Tillers are only used for taxi, depending on aircraft type the tiller is deactivated above a certain groundspeed. Tillers can turn the nose wheel significantly more (by a factor of 10 and more) then the rudder pedals. On longer aircraft like the B777-300ER the tiller can turn the nose wheel 70 degrees either direction and also turns the main gear aft axle to help with steering around tight corners. Rudder pedals are used for taxi, take-off and landing on transport category aircraft and steering angle on the B777-300ER is limited to 7 degrees either side.

Pusher wrote:There is a lot of opinion in this thread. However, like most things aviation, aerodynamics are based on science, so are VG's. Placement (location and angle), aircraft wing and VG shape all factor in. Fact is that VG's delay boundary layer separation at high angles of attack. How much does a particular aircraft type benefit from it? That all depends on the factors mentioned before.

Anyone who is interested in unbiased facts, including some fancy math can read it here:

http://orbit.dtu.dk/files/5580397/erl8_1_015006.pdf

https://upcommons.upc.edu/bitstream/han ... sAllowed=y

Hi all,

Well I hope you can read through them and in my case, even contact the author of one of the papers....

The first paper is completely inconclusive as the focus is not the test the benefits of the VGs, but rather the methodology for measuring them, therefore will not comment further on it.

I contacted the writer of the second paper, and here are important aspects into his writing ( feel bad for the guy as there have been several high profile cases here for bogus/plagiarized papers... ) but here are some of the issues I find with this paper, the did not used a calibrated instrument to measure wind speed (the used eyeball to see where the anemometer was)- they ran the test in different days, they did not record any of the environmental factors such as pressure, temperature, and relative wind speed and they did not used a data logger, which preaty much sums up to nothing. I asked about the anometer they used, and he will get back to me, but in general the trend here is to use low duality instruments which leads to a large variance in measurements.

This test also did not measure pressure differences over the airfoil, which should have been done to collaborate a % increase in Cl_max in flight.

While I’m sure that the benefits of VGs are cuantifiable in the lab, I stand by my claim of <10% overall, and that most pilots will not be able to distinguish those benefits even those who test the edge of the flight envelop. ( here is my biggest problem with VGs, if you Vs is say 35mph, whe you aproach that speed, some airplanes will just buffer between retachment staits of the attached flow giving you a warning ⚠️ of your stall speed, this does not happen in a VG, it’s a sharp inverte v shape, giving you no time to react and what happens in reality is that you tend to fly with a little more margin approaching Vs, which negates the benefits in the first place.... )

I’m happy to be aducated otherwise please look at the NASA site, find a compelling document stating otherwise and I’ll toast to that changing my stance.

The Inv-V behavior suggested above has been my experience in Cubs and now the Taylorcraft, but that's with Micro VG's that are offset an equal spanwise distance from the LE. I'd like to try the offset VG's from CC to note any differences before installation.

I think my first set of Micro's on a Cub lacked them in front of the fuel tanks, and also had no tail installation so there may be a difference in behavior. Also flaps or not (or degree of flap deflection) should vary the AOA of that portion of the wing and may affect the stall. Experiments with that would be interesting.

Gary

SpainCub wrote:

While I’m sure that the benefits of VGs are cuantifiable in the lab, I stand by my claim of <10% overall, and that most pilots will not be able to distinguish those benefits even those who test the edge of the flight envelop. ( here is my biggest problem with VGs, if you Vs is say 35mph, whe you aproach that speed, some airplanes will just buffer between retachment staits of the attached flow giving you a warning ⚠️ of your stall speed, this does not happen in a VG, it’s a sharp inverte v shape, giving you no time to react and what happens in reality is that you tend to fly with a little more margin approaching Vs, which negates the benefits in the first place.... )

I’m happy to be aducated otherwise please look at the NASA site, find a compelling document stating otherwise and I’ll toast to that changing my stance.

Nobody disputes your claim that VG's benefit performance is <10% overall. However, it is a fact that VG's delay boundary layer separation at higher angles of attack. As such airflow around control surfaces at high angles of attack separate later and as such stay effective at higher angles of attack. The stall behaviour you mentioned is grossly generalized and depends on the wing profile and stall behaviour for a particular aircraft. I do not dispute that your stall assessment might be correct for some aircraft. Some wing profiles might even have close to zero benefit with VG's.

However, for some GA aircraft, VG's improve control surface (aileron and elevator) effectiveness at high angles of attack and might delay stall onset to a higher angle of attack which reduces stall speed for a given weight.

Reduction in stall speed might or might not result in a lower approach and touchdown speed, if it does - less energy to dissipate for stopping, resulting in a shorter landing distance.

As for pilots being able to distinguish those benefits, again it depends entirely on the aircraft and pilot. Some aircraft benefit from better controllability at higher angles of attack and/or others with a reduction in stall speed. If the stall speed was high to begin with I am sure a proficient pilot should be able to distinguish between those benefits.

IMHO a performance improvement above 5% but less then 10% is still significant, especially on heavier GA aircraft with a higher stall speed.

Even if the VG's only improve the flare characteristics of a particular aircraft I would call this to be a benefit and reason to install.

If you research Micro VG's over on the Supercub.org website, there is an abundance of verified testing data submitted by Jerry Burr. You might find it most interesting.

deleted

MTV

"Total bullshit. Learn to read." Touched a nerve there.........

Interesting thread to say the least. Anyway just for the record I fly airliners and always.....always have my feet on the rudder pedals. Except during cruise with the AP on. Once I use the tiller to align the plane with the runway on takeoff it’s all rudder pedals from there on out.
To the original posters question. I installed Micro Aero VG’s on our C-140 and it stalled at quite a bit higher AOA than before. So much more in fact that even with 8.50x6 tires the tail would hit WAY WAY before the mains. I would not even be stalled then while trying to three point it. Now with 29” Bushwheels it is almost a perfect three. Just an observation though as I almost always wheel land to be easy on that fragile TW assembly.

SpainCub wrote:( here is my biggest problem with VGs, if you Vs is say 35mph, whe you aproach that speed, some airplanes will just buffer between retachment staits of the attached flow giving you a warning ⚠️ of your stall speed, this does not happen in a VG, it’s a sharp inverte v shape, giving you no time to react and what happens in reality is that you tend to fly with a little more margin approaching Vs, which negates the benefits in the first place.... )

I have flown a 170B with and without VGs on a Horton cuff (2 different planes).
I found the wing with the VGs had noticeably more responsive aileron control at mushing speeds which I liked and comes in handy when landing in gusty crosswinds.
On the other hand, like SpainCub said, the VGs hold the airflow very well - until they don't - and then it is a much more aggressive and sudden stall.
The wing that doesn't have them installed gives you plenty of warning with less control when you get slow.
On another note. Try as I might I couldn't get the VG 170 to stall flat. It always dropped a wing. The non VG 170 stalls much gentler and flat when coordinated. It could have been a wing rigging/concentric issue.

Here's a quick search result of rigging Cessna wings: http://cessnaowner.org/the-right-way-to ... ing-plane/

With a C-185 I flew they did the controls and cables per spec, then the rear wing attach eccentric fittings over a few test flights. That fixed the inflight and stall behavior and made it consistent. I was doing lots of slow flying with a Sportsman kit and it helped. However I did wear out a set of wing flap brackets in a few years.

Gary

Quote:
"You will note that between Test#1. and Test#2. there is a remarkable difference in the stall speeds at less than ½ flaps. At full flaps there is no change. It was determined that the V.G.?s were blanked by the leading edge in AOA?s that were attainable by use of full flaps. Each succeeding test moved the V.G.?s forward, with a resulting decrease in stall speed. Test#5 or .38% of chord was impractical due to the leading edge curvature."

This quote was taken from the supercub forum wrote by Jerry Burr. It is a good article to read. But, all things being equal it is hard to duplicate test on different types and models of aircraft. As noted in other post, rigging issues, loose fabric, flaps, Mods, etc, could all effect the stall characteristics of a given plane. I am thinking that there may not be a cookie cutter approach to placement of the VGs on a specific model of aircraft. Even here, some guys with the same planes love them and some feel exactly the opposite: )
For my Pacer, I have no problem with the way it stalls, other than the elevator control is lacking at low airspeeds. And I think that the placement of those VGs would probably be standard across the same model plane. But the wing is a different animal altogether.
I find this interesting and am considering the idea that there is a sweet spot for every plane. .02

A lot of this stuff sounds like a tempest in a teapot.

1) Vg's absolutely do work (ask any Baron driver who has flirted with Vmc with and without Vgs). There has been serious testing done and the fact you can find them on most Transport Category airplanes are testimony to their effectiveness.... interesting side note that most of the time I see them installed for the ailerons.... with those tremendous Fowler Flaps I expect they aren't that effective with flaps. Humm, maybe they wouldn't be that effective with the semi-fowler flaps on the Skywagon, just a thought. My tuft testing of the Sportsman Cuff/WingX wing stall performance at different flap settings pretty much showed there was very little boundary layer separation on the inboard section of the wing... so that makes sense (there was separation on the flap itself).

2) Of course there is no cookie cutter solution for placing Vg's.... the Vg effectiveness is utterly dependent on the airfoil they are placed on, the location and the purpose. Delay the stall progression, improve roll control, etc. I can totally imagine that there are some airfoils that Vgs would not be effective on at all.

3) Who in the GA world can afford to spend the money on flight test equipment to verify the claims of each STC holder? By the way if the improvement in performance is 5%... that is significant in the GA world (5 kts is a big impact at 100 kts, but 22.5 kts is not a big chunk out of 450 kts). Anecdotal evidence is what we live by.... and the FAA doesn't require exhaustive effectiveness testing for STC'd products (as opposed to safety/ structural testing). What do we need, a Consumer Reports for STC'd performance products? Who pays for that?

4) Any upgrade is a personal choice for a personal airplane. If it works for you then.... choose. If it doesn't then don't do it. If you don't choose to install XXX, it doesn't make you smarter. More frugal perhaps, but not smarter. For example I don't use Marvel Mystery Oil, for me its no mystery.

5) I do note that WingX on my Skywagon wing reduces roll rate. Did I quantify that? Not scientifically, didn't log data. It is anecdotal... I felt it. Others have reported it, and I can confirm it. I FEEL it. I really like the impact WingX has on my Takeoff roll. I am looking forward to adding Vgs to get back some of that roll authority, others have reported it and it makes sense to me. It's my airplane, my money and my choice, thank you very much. I may be an idiot for installing it, but hey, I own an airplane (or does that make me an idiot... what comes first?). So far its a free country-ish and still MY choice.

And all that is my opinion, sorta, and worth what you paid for it.

gunny

buck_justice wrote:So, are they effective on the Pacer? Does it really benefit from the generators?
Does MicroVG use the small or the large generators on the wing and tail?
Is the placement the same as on the Cessna 172?

I’m going to install them on my Sedan after talking with another Sedan owner who praised their benefits.

A good friend of mine is a hunting guide and works his Pacer for a living. He installed VG’s on his bird recently and had a lot of good to say about the change they made in his plane’s slow flight characteristics.

I have a question on the installation of BLR vg's on my Cessna 185.
The Sportsman Stol kit as well is installed on the plane.

The instructions for installing the VG's are to measure forward from the back of the wing to determine placement. It seems odd that placement is not determined by a distance aft from the leading edge. The issue come in when one installs a different LE cuff like the Sportsman which now puts the vg,s much further back of the LE. I thought the placement of the vg's in general was a distance aft of the LE.
As I look at mine they do seem much farther back then other vg installations from different manufacturers on the 180/185 series.

Wondering if anyone has any thoughts on this.

Tom

a3holerman wrote:I have a question on the installation of BLR vg's on my Cessna 185.
The Sportsman Stol kit as well is installed on the plane.

The instructions for installing the VG's are to measure forward from the back of the wing to determine placement. It seems odd that placement is not determined by a distance aft from the leading edge. The issue come in when one installs a different LE cuff like the Sportsman which now puts the vg,s much further back of the LE. I thought the placement of the vg's in general was a distance aft of the LE.
As I look at mine they do seem much farther back then other vg installations from different manufacturers on the 180/185 series.

Wondering if anyone has any thoughts on this.

Tom

Threeholerman,

I have a thought on it, don't install the VG's. You already have a Sportsman kit which really makes an amazing airplane, what more could you realistically expect to gain from adding VG's? Since it sounds as if no one (BLR or Micro) has actually done any real testing of their kits on Sportsman equipped airplanes the best placement would only be a guess at best. Maybe they have done this testing but I haven't seen any data or instructions as to where to mount them. When installed on a Sportsman airplane is the placement that one puts them the best place? Does it improve performance? Does it improve the handling qualities? Does it improve stall behavior or does it turn the stall into a wicked monster? Until the best placement on a Sportsman airplane is determined by actual flight test data I would not install them on any Sportsman airplane. Another question, if someone was to spend the money to do extensive testing would the results say that they actually help a Sportsman equipped airplane or not? Those are my thoughts.

Kurt

If any of you guys have pulled off the VG's that are the size they use on a Maule because they don't work I would like to buy them from you.

I will also state with no proof other then my time in the seat of 3 different Maule type aircraft that they do work.

1st Maule M5-235C, (wing 30'10") I owned that airplane for probably 2 or 3 years before I put them on and it was a night and day difference with that short wing.

2nd Maule a.k.a. Bushwacker of Big Rocks and Long Props. I flew Bushwacker for 2 months after completing the build before putting them on, maybe not as noticeable difference as the short wing M5. This experimental airplane had the biggest wing (33'8") and smallest ailerons ever put on a Maule with an angle of incidence change on the wing of 3/4" at the front hinge attach point, it still made an apparent difference.

3rd time around is Bushwacker 2.0. I extended the wings by another 12" each (around 36' wing span now) extended the ailerons to 78" and shortened the flaps to 114", changed the angle of incidence at the front attach point by 1 3/4". Without VG's this airplane would be dangerous, you could stall the wing in ground effect with an attitude that felt normal visually looking out the airplane at 3 point attitude. My first thought was this is not good I totally screwed up changing the incidence as much as I did. This airplane has the standard washout built into a Maule wing but only about .8 degrees of Dihedra. I decided to put VG's on it before doing anything else. It was not only night and day difference in ground effect but makes the airplane as safe to fly as the original Bushwacker playing around at 50 to 100 feet off the ground on rivers like I do. I can not give any feed back on any other airplane other then a Super Cub and Maules but on a stock Super Cub wing I would have them and without a doubt on a Maule wing.

I am serious about my offer to buy ones that have been removed, I am in need of some right now!

a3holerman wrote: I have a question on the installation of BLR vg's on my Cessna 185.
The Sportsman Stol kit as well is installed on the plane.
The instructions for installing the VG's are to measure forward from the back of the wing to determine placement. It seems odd that placement is not determined by a distance aft from the leading edge. The issue come in when one installs a different LE cuff like the Sportsman which now puts the vg,s much further back of the LE. I thought the placement of the vg's in general was a distance aft of the LE.
As I look at mine they do seem much farther back then other vg installations from different manufacturers on the 180/185 series.
Wondering if anyone has any thoughts on this. Tom

Re this year old post...
I've heard (almost) nothing but good about adding VG's to a Supercub or Pacer wing.
Cessna owners seem to blow hot and cold on them.
I put a set of Micro VG's on my old C150/50TD & was underwhelmed by the results.
I doubt I'd ever put a set on another stock Cessna wing.
But I've heard that a Sportsman-equipped Cessna wing responds well to VG's.
Not so much stall speed, but in keeping the aileron effective at the lower flying speeds possible with the cuff.
I suspect that most of those installed are Micro.
Dunno about the Cessna, but FWIW the placement of BLR VG's on a Cub wing
seems to differ quite a bit from the placement of Micro VG's.

a3holerman wrote:I have a question on the installation of BLR vg's on my Cessna 185.
The Sportsman Stol kit as well is installed on the plane.

The instructions for installing the VG's are to measure forward from the back of the wing to determine placement. It seems odd that placement is not determined by a distance aft from the leading edge. The issue come in when one installs a different LE cuff like the Sportsman which now puts the vg,s much further back of the LE. I thought the placement of the vg's in general was a distance aft of the LE.
As I look at mine they do seem much farther back then other vg installations from different manufacturers on the 180/185 series.

Wondering if anyone has any thoughts on this.

Tom

Tom,

I assume from your post that the VGs are already installed?

In my experience, BLR takes a very different approach to location of VGs on both Cub and Cessna wings, compared to Micro. Probably one of the reasons the owners (or former owners) of those companies split up....they were originally partners I believe.

But, regarding the relationship between VGs and Sportsman, first thing I'd do is call Willie Steen in Polson. I'm betting he's played with both kits, and can give you some thoughts.

MTV

a3holerman wrote:I have a question on the installation of BLR vg's on my Cessna 185.
The Sportsman Stol kit as well is installed on the plane.

Tom, you are installing an STC on and STC and are in uncharted territory. If it were me, I'd toss em and buy the Micro VGs. These are landmarked from the leading edge using a tool. THere are hundreds if not thousands of Sportsman + VG birds out there. It is a fantastic combo.

One thing, is that VG's work on my S7-S, until they don't. Meaning, that if I push the plane to it's utter most limit (high AOA, low airspeed) and it finally gives it up, it will bite. Like right now! Probably more then the stock wing without VG's, as I recall (it's been 3 thousand plus hours since I've flown an S-7 without VG's) BUT, I wouldn't really call it a bad thing, as when it does this, bites, it is at a speed so slow one would have to be sound asleep not to be aware that something was going to happen. I believe this phenomenon has been addressed on this thread, and given a more technical name. It is a small price to pay for the increased low speed/high AOA performance and hasn't proven to be a significant drawback to having them. They seem to make the wing "work harder, longer", but like a friendly dog pushed to it's limit, it will for sure let you know when you have finally reached the limit. I do know that when it happens, the vary sharp break, I for sure have wrung every bit of performance out of it, there ain't any more to give.