Whose mod is that?

Idaho Supercub

Grasstrip, whose STOL kit is on that 182? The Sportsman cuff seems to be the one everybody talks up nowadays. I just googled it, Steene Aviation (the interior plastic people) sell it now- about $1900.
Oh, Idaho SC, surf the supercub.org site for info on the thrustline mod-- a long thread on it there.

Eric

I know I'm gonna get yelled at here, but I'm betting the best STOL kit out there is a pilot who's well versed and proficient in his/her airplane, and who understands how to fly all corners of the envelope.

Can't tell you the number of tricked out Cubs, Maules, 185's, etc. that I saw show up at PAOT every fall for moose season, with pilots that couldn't fly a C150 on a calm day off 10,000 feet of paved runway. These guys would get their flying asses kicked by some Eskimo kid with 50 hours total, flying a ratted out village C172 or Cherokee.

Gump

Hey Gump


Speaking strictly for myself here. I make no claims of being any kind of good pilot. I've only been doing this "backcountry" flying for a couple of years, but I am very interested in it, and do everything I can to learn more and be better. I read everything I can about it. I talk to anyone that I think I can learn from. I read this forum religiously looking for tips. And I try to fly atleast 1/week to get some kind of proficiency.

For example I agree with you that a good pilot can do more with, say a stock 180, than a poor pilot with every mod he can get on the same 180. There is no substitute for experience. But I do feel that some of these mods do make things easier and help reduce the stress on the plane on the off asphalt strips.

I had hoped that it might help me be a better pilot sooner and possably help out if I was in a marginal situation.

Has it worked. Can't really tell you for sure. I feel like it has. My plane performs really well. But more than anything. I'm having a ball. That's priceless.

Gary

shortfielder wrote:There is no substitute for experience. But I do feel that some of these mods do make things easier and help reduce the stress on the plane on the off asphalt strips.

Oh, I agree wholeheartedly, and VG kits on airplanes like the Scout and the other STOL kits are wonderful.

All I'm saying is, that for a lot of guys, especially newer guys, spend the money on gas for flying and learn how to make your airplane sing and dance. Make the seat of your pants part of the airplane. Get to that point, then add the STOL kits, and then you'll be getting your money's worth.

I learned float flying from Dave Wiley a long time ago in a C-85 powered T Cart. I then bought one of the things myself to really learn how to fly floats. That airplane was a one-finger airplane. Two fingers was being ham fisted and you'd never get it on step if heavy. I flew the shit out of that thing, and really developed a feel for how the floats were sitting in the water. It wasn't from the bigger floats and higher horsepower that I looked good, it was the exact opposite. That underfloated gutless little Taylorcraft of mine taught me how to fly to the edges, and taught me to feel the airplane lift and pull.

Gump

Here is the way that I look at STOL devices and kits:

I don't install STOL devices so that I can fly significantly slower approaches to short strips. That will get you hurt, if you do it enough. The reason? Every one of those kits that is at all effective allows the airplane to operate at a higher angle of attack prior to reaching critical angle of attack. That means that if you DO stall the sucker, you are in there deeper, and the results are often rather "abrupt", as anyone who's done a lot of stalls in an RSTOL equipped airplane can attest. Doesn't happen every time, but every once in a while, one of those will go a little aggressive.

Instead, I view a STOL kit as a device that will allow me to approach at pretty much normal speeds in even somewhat squirrelly conditions, and if I have a brain fart and fly into something I should have seen coming, it may provide that extra margin of safety that will permit me to land, change my underwear, and go on with life.

That is the key to safely using STOL devices, in my opinion.

In that one weird, unexpected little gust event, that kit might just allow you to fly it to landing, as opposed to making a smoking hole.

MTV

My take on STOL kits and high lift devices in general, including VG's, is that they seem to gain in the low speed area by robbing from cruise. With enough mods like STOL kits, big tires, Borer props etc., you may end up with a 90 mph airplane that has lost a lot of it's cross country capability. It all depends on what your needs are. If you need to get into and out of places you can't now or just want more safety margin and are willing to lose a little cruise speed, go for it. If you are like me that unfortunately has to fly from one 5,000 paved runway to another 90% of the time and the amount of fuel I burn for the distance traveled is a factor, then I don't need these things.
I want the AK bushwheel 29x11-10 wheels, but I know that I don't need them. I still think they would look cool on My Maule though
Sometimes the best "mod" is a more capable airplane.

Actually, most of the true STOL mods don't decrease cruise speed appreciably, though most do add some weight, and weight of course, affects speed.

The Robertson kits are completely invisible to the airplane aerodynamically, when the flaps are retracted.

I've installed Sportsman kits on a few airplanes, and none lost any cruise speed that I could discern. Maybe there was a tiny degradation, but certainly not much.

At cruise AOA, the Vortex Generators don't even "see" the relative wind in most applications. They are positioned NOT to work at cruise AOA, only at high AOA.

The wing extensions are an interesting case, where in some cases, they actually INCREASE cruise speed, due to the change in aspect ratio and lift characteristics.

So, I don't worry much about speed loss with any of these devices.

Bushwheels are NOT a STOL device. They are just tires. Magnificent tires, mind you, but they do nothing to help the airplane fly slower.

MTV

Down low, 2000 DA on my 83 Maule M-6-235, I went from a full throttle speed of 158 mph indicated to 150 mph indicated with Microaerodynamics VG's. At cruise power it was about 5 mph loss down low. My best altitude for speed used to be between 7 to 9 thousand ft PA where I got 132 kts true. Now my best altitude is between 9 to 11 thousand PA where I will still get 132 kts true. Not sure of why, but I am sure of my results. Stall speed with flaps retracted dropped a couple of mph, flaps down the same. The critical angle of attack definately changed though, because to keep the stall warning 5 mph before stall, I had to bend it down significantly.
VG's on my Maule are not a STOL device, I cannot fly slower now than before, but I do have more elevator authority and aileron authority than without.
The Flint tanks are not considered wing extensions, but they do extend the wing. On our C-210 they did lower the stall speed and it will get in and out shorter than without them if the weight is the same. They slowed the 210 down about 3 or 4 kts.
I think the same "mod" may have different results on different airframes, so blanket statements about the effect of these mods just can't be made. What works on a Cessna, may not on a Maule or Piper or vise versa.

a64

If your stall warning AOA changed significantly, the IAS should have changed proportionatley. I would think that IAS would be somewhat inaccurate at these high AOAs. The pitot tube is way out of line with the relative wind. Once again I am confused.

Knowing what you now know, would you put the VGs on your Maule?

flyer

a64pilot wrote:Down low, 2000 DA on my 83 Maule M-6-235, I went from a full throttle speed of 158 mph indicated to 150 mph indicated with Microaerodynamics VG's. At cruise power it was about 5 mph loss down low. My best altitude for speed used to be between 7 to 9 thousand ft PA where I got 132 kts true. Now my best altitude is between 9 to 11 thousand PA where I will still get 132 kts true. Not sure of why, but I am sure of my results. Stall speed with flaps retracted dropped a couple of mph, flaps down the same. The critical angle of attack definately changed though, because to keep the stall warning 5 mph before stall, I had to bend it down significantly.
VG's on my Maule are not a STOL device, I cannot fly slower now than before, but I do have more elevator authority and aileron authority than without.

This has been almost exactly my experience on my '79 C-180. About 4 knots loss at the same power setting below 7,000; about 2-3 knots loss above 9,000. I haven't checked much higher yet, but my guess is that by 14,000 the loss would be negligable. VG drag seems to go up linearly with indicated airspeed.

I have, however, very definitely been able to reduce power-on approach speeds by 5 knots and still be comfortable in calm conditions, and the airplane definitely comes off the ground earlier. This translates into being able to go into some of the shorter Idaho strips at about 300 lbs heavier than I was comfortable with before. A weeks worth of beer and steaks instead of two days! Crosswind handling is more authoratative too. Remember, the MicroAerodynamics installation on the 180 has VG's on the rudder and under the stabilizer.

All in all, since 90% of my flying now is within 300 nm and mostly in the dirt, it was a good mod.

Rocky

For the experimental group, here's a neat website that makes vortex generators, mostly for the Zenith aircraft and derivatives:

http://www.stolspeed.com/content.php

They have done quite a bit of flight testing. The 701 and Savannah seem to do quite well without their leading edge slats and the VGs installed. I've been chicken to make the change, but I'm still facinated.

It is pretty funny that he references my YouTube video at the bottom of the Savannah page.

tom

flyer wrote:a64

If your stall warning AOA changed significantly, the IAS should have changed proportionatley. I would think that IAS would be somewhat inaccurate at these high AOAs. The pitot tube is way out of line with the relative wind. Once again I am confused.

Knowing what you now know, would you put the VGs on your Maule?

flyer

Flyer,
I think that with full flaps and power off the Maule is down so slow that there just isn't much more lift available. Yes the VG's definately increase the AOA at which stall occurs, but I'm guessing that with the Maule that's so slow that even with the higher AOA there just isn't much reduction in speed. The greatest reduction in stall speed is with the least flaps. Now to be honest with full flaps and power off my M-6 doesn't really stall, that is it won't drop a wing unless you do something stupid with your feet. It just sort of "mushes", but the vertical descent is so high that it's like an autorotating helicopter, but her nose never really drops completely. Maybe at full gross and a farther aft CG where she should fully stall, then there would be a bigger difference. I didn't test there.
The stall break is at a slower airspeed with the flaps retracted, but it is more dramatic, it's almost as if the stall was delayed, but when it did stall, it suddenly "caught up" to where it would have been with out the VG's.
If I had to do it again, I wouldn't, but then I rarely get to fly in the "back country". I would have bought a couple of hundred gallons of Avgas instead.
The way BD built my airplane it would indicate 160 mph with everything pushed forward, which is awfully respectable for an airplane that can get in and out in few hundred feet. I improved the airplane with a three blade prop and added 16 lbs. and lost 2 mph. I further improved the airplane with VG's and now it will indicate 150 mph. Sometimes I wish I had my 16 lbs. and 10 mph back even though the three blade and VG's look cool

Seems to me from what I've heard is that ragwing airplanes (Cubs, etc) seem to get the most out of VG's, and metal wings (in other words, Cessna's) seem to get more improvement from leading edge cuffs. Some guys have added VG kits to their cuffed wings. Anyone here who has put a VG kit (only) on a Cessna metal wing, & what is your take on it? In particular, I'm curious about VG's for the 150-- I'm thinking of getting a 150/150 taildragger, and from what I can find on the internet, a sportsman cuff kit would run about $1900 and a Micro VG kit only about $700. VG kit seems like a quicker install too. What's the difference as felt from the pilot's seat?

Eric

zero one victor,

Look at my earlier posts. My Cessna 170 (similar wing to the 150) has an unmodified wing--no cuff. I installed Micro VG kit. I noted a slight softening of the stall, making stalls even less of an adventure than they were to start. Bear in mind that a Cessna stock wing is a very forgiving wing in any case, and these things just made the stall a bit more benign.

They gave me a LITTLE more roll authority at high AOA.

I was not able to measure consistently ANY reduction in stall speed. There was also no NOTICEABLE change in landing speeds.

I have installed Sportsman cuffs on several Cessnas, and they also soften up the stall, perhaps more than the VG's. The big difference is that the Sportsman kit really changes the stall speed of the airplane. This is measurable and it is noticeable in landings. The Sportsman also provides substantially better roll authority at high AOA (the kit includes aileron gap seals).

I don't think the differences in cuff vs VG has anything to do with fabric vs metal wings, but rather airfoil design. Note that Cal Center designed and got approved a leading edge cuff for Super CUbs. I never liked them, but they did what he wanted them to.

The reason I went with the VG kit as opposed to the Sportsman was the same as you are looking at: Dollars. If I had it to do again, I'd either go with the Sportsman kit or leave the wing stock.

Note that another issue on a 150 is weight. The Sportsman kit adds a little bit of weight to an airplane that doesn't have the best useful load to start with.

MTV

01V
I had a 1961 C-150/150 TW. It was a lot of fun. Great 1 person plane. Could put 2 in but pretty tight and not much left over for gear. I did make a little extended baggage compartment and that helped for a little extra room.

Pay attention to the stc's. There is one out there that will let you raise the gross weight and you defineately want that. Mine used 140 gear and I think that would be preferred also. I think it was Doyne, or something like that. I think the engine stc. may have been a Peterson and it also alowed 180 HP.

Another thing that I would recommend would be to have the patroller tanks. I think they will give you an extra 17-18 gals. which you will want with the bigger engine.

Probably the most "Fun" plane I've had to fly and the lowest $/hr.

As far as the stol kit versus VG's. I went with the Sportsmans because it was hands down preferred and I think about $400.00 extra. If you can have the best for a little extra, then I think it's a good idea.

I went with the stol kit to lower my stall speed and the VG's to get more authority of the control surfacesa at the slower speeds and have been very happy.

Gary

I have thought about putting Micro VGs on my Maule M-5. Micro advertises No Reduction in Cruise Airspeed with Micro VGs.

According to A64, there is some reduction in cruise airspeed.

I e-mailed Micro Aerodynamics and asked about reduction of cruise airspeed on Maules. I wanted to know what tests they had performed to be able to back up their statement.

Charles wrote that they had sold VGs for over 500 models and they had only tested the VGs on 5.
I was disappointed in his response and in his tone.

My concern was of a lessening of performance on my Maule.

His response was "If you want to go fast, sell your Maule and buy a Mooney".

Does anyone else have cruise speed changes caused by the Micro VGs?

flyer

Flyer,

You have now experienced the full gamut of testing that Micro does on their kits.

So, now read their advertising.

MTV

Think about how VG's work, whoever made them. They work by adding energy to the boundry layer, thereby delaying airflow seperation. Where does this energy come from?
There is no free lunch. A theory is that by delaying this seperation you basically create a laminar flow wing and this laminar flow cancels out the drag caused by the VG's. Sounds cool, but it doesn't work.
VG's do delay airflow seperation, but they produce drag, they have to.

a64pilot wrote:There is no free lunch. A theory is that by delaying this seperation you basically create a laminar flow wing

Question for you guys that have flown VG equipped airplanes in crap weather. How does icing effect them and the wing if ice can/does build up on them?

I've only flown a couple VG airplanes, and that was on warm, sunny days.

Gump