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Wing and stab design

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tahoedirk
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Re: Wing and stab design

Postby tahoedirk » Tue Jun 06, 2017 4:16 pm

Cool Tom build it and enjoy !!

I have discovered the perfect blend of fun and frustration trying to mate and tune these things. Well almost a perfect blend, the pitch of the stab is most critical.

TomW
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Re: Wing and stab design

Postby TomW » Tue Jun 06, 2017 4:50 pm

Tahoe,
Any suggestions? You think the curve along the span is OK? I copied it from Levitaz. What is the span curve doing?
Wing outline is basically same idea as Moses, but Levitaz has more sweep.
I kept outline so lift center is hopefully similar to moses wing.
What will adding more sweep do?

mcfly777
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Re: Wing and stab design

Postby mcfly777 » Fri Jun 09, 2017 8:35 pm

TomW,

Here I'll post my attempt at designing a foil. I bought a software that will let me design and simulate a foil (with the stab), so I can design for exactly the speed, lift, and drag that I want. I used a software called 3DFoil ( http://www.hanleyinnovations.com/3dfoil.html ) which does the job. I looked at an existing foil plan (Liquid Force) and tried to copy that.

Disclaimer: I'm not an engineer and can't claim to understand a lot of the technical aspects of this.

Disclaimer 2: I have made these wings, but I have not tried them in the water. So all this is theoretical. With more experience (since I tried this I bought a Moses Fluente foil), I see that this design is prob too high aspect for my liking, probably very fast (assuming you can keep it thin) but also very twitchy longitudinally. Again this is speculation.

Design objectives
- Enough lift at around 7-8kts
- higher aspect in order to decrease drag
- use a known foil profile that people already use
- not overly complicated to print and add CF

At the end it requires about 0.5 hp to go at 15 knots with 250lbs on it. I figure that is very easy for a kite to provide.

Top view
2017-06-09 12_22_49-Dr. Hanley's MSA - 3DFoil (8-Surfaces).png
2017-06-09 12_22_49-Dr. Hanley's MSA - 3DFoil (8-Surfaces).png (11.19 KiB) Viewed 611 times
Surface stats
2017-06-09 12_24_58-Dr. Hanley's MSA - 3DFoil (8-Surfaces).png
2017-06-09 12_24_58-Dr. Hanley's MSA - 3DFoil (8-Surfaces).png (21.54 KiB) Viewed 611 times
Coefficients for the system
2017-06-09 12_28_45-Dr. Hanley's MSA - 3DFoil (8-Surfaces).png
2017-06-09 12_28_45-Dr. Hanley's MSA - 3DFoil (8-Surfaces).png (17.21 KiB) Viewed 611 times
Stability (longitudinal): neutral point is about 15 cm from the front, right where the mast should be.
2017-06-09 12_29_59-Dr. Hanley's MSA - 3DFoil (8-Surfaces).png
2017-06-09 12_29_59-Dr. Hanley's MSA - 3DFoil (8-Surfaces).png (16.09 KiB) Viewed 611 times

TomW
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Re: Wing and stab design

Postby TomW » Fri Jun 09, 2017 10:34 pm

Wow. All those numbers. I don't understand anything.
I'm more interested in the principles. Like:
What does anhedral provide. And what behaviors arise out of different anhedral curves / shapes.

bigcane
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Re: Wing and stab design

Postby bigcane » Sat Jun 10, 2017 8:27 am

Hi Tom, I made a bigger wing for cruising on my Moses Comet when I am not in the mood for riding fast. It was around 600cm in surface area and about 11 to 12% thickness. The profile was eppler 193 or 222 or something. Works perfectly with the same stabilizer. I think surface area, thickness and profile shape are the important variables on a wing, the others don't matter much. By the way I tried racing with the bigger wing on the Comet in light winds, I was thinking it would help with the tacks and getting going. Big mistake as it was way too slow especially downwind. Got back on the Moses race wing, much better even in super light wind.

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Re: Wing and stab design

Postby TomW » Sat Jun 10, 2017 10:22 am

Big cane,

Interesting. Can you share your design file? Or just a drawing or photo?
How did you make it? ( even tho this is a wing design thread)

bigcane
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Re: Wing and stab design

Postby bigcane » Sat Jun 10, 2017 11:19 am

I built the wing the hard way. Hot wired some foam cores for a plug, glued them together, covered with fiberglass and epoxy, lots of sanding, then built a mold. Once you have a mold, making a wing only takes 2 hours. But I think you could build a pretty good cruiser wing by shaping a plywood core and then vacuuming carbon onto the outside. Vac on extra carbon so that you can sand some of it off to get a good shape. Don't forget to make the middle of the wing where the bolts go through solid carbon or fiberglass. make big holes with a hole saw and fill these up before shaping the wood. The wing I built was 58 wide and 13 cm chord in the middle
Attachments
IMG_0014.JPG
IMG_0013.JPG
IMG_0012.JPG
IMG_0010.JPG
IMG_0009.JPG
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NYKiter
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Re: Wing and stab design

Postby NYKiter » Sat Jun 10, 2017 12:56 pm

I like the way you did the molds. Can you please explain a little more about this process? Looks like you have cloth over the boards etc.? Did you use the molds to compress the fiber cloth or did you use vac bags?

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Re: Wing and stab design

Postby Bille » Sat Jun 10, 2017 8:39 pm

bigcane wrote:
Sat Jun 10, 2017 11:19 am
I built the wing the hard way. Hot wired some foam cores for a plug, glued them together, covered with fiberglass and epoxy, lots of sanding, then built a mold. Once you have a mold, making a wing only takes 2 hours.
...
GOOD JOB !!! :thumb:
It looked like a PFP mold at first ; then i realized, the white was just the surface-coat !

Bille

TomW
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Re: Wing and stab design

Postby TomW » Sun Jun 11, 2017 6:01 pm

The wing I'm on now, the moses 548 is actually pretty slow at lowest speed. Now at session nr 15 is seems rather easy to fly.
Let's say I want to build a slow but agile wing.

The 548 has 548 span and about 135 chord.
What's the performance impact of and best way to get Slow & Agile?
Only increasing span ?
Only increasing chord ?
Increasing anhedral ?
Decreasing anhedral ?


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