Backcountry Pilot • R STOL or sportsman profile?

R STOL or sportsman profile?

Have you modified your aircraft? STC? STOL Kit? Major rebuild from just a data plate?
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Re: R STOL or sportsman profile?

Thanks for the advice Mike, I am transitioning from a Stinson 108 in which I could easily overpower all the Controls, my learning experience in the 206 happened in a strong gusting crosswind takeoff while trying to hold the airplane down it was trimmed to where it wanted to fly at 50 mph and as I tried to keep it on the ground it became light on the tires, A big gust hit that seaplane tail and it weathervaned into the crosswind While skipping along on the ground, this all happened in a second and I was surprised because I had rudder in to track down the down the runway fine until it became light on its wheels, The sharp yaw surprised me and I did not have enough upwind aileron in. … at that speed with the crosswind and 20° of flaps it was a little hairy not being able to put the wing back down with the ailerons. Although this was a learning experience and due to pilot error, it got me wondering if VGs would have given me a little more control in that situation .

As I get a few more hours I’m learning how important trim is in the 206 and I think if I’m taking off in a big wiind and have the runway I will use less flaps for takeoff so I can rotate at a higher speed with more air over the control surfaces. …This probably goes under dumb questions that are only dumber if they remain unasked, but on a tricycle gear Cessna if the nose wheel is planted on the ground do you have less rudder deflection because of the steering interlink?

By the way I did realize that it is definitely a standard Robertson store cop on the wings, for some reason there is an end plate that protrudes in the shape of a sportsman store upon which the wingtips are mounted.
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Re: R STOL or sportsman profile?

daedaluscan wrote:Paperwork has always confused me. It seems very surprising to me that you could combine a Sportsman cuff with the remains of Robertson STOL kit.

Can someone explain?


What’s your question? What do you mean by “the remains of Robertson STOL kit”?

The RSTOL kit droops ailerons, and on early Cessnas, it added a mild leading edge cuff, plus stall fences on top of wings. Once Cessna came out with their “Camber Lift Wing”, which was basically a knock off of Robertson’s cuff shape, Robertson did away with their cuff as part of the RSTOL kit

So, on a RSTOL equipped Cessna, adding the Sportsman is no big deal. You just tell the dealer which leading edge you have.

Of course it is the responsibility of the installing IA to verify the compatibility of the two mods. That said, there have been a LOT of Sportsman kits installed on RSTOL equipped Cessnas. It really makes a nice combination.

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Re: R STOL or sportsman profile?

I thought it meant removing the Robertson cuff and replacing it with a Sportsman. I was not aware that there was no cuff on later wings.

I suppose my question is answered in you’re last para, but it seems counterintuitive to me, given how hard it is to obtain an STC, that the two such obviously interacting mods would be allowed without testing. When I first met my AME he strongly advised me not to attempt to apply logic to aviation regulations.

I don’t doubt that they work well together.
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Re: R STOL or sportsman profile?

daedaluscan wrote:I thought it meant removing the Robertson cuff and replacing it with a Sportsman. I was not aware that there was no cuff on later wings.

I suppose my question is answered in you’re last para, but it seems counterintuitive to me, given how hard it is to obtain an STC, that the two such obviously interacting mods would be allowed without testing. When I first met my AME he strongly advised me not to attempt to apply logic to aviation regulations.

I don’t doubt that they work well together.


I think the important thing in this case is that the two kits act in somewhat different methods toward a common goal. Other than the cuff, which is really a non issue, as noted, there is no real "interaction" mechanically between the kits.

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Re: R STOL or sportsman profile?

I fly 185s with a variety of wing mods. The plane we primarily operate has Robertson, Sportsman, WingX, and VGs. I have flown another airplane with the same set of wing mods. The combination of all of those mods is my favorite 185 wing. While Mike is right that the beaver drivers, including me, don't complain about beaver drooping ailerons, I will say that on the Robertson equipped 185s, I prefer to skip the 30 degree setting, which is maximum aileron droop. It feels like aileron effectiveness is pretty low in that configuration, so I just use 30 degrees as a transition between 20 and 40.

The Robertson kit has an unintended consequence of eliminating the smooth transition of the stall from the wing root out to the tip. On a Robertson wing, the wing tip can actually be the initial point of stall, which contributes to aileron ineffectiveness at slow speeds.

The VGs do seem to help, but not a lot, with the aileron function.

Bottom line, having flown a lot of different installs, if I had a Robertson equipped plane I would not hesitate to add any of the other 3 mods mentioned above. If I had a plane without a Robertson, I would still add those other 3 mods, but I might skip the Robertson due to the cost and complexity if I was the one affording the installation.
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Re: R STOL or sportsman profile?

Any wing extensions also reduce aileron effectiveness, sometimes significantly. Just saying....

Not to suggest that wing extensions aren't a good thing.....like the RSTOL, they offer a lot of benefits. You just have to decide if the benefits out weigh the (minor in my opinion) down sides.

I totally agree that proper and directed management of flap deflection can minimize much of the negative effects on aileron effectiveness with a RSTOL equipped plane. I've worked them in a lot of crosswinds, and as noted above, the sketchiest situation I had was a heavy takeoff on floats with a gusty crosswind. There's just no way to make that very pretty. Slept more than a few nights in that 185, waiting for the winds to calm down.

Landings, it's easy to stack on a few extra knots to penetrate the gusts till you get the gear planted.....assuming you have a long enough runway. And, no, that doesn't mean add fifteen knots to landing speed..... :roll:

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