Rad new Stunt airfoil!

Here's an airfoil contour shot of my new stunter wing panel.

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Vital stats: Root is 12" Chord, 2.5" Thickness, High Point at 30% of chord, TE Height of .25". Tip is 8" Chord, 1.5" Thickness, High Point at 60%, and the Trailing Edge is swept forward 5". Note the swept forward Leading Edge!

I'm expecting this wing to control the common tip vortex turbulence problems for CL Stunt..

(Yeh, right! I was just playing around with interpolating StuntRibX airfoils, and thought it made an interesting looking wing..)

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"It rubs the lotion on its skin,
it does this whenever it's told.."
-Buffalo Bill, in "Silence of the Lambs"

The real interesting thing would be trying to figure out how to do the leading edge...

Larry,

Got the test program. Only concern I had based on the graph you sent is the flattening of the LE as comes toward the tip. But I'm just starting to play with it. Will report in a day or so.

This is so cool!

Larry, do not you afraid of low yaw stability of that swept forward wing? I think it will be very difficult to trim.

Is it flapped wing? Are you sure that the sharp LE on tip airfoil is good combination with that relatively thick airfoil with high point at 60%? I mean problems with partial separation at low AoA, “bump on polar” problem or so …

I was just fooling around, Igor..

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Here's something a little more conventional: Root is 11" chord, 2.25" thickness, 27% of chord high point, 1/4" trailing edge. Tip is 9" chord, 2" thickness, 22% of chord high point, zero sweep in TE.

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"A little sincerity is a dangerous thing, and a great deal of it is absolutely fatal." -Oscar Wilde

>I was just fooling around, Igor..
>
>[photo not recovered: 403a055a42822684.jpg]
>
>Here's something a little more conventional: Root is 11"
>chord, 2.25" thickness, 27% of chord high point, 1/4"
>trailing edge. Tip is 9" chord, 2" thickness, 22% of chord
>high point, zero sweep in TE.
>
>[photo not recovered: 3e69bb3870f12ad5.jpg]
>
>"A little sincerity is a dangerous thing, and a great deal

Looks like a TP stretched!

>>>I was just fooling around, Igor.. <<<

But suggestive anyway ...

fooling around is half the fun!! you might want to try this with a cheap, unsheeted foam wing first and see how it goes, just to save time and building effort. Not much point in putting 50 hours of painting into a prototype plane.

Or, read all about a forward swept competition stunter with my Skyfire article in Model Aviation a couple of years ago. (Feb. 2002) Highly competitive.

I would think that a moderately forward swept and tapered wing would have some aerodynamic advantages for C/L stunt, but the construction would be tricky for bigger and heavier models because the planform tends to be structurally divergent. That is, when the plane loads up in manuevers and the wing flexes, the wing tips tend to gain AOA rather than shed it. The results could be surprisingly dramatic....

>>>I would think that a moderately forward swept and tapered wing would have some aerodynamic advantages for C/L stunt<<<

Some advantages and some disadvantages. The sweepback causes a movement of center of pressure sidewise as reaction to side flow caused by wind or yaw. And that effect is on lift (roll) as well as drag (yaw).

I did several equivalent models in past with different sweepback, and it looks that while small sweepback allows to make perfect trim for SOME conditions, more sweepback can make the model more universal or easy to trim and better dampening corner yaw. My choice is more sweepback probably because of our turbulent fields, where the sweepback gives some advantage.

Larry, do not you have the text in binary form?

You should be able to order the complete article and plans through the AMA website. If that fails, contact me and I'll see if I still have the file.

The plane had a hollow foam shell wing with brown wrapping paper, epoxy impregnated on the surface to make a strong structure. There was an internal spar for part of the span. In retrospect, it should have been full length.

The full construction with photos is presented in the article.