I have a friend who is buying a Cessna 172 with Robertson STOL and VGs.
What are the opinions of the Robertson STOL?
The owner of the plane didnt like it much because he says he looses too much aileron authority.

Thats a common complaint. Sportsman is much more popular...

motoadve wrote:I have a friend who is buying a Cessna 172 with Robertson STOL and VGs.
What are the opinions of the Robertson STOL?
The owner of the plane didnt like it much because he says he looses too much aileron authority.

A Robertson STOL is Great, Complete different animal than a Sportsman, Which is also a Great addition!!
You fly a Robertson different than a normal Cessna wing!! And to the guys who don't like it because they run out of aileron, They just have to go back to basics and learn how to use the RUDDER!
My $.02

When I bought the 185 it had a Robertson Stol kit on it. I never had much of a problem with aileron response but rarely did I fly deep into the envelope where such things would be more apparent. I was told by Micro VGs that putting on their VGs would improve roll authority, I just never did. I found that a good solid approach provided a good and safe landing. Same with a take off, no miracles needed no miracles provided. You can't buy ability and common sense.

While flying around other TW pilots in BC, their opinon was Robertson was the best of the stol kits but probably not worth the extra cost when compared to other kits. I did put a Bush Stol kit on my T-210 and that was probably the biggest waste of money I ever invested in a plane.

If you just want to spend $$$ on your baby, there is a virtual unlimited amount of choices and the process of deciding is lots of fun. If the plane comes with a Robertson, I would count that as a bonus.

My plane has components of the Robertson kit, I can't say how they compare to the Sportsman but I remember coming to the conclusion that if i had the Sportsman cuff with the Robertson components I already have, I would be in tall cotton. I will say that there's a vg setup out there that won't work on a 182. My plane had them for awhile and nearly killed everyone that flew it. "nothing short of terrifying" is how one instructor described his experience with them.

I will say that there's a vg setup out there that won't work on a 182. My plane had them for awhile and nearly killed everyone that flew it. "nothing short of terrifying" is how one instructor described his experience with them.

And what setup is that?

My experience with Robbies, and various piilots that fly them is that they are to the wing what a tailwheel is to landing gear.

That is to say that if your handling of the aircraft during landing phases has any weakness (particularly in directional control) it is going to be glaringly magnified by the addition of an RSTOL. If you are the pilot that leans heavily on aileron for directional control, you will be sorely disappointed by an RSTOL, likewise if you are the pilot that does not need to fly slower than standard wing book speeds, you will never meet it's virtues.

OTOH, if you are both proficient and competent in anything a landing phase is going to throw at you, then you simply can not argue against an RSTOL.

As an example, an RSTOL equiped early Cessna 180 will have a book approach speed slower than a PA-18 Supercub! Yes Slower... 51 MPH for the RSTOL 180 vs 70 normal ops or 60 short field ops for the Cub. Although the RSTOL 180 will be comfortable at that approach speed with over 1000 extra pounds of weight! Also just like the Supercub which can be flown slower than book speeds in competent hands, so can the RSTOL equipped 180.

I have said this before, I can and do routinely fly my 180 anywhere I will take my cub, save the boulder piles....

Crosswinds... lets examine this. If we can fly a Cessna 180 at max gross comfortably at 51 MPH, why are we concerned about crosswind? Because at this point either you are landing in the sticks, where you will simply land into the wind, or you are at an airport, where at 51 MPH approach and 40 MPH +/- touchdown speed you can literally land across the runway... so remind me please why crosswind in a Robbie should be an issue?

But enough about the 'wagons... want to really appreciate RSTOL? watch a 3 series RSTOL Cessna operated by a competent pilot sometime... That will make a believer out of the most adamant nay sayers...

Take care, Rob

And what setup is that?

I can't remember. The story though is interesting in that the previous owner of my airplane was having lunch at the field in Hamilton MT when he struck up a conversation with another pilot. In the course of conversation it turned out the guy was the inventor of the vg's, so he came out and looked at the plane. He couldn't figure out how it flew at all because either the style or the arrangement was meant for a piper wing. Once they were taken off, the thing flew normal. I've never repainted it , so I can still see where they were, they even had them up the vertical fin on both sides.

I claim no expertise re: VGs, but everything I've read about them is that if they're going to work, they have to be installed on the right place on the wings and tail feathers. Perhaps yours weren't properly installed.

Cary

My first 185 had Robertson STOL. I loved it, flew it all over Central America in and out of crap jungle strips in beyond hot conditions. It never let me down and was easy to handle. When I went looking for this 185 I wanted Robertson again, but couldn't find one in a configuration or condition I wanted. The one I got had VG's installed. Liked them so much I took them off and haven't missed them at all. If I can source another Roberson kit, I'd buy it. It is a bitch to rig, but well worth the result. I also liked the stall fence, which smooths out flow to the ailerons in addition to controlling span wise flow.

Cary wrote:I claim no expertise re: VGs, but everything I've read about them is that if they're going to work, they have to be installed on the right place on the wings and tail feathers. Perhaps yours weren't properly installed.

Cary

That's probably the case, and I never saw an stc in the logs. The cautionary tale though is that they were installed with precision using a methodology derived from somewhere. I'll snap a pic of the placement that definitely doesn't work.

I have flown my C205 with a Robertson for 20 years or so. I really like it and have never felt I ran out of aileron control. I think as others have said, "learn to fly it". Been in lots of backcountry short strips and right down to the Robertson's book speeds often less, it has been very comfortable. Lots of experimental cub guys using drooping ailerons for max stol. Have found rudder is your friend!

what's the weight difference for the Robertson vs. the Sportsman?
and how much weight is added, to say a 180.

I too love the Robertson equipped Cessnas. A 37 knot stall speed on a gross weight 185......and that is a well documented and reproduce able figure, unlike many so called "STOL mods". Like any other airplane, an RSTOL equipped airplane does require some pilot participation, as Rob noted.

I flew one RSTOL 185 some 2500 hours and loved it. Our maintenance guys wanted to try adding a Sportsman cuff to an RSTOL 185, so they did mine. That made a big difference in the plane, making stalls even gentler, and reducing stall speed even further. I really had to re-learn how to take off on floats, but once I figured it out, it was an ass kicker. It regained some roll authority at high alpha, probably due to the aileron gap seals that come with the Sportsman kit.

As to weight increase, it depended on what model year you're modifying. The early Cessnas did not have a cambered leading edge, and the RSTOL kit for those included a leading edge cuff as well. Later models didn't require the cuff, due to the cambered LE. Otherwise, the primary weight increase with RSTOL is due to the added balance weights in the ailerons. Not sure of the total added weight, but it's not huge.

Finally, part of learning to fly an RSTOL airplane is learning what flap setting to use when. Different flap settings change the amount of aileron droop.

A great system. Too bad it's so expensive to install.

MTV

As usual MTV is correct...

RSTOL totally depends on what year you're modding, and the current configuration of that wing.

Best case scenario is modding a late model, or already cuffed early plane. Then RSTOL will add 13#'s @ 60".
FWIW Sportsman will add 15# @ 33" so not necessarily a lighter way to go. Nor is that added weight in an ideal CG, but I digress..

Worst case scenario for an RSTOL install is an early virgin wing, with the optional flap actuated elevator trim system. This because it won't even have the Cessna camber cuff that is present on all the later birds. So calling that extra weight may be a bit unfair. In this case you will be adding an RSTOL cuff which is nearly identical to the Cessna cuff, and as I understand it, the Cessna cuff was designed and to emulate the RSTOL cuff. In this case you will be well over 20#'s, I don't have the exact W&B on that kit handy, but IIRC 27# sounds right. Bear in mind in this scenario you are adding a cuff in conjunction to the droop and trim. In other words this is almost the weight-wise equivalent of adding the RSTOL and Sportsman, although IMHO, if a guy had a virgin wing he'd probably be better served by foregoing the RSTOL cuff and just adding the Sportsman in it's place.
Take care, Rob

I certainly won't bash Robertson STOL, but I think it's no longer available, and it was very expensive compared to any other STOL kit. I may have told this story here before (tend to get repetitive as I get older ):

My airplane pard and I traded our Skylane in for a new TR182 in 1979, soon after Cessna started making them. Within a few weeks, my pard started talking about having a Robertson installed. At that time they ran about $20K. I asked him why, and he said that he wanted to be able to visit patients who lived on some of the ranches, and yet he couldn't make the first turn-off at LAR like he used to be able to do with the Skylane (that turnoff is roughly 1500-1600 feet from the approach end of 21). I suggested that before we invested in such a pricey addition, maybe he should first learn to land the TR182 as it was designed to be landed.

Interjecting here, one of the hardest things to do is to teach a good friend to fly differently. It's a little like teaching your spouse or kid--the close relationship gets in the way. I was a CFII at the time, but rarely would he listen to me, no matter how diplomatic I tried to be. Also, I don't mean to be overly critical of him--he was and is an excellent pilot.

He asked me what I meant, and so I asked him why he regularly used 80 knots as his final approach speed. His answer was classic: "Because it's a faster airplane, it needs to be landed faster." That the book speeds weren't materially different from the Skylane's hadn't really registered with him. I suggested that we should do some practicing, and so we agreed to do that the next day. But I cheated--I went out and practiced with different approach speeds at the weight we were going to use the next day. I found that 55 knots worked really well, that 50 knots was too slow because I ran out of elevator authority sufficient to keep the nose from dropping.

The next morning, we flew--a rare windless morning in Laramie. First I asked him to do slow flight with full flaps. He slowed it to maybe 60 knots (as it turned out he had been taught that was sufficient), so I asked him to slow it until the buzzer remained on, which frankly bothered him. Then I asked him to do turns, and he did the little bitty 5 degree banked turns. I suggested 30 degrees, and he said, "It'll fall out of the sky!" "No it won't." "Then you do it." So I did--and it didn't fall out of the sky--the stall burble just barely started.

Then we went to land, and I suggested that he slow the airplane down to 60 KIAS. "No, it'll fall out of the sky!" "No it won't." "Then you do it." So instead, I slowed it to 55 KIAS, and he said, "You're going to kill us!" "Nope." I landed, and we rolled to the first turn off, where I turned off without braking. "Now you try it."

His first approach was at 75 KIAS, and of course we rolled past the turn off. We went around again, and this time he tried 70. Still past the turn off, even with heavy braking. Once more, and this time at 65, he was able to stop before the turn off with relatively moderate braking. He said he wasn't about to go slower, although he'd seen me do 10 knots less without any difficulty.

My point is not to denigrate any STOL kits, but just to say that sometimes better pilot technique is all that is needed instead. Since flying with an AOA indicator in my airplane for the last 4 1/2 years and almost 300 hours, I've noticed that my approach airspeed is just about book only when the airplane is at gross. Otherwise, it's often significantly lower, depending on the load. The previous owner of my airplane installed Madras droopy tips, which make some difference in positive aileron control at low airspeeds but cause enough drag that the cruise speed is about 5 mph less, and I've had installed flap gap seals, which brings the cruise speed back up again. But none of that seems to make much difference in stall speeds or approach speeds (but the droopy tips look cool, right? )

Cary

Although no longer actively marketed for single engine aircraft, Robertson STOL is still available.

Rob wrote: As an example, an RSTOL equiped early Cessna 180 will have a book approach speed slower than a PA-18 Supercub! Yes Slower... 51 MPH for the RSTOL 180 vs 70 normal ops or 60 short field ops for the Cub. Although the RSTOL 180 will be comfortable at that approach speed with over 1000 extra pounds of weight! Also just like the Supercub which can be flown slower than book speeds in competent hands, so can the RSTOL equipped 180.

That is kinda a misleading statement, given a cub flown at 60 would be more like a slow cruise in real life. For me 40 is more like it for most "real world' backcountry ops, not that I fly a Cub often anymore.
And of course, add 1000lbs and add 5-10kts to the stall speed.
Just being realistic here, not saying RSTOL isn't a great mod, just that you can't turn a Skywagon into a Cub...

I enjoy that story everyone you tell it, Cary. Reminds me to fight complacency!

good story Cary, pilot skill and comfort are needed for any plane, with or without a STOL kit.
MTV, how slow did the Sportsman/Robertson STOL 185 get?