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Max wing thickness for ultra low takeoff

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Bletti
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Re: Max wing thickness for ultra low takeoff

Postby Bletti » Tue Jul 18, 2017 9:39 am

I can't find it on that site either but it's a common, more modern, sailboat hydrofoil profile favoured for it's performance at low Reynolds number and with cavitation.

Here's a comparison between it and e817 http://www.foils.org/hysecdes.pdf

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Re: Max wing thickness for ultra low takeoff

Postby plummet » Tue Jul 18, 2017 10:37 am

I also think 1" is too thick. I say roll with 1/2" and
3/8.
Manually shaping 1" down to 1mm at the trailing edge will be a freaken pain in the are. I used an angle grinder and 36 grit in manually shaping my bamboo cores. Got dammit it took a. Long time! And that was only 14mm thick when I started

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Re: Max wing thickness for ultra low takeoff

Postby NYKiter » Tue Jul 18, 2017 11:30 am

Funny, I modeled out the spit on an E817 and it doesnt look like the profile...

Bletti
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Re: Max wing thickness for ultra low takeoff

Postby Bletti » Wed Jul 19, 2017 12:48 am

plummet wrote:
Tue Jul 18, 2017 10:37 am
I also think 1" is too thick. I say roll with 1/2" and
3/8.
Manually shaping 1" down to 1mm at the trailing edge will be a freaken pain in the are. I used an angle grinder and 36 grit in manually shaping my bamboo cores. Got dammit it took a. Long time! And that was only 14mm thick when I started
For now I'm planning on ordering 3/4" and 1/2" for 6" chord and 4.5 chord wings which matches the max thickness for the h105 profile. I'll be wearing a bunny suit and respirator so the dust won't bother me too much even if it takes all day and night.

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Re: Max wing thickness for ultra low takeoff

Postby Bletti » Wed Jul 26, 2017 7:57 pm

Alright, new plan. Instead of g10 I'm thinking of doing balsa core with carbon as it will be slightly cheaper, easier to shape, and much lighter. Thanks for all the input so far everyone. Going to aim for 1000-1100 cm^2 surface area and ~20mm wing thickness.

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Re: Max wing thickness for ultra low takeoff

Postby faklord » Wed Jul 26, 2017 8:50 pm

Bletti wrote:
Wed Jul 26, 2017 7:57 pm
Alright, new plan. Instead of g10 I'm thinking of doing balsa core with carbon as it will be slightly cheaper, easier to shape, and much lighter. Thanks for all the input so far everyone. Going to aim for 1000-1100 cm^2 surface area and ~20mm wing thickness.
Having contours built into the core material makes shaping much easier
If using something like Balsa for a core, it might be worth considering building the blank for the core from thin sheets of balsa to make a balsa 'ply' (maybe 1/16" sheets and with alternating layers at 90 deg to each other) the resulting contours will make it much easier to see and correct any asymmetry between the left and right wings.
At the expense of slight weight increase (but still much lighter than g10) It would be easier just to use bought plywood for the core.

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Re: Max wing thickness for ultra low takeoff

Postby BWD » Thu Jul 27, 2017 12:41 am

I bet 20mm will be thick enough. I had an interesting time the other day expecting 10 knots but getting 6-8, with zeeko carver wing, paipo,12m cloud and 80kg.
There were lulls below 6 that had the kite starting to fall, but I could get up in puffs and once moving no problem foiling. I think the carver is about 700cm^2 and it's no thicker than 20mm I believe...

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Re: Max wing thickness for ultra low takeoff

Postby Bletti » Thu Jul 27, 2017 4:15 am

faklord wrote:
Wed Jul 26, 2017 8:50 pm
Bletti wrote:
Wed Jul 26, 2017 7:57 pm
Alright, new plan. Instead of g10 I'm thinking of doing balsa core with carbon as it will be slightly cheaper, easier to shape, and much lighter. Thanks for all the input so far everyone. Going to aim for 1000-1100 cm^2 surface area and ~20mm wing thickness.
Having contours built into the core material makes shaping much easier
If using something like Balsa for a core, it might be worth considering building the blank for the core from thin sheets of balsa to make a balsa 'ply' (maybe 1/16" sheets and with alternating layers at 90 deg to each other) the resulting contours will make it much easier to see and correct any asymmetry between the left and right wings.
At the expense of slight weight increase (but still much lighter than g10) It would be easier just to use bought plywood for the core.
Good Idea with the alternating grains. What I think I'll do is use 4 or 5 3/16th sheets and put a layer of thin fibreglass in between for a little added rigidity and contour lines. I might even add some pigment to the resin to help with the shaping. Alternatively, I'm trying to ask around to find someone with a wood cnc as it would be super easy to route the rough shape then sand smooth. I've even thought about building some kind of rig to use a router in sweeping passes that i can adjust and tweek with each cut to get a similar manual profiling. If I keep the wings straight (and maybe shave the tips and ends more rounded after ) it wouldn't be too difficult. Most likely I'll end up sanding as I'm not an expert woodworker though.

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Re: Max wing thickness for ultra low takeoff

Postby Bletti » Thu Jul 27, 2017 4:33 am

BWD wrote:
Thu Jul 27, 2017 12:41 am
I bet 20mm will be thick enough. I had an interesting time the other day expecting 10 knots but getting 6-8, with zeeko carver wing, paipo,12m cloud and 80kg.
There were lulls below 6 that had the kite starting to fall, but I could get up in puffs and once moving no problem foiling. I think the carver is about 700cm^2 and it's no thicker than 20mm I believe...
The Carver wing is roughly 12-13mm thick x 6" x 24" by my measurements (if you have a calliper or can more accurately measure yours that would be awesome!) . I could probably go thinner than 2cm and get a wider speed range but I believe I can get better lift efficiency in the low end even if I sacrifice a few knots of top end, which I don't care about on a slow speed surf foil. This is my $100 alternative to buying a complete surf foil. :D

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Re: Max wing thickness for ultra low takeoff

Postby BWD » Thu Jul 27, 2017 2:17 pm

I'll work on that, have to improvise something...
I am not the carver but will admit it was really nice to use the smaller and LIGHTER wing the other day when wind was higher.
I would love to have a 900cm^2 version especially if lighter...


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