Hi everybody,

I'm doing a little science experiment in a few weeks, just for fun.

Many of us have done slotted flaps on our models, most easily built with a simple Robart hinge point, where the hinge hangs below the wing.

I wanted to experiment with double-slotted flaps, and eventually triple-slotted flaps, simply because I haven't seen anyone else do it.

So, if you're interested in following along, the article is at http://www.nextcraft.com/j46_highlift01.html

I'll be using the flap design in the attached image, and we'll see where it goes from there. This model will also use spoilers (slot-lip ailerons) for roll control, and have a T-tail... Why not?

Very good! Liked your high-lift page, and the reference to Andy Lennon.

Your "double-slotted" flaps are similar to those used on the deHavilland Otter and Buffalo. Martin Rousseau has some drawings of these flaps at his site:
http://www.mraerodesign.com/buffalo/BUFFALO.HTML

I have a Bruce Tharpe Flyin' King that I'm doing STOL work with. I have an extra wing that has fixed LE slots, slotted flaps, hoerner wingtips, and other low-speed enhancements. This is in-the-works, I have the wing basically framed up but not completed.

Eric Kler has an STOL page at his FUBAR site: http://www.fubarhill.com/ .

I'll be following your project with interest.

Thanks Bill,

I had seen the Martin Rousseau page when I first did some "Google" searching for flap info, but hadn't seen the Fubar page until now.

Why don't you (and anyone else who is interested in STOL) jump in here and add their photos and info? It would be nice to collect a lot of this information, and the results, on one thread, rather than spread out over several.

PS> Have you seen this "LEGO" hinge? Check it out at http://pages.sbcglobal.net/anders/flap/

Cute, and actually informative.

It _would_ be a good idea to take more photos to document the STOL wing construction. The outer wing panels do not have the fixed slots sheeted (just "framed up"), and this would be a one-time opportunity to show that construction.

I'd do the slots differently the next time-- these built-up slots are too labor-intensive and will be a nightmare to repair if there is ever a mishap. I'll use a different method on the next STOL plane (a scale Storch).

Five or so years ago we had a massive discussion on RC* about STOL techniques. I have the printed version somewhere at home, but the electronic version is long since turned to aether. Let me see what can be done to share that archived material.

Hop on in, folks...

--Bill

Hi Mike,

My 21.5lbs, 97"wingspan Cap can take off in about 8 ft, harrier land in about 2ft. Does this count? ha ha

Nice to see you still at it!!!!!!!

Hi Darrin,

I hate you IMAC types. (kidding, of course)

Power to weight ratio is a great way to do this task, and I don't imagine I'm inventing anything seriously new and radical. The double and triple-slotted flaps are just something I haven't seen done before on a model, and I'm interested to see if the performance is better than single-slotted flaps, on a somewhat more highly loaded model. And... It's a bit of a mechanical challenge that I hope to apply on some future scale projects.

PS> A friend of mine here, Steve McLaughlin, who is a Pattern/IMAC wiz, recently got one of the new Extras from composite-arf.com Man! The quality of those kits is something else. Steve let me have a VERY close look at it, and it really is immaculate in every way. I've heard that it's a combination of vacuum bagging and heat, in their manufacturing process, that gives those results. Really impressive.

Mike,

At the Dayton Airshow, Dryden Research Center had one of their F-15's with the elastmeric wing. Basically they have a leading edge flap that they mix in with the ailerons, this twists the wing and gives directional control.

Wow, wing warping. It took us a hundred years to get back to twisting the wing.

Anyway, I would imagine that a derivitive of this concept might be the ticket to some serious weight lifting and short field work. The mixing would be the trickest part and possibly should have a knob that could override the mix. A gyro could be helpful to if you set it to think it's flying level when it is acually at a high AOA.

Just a thought. have fun tinkering!

Darrin


P.S You should see parts out of a autoclave!!! Their amazing!!!
Heat, Vacuum, and Pressure.

These are the flaps I installed in my citabria, the plane really ballons when they are dropped all the way, about 70 degrees of flaps. the plane flies really slow to but always be ready to punch the throttle if a stall happens.

I love flaps. A buddy of mine just got one of the Great Planes Lancair ARFs, and it's got really beautiful handling with the flaps down on landing approach.

I'll have my new (double-slotted flaps) testbed flying in a few weeks, and will post the results here.

Flaps and slots are standard STOL equipment, but but has anyone looked into the elevator/stab modifications on STOL planes?

On the Feiseler Storch, the elevator has a flat slat on the bottom of the stab, at the elevator hinge line and attached to the elevator and parallel to the elevator. Evidently, this "slat" keeps the airflow from detaching from the elevator during heavy elevator deflections and "stalling" the stab.

Similarly, on the PZL Wilga 35, the aerodynamic counterbalances of theelevator are fitted with what look like inverted slats on the LE, again to keep the stab from stalling at extreme elevator deflections. I'm sure that other examples can be found.

I winder if there is any need to apply this principle to our STOL models (except for scale consideratons)?
--Bill

Bill, I suspect that we can get away without those elevator aids. Full size aviation generally fly with a much more conservative CG position than we do. Thanks to that there's USUALLY lots of elevator authourity on our models and if it does seem like we are loosing the downforce before the wing actually stalls then it's easy to move our CG's back a little for a finer balance and reduce the throw to compensate for the boost in sensitivity. But in full size that would lead to mucho overcontrolling and possible spin scenarios so you seldom see that other than perhaps in aerobatic planes.

Dago Red. Your Citabrial may balloon when the flaps first drop but I suspect that if you let the model slowdown you can remove most of the down trim as the model reaches it's new flight trim. At least that's what I found with a glider I have. Of course if you're just using them for extra drag while the nose is pointed down so that the speed stays fairly constant then you would need to keep the down trim in there. Steep landing approaches being a fine example of that.

Andy Lennon's book deal quite a bit with enhancing elevator power. I think he uses slats on some of his stabs.

It's hard to tell the difference by watching, but some stalls on various airplanes are from the wing itself stalling, while some are from the tailplane stalling. The nose drops(at least) suddenly either way.

Mike, I'm in!! I don't have much info. or pics, give me some KEYWORDS, I love to dig!! ? What scale are we talking about?

gjs,

Not sure what your question is, but the article on my site is at http://www.nextcraft.com/j46_highlift01.html

More progress and photos coming later next week.

Its not exactly STOL but some of the later F-4 Phantoms had a fixed slat on the leading edge, bottom side, of the stabilator. It was effective in maintaining fuselage attitude in landing to the point that they put up with the drag of it for the rest of the flight.

Mike,

I did some digging for info on high lift but did not come up with much, too technical where I was looking.

What intrigues me is the research going on with Low Reynolds numbers wind tunnel testing. Drela and most are going to thin sections. Is this just for speed? don't know.

. I read something about "articulated control surfaces" and Thinner sections that perform better than Scaled down control surfaces. The analogy was made that if an airliner flys through a sea of ping pong balls, a model flys though a sea of Basketballs. What I gathered was that a lot of the wetted areas of 'full size' don't scale down. Thinner is better, slots maybe should be wider, slats thinner. The air doesn't scale down, it's thick and gooey at small scales.


Later, GJS

gjs,

I think you've misunderstood my posting.

I already know all the things you mentioned, and am not looking for any one to do research on the net or elsewhere. (although I'm sure we all appreciate your effort) I already know that the data we would be looking for does not exist.

What I'm doing instead is building some physical models of things I haven't seen done before, and then we'll know if, for example, double-slotted flaps are more effective than single-slotted flaps, at this size. My experience in the past tells me that it probably will not make much difference, but it's an interesting project, regardless. (Reynolds number "cutoff" for airfoil effectiveness at typical model speeds seems to be about 5 inches chord.)

I've already created a "High Lift" section on my web site, aside from the model construction article, at http://homepage.mac.com/mikejames/rc...ite/index.html and several people have contributed ideas on the mechanics of these things.

Hello Mike, I see your interest on flaps.
Seeking information about the "Bugatti R100" I found the detail of the original design of its very special flaps, patent by Bugatti in 1942. They were and are very original.
Down I enclosed an image of them.
Greetings, Angueto

Hi Angueto,

Thank you for posting the image.

For those of you interested in the Bugatti, here's an informative site, at http://home.uni-one.nl/bugatti/baa/