Has anyone ever put a wing leading edge slat or a fixed slot on a Cessna wing?
There must be thousands on mods for these planes but I have never heard of a slat wing 100 or 200 series Cessna. Wren and Peterson conversion come to mind. I have never been very impressed by either but with all the wing mods the wren had, it still doesn't have a slat.

this 172 has some slats its also in north Korea

cstolaircraft wrote:this 172 has some slats its also in north Korea

Windshield wipers too.

It is likely that nobody has put slats or slots on a C-100 series because once the airplane is built it would be a tremendous pain in the butt to put the slats and all the new structural reinforcements in. Much easier to do on the production line of course.

It seems very likely that there would be some worthwhile benefit form the slats on a Cessna just like there is on the Helio Courier. However, I think most people would agree that the Sportsman (and perhaps other) STOL leading edge cuff provides most of that benefit at a small fraction of the time/effort/money that a fixed (or perhaps even a movable) slat/slot would provide.

The fixed leading edge cuff also apparently does not reduce the aircraft's cruise speed by any appreciable amount, and a fixed slat would cost more speed by far.

One reason not to install slats on a Cessna is that slats do their work at high AOA. Most 100 series Cessnas run out of elevator at forward centers of gravity and don't hit super nose high attitudes at low speeds even at aft CG points. So, as others have mentioned the pain in the butt wing modification, one would also need to make extensive tail mods to get enough energy to use the slats. At this point, you might be asking yourself why you didn't just buy a Helio.

I found a photo of this Cardinal wing...

I think the Cardinal used a different airfoil than the 2412 used on most all other strutted Cessna singles. I believe it's supposed to be some sort of laminar flow design? Interesting that Robertson would monkey around with it, most people who buy Cardinals nowadays aren't looking for STOL performance. Maybe they were when they were new.

PAMR MX wrote:I found a photo of this Cardinal wing...

Those look like Krueger flaps. https://en.wikipedia.org/wiki/Krueger_flap

This arrangement does increase the lift coefficient, but they aren't as effective in controlling the boundary layer as real slats are. A well designed slat will make an airplane practically stall proof in wings level coordinated flight.

I was gonna say that they reminded me of the new-ish Doug Keller compound Cub flaps.

hotrod180 wrote:I was gonna say that they reminded me of the new-ish Doug Keller compound Cub flaps.

He meant the leading edge device looked like a krueger flap. I agree.

They fold out from the bottom of the wing to increase the apparent camber. While this is good for making a "high-speed" wing perform better a low airspeeds, it doesn't do the same as a slat or slot.

The Cardinal experiment was one of Raisbeck's efforts to look at what it might take to increase the aspect ratios and wing loadings of light airplanes. The results are pretty marginal for all the torture they went through to demonstrate the technologies.

http://cafefoundation.org/v2/pdf_tech/High.Lift/AIAA.1977.High.Lift.Cardinal.pdf

Very painful way to gain several knots, reduce useful load by quite a bit, and change the clean stall characteristics to something requiring Wet Ones and new shorts afterwards. High wing loadings are seldom advantageous without quite a bit of excess horsepower. Parasitic drag is still large for the Cardinal, and per the test results, it could only muster a bit more speed and actually required more power than the stock design up until it reached about 120 mph. That means lower rates and angles of climb. The dynamic stability also took a predictable hit, and it was too hard to even collect frequency data at 120 mph or above apparently. Oh well.

But in true form, if you skip the data and jump right to the "Conclusions", Raisbeck pays homage to his funders:

...... In summary, there significant advantages increasing wing loading typical light aircraft.

This is a good reason why very basic, 70 year old rules about wing area and moderate loading are so much more effective at achieving low speed results with our small airplane. Wing section usually has a lot less to do with performance than people usually think. Variable geometry often adds a great deal of weight in exchange for heroic efforts and a little lower landing speed and stability. And excess horsepower and low parasitic drag rule the speed queens.

Wow thanks for all that info. I only had the photo with no story on the cardinal.

lesuther wrote:..... and change the clean stall characteristics to something requiring Wet Ones and new shorts afterwards.....