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Simple Slats....Maybe

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StarJar

Well-Known Member
Joined
Sep 6, 2011
Messages
1,723
Location
El Centro, California, USA
Mulling over an ultralight I want to design, I really wanted to use full span slots, or even better, slats. The slots were attractive, because they are so much more do-able than slats. Right? But like a spoiled brat, I kept thinking about slats.

Then, one day, I had an idea. I did some research, and some testing on JavaFoil (once I figured out to enter in slats/slots).

So, the idea is that the cruise-angle air closes the slot (at the top), and the slow- flight air opens the slat, by blowing up through it, and pushing at a more direct angle below the pivot.

There would be a single pivot-point positioned where the differences in pressure, acting on the LE slot-element or curved plate, would change the position of the plate when the angle of attack reached the desired angle, (about 10 degrees AOA)

The bottom would always have a gap, but at least the top will block the flow of air, up through the slot.

An aditional possibility, is that that the element could be shaped to create a leading edge droop (not shown), when the slat is open, but go back to normal when the slot is closed. You could have about a 10degree droop, although it would be for a small portion of the leading edge.

When i first started writing this post, I thought a pivot at the bottom would work, but in reading my own writing, I realized that the pivot would have to be farther up, because there still will be air acting on the front of the plate, even at higher AOA's. But the air trying to push up through the slot, and the relative wind hitting more directly on the lower shape of the plate, should allow it to work, as described.

Opinions, questions, ideas for improvement, or changes, or things I am not seeing, are welcome.

All I've done so far, is tested a few shapes on Java Foil, basically to see what kind of Max CL is possible, for slots in general. I found that with 10 degrees of full span flaps (flaperons) I could get about a 2.3 Max Cl, at 15 deg. AOA. At 22 deg. it started to peak out at 2.5 Cl. This was a full-wing run with an AR of 5.

I would love to get slat cruise-performance without all the difficulty normally MMMM.JPGinvolved with them.

If anyone is interested trying the idea also, let's get together and share notes. I'm not interested in a patent at this time.

PS I had some better drawings, with longer slats, that contoured with the wing better, but somehow they didn't get saved on my Turbo Cad:depressed.
 
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