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Old Jun 14, 2006, 04:16 PM
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Need help on airfoil

Hi All,
I needed some help on an airfoil for an AP/UAV plane I'm building.
We needed a high lift, slow wing. The design is essentially a flying wing with a body tube running the full length in the middle. The motor will be a pusher in the tube, and the nose will have a bubble for the camera.
The wingspan will be about 30" Root cord about 22", and tip cord 10". We're looking for an airfoil that is not quite flat bottom, but had a bit of camber. I'm not quite sure where we could look at a database of airfoils. I was thinking maybe one of the Epler ones might be good. Is there any you guys could recomend, and any database with some examples?
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Old Jun 14, 2006, 04:50 PM
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Look here....
http://www.mh-aerotools.de/airfoils/
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Old Jun 14, 2006, 08:33 PM
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Nampa. Idaho
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Thatís a good link Sparky Paul. Thanks for posting that.

Medve,

It's pretty easy to make a flat bottom airfoil to get what you want. The venerable Clark Y or maybe better, the Gottingen 398 would be great for your application. I'm going to use the Gottingen 398 on my next big UAV. It's thicker than the Clark Y and generates more lift at the same angle of attack as the Clark Y. Almost like having small flaps built in. It also has a more rounded leading edge which tones down the pitch response. That makes for a nice stable and slower tilting action for a camera set in the wing. Wings are pitch sensitive when compared to conventional designs with long tail moments. Of course for slow flight, nothing beats light wing loading. Nothing.

You have 480 square inches of wing in your design. The all up weight of the plane needs to be around 50 ounces or so, (3.1 pounds) to have trainer like flying qualities. Is that reasonable for you? You may want to consider working out a size based on what you expect your final weight to be.

Use this helpful calculator. http://www.csd.net/~cgadd/eflight/calcs_wingload.htm

It's just an idea though. There are lots of modern airfoils that could give you a wider speed range but they might have to be built with a much higher aspect ratio than you're describing. A delta or wing style plane is a little different than what I build. You might see an ad appear in this thread for ready made wings. Good Luck.

Dan
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Old Jun 14, 2006, 08:49 PM
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Dan,
where can I get a cross section of the Gottingen 398? For something to work off of?
Thanks for the info. This is exactly what we are looking for.
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Old Jun 14, 2006, 09:08 PM
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I couldn't find a match for Gottingen 398 in Profili.. There was a GO-398 and a GOE-398
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Last edited by typicalaimster; Jun 14, 2006 at 09:18 PM.
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Old Jun 14, 2006, 10:09 PM
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Excellent. typicalaimster got a good copy there with the GOE 398. Not the GO 398B. The 398B is very close to the Clark Y. I'm so old school I plot the ordinates on graph paper to full scale and use a french curve to connect the dots and bring the airfoil to final shape. Scott comes up with the good stuff. You can copy that and scale it to your needs. Thats the airfoil though. I can tell by looking at it. There's not many around like that. It's slow flying, high lift with high drag as well. More power won't make it go much faster. Just lift more.

Dan
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Old Jun 15, 2006, 05:44 AM
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I had a similar project a couple of years ago and used Got803. Will try to attach data. DXF format CAD outlines of the top and bottom templates for hot wire cutting the airfoil. Simply scale up or down in a CAD program.

http://www.rcgroups.com/forums/showa...hmentid=&stc=1
got803.zip
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Old Jun 15, 2006, 11:24 PM
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Actually wait.. I think you and I are working toward the same sort of project. On my swept delta I'm working on my cord is 14" and my tips are 9". The wing itself is about 32" wide. I might beef up the design a bit after I bring it out of alpha. I was going to use a rocket body tube for the center fuse. As things develop things are changing...

I was browsing Profili and found a "Delta 400" airfoil listed. I was going to use this airfoil to start out with and go from there. Sparky Pauls web page lists a few MH airfoils for flying wings. I'll attach the MH-60 profile so you can compair. I'll also attach the GOE-398..

Dan were you making a flying wing with this or a straight wing? I created my RPV's with a Clark-YM but they were straight wings. I was switching to the other profiles since they are a bit more sleek.

Medve if you find an airfoil let me know and I can run it off and send it over in DXF. Just get me the specs you need.
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Old Jun 16, 2006, 05:35 PM
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Quote:
Originally Posted by typicalaimster
Dan were you making a flying wing with this or a straight wing? I created my RPV's with a Clark-YM but they were straight wings. I was switching to the other profiles since they are a bit more sleek.
I was going to make a constant chord wing with it. If you have better airfoils recommended for flying wings, it won't hurt my feelings any to put them up. You're a good builder Scott.

Dan
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Old Jun 16, 2006, 09:59 PM
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Typicalaimster, I'm using a 3" dia. clear plastic tube I got at Tap Plastic for the body.
I think it sould be about perfect. Thin but firm. I'm thinking of putting rails inside and running a thin flat ply sheet inside with mounting holes cut out for all the gear. that way I can pull the guts out to work on it, and not have to take everything esle appart.
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Old Jun 18, 2006, 03:08 PM
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Clark Y is the way to go
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Old Jun 18, 2006, 05:17 PM
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Quote:
Originally Posted by andyg
Clark Y is the way to go
Why?
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Old Jun 19, 2006, 08:37 PM
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quick easy and effective
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Old Jun 19, 2006, 08:50 PM
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I've heard some of the Eppler airfoils are quite good as well. though I haven't run into any on line that I could view.
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Old Jun 19, 2006, 09:46 PM
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Which ones do you need? Some look like trainers some look like pattern. Aka some are flat, some are symmetrical

Nastytoes has the E-192 on their site. I think he uses 2 others.
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