Slots -if it works, why not more?

Maybe because building or making an ordinary airfoil is simpler and it's also more durable? That is an interesting piece of engineering though.

I dunno - plate wings are quick, simple and pretty durable.
If it were an essentially simple thing to add slots to the profusion of barely manuverable profile plans available (or easily drawn up from 3-views, rubber model plans, etc.) it'd be a real boon to someone (me!   ) who'd like to build a fleet of worthwhile 1/2As quickly.
Maybe it takes engineering knowledge to design, maybe each wing might need different specs, maybe only works on 1-piece wings - who knows?
I'll bet someone on the forum could tell us.

Yes, plate wings are durable but I can imagine that slot thing will break easily.  

Not sure what is the science behind it... The little strip probably creates turbulence and it in turn will help to create a better vacuum above the wing. This in turn would cause better lift with a smaller angle of attack, just like a "proper" airfoil. Maybe

But on the other hand, sanding an airfoil into a 1/4" slab wing is quick and easy to do and almost guaranteed to work, so not many people are looking for alternatives.

It would be interesting to see this type of wing in action. Maybe even on a free flight model

I know nothing of aero-engineering but the AoA on Dancer is considerable with the slots.

As for fragility, on a low or midwing (as most profiles are) there wouldn't be the crash risk seen here.
MOF, maybe the slot wing (?) could tie to the fuselage to lessen inertial damage to the slot assy in a crash.
As I said, I dunno.
And as you said, interesting to see.

I agree with Kari's thinking, on how it works. It's a bit fugly though.. and would need to be sealed/painted before assembly. Lift is good.. but for stunt; the wing should be symmetrical. "Flat" is at least symmetrical. If there were top "and" bottom L/E slots.. well, that would be interesting.. but no less complicated than say; a diamond-airfoil and covering would be to construct. Considering a constant-chord wing; how about gluing L/E stock O/C to a sheet-wings' leading-edge? There'd be a lot of turbulence with the blunt 90-degree rear-edges.. but might that be advantageous? Maybe back-up that L/E top/bottom with T/E stock; feathered-down smooth with the sheet-wing? Then if you're really curious... build some same-span sheet-wings having shorter chords.. but keeping the as-per-plan CG unchanged.. which can be measured from the L/E.

The point prompting my question is the statement that the slot, apparently to some significant degree, allows a flat plate wing (the easiest thing to build) to emulate a full airfoil.
Sheet wing, profile 1/2A is about the simplest thing going but few are what one would call capable stunters.
Looks like here's a simple solution if slotted wing design IS simple.

At that point, i'd consider a 'built-up' wing, as the time to build wouldn't be that much more and performance would be significantly better.

Years ago i designed a 1/2a Nobler with flaps in an attempt to pick up an extra 20-25 points flying a flat wing plane in 1/2a stunt contest.

Lol, it was a big waste of time, i could of built a constant cord wing without flaps in a lot less time and fly circles (?) around the flat wing!

wha-tah-hey wrote:I know nothing of aero-engineering but the AoA on Dancer is considerable with the slots.

As for fragility, on a low or midwing (as most profiles are) there wouldn't be the crash risk seen here.
MOF, maybe the slot wing (?) could tie to the fuselage to lessen inertial damage to the slot assy in a crash.
As I said, I dunno.
And as you said, interesting to see.

I see where this would generate lift, but what about outside maneuvers?

Why do I want to make that into RC .049?

Slots work well, but must be carefully engineered and evenly constructed. In stunt it has been determined that elimination of slots makes for more stable flight.

Phil

The caption notes only "acting like a proper airfoil" and the article says "A unique feature of the Dancer is use of a leading edge slot to enhance lift and stall characteristics of the flat airfoil of the wing."
Which I thought, since it also works inverted, to imply some useful "stuntability".
But remember, I don't know.

A KFM airfoil acts like  traditional airfoil and is a cinch to build. I have one on my carrier plane and it's almost impossible to stall.

It's like a jib's effect on the sailboat's main - creates a slot between the sails, speeds air over the main.
https://www.youtube.com/watch?v=xivue7RrbGw

With the first photo I assumed the "slot" was same angle as flat wing

But looking at the side view I see 2/3 things

The Angle of attack (AOA) of the wing is very positive relative to the thrust line, and the stabilator/elevator is at zero AOA

The included "slot" appears to have a very negative AOA relative to the main wing AND the thrust line

I have a few slab wing ideas and may replicate this to see what it does for aerobatic maneuverability for a plain jane slab NARROW chord wing

Fantastic, Fred - I suspect others have tried a slot, but I didn't find anything about it's use on a more common sheet wing.
Possible variations in slot height, relative AoA, slot chord and who knows what (not me) are too daunting for me to experiment with. I don't have a clue whether there's math and engineering that allows direct design.
I've been hoping some industrious fellow would take the bit in his mouth and run with it.
Please let us know what you discover!

wha-tah-hey wrote:Fantastic, Fred - I suspect others have tried a slot, but I didn't find anything about it's use on a more common sheet wing.
Possible variations in slot height, relative AoA, slot chord and who knows what (not me) are too daunting for me to experiment with. I don't have a clue whether there's math and engineering that allows direct design.
I've been hoping some industrious fellow would take the bit in his mouth and run with it.
Please let us know what you discover!

I second that Terry. Jim's "KFm-airfoil" example is the first I've ever seen. It's a wild concept! I'd still like to find-out whether it could be simply-applied to a zero-incidence sheet-wing, to produce symmetrical turbulence above and below.

When you think about it.. flat/sheet-wing models fly fast.. even with a mild engine. There's little turbulence to grab air and slow them down. The elevator is sensitive.. because it's doing double-time. That leaves less time and space for maneuvers.. in my way of thinking. The elevator-inputs are actually stabilizing the CG.. .. from a point furthest from it.

I think that's why most sheet-wing C/L designs are difficult to fly a pattern with.

KFm airfoils work pretty good in foam on 'lectric rc.

Phil

It says FOR THE TINDERFOOT , MAN ck. out that off set in the rudder 3/4" that should keep some tension on the lines . Interesting but i think i will pass have enough not built planes and things now

I've seen plasticor stunt trainer wings with one or more staggered layers which I guess work as a KFm-type airfoil.
But I'm still hoping someone with technical knowledge of slot design will pop in and explain the black arts involved.
It seems a simple matter to add a slot during a build or even to an existing sheet wing if the aerodynamic principles don't require a supercomputer to design.

fredvon4 wrote:

...
The Angle of attack (AOA) of the wing is very positive relative to the thrust line,  and the stabilator/elevator is at zero AOA

The included "slot" appears to have a very negative AOA relative to the main wing AND the thrust line

...

+1
I noticed these things too right away, seems like the plane would have counteracting forces.

Looking over the article, I realized the author's remark about acting like a proper airfoil most likely refer to only a flat-bottom airfoil.
Still, if true, a slot on the bottom should also work similarly.
Question is: does the slot's AoA as shown depend on the wing's AoA or would it be the same for a flat wing?
Any designers out there who can help?

Not to be too snippety but your talking about angle of incidence, angle of attack is related to airflow.

Not to be argumentative, crank, but they seem to be pretty much the same:
http://www.dictionary.com/browse/angle-of-incidence
angle of incidence
noun
1.
the angle that a line or beam of radiation makes with the normal to the surface at the point of incidence
2.
another name for angle of attack
3.
Also called rigging angle of incidence. the angle between the chord line of an aircraft wing or tailplane and the aircraft's longitudinal axis

Angle of incidence is set in design and build and not changeable, attack is controlled by the pilot in flight.