Hey - so I am about to do the final step of the wings (outside paint). Polytone sprayed into tacky epoxy primer.
My question is, how am I best to attach the VGs, under or over the paint?

Should they be stuck onto the metal skin and painted over to make sure they bond strongly, or can I get away with sticking them to the paint (of course then they are only attached as strongly as the paint they are stuck to). Ideally I like the look of the clear plastic kind *(unpainted) to preserve the clean lines of the wing. But that's secondary to having them stay in place.

Ps. Any recommendations on the brand?? Spruce sells a power of different kinds and I've no idea which work best: http://www.aircraftspruce.com/categories/aircraft_parts/ap/menus/ap/aerodynamics_vortex.html

I've always seen over the paint, when they rip off due to a fueler, I've see them take the paint and primer with them. On a metal plane

What kind of aircraft are you putting them on? I have the set I took off my 185, includes wings, rudder and tail. Make you a smoking deal. BTW, mine where on the paint, usually they are put on the paint.

They're for the Bearhawk. And yep they are ususally added over the paint as an afterthought.... If I attached them to the metal and used alloy ones, they should never really break loose or snap off. But they need to go under the paint in that case. But I'd bet sharp alloy ones will wear holes in the plane's cover.
If I put the clear flexi-plastic ones over the paint, I'd bet they wont last forever and will take paint with them - paint isnt that strong and you're messing around up there refueling all the time... But then again they might be easier to replace too.

What kind have you got Dogpilot? Why did you take them off? I can get experimental ones for about 70 bucks, so you'd have to be offering a real sweet deal if you paid the going 1450 for Cessna VGs...

They are Micro Aerodynamics. I (me not anybody else) don't like what they do. Besides being a veg-O-matic to you when you fuel, they are primarily a source of drag. Even a primitive aerodyamacist, flint wielding one like me, knows a vortex is drag. Folks go to extraordinary lengths to overcome the vortex at the wing tips, but see no problem adding 150 small ones all over their aircraft. If I want to improve STOL performance in the 185, all you need is a stall fence and two larger vortex generators in the mid span of the aileron, preferably ones that generate their vortex at high AOA and not in cruise. I've had installations on other aircraft that did just that. Or one could just get Robertson STOL, it was awesome. I just felt vortex generators all over the wing and tail was a bad idea, lots of drag where it was not needed.

I have no intention of a flame war, I removed them on mine. I think that everybody that wants them and find all kinds of performance enhancements should go for it. However, if you look at the websites for these items, there is no documented proof of any performance enhancements, no charts, tables, nothing with the STC either. If you look at the supplement for Robertson, there are charts and tables with all the performance improvements. You would think, if they did something useful, they would be anxious to trumpet the facts, like in the form of charts & tables, not testimonials.

Oddly enough, the DHC-5 Buffalo, 52,000 lbs lands in 385' (done it). Not one vortex generator. In most large aircraft, they are there to fix problems after the fact.

PM me for details on mine.

Interesting perspective.
It makes me think seriously about flying the plane without them installed, and then doing a temporary install to see what changes happen to airspeed at the upper and lower limits. In fact, decision made. Thanks!
Over paint it shall be, and taped on to begin with...

I was told they won't stick to bare metal - you have to stick them to the paint. Surely this is covered in install instructions.

If you use the proper adhesive, they'll stick to most anything.

I fully agree with Dogpilot on VGs on Cessna wings. I have them on mine, and were it not for taking a lot of paint off, I'd take them off.

Other airplanes, they do wonders. So, If I were you, I'd finish the airplane, fly it enough to get a good feel for it, THEN do a temporary installation with double sided carpet tape. Fly it and see if you like it. If not, peel em off, and go on with life.

You'll never know what it flew like without them if you stick em on from the git go.

MTV

"It makes me think seriously about flying the plane without them installed, and then doing a temporary install to see what changes happen to airspeed at the upper and lower limits. In fact, decision made. Thanks!
Over paint it shall be, and taped on to begin with..."

This would be a very good decision when it comes to the bearhawk.

If you get the Stolspeed ones (from Oz) they come with skinny double-sided tape. Stick very well & will come off with steady side pressure & then lift it when it starts to come off. Only $100/set.

I lost 5 mph & didn't notice any slow speed handling difference (what I was looking for) so I added them to the spare parts box in the shop. I think I'll try adding just a few to the outboard end of the ailerons. Oh, and according to Jerry Burr's testing they need to go within a couple inches of the LE. Farther back & they're a waste. Some folks claim good improvement in aileron effectiveness, but some of us didn't see it. I recon Mr. Piper got it right.

Not that this is anything scientific, but for several years my hangar neighbor at old Downtown Fort Collins had VGs on his 180hp 172N. I have Madras tips on mine. So one day we were comparing our airplanes. I asked him how he liked the VGs, and he bragged that they really made a difference in slow speed handling--gosh, he could make his final approach safely at 60 knots!

My recollection, since it had been awhile since I'd flown a 172 with knots on the IAS, was that he was still flying final at a normal approach speed, not less. And for sure, he was not flying final slower than I was consistently flying my 63 P172D, which has only the Madras tips and not the later Cessna leading edge cuff. I didn't have my AOA gauge yet, and I hadn't taken the time to determine the actual stall speed of the airplane since I'd only had her for a few months past the new engine, but I usually used 70 mph, sometimes less (now I use less when I'm alone, right around 60 mph, and a bit faster when loaded), with full aileron authority.

Nobody likes to hear that they've spent a couple of AMUs unnecessarily, so all I said was something like "interesting--I guess I'd worry more about getting cut up while refueling." He agreed that was a problem.

But it sure made me question whether they really do enough to warrant the expense or effort, at least on a Cessna single.

Cary

Battson, have you spoken with anyone that has flown their BH with and without VGs? Everything I have ever heard about the BH has been that they perform great. I can't recall hearing anything about putting VGs on them or why they would need them.

It's come up on the Yahoo group a few times over the last few years. Lots of guys are using them.

The concensus seems to be that the stall speed does come down a few knots in all cases - up to 5 by reports, with no impact at all on crusing speed with a 540 (but those things are so overpowered anyway how could it) - you can bet that hit's the fuel bill to the same effect. BUT - not everyone reports the same results, some have more success than others.

Mike was using them, and will probably comment once he's flown home.

In fact when they tested on Prototype II, they shaved 11kts - 11 KIAS off the stall with power on and full flaps (31kts stall)- this is thought to be a factor of the pitot tube effectiveness, but wasn't tested against a GPS (this is Bob's plane remember, so no electronics). They increase the AoA you can fly at to a point that the pitot is likely not giving accurate results. I expect a GPS test would bring that reading up to more like 37-40.
I should add that Bob said he didn't like the VGs, because the nose angle was so high, using that speed range which the VGs enabled was uncomfortable as the pilot.

whee wrote:Battson, have you spoken with anyone that has flown their BH with and without VGs? Everything I have ever heard about the BH has been that they perform great. I can't recall hearing anything about putting VGs on them or why they would need them.

To the point about refueling - for experiementals you buy semi-flexible plastic ones which can't hurt you.

On a good, clean, prepped surface, vgs won't care what you put them on. I've never had a problem fueling with them, and have flown them on may different planes. I don't know anyone who has had their wing covers shredded by them either.
I happen to know the gent that did the flight testing for the Micro Dynamic STC (for cubs) to say there was no testing or data is a grossly inaccurate. But that still doesn't mean everyone will like what they do, and as MTV pointed out, their effects differ on different wings.
There is also a tremendous amount of difference in what vg shapes, and varying locations will do. The plastic ones are not the same as Micros, nor as BLRs.
I am currently using them on 3 different wings, one of which is the same airfoil as your BH. The ones I am using suit my mission well, and the ones I am using are 'blind' in cruise, consequently none of these airframes saw a loss in cruise this still doesn't guarantee they work for everyone's mission.
I agree with dog's assessment of the Robertson, and I think he would really like a VG equipped Robertson.


VGs are a lot like an energy drink....


A long long time ago I was buying a couple red bulls to put In my cooler for mid day. My opinion of Red Bull is that it is about on par with a stout coffee, and if you've ever been to Phoenix in August , you know how pleasant a mid day coffee sounds...
anyways, the cashier asks me 'hey, do those things really work?' Now by this time I had heard this a few times and patience has never been one of my strong suits, so my answer mighty been kinda short. In fact I think it went something like this;

If you are looking for liquid crack, then no Red Bull doesn't work. If you could use a little coffee to close your afternoon, but can't imagine a hot drink in this 110* heat, then ya, Red Bull is gonna do the trick just fine.

I guess what I'm trying to say, is that if you are looking for magic out of VGs you will likely be severely disappointed. The actual mph reduction in stall will be so small that if that is really all you want it will not be worth it. On the other hand if you have plenty of time in the same saddle and no tiny improvement or deduction goes un noticed than you will likely be pleasantly surprised. My opinion of a well placed and designed VG is one that works right before the wing breaks. This is where the micros work. If you don't spend much time there, they will be a waste of time and money to you.

One final thought, some planes feel better with a clean stall. And some pilots want a clean break. In either of these cases, VGs will be a negative...

My chief pilot is a dyed in the wool 3pt guy, and he wants a very predictable solid break. Consequently he despises what VGs do on pretty much everything he's flown.

Take care, Rob

We have VGs installed on our Pacer and on the Super Cub.... On the Pacer they are great.. On the Cub, not so much... Will probably take them off of the Cub when we recover the wings. The biggest gain on the Pacer is the ailerons are much more effective when flying slow at altitude.. Without them, the aileron control sucks...

Last week I helped install a set of Stol Speed VG's on a RV6.... So far the owner is loving them... Way more control when slow and the stall is a lot more milder.... Did those VG's with different spacing in order to get the wing to stall at the root first since the RV wing has no washout...

As many VG'S installations I have done over the years I can say that the airplanes that benefit the most from them have short wings.... The control at slow speeds is so much improved, especially with the Pacers short ailerons...The only benefit I see with airplanes with long wings is loaded and at altitude when flying slow the airplane is more stable and controllable.....

Keep in mind this is just IMO.....

Brian

You can also use clear rtv silicone to temporarily install them.
Don't give up on the first try move them up and down in small increments there is defiantly a sweet spot and where they recommend putting them is a compromise.

Personally, I would prefer the flexible sharkfin-shaped stolspeed VG's to the squared-off aluminum Micro VG's. Cheaper too. But the advantage to Micro is that (for most airplanes anyway) they provide a template for mounting locations.
I have heard good things about VG's on Pacers, but mixed reports on Cessnas. I waffled back & forth for a few years, but finally ponied up for a set for my C150/150TD. I hate to admit that I wasted my money, but IMHO the improvement is VERY subtle. Maybe a mph or two off the stall speed, and maybe a bit better low-speed aileron & rudder response, but like I said-- very subtle. If I was to do it again, I wouldn't do it again, at least on a Cessna wing. Luckily the kit for the C150 is only about $700, compared to about $1400 for the four seaters.
The Sportsman cuff is probably the way to go for a Cessna, but unfortunately it's a couple grand just for the kit plus a fairly involved installation.

Again, not looking to flame on this. I did fly mine in both configurations. I didn't like what the VG's did, mainly slow the aircraft down at cruise. The 185 doesn't need much help at slow speeds, woks just fine when stock, and better with Robertson, not sure if it is $30K better (if you go to Canada to get the STC, not offered by Sierra anymore).

If they did testing, then where are the results? There is nothing published, and nothing comes with the STC. If you go to their web sites, they offer no data or tables for your specific model, just claims. Again, if they do what they claim, where is the factual, normal format, aviation tables and charts showing it?

Here is the kit, not a single chart, placard or supplement in it. So apparently it does not alter the flight characteristics. Even if you get an STC for a prop, if it alters the flight characteristics, then you get a supplement, charts and a placard:

Paint the vgs and put them on the painted wing. Loctite 330 is normally used for a permanent installation. For removal, grab the vg and twist like you are winding a clock. They should hopefully pop off.

Other thoughts on other replies. If it goes on a certified airplane it was flight tested. If the manufacturer choose to certify them "as good, or better" then there probably will not be a supplement, but that doesn't necessarily mean there is no benefit. You just can't take credit for it in the performance. I'm not trying to defend Micro as I do not agree with their one size fits all solution. They have essentially the same "solution" for all the airplanes, vgs on the wings, horizontal, and vertical. Even if the vgs are not needed everywhere.

I'm not meaning to put down other pilot's operating experiences. If they didn't work then I wouldn't leave them on either. I think the BLR kit (STC owned and developed by Aeronautical Testing Service) is a better solution for the 185 anyhow.

The reason there is no approved supplement??? Pilots are relatively cheap. Mostly out of necessity (rather put the money in the gas tank - that's me ). Putting together a FAA approved manual is time consuming and big $$$. That just makes the kits more expensive. Also note that the price of these vg kits is probably within 20%, if not the same price, as when they were introduced 30 years ago. Can you think of any other product where that is the case?

You may get a few knots slower stall speed, better control authority, etc., but I think the real benefit comes in the form of safety. A quicker stall recovery, less altitude loss in a stall, or protection from the secondary stall. Additionally, if I get a gross weight increase with the vg kit and I'm a 135 operator, I'll buy it so I can legally haul more money making shtuff.

hotrod150 wrote:Personally, I would prefer the flexible sharkfin-shaped stolspeed VG's to the squared-off aluminum Micro VG's.

I understand that wind tunnel testing has shown the sharkfin shape to be superior to the squared-off shape in terms of vortex generating ability.

I would not pay $1400 for VGs if I owned a Cessna, but 69 bucks I can handle even if they don't work out.