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Max wing thickness for ultra low takeoff

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Bletti
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Max wing thickness for ultra low takeoff

Postby Bletti » Mon Jul 17, 2017 10:12 pm

I'm thinking of buying some g10 and shaping my own light wind wings for my Zeeko spitfire. Sup/surf foils are super beefy (3-4 cm+ i think but I've never actually measured if anyone knows?), but I wonder how thick would be too thick for a canard kite foil, that might be paddle surfable. I was thinking of getting 1 inch (2.5cm) g10 for the main wing (~20 inches by 5) and 3/4 inch (1.9cm) for the smaller front canard wing (14 by 4.5 inches). Is that too thick? Worst case if it is too thick I can simply sand them back till they are thinner so I'm not too concerned other than it being a bit of a waste. Anyone have any advice or opinions?

Also is there a preferred aerofoil profile for low takeoff? I'll be doing straight wings with maybe a slight sweep.

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NYKiter
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Re: Max wing thickness for ultra low takeoff

Postby NYKiter » Mon Jul 17, 2017 10:59 pm

Way too thick...and WAY too expensive. I would go with 3/8" and 1/4"
why would you want that low of a take off?

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Re: Max wing thickness for ultra low takeoff

Postby BWD » Mon Jul 17, 2017 11:23 pm

think how easy it would be to shape it from 2cm corecell or similar.
Cut out a section around the mast attachment, and fit a block of g10 in that for torque/compression resistance.
Laminate with carbon to about 2mm skin thickness.
Cost probably similar if not less, way lighter and you'd even get to shape a little g10.
might be a little more complicated, but you would't have to grind until your arms and tools give out.
just a thought....

Bletti
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Re: Max wing thickness for ultra low takeoff

Postby Bletti » Tue Jul 18, 2017 12:01 am

NYKiter wrote:
Mon Jul 17, 2017 10:59 pm
Way too thick...and WAY too expensive. I would go with 3/8" and 1/4"
why would you want that low of a take off?
Can you explain why sup/surf foils are so much thicker then? They'd be double to triple 3/8th at least. I priced 1" and 3/4" g10 for $160 delivered to Oregon compared with the spitfire xlw wings at $565 usd delivered with tax to BC.

I figure I'll have the smaller stock wingset to mount to have very good agility and want to push the other end with slow take off to the limit to justify the second wingset. Locking in super slow on the edge of a wave would be the goal and contrast the top bottom turn style of the stock spitfire wings.

If you read some of the other forum post people are using surf foils to lean and I want to make a canard hybrid.

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Re: Max wing thickness for ultra low takeoff

Postby Bletti » Tue Jul 18, 2017 1:39 am

BWD wrote:
Mon Jul 17, 2017 11:23 pm
think how easy it would be to shape it from 2cm corecell or similar.
Cut out a section around the mast attachment, and fit a block of g10 in that for torque/compression resistance.
Laminate with carbon to about 2mm skin thickness.
Cost probably similar if not less, way lighter and you'd even get to shape a little g10.
might be a little more complicated, but you would't have to grind until your arms and tools give out.
just a thought....
Thanks, yes if I knew exactly what I wanted that's what I'd do, but i think making a first version, even if it's a bit heavy, from solid g10 will give me far more flexibility to shape it and reshape it, tweak angles, etc till I get the configuration and balance I want between the wings. I'll likely oversize the front wing then ride it before sanding it back.

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Re: Max wing thickness for ultra low takeoff

Postby BWD » Tue Jul 18, 2017 2:57 am

Either you don't mind spending lots of time with a grinder or you haven't thought about what it will be like trying to turn ~75% of a huge slab of glass and epoxy into dust?
To me this would be a big pain, and you can't sell that dust for the $400 or so it cost you before it was dust. And will cost more than a set of zeeko XLW wings. It would be an accomplishment, though.

Bletti
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Re: Max wing thickness for ultra low takeoff

Postby Bletti » Tue Jul 18, 2017 3:17 am

BWD wrote:
Tue Jul 18, 2017 2:57 am
Either you don't mind spending lots of time with a grinder or you haven't thought about what it will be like trying to turn ~75% of a huge slab of glass and epoxy into dust?
To me this would be a big pain, and you can't sell that dust for the $400 or so it cost you before it was dust. And will cost more than a set of zeeko XLW wings. It would be an accomplishment, though.
A dremel, rasp, and belt sander with 50 and 100ish grit will make quick work of g10 and I have plenty of time to tweak. :D This forum post shows it's been done before (viewtopic.php?f=199&t=2394894) It's less than 1/3rd the xlw wing price (only $160 through professionalplastics) for 2 oversized wing blanks so i could build 3 iterations, filling the whole neighbourhood with g10 dust, if i mess up the first time and still do alright.

But getting back on subject, how thick is too thick of low speed wave wings?? I think an inch is around that point.

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Re: Max wing thickness for ultra low takeoff

Postby mopman365 » Tue Jul 18, 2017 6:31 am

I'd also rather sand a block of Corecell or plywood, but on the thickness, i'd say that depends on your wing's chord. Most are between 9 and 11% of the chord from what i've read (no expert). So if you go for a large 200mm chord wing, final thickness around 20mm. If shaping from plywood, you could shape a 16mm sheet and glass/carbon about 2mm each side.
Suggested profile: http://airfoiltools.com/airfoil/details?airfoil=e818-il
Enter your chord and print template: http://airfoiltools.com/plotter/index?airfoil=e818-il

Bletti
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Re: Max wing thickness for ultra low takeoff

Postby Bletti » Tue Jul 18, 2017 8:14 am

mopman365 wrote:
Tue Jul 18, 2017 6:31 am
I'd also rather sand a block of Corecell or plywood, but on the thickness, i'd say that depends on your wing's chord. Most are between 9 and 11% of the chord from what i've read (no expert). So if you go for a large 200mm chord wing, final thickness around 20mm. If shaping from plywood, you could shape a 16mm sheet and glass/carbon about 2mm each side.
Suggested profile: http://airfoiltools.com/airfoil/details?airfoil=e818-il
Enter your chord and print template: http://airfoiltools.com/plotter/index?airfoil=e818-il
Thanks. Yes, I wish i could commit to building it out of corecell or plywood, but I have a feeling I'm going to want to do plenty of tinkering and solid g10 will give the flexibility to reshape to get the balance between the wings right.

Any reason in particular you'd chose e818, instead of say h105, for a low stall speed design? H105 has 12.5% thickness/chord so a 5" chord would be 5/8th thick, so maybe I was a little too girthy on my intial guess :lol: 'm still playing with rough numbers in an excel sheet at this point. Thanks for the advice!

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mopman365
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Re: Max wing thickness for ultra low takeoff

Postby mopman365 » Tue Jul 18, 2017 9:27 am

> Any reason in particular you'd chose e818, instead of say h105, for a low stall speed design? H105 has 12.5%

Could not find H105 profiles on that site. You can also bump the printed thickness to 12.5% using the "Thickness (%)" on the plotter page. I used e818 (9.4%) instead of e817 (11%) because I was shaping the core and had to allow for 4mm extra carbon in total.


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