Author Topic: Yet another diy wing  (Read 52205 times)

Beasho

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Re: Yet another diy wing
« Reply #15 on: October 21, 2019, 02:32:28 AM »
Eppler817. The characteristics look ideal for our low speed, wide range applications, especially given the big variations we use in angle of attack. Most hydrofoil watercraft don't pitch as much. I've never seen an airfoil like this in use. Could be worth a try.

http://airfoiltools.com/airfoil/details?airfoil=e817-il

What Reynolds numbers are we dealing with?  I could dust off the calculations but are they 10,000  or 50,000 or 200,000 ???

jondrums

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Re: Yet another diy wing
« Reply #16 on: October 21, 2019, 10:23:41 AM »
you know the exact speed we ride better than anyone else!

I expect Reynolds number of 1e6 - 2e6 depending on chord and speed of course

http://airfoiltools.com/calculator/reynoldsnumber?MReNumForm%5Bvel%5D=5&MReNumForm%5Bchord%5D=0.28&MReNumForm%5Bkvisc%5D=1E-6&yt0=Calculate

SUPeter

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Re: Yet another diy wing
« Reply #17 on: October 21, 2019, 01:02:39 PM »
Hi Ponobill!  Hope all is well and flying ihas been frequent.  The Eppler 817 is designed for high speed hydrofoils in the 30-45 mph range.  Tom Speers redesigned the shape for sailing dingys used  at a much slower speed, say 15-20 mph.  He named his profile the H105.  Somewhat similar but different.  My last high aspect wing uses this H105  profile throughout the span.  I love it but in the future I will use a more rounded or blunt front nose.   This will widen the range of AoA before a stall occurs.   From pictures, it would seem that Gofoil uses a somewhat similar profile, blunt nose included.  Some of my past posts, forget which, show this H105 profile in pictures.  Google it,  Easy to find.

« Last Edit: October 21, 2019, 01:05:57 PM by SUPeter »

jamallstar

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Re: Yet another diy wing
« Reply #18 on: November 09, 2019, 02:18:04 PM »
I agree with supeter, having seen various racing yacht foils up close, from moths to volvo70 canards and gc32 foils, the bigger and faster the boat the closer to that h105   section the foils become. You can see it here on the 100' trimaran macif

Ive finally got around to shaping the underside of the gull wing. Not quite there yet but not far off, next will be rebates for uni reinforcing.

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jamallstar

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Re: Yet another diy wing
« Reply #19 on: November 11, 2019, 09:47:46 AM »
More sanding. Dug out the foam in the trailing edge and tips as these will be solid carbon. Did a 200mm square rebate in the centre for 2 layers of bi ax reinforcing over the mounting plate. Was thinking about a little trench running the full span to fill with unis to form a spar but im not sure if it will need it or not

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Wetstuff

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Re: Yet another diy wing
« Reply #20 on: November 11, 2019, 11:49:34 AM »
"If beauty is...", you hit the mark, JS.  The Kittiwake first came to mind, but maybe the Albatross. (I read that some only flap their wings once in a 500mi flight, so the shape must be pretty efficient).

https://scx1.b-cdn.net/csz/news/800/2017/engineerside.jpg

Jim

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jamallstar

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Re: Yet another diy wing
« Reply #21 on: November 13, 2019, 01:28:55 PM »
It does bear some resemblance!

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jamallstar

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Re: Yet another diy wing
« Reply #22 on: November 16, 2019, 11:44:32 AM »
Shes coming along nicely now, got the bottom laminated -
 2x 300g DB patches over the mounting plate, 1◊ strip 300g unis spanning 3/4 of the wing, 1x 300g unis at 45 degrees and 2x 200g twill over the whole lot.

Once that was dry i dug out the leading edge and filled it with some individual strips of unis and then bog.

Next i filled in the trailing edge and wing tips where i had dug all the foam out before laminating to get carbon on carbon contact, now the fun part. Sand it all!



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jamallstar

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Re: Yet another diy wing
« Reply #23 on: November 16, 2019, 11:46:03 AM »
-

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jamallstar

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Re: Yet another diy wing
« Reply #24 on: November 16, 2019, 11:55:34 AM »
Total weight so far is 1085 grams. Not bad!

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surfcowboy

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Re: Yet another diy wing
« Reply #25 on: November 16, 2019, 02:39:59 PM »
Nice work man. Canít wait for the ride report.

kiwi

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Re: Yet another diy wing
« Reply #26 on: November 16, 2019, 04:37:07 PM »
Far out 1085g?! Thats nuts how much carbon is on it?

jamallstar

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Re: Yet another diy wing
« Reply #27 on: November 16, 2019, 08:42:44 PM »
Cheers surfcowboy, I cant wait. So tempting to throw it in the water before paint

Kiwi theres 2x  3 or 400g DB patches 200mm square + 2x 200g twill on the top, and the same on the bottom but with a layer of 300g unis on the 45* and a 100mm strip about 3/4 of the span. Feels pretty stiff

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jamallstar

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Re: Yet another diy wing
« Reply #28 on: November 25, 2019, 08:03:15 AM »
And the (sort of) finished product. I made the fuselage a few months ago with an axis front wing mount for accurate comparisons.
The gull wing is super easy to flat water sup start, easier than the axis 102 and much easier than the axis 1000 high aspect to get going, fairly similar once up and pumping to the 1000, maybe a little bit slower owing to its size and leading edge shape but it turns like a wing half its size.
Few pics from my second dock start session on it. Ive got the tail wing at zero right now but ill try a few different angles later in the week when we get some onshore breeze for upwind/downwindera


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jamallstar

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Re: Yet another diy wing
« Reply #29 on: November 25, 2019, 08:06:06 AM »
Trying out her carve ability

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