Micro VGs - yea or nay?

fiveoboy01

fiveoboy01

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Dirty B
Considering these for my airplane. If you do some reading, they do seem to make a significant difference in stall speed, takeoff performance, and low-speed handling. Anyone here have experience with them?
 
On my old Cub and current Skywagon. Reduced stall is unnoticeable. More solid controls at slow approach speeds and in gusty winds are achieved. If you fly slow you may notice a flatter attitude. If you don't fly slow you won't gain anything.
 
Makes it a pain in the ass to wash and wax.
 
Installation is crucial to performance. Washing with a long bristle brush is a non event. Waxing much more hassle, but...how often do you wax? How often would slower landing speeds with good control be nice? Save on tires and brake pads...
 
I say nay, keep it stock. If the were really that good, the mfgs would put them on from the factory.
 
I wipe down the leading edges after most flights, and try to wax at least yearly, sometimes twice. Don't use a brush with any bristles, I use Aerocosetics Wash n Wax--squirt on, scrub lightly with a terry cloth towel, wipe dry with another towel. No water, no soap, no brushes, no taxiing to the wash rack and back. Also, no VGs on the plane, but not because of washing and waxing.

Ask about the effect on cruise speed. Yes, VGs help with low speed control, but I've heard many different numbers for loss of cruise speed. I easily go in and out if 2000' grass fields as is, so it don't feel the need to dirty up my laminar flow wing with stick-ons. Just be sure to paint them first.
 
People talk about them as if they lower stall speed with no loss of cruise speed. That sounds like a free lunch so I'm still skeptical. Someone convince me.
 
petrolero said:
People talk about them as if they lower stall speed with no loss of cruise speed. That sounds like a free lunch so I'm still skeptical. Someone convince me.
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Your plane is the exception to the rule it seems.

A while back, over at CPS or CPA, there was a long thread about VGs. Everyone loved them and saw no decrease in cruise speed. Except the guy with a retract 182. I don't recall how much speed he lost in cruise, but it was significant. He worked with the VG engineers and they tried various tweaks but nothing ever fixed the problem.

So, he took them off and sent them back for refund (I'll bet that was a PITA).

Anyway, the prevailing theory (iirc) was that the VG placement on the retract 182 wasn't designed and tested separately from a stiff leg 182, that a retract has a slightly different angle of attack, and thus the placement of the VGs should have been adjusted. But without going thru the design and testing, they didn't know what adjustments should be made exactly...and they didn't see a big enough market to justify the testing at that time.

I'd love to have VGs on mine except, as Ed points out, when it's time to wash/wax it.

Also, remember, if you lose a few of them then your aircraft may be unairworthy...I don't recall exactly how many you can lose before you're grounded. This likely varies by type/model also.
 
installation is simple. inconvenience is a non-issue, and that from a guy who uses wing covers all winter. the kit includes spares in case any are lost. loss of 5 on a wing is an airwortiness problem on paper but the plane will fly fine. no speed penalty on my planes are any of the dozens of others I'm familiar with. if you don't operate in 500' or fly slower than 60 in a Cessna or 40 in a Cub (for examples) you likely won't even know they're there. for STOL operators they make sense.
 
Retractable VGs? Deploy like a speed brake for TO, slow flight and landing -- retract for climb, cruise and the wash rack.
 
I read a few articles on them. My takeaway is that the speed loss is 1/2 that of what you gain in reduced approach speed. I remember something about a bonanza test, it lost 3-4 kts in cruise speed but a normal approach was flown 7kts slower, and commented the ailerons were much more effective at low speed/high AoA.

There are a lot of STC's and the effects will be different for each type of aircraft. A super cub might not lose any noticeable airspeed, while a mooney might lose 3 knots. On some twins, they are so effective its a no-brainer to add them. On a 310R Vmc is reduced by 10kts (the stc includes a new airspeed card) and you get a gross weight boost of around 150lbs.

I was reading about them for a Swift, unfortunately there is no STC or data I can find. I thought it worth looking up, as the airplane is not great at landing on short fields. A normal approach is 80mph, 75 over the numbers and do a wheel landing with a little speed. To get it stopped in under 1200' you need to do a short field approach about 6-7mph slower and touch down in a tail low wheel landing. In this attitude, the ailerons blank out almost completely.

The Swift originally had wing slots to keep the ailerons 'alive' at low airspeeds, however on most airplanes they have been deleted to reduce drag.

993362.jpg
 
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dell30rb said:
There are a lot of STC's and the effects will be different for each type of aircraft. A super cub might not lose any noticeable airspeed, while a mooney might lose 3 knots. On some twins, they are so effective its a no-brainer to add them. On a 310R Vmc is reduced by 10kts (the stc includes a new airspeed card) and you get a gross weight boost of around 150lbs.
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I think you hit the nail on the head about different effects on different types. A slick airplane like a Mooney or Bo is going to see a greater cruise speed loss than an already draggy airplane.

VGs do indeed reduce VMC on twins, but you can have additional drawbacks as well. One of the issues with VGs in Barons for example is that they can create control issues if you ever have the cabin door open in flight. So whereas something that would normally be a total non-issue could be more challenging to deal with if you had VGs installed. In the Baron (B55) the VMC is low enough that I never felt the increased safety factor was worth the added cost and hassle of VGs, but other airplanes can see greater benefits.

Not to disparage the OP, but this is a question best asked on a type specific board, as the results will vary between different aircraft types.
 
The OP asked for experience reports. Qualify your replies by including aircraft model your experience applies to. Simple.
 
Had them on my Cherokee and would happily put them on my Mooney if I had the coin. Mine was one of the fastest Cherokees I ever saw, and it wouldn't give a clean break on stall. I used to fly around at 35-40 mph indicated. Used to wash that airplane at least once if not twice a year, wax it once a year. Never had any problems whatsoever.
 
I have several hours in a 172 that had them, and it was a very noticeable handling benefit in the slow flight/stall phase vs. 172 that was not equipped. Outside of that, they went unnoticed, no real change in cruise speed. If I had a backcountry/STOL machine I'd have them on in a second.
 
Bought my 1968 Cardinal with VG's installed. Other folks who have flown my plane say they notice the difference on landing and no difference in flight. It takes a little care to wash and wax but no big deal. I have not thrown a tarp over the wing when camping as much as I would like but that is only a couple time a year.
 
Lachlan said:
Many mfgs do put them on "from the factory."
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Well then, those would be ok.

I think they usually slow the plane down and decrease the stall speed. At least the ones on the Super Cubs and Husky's do that. Neither of those planes need them IMO, they are already STOL. Some planes might benefit. Some of the Boeings come with them installed!
 
dell30rb said:
There are a lot of STC's and the effects will be different for each type of aircraft. A super cub might not lose any noticeable airspeed, while a mooney might lose 3 knots. On some twins, they are so effective its a no-brainer to add them. On a 310R Vmc is reduced by 10kts (the stc includes a new airspeed card) and you get a gross weight boost of around 150lbs.
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For the most part I see them as an insurance policy. I don't notice them they are just there doing their thing... I have noticed that the control are solid during slow flight and during stalls, so they do work... As for washing / waxing, they're no more of a problem than anything else that's attached to the plane... YMMV!!!
 
Stewartb said:
On my old Cub and current Skywagon. Reduced stall is unnoticeable. More solid controls at slow approach speeds and in gusty winds are achieved. If you fly slow you may notice a flatter attitude. If you don't fly slow you won't gain anything.
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That.

I've flown planes with and without them, everything from older tailwheels to 206s and 207s.

When it comes to STOL stuff I look for hard numbers, as in a POH supplement with new stall speeds.

Case and point for both aspects, my plane has a Robertson STOL kit, which is basically wing fences and connecting the ailerons to the flaps, so when you pull the flaps down your ailerons droop. The Robertson kit comes with a supplement with the new stall speeds and new VFE speed.

Now the issue with this kit is you loose aileron sensitivity at low speeds, thus many people will install VGs to correct this issue, the VGs ain't helping your get a lower stall as much as they help you control the airplane at lower speeds.

Personally I don't have VGs, though I have considered adding them because of my Robertson.




IMO unless you notice you're not getting the amount of control authority you would like at the low speeds YOU fly, I wouldn't bother with VGs.
 
petrolero said:
People talk about them as if they lower stall speed with no loss of cruise speed. That sounds like a free lunch so I'm still skeptical. Someone convince me.
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The loss of speed has to come from an increase in either parasitic and/or induced drag.
At low speeds and high angles of attack, the flight regime where these VGs are supposed to be most effective, the increase in induced drag from the increased lift is probably irrelevant to most.
Parasitic drag related cruise speed loss is likely to be most pronounced for laminar airfoils and might not be large enough to be measurable for a high-camber, high-lift airfoil where the boundary layer in cruise separates fairly early anyway.

I'm unconvinced the improvement putting them on my fat-wing Aztec will compare with doing the same with a slicker, faster twin.
 
steingar said:
Used to wash that airplane at least once if not twice a year, wax it once a year. Never had any problems whatsoever.
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As you would correctly guess from my tagline, I care about cleaning airplanes. I also fly a Maule with MVGs.

1) When cleaning the leading edges after every flight (hopefully using
http://planeperfect.us/products/wwb) you'll find that the vast majority of the bugs aren't as high up on the edge as the MVGs. So from a daily cleaning standpoint they don't really interfere that much.

2) For the times that you do need to clean/dust that part of the wing, wiping the plane from front to back makes things tons easier. The MVGs want to grab the towel if you wipe them backward. They are rounded on the front and allow you to clean if you wipe them in that direction.

I'll also say that, at least on a Maule, I really like them. But then, with a Maule, we do fly into strips that are short. If I were flying an Archer I'm not sure I would be flying into strips where I needed to be within a couple knots of losing lift so I would probably not bother with them.
 
I have flown several 172 models, from Cessna factory wing tips to STOL kit-fitted versions, to just plain VGs. The VGs were noticeable by an increase in aileron authority at slow airspeeds/high alpha. The STOL kit decreased stall speed by ~5KIAS and also allowed flight at really high AoA before the break. I like micro VGs and think that they have their place on certain aircraft for certain reasons. I've never flown a twin, nothing to add on that mission.
 
Yes!

I am a firm believer of these - made a big difference on my Commander. Lower stall, no perceptible impact on cruise.

They are some transport aircraft that use them. For a reason.
 
A friend put VGs on his 182 and loves them. I can't answer airspeed details about his airplane, but he put them on during a repaint right after flying our Robinson, and he kept remarking about how "stable" our aircraft feels at low speeds. I suspect the VGs were to scratch that itch on his own airplane, a lot cheaper than a Robby kit.
 
Without with Robertson kit they don't offer as much
 
James331 said:
Without with Robertson kit they don't offer as much
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Well the Robby is pretty fun, but doesn't have VGs. We have two stall fences on top. And putting a Robby on is a lot more expensive than gluing on some VGs. You get to play with aileron re-rigging and what not. The Robby seems to also pretty much destroy (due to added friction) any ability the original Cessna 200 A/P had to actually fly the airplane. Not that a Cessna 200 could actually fly well when new...

I wouldn't go out of my way to buy a 182 with a Robby kit. It's a novelty, but unless you have a specific need for it, the 182 is pretty capable without it. I just happened to join a co-ownership that had a Robby equipped one.

Thus, why I think he's probably ended up with "the best possible of both worlds" adding his VGs. He gets a bit of a low speed benefit that's granted, not well qualified until you do it and see how you like it, and not a big hit on the top speed. We're easily 5 knots slower than a non-Robby 182, and I'm pretty sure it's from added drag from those stall fences. Could also just be that we're a little out of rig, though.
 
denverpilot said:
Well the Robby is pretty fun, but doesn't have VGs. We have two stall fences on top. And putting a Robby on is a lot more expensive than gluing on some VGs. You get to play with aileron re-rigging and what not. The Robby seems to also pretty much destroy (due to added friction) any ability the original Cessna 200 A/P had to actually fly the airplane. Not that a Cessna 200 could actually fly well when new...

I wouldn't go out of my way to buy a 182 with a Robby kit. It's a novelty, but unless you have a specific need for it, the 182 is pretty capable without it. I just happened to join a co-ownership that had a Robby equipped one.

Thus, why I think he's probably ended up with "the best possible of both worlds" adding his VGs. He gets a bit of a low speed benefit that's granted, not well qualified until you do it and see how you like it, and not a big hit on the top speed. We're easily 5 knots slower than a non-Robby 182, and I'm pretty sure it's from added drag from those stall fences. Could also just be that we're a little out of rig, though.
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Indeed, I got a Robertson kit on my 185, just saying the only reason I've debated adding VGs was due to what the Robertson does to your aileron authority at low speeds.

Without the Robertson kit I probably didn't even debate adding VGs to the plane, if that makes sense.
 
So with better control at slow speeds and if no noticible reduction in stall speed, does that mean that one of the indicators of an imminent stall has been "muted"? I'm thinking more from a student stall practice point of view.
 
The VGs were already installed on my T182T so I don't know the magnitude of the affect they have on the operating parameters. I normally get slightly less speed and slightly higher fuel burn than POH numbers, but there could be other factors in obtaining numbers different than book values with this age of plane.
I've no issue with cleaning the wing & tail with the VGs installed.
I do notice that its hard to get a power on stall in this plane. It just continues to mush along after passing thru the Vs marked on the airspeed tape.
Anyway, the VGs are no problem and I'm fine having them. They'd be a must if I was doing something like pipeline patrol in a 182 or similar.
 
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