto the VGs while painting. Double stick tape on paint stirring sticks. You can easily get to all sides of the VGs with a touch up gun. We used Poly Fiber Aerothane. We had no special problem with the templates sticking on the wing.
Darrel

Darrel Starr said:

Here is one way to hold onto the VGs while painting. Double stick tape on paint stirring sticks. You can easily get to all sides of the VGs with a touch up gun. We used Poly Fiber Aerothane. We had no special problem with the templates sticking on the wing.
Darrel

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I learned something again! never thought of putting them at an angle! thanks Darrel...

I use 1/4" rib stich tape upside down, you want as little as possible touching tape(you have to trim paint with xacto knife where it 'bridges' onto tape after removing them from the tape, where as the part that was in the air has no funky edge)

I have installed Micro VG's on several airplanes, and courierguy's warning about the templates is dead on. But, I have found a way to do it better. The trick is NOT to apply ALL of the templates at once. I apply 2 or 3 templates down the wing, glue on the VG's and then immediately remove the templates after the VG's are stuck good. I then move on to the next set of templates. They only stay on for maybe 10 to 15 minutes MAX, and I have never have had residue problems doing them this way.

Brian.

My buddies generally see dramatic improvement in aircraft handling in all flight regimes with VGs. When more become available, they add them.

I have yet to detect any difference on the landing approach, although at altitude and very slow I do detect sllightly better handling. I detect no difference at all at normal speeds. They should increase aileron effectiveness at very slow speed, but a stock Cub has quite good aileron response right through the flare. The Micros seem to make normal spin entry difficult, but that was on only one aircraft. The AMDs allowed normal spin entry.

They will reduce your top speed, but you will not be able to measure the difference.

for lack of an aerodynamics degree, I can only say it will allow a dramatic increase in angle of attack.

Have no way of measuring that, or which is most effective, but with the VG's and the Thrustline, I can take off in deep snow with bushwheels, with the stick all the way back, the wheels will eventuall come up out of the snow and start flyingwhile the tailwheel is still stuck in the snow, then when the tailwheel does come out of the snow the airplane will pitch up pretty dramatically and still keep flying and climbing.

don't recommend anyone try that unless their life ins is paid up, and don't know how that relates to a floatplane.

I think the Vortex Generators (both kits available) are well worth installing on a Super Cub.

It is extremely difficult to accurately measure stall speed at the angles of attack that a cub stalls, so it is really tough to determine that the stall speed significantly decreases with the installation of VG's on a Cub. In my experience at least, I really don't think the stall speed changes SIGNIFICANTLY with VG installation.

But stall speed isnt' the only variable that can benefit from VG's. In my opinion, one of the biggest benefits of the VG installations is that they help the wing hang on in a stall, with much less tendency to roll off in a stall. The stall becomes pretty much a non event, with a mellow straight ahead mush.

Secondly, the VG's keep the airflow over the ailerons attached deeper into the stall, and thus aileron effectiveness is GREATLY improved at high angles of attack.

As Brian notes, the VG's permit the wing to fly to a higher angle of attack, and there are those characteristics to consider.

On floats, heavy, getting the airplane out of the water, and hanging on the wing is the real task. With the VG's the wing will hang on much better when you get the plane out of the water. In gusty conditions, crosswinds, etc, that airplane will be less apt to settle back into the water.

You'll also have better roll control as you drag it out of the water. The heels of the floats won't permit you to get airborne at a much higher AOA, but once out of the water the airplane will hang on much better, and be much less demanding to fly in that regime.

It only takes one encounter with gusty crosswinds on takeoff on floats to appreciate this characteristic.

Put em on.

MTV

I think with the VGs you have similar control at 40mph as you used to have without VGs at 50mph. The actual break of the stall is close to the same speed you just feel in complete control even deep into the stall. I have a 7GCBC, at idle my plane will not break, it just drops nose high with full aileron control at about 500fpm. I have to add power to around 1200rpm to get enough tail authority to get the nose high enough to get a break, and then if you still hold the stick all the way back and apply a-bit more power the stall is over instantly.

They are a must have for the cost.

MTV wrote,

On floats, heavy, getting the airplane out of the water, and hanging on the wing is the real task. With the VG's the wing will hang on much better when you get the plane out of the water. In gusty conditions, crosswinds, etc, that airplane will be less apt to settle back into the water.

You'll also have better roll control as you drag it out of the water. The heels of the floats won't permit you to get airborne at a much higher AOA, but once out of the water the airplane will hang on much better, and be much less demanding to fly in that regime.


This is what I have been told about installing them when on floats. I just had the wings recovered and the mechanic quoted me the almost verbatim as to what Mike said above. I will probably have them installed this spring before I go on floats. I have to climb out of some small lakes with hills around so I am thinking the VG's may help with climbing out over the hills.

Don,

Just to clarify, I wouldn't suggest using these capabilities of the VG's to CLIMB out.

When operating on floats, the challenge is accelerating the floats through the water to a reasonable FLYING speed prior to launch. As a consequence, on floats, many times, you'll drag the plane out of the water at MCA (minimum controllable airspeed), largely because you don't have much choice. On wheels, it's relatively easy to accelerate on the surface, compared to floats. Now, the Super Cub accelerates better than the majority of floatplanes, but you can still easily find yourself in this situation: Close to the surface, right at MCA, in ground effect, trying to accelerate.

THis is where the VG's really shine. They help the wing hang on and give you better aileron control at high AOA.

Certainly in a climb, the extra margin is also valuable, since gusty wind conditions can cause some momentary "hiccups" during a climb out as well.

They are worth installing, in my opinion.

MTV

I have a PA-18-180 with stock wings. I flew the plane for 400 hours without VGs on Edo 200 floats, 31” bushwheels, and skis (Aero 3000, and Landes LW 2500). I then added Micro Aero VGs and have flown the plane another 300 hours. Here are my observations about the VGs.

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PA-18-180, stock wings, without VGs:

Power off, full-flap stall – With the stick full-aft, the plane gently buffets with a gentle porpoising motion as the plane gains and loses a touch of speed in and out of the stall. The plane is controllable moving the stick right and left. Not particularly scary. I don’t spend much time in this configuration, so I don’t place much emphasis on flight characteristics here. However, this is where most people will expound on the gentleness of their aircraft in the stall. I test flew a Sportsman 2+2 at the factory, and the test pilot told me that the plane would just “mush” in the stall while remaining totally controllable. He meant specifically the power off stall and did not demonstrate the characteristics of the airplane in the power-on stall. He wouldn’t allow me to perform nor would he perform power-on stalls. I’m guessing if they did this, they wouldn’t be able to tell me that their plane did not break in the stall.

Power on, full-flap, constant altitude stall – While increasing angle of attack and adding power to maintain altitude, my plane would stall in a nose-high attitude with the stick about three quarters aft and power around 2200 RPM. The break was crisp and abrupt with minimal to no buffet prior to the stall. Of course, I know the stall is approaching, but when it goes, it goes. Flying, flying, flying, ….not flying.

Full power, clean configuration (an oxymoron I know) or with 20 degrees flaps, departure stall – The stall is pronounced with a crisp break like in the previous example.

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After Micro Aero VG installation:

Power off, full-flap stall – With the stick full aft, the plane is truly controllable with the classic “mush” feel. Rate of descent is constant with no pitch oscillations. As mentioned earlier, since I don’t spend much time in this configuration, the stall behavior is not as important to me.

Power on, full-flap, constant altitude stall – This is where I do spend time (not the exact condition, but similar - more of a classic approach stall), especially when spot landing a very short strip. At altitude, as the stall develops, the first thing I notice is that my stick begins to move fore and aft (not sure of the actual deflection, but definitely noticeable). This precedes the buffet, which is significant compared with my experience without VGs when the airplane will break without much warning. With VGs, the airplane is clearly communicating with me that the stall is developing and gives me ample warning to adjust pitch or power or both to prevent further development. If I continue to increase angle of attack, the plane will definitely break, but not as crisply as without VGs. The stick continues to move (a poor-mans stick shaker) and the plane buffets as the nose drops.

Full power, clean or with 20 degrees flaps, departure stall – The stick is back, but not fully aft at the stall. As the stall begins, the stick begins to gently oscillate fore and aft as it would in the previous configuration, except that the stick movement occurs a bit later into the stall and doesn’t provide as much warning. However, the buffeting and stick shaking as the stall develops is ample warning to change angle of attack. The break is not crisp, but rather buffety (I know it’s not a word, but you get the idea)

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My conclusion after installing Micro Aero VGs is that I am happy with my decision. Since most airplanes have benign stall characteristics during the power-off stall with or without VGs, I don’t give much credence to claims of benign stalls if there is no mention of stall performance with significant power. With VGs, my airplane talks to me and gives me ample time to make a power or AOA adjustment to reverse the stall development. Prior to VGs, my plane would enter a stall abruptly without much warning (at high power settings). For me, the value of VG’s is not flying 3 mph (or whatever the claim is) slower, and I don’t fly into shorter gnarlier areas because I fly slower. It’s more that when I’m flying on the ragged edge, I can detect a problem instead of wondering if I’m too close to the break to be comfortable. And in case you are curious, I have never had the plane buffet on me during normal operations except on occasion during a maximum performance takeoff when I lift off with a pull of full flaps and enter ground effect. For a brief moment here, I occasionally sense the plane on the edge until I accelerate and reduce the AOA.

I have both leading edge cuff and vgs on my 12.I like them both.I also put splash rails all the way down to the step on my edo 2000,a lot quicker getting on the step.

OK so I'm very sold on the idea of putting VGs on my floatplane, wings & tail. NO negatives reported.

So what's wrong w/the cheaper ($100/set) plastic ones? They claim durability & UV proof, & if a few did break they're only a buck apiece.

Are they STC'd? Or does that matter?

Plastic: Do you fly in winter? Does it get cold where you fly in winter?

I wouldn't even THINK of plastic VGs on an airplane that operates in winter my own self.

MTV

Here are some notes I made to myself after installing Micro VG's:


Notes on flight characteristics prior to installation of VG’s:

With two people on board it stalled about 47 mph w/o flaps, stall was very gentle

Approach to wheel landings at about 50 mph, touch down speed was in mid to high -40’s

With full power will fly at 37-38 mph

After Installing Micro VG’s

Won’t stall now, there is no stall break, the Cub just descends at about 7-800 fpm. If it were stalling it would be in the low to mid 40’s.

Approach to wheel landings in high 40’s mph and touch down in very low 40’s. Took 4-5 mph off of a comfortable touchdown speed.

With about 50 hours on it now with VG’s, more comfortable now with touchdown speeds about 41-42 mph and takeoffs about 39-40 mph.

Will pick up a low wing with aileron at slow speeds.

why not make your own thurstline kit too.....because the folks who STC'd these devices put in a ton of development time and money to certify them; in many cases at great sacrifices to themselves to bring them to market.
In my book buying from them is the right thing to do.

How does one know if they have the micro VG's or the standard? Is there a difference in flight characteristics between the two?
I just bought a PA-12 with VG's on it but am now wondering what VGs I have. I believe cub crafters put them on and there are no VGs on the underside of the tail, there is a fin attached just forward of the tail on the emenage on both sides.
The weather finally looks decent for this weekend and I'm going to go do some slow flight and have some fun flying :-D

Richard Deblack said:

How does one know if they have the micro VG's or the standard? Is there a difference in flight characteristics between the two?
I just bought a PA-12 with VG's on it but am now wondering what VGs I have. I believe cub crafters put them on and there are no VGs on the underside of the tail, there is a fin attached just forward of the tail on the emenage on both sides.
The weather finally looks decent for this weekend and I'm going to go do some slow flight and have some fun flying :-D

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You have the VGs that CC owns the STC for.

The CC VG kit has them staggered where the ailerons are and also the leg slasher plate by the tail.

The Micro VG kit just has the VGS on the wing and the bottom of the tail.

Tim

One thing for me that's interesting. After flying more than 200 hrs with Micro VGs, my attitude on landing is so nose high, that I have problems to see the ground in front of me. Before the VG-time I could see everything, now I feel like flying something like a C180. But I have absolutely no unsafe feeling, except that my visibility became limited.
C.M.

corvus-migrans said:

One thing for me that's interesting. After flying more than 200 hrs with Micro VGs, my attitude on landing is so nose high, that I have problems to see the ground in front of me. Before the VG-time I could see everything, now I feel like flying something like a C180. But I have absolutely no unsafe feeling, except that my visibility became limited.
C.M.

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I have the Micros too and find I do come in very tail-low as you've described but, at least with my normal CG, if I give it just a bit of power right before touchdown the tail comes up and the Cub is flying on the edge and over-the-nose visibility is very good. The little touch of power doesn't increase the airspeed, it just seems to raise the tail. That makes for a just right attitude for a wheel-landing.

I would guess I have about 500-600 landings now since installing the VG's and it has taken some experimenting to get proficient enough to feel comfortable with 300-400' LZ's on 31's but the VG's are a real advantage, in my opinion.

With take-off's on skis it is easier to find that sweet spot between drag and lift and too much AOA sticks the tail back in the snow.

mvivion said:

Are they STC'd? Or does that matter?

Plastic: Do you fly in winter? Does it get cold where you fly in winter?

I wouldn't even THINK of plastic VGs on an airplane that operates in winter my own self.

MTV

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I've had the plastic VGs on for 3 or 4 years, and I fly in the winter. Not much below 0, but 5 and above routinely. so far so good.

Tim

I have micro vg's and an attempted stall would just put me into a mush with good aileron control and with power you just got behind the power curve in a faster descent so i had the wing washout changed from 2.5* to 1.8* and now the nose will fall about 1/2 back to the horizon and i like that a lot better.