185 vortex generators

[hotrod180]

I believe they were for his EXP Cub. Few Cessna's can fly that slow. A good file and even Cubs can have 4 notch flaps. Gary

Jerry has owned that cub for about a hundred years (exaggeration, but since 1972 anyways),
and done a shitload of stol mods on it.
If it has 4 notches of flaps, at who knows what degree of deployment, that wouldn't surprise me at all.
He was winning the alaska stol contests in his "white Hawk" when it was still being held on the beach.
I believe he worked a lot with Charlie White when Micro Aero developing vg kits for cubs.

 

[hotrod180]

Micros on some Cessna's also employ them on the vertical stabilizer in front of the rudder. Given that yaw control can be demonstrated to be lacking at times, why not for all applications? Somewhere in the stall sequence the wing and elevator can loose authority, Why not the rudder as well? A dead of winter thought.

They do. From the Micro Aero website:

 

[hotrod180]

....My 180 VG experience was with the Sportsman Kit (increases the chord) with Micros (applied with standard chord template). That particular combination should never have been allowed. On that aircraft I added ten mph to the approach speed, as compared to the stock wing with Cessna cuff.....

Whoever owns that 180 should get ahold of Micro Aero and ask about VG placement with the sportsman cuff.
There's been a lot of these installations done, and I'm guessing the VG's would be placed farther forward on the wing.
They sell a "re-paint kit" with a bunch of VG's, and would probably give him a different placement template
if he can document that their STC had been purchased for that particular airplane.

 

[hotrod180]

........I put Micro VGs on the wings and tail feathers of my 180K stock Cessna camberlift wing.......

I'm curious as to what year Cessna started with the "camber lift" or "camber cuff" wing leading edge?
The "year model changes" article says in 1970 "conical camber wing tip decreases wing span 4 inches" for both the 180 & 185.
I assume that's also when the leading edge was changed?

 

[Cardiff Kook]

I'm curious as to what year Cessna started with the "camber lift" or "camber cuff" wing leading edge?
The "year model changes" article says in 1970 "conical camber wing tip decreases wing span 4 inches" for both the 180 & 185.
I assume that's also when the leading edge was changed?

I think it was 1973

 

[skywagon8a]

I think it was 1973

Yes.

 

[hotrod180]

Thanks.
I took another look at the article, yep:

1973 1) "camber lift" wing with bonded leading edge....

for both the 180 & 185.

 

[BC12D-4-85]

An experienced ex-military and civilian commercial pilot mentioned that with the Cessna factory cuff it would lift off without consciously adding more elevator. Or something like that (50 years ago comment). Just start elevating tail low before the original wing. He flew both together so I assume he was right.

Gary

 

[DJ]

Proof that marketing works is a "STOL cuff" on a stock O-200 powered C-150.

Sent from my SM-G965U1 using SuperCub.Org mobile app

 

[BC12D-4-85]

Here's an earlier thread on VG's that keeps on giving via Jerry's comments on placement> https://www.supercub.org/forum/showthread.php?37737-Home-Made-VG-s

Found another: https://www.supercub.org/forum/showthread.php?19433-VG-s-which-are-the-best-ones&

Gary

 

[Dog]

Interesting. Do the Wing X extensions not reduce roll rate on these airplanes?

MTV

They do not improve role rate, but much less so than the Robertson does.
With VG's and Wing X I get most of it back to have the extra performance and back to about standard aileron response.
The aircraft carries a gross load much easier, better altitude performance and climb -- cooler running engines.
It allows the aircraft to get up on the step as I call it and cruise at the same attitude on floats as it would with the same load on wheels at the higher speed.
By the way the 4 inch reduction on wingspan on the 73 camberlift wing was the tips they are a couple inches shorter each side. I have one of each and a hangar thats tight so I get to see it every time I bring in the B model.

 

[BC12D-4-85]

Sportsman's tips add aspect ratio to the wings via a trailing edge extension. The rear wing's length has significance for lift.

Gary

 

[Steve Pierce]

Charlie told me the story of Jerry walking in his place wanting to put VGs on a Cub. The rest is history.

 

[Cardiff Kook]

I know three of the respondents to this thread in real life. Three gentlemen I trust. Three with more Skywagon time than most of us will ever fly. When Mike, George and Pete talk listen.

Didnt mike, george, and pete say they werent worth it? Or am I mixing things up here?

Found this video interesting from Jim Richmond.

 

[sj]

Didnt mike, george, and pete say they werent worth it? Or am I mixing things up here?

I think most would say they do what they are intended to, but the difference is way less dramatic (even not noticeable for some folks) than on the Cub.

I’d much rather have a wing cuff, but I could afford vgs…

sj

 

[sj]

P.s. thanks for taking time to search and find some of these good old threads before starting a new one!

sj

 

[stewartb]

Cardiff, are you on the fence about adding VGs? A good friend and probably the best pilot I know schooled me on VG’s on Skywagon wings. BLRs (VGs set aft of the leading edge) improve aileron response at high angles of attack while Micros (VGs set along the leading edge) focus on stall speed, so don’t do anything for ailerons but simply let the plane fly normally at a handful of mph slower than without. If you don’t fly your plane at MCA near the ground you probably won’t think much of VGs. If you do fly slow for more than a few seconds of straight flight on short final? You’ll probably be a fan.

Happy New Year!

 

[aktango58]

Didnt mike, george, and pete say they werent worth it? Or am I mixing things up here?

Found this video interesting from Jim Richmond.

Not exactly what I said.

Stewart and Mike said it well: If you want short field performance, after learning to fly the plane well:
The Sportsman's cuff will give you the most dramatic increase in lift and reduction of stall speed through wing area and camber to the front of the wing, but add a touch of drag
The Wing-x will give you more lift through wing area at the tip, thus reducing the stall speed, BUT much reduced roll rate
VG's mellow and slow the stall speed, AND give you much better control response at slow speed, (remember they are on the wing and tails). The down sides are as Mike says: pain in the tail to fuel, slows the plane's cruise speed due to drag, wing covers hang up on them, and they WILL collect ice, especially in wet snow conditions.

So in choices one must ask where to put your dollars. VG's are the least intrusive and lowest cost, but give a positive control improvement low and slow.

Most 180/185s I see flying around can do everything the owner wants to do in a bone stock plane. Not everyone demands the performance we ask of our working planes, but mostly the modifications add safety margin for our operations.

 

[BC12D-4-85]

Consider the wing loading (aircraft weight/square foot of wing area) of the stock PA-18 vs C-185. Cub: 1750#/178'= about 9.8#/sq ft. C-185: 3350/174'= 19.3#/sq ft. Cessna 2x the Cub.

Carrying about half the wing loading at GW (Cub's higher with 2000# kit; 11.2), the Cub can take its time to respond to a stall as AOA is increased. The Cessna will respond and drop quicker especially with flaps 40 and heavy with forward CG. Both benefit but the Cub takes a bit longer to finally let go.

That may be one reason we feel there's a benefit with VG's on a Cub more than with the Cessna? The Sportsman cuff does let the Cessna hang on longer at minimum airspeed with the stall horn talking.

Gary

 

[BC12D-4-85]

Another way to compare wings (and maybe the effect of LE devices) is examine the diagrams above. One is for the Cub (left; USA-35B; it's similar), and the Cessna's NACA 2412. Note the shape of the coefficient of lift line (Cl) as the critical angle of attack is approached and then exceeded. That line can vary per airfoil by factors, but here assume they are similar.

The Cub's appears more gradual and flatter, while Cessna peaks then falls quickly. Adding VG's, a cuff, or other LE devices can soften or smooth that line. We would need to see the 2412 diagram with VG's added to really note any effect. Same for the Cub of course.

As far as the effect of increased wing loading vs stall speed and behavior (the Cub vs Cessna in the Post above), put a Cub in a 60* coordinated level flight turn, then stall. The G or wing loading about doubles, and the stall speed increases about 1.4 times that experienced in level flight (^xSQ RT of the wing loading). Flaps up that's ~47x1.4=65.8 mph. That will wake you up. Now it feels similar to a C-185 when it breaks.

 

[mvivion]

This discussion to date has been based solely on “personal feel”.

The Robertson STOL kit for the 1985 Cessna 185 provides a Flight Manual Supplement which states that the RSTOL C 185 stall speed with 40 flaps is 37 knots. Compare that to the stock wing stall speed with 40 flaps at 49 knots.
Those are actual flight tested numbers, verified to the FAA. And, that RSTOL 185 will have the airspeed instrument re-marked to those Robertson numbers.

So, what do the Vortex Generator kit AFM Supplements offer as their change in stall speed? Is the airspeed instrument required to be re-marked after installation of VGs?

Basically, there are a couple different ways to certificate these things. Robertson took the more rigorous path.

 

[BC12D-4-85]

With VG's the approved aircraft met the performance standards when originally certified. Any benefit is left up to the user to determine post installation.

Gary

 

[mvivion]

With VG's the approved aircraft met the performance standards when originally certified. Any benefit is left up to the user to determine post installation.

Gary

Yep…..

 

[BC12D-4-85]

Here's one opinion on SE aircraft VG's with data and impressions. Twins are noted and different.

Vortex Generators: Got STOL? Think Twice - Aviation Consumer

When things go south and you have to park an airplane in an unintended location, touching down at a lower stall speed means less energy to dissipate in the crash. Energy is a squared function, so reducing impact speed, even a little, pays big dividends. In a twin, reducing Vmc means reducing the...

www.aviationconsumer.com

I would not leave ground in a Taylorcraft without them, but that's particular to that wing. It tends to stall at the leading edge first.
Gary

 

[stewartb]

pirep- I’ve never had any problem with VG interference with wing covers or during fueling. I’ve watched lots of guys struggle with wing covers through the years without VGs installed so it stands to reason that some guys must struggle with VGs. The problem isn’t the VGs. And for fuel hoses? Managing those is easy. Hoses don’t do damage, people do. If you think VGs are bad, try being careless with slats!

 

[stewartb]

This discussion to date has been based solely on “personal feel”.

The Robertson STOL kit for the 1985 Cessna 185 provides a Flight Manual Supplement which states that the RSTOL C 185 stall speed with 40 flaps is 37 knots. Compare that to the stock wing stall speed with 40 flaps at 49 knots.
Those are actual flight tested numbers, verified to the FAA. And, that RSTOL 185 will have the airspeed instrument re-marked to those Robertson numbers.

So, what do the Vortex Generator kit AFM Supplements offer as their change in stall speed? Is the airspeed instrument required to be re-marked after installation of VGs?

Basically, there are a couple different ways to certificate these things. Robertson took the more rigorous path.

Do you really think comparing the installation of a Robertson kit to VGs is apples to apples? You’d be the only one. The flight testing requirements make perfect sense for a complicated mechanical system that interacts with and changes the flight control systems and positions. The absence of equal testing requirements for a simple surface applied VG that’s universally accepted on large commercial wings also makes sense. There is no operational training necessary for VGs. No AFM supplement. No lurking danger if a pilot flies the AFM speeds. That doesn’t mean they don’t provide a benefit.

 

[stewartb]

A thought about RSTOL. I know guys who love it but I don’t know anyone who’s loved it enough to buy and install a kit in this century. I don’t even know a guy that knows a guy. Yet I know guys willing to spend a half million dollars on modified Cubs. Maybe Skywagon owners are the cheapskates in aviation.

 

[BC12D-4-85]

Juries can be convinced of many things, but there is this regarding VG's from our local Newspaper.

"A Fairbanks jury awarded the widow of ********** $3.5 million on Tuesday, finding that ******** was at no fault in the plane crash that claimed his life.....******* died after crashing his single-engine Bellanca Citabria 7GCBC about 17 miles southeast of Fairbanks...

The ******* family maintains that ********* was a meticulous pilot who was put in a bad situation when a tail stall caused the aircraft to suddenly flip and begin plummeting to the ground.....

Tail stalls are rare and possible in aircraft with vortex generators, small wedges or T-shaped tabs added to aircraft wings to improve handling at slow speeds....

******** was on a test flight after having work performed on his airplane, including installation of vortex generators.

“The issue was failure to warn,” said ********, attorney for the ******* family"

Note: The pilot was accomplishing the requirements of 14 CFR 91.407 (b)

 

[hotrod180]

A thought about RSTOL. I know guys who love it but I don’t know anyone who’s loved it enough to buy and install a kit in this century.....

I didn't even know if R-STOL was still available these days.
I googled it & found this.

https://skyway-mro.com/wp-content/uploads/2019/04/RSTOL-brochure_2019-web-2.pdf

I just emailed them, asking about price & availability.
I will post the results if/when they respond.

 

[skywagon8a]

I didn't even know if R-STOL was still available these days.
I googled it & found this.

https://skyway-mro.com/wp-content/uploads/2019/04/RSTOL-brochure_2019-web-2.pdf

I just emailed them, asking about price & availability.
I will post the results if/when they respond.

If you are considering this....be aware there is less up aileron when the flaps are not up. This means you will have less roll authority in a crosswind. That being said, takeoff speeds will be reduced by as much as 12 mph. I loved mine, but it was a different system in which I could choose whether or not to droop the ailerons as they were eclectically powered independent of the flaps.