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Nomad's DIY foil build

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NorCalNomad
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Re: Nomad's DIY foil build

Postby NorCalNomad » Tue Aug 09, 2016 5:21 am

You must not have seen too many mast as a 2 axis symmetrical foil shape isn't as efficient as say a symmetrical naca shape. I have yet to see a carbon mast with a 2axis symmetrical foil.

It's pretty easy to make a laminated structure far stiffer than an alum. one as long as you know some basics of your forces, lamination, and layup processes. Should even be not that hard with a male mold that also adds stiffness to your part.

UPDATE
Been gone on work trips for the last 2 weeks.

I've finished up shaping my mast, wings, and I think I'm only going to do some minor profiling on my fuselage since I'm tired of looking at it broken :oops:

So up next is overdrilling my mounting holes in my wings, fuselage, and baseplate. Then filling those back in with resin, and drilling them to the proper size and installing the t-nuts. I wanted to do this first so that after my lamination I won't have to worry so much in having accurate holes or really true surfaces to make the mounting holes square (I can true say the wing to fuselage mating surface off of the bolts).

NorCalNomad
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Re: Nomad's DIY foil build

Postby NorCalNomad » Tue Aug 09, 2016 5:40 am

Just found this thread on SeaBreeze.

http://www.seabreeze.com.au/forums/Kite ... e-grinder/

A SKATEBOARD FOR A WING! fuck me that could have saved me a load of time. Will have to try one of these

kitexpert
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Re: Nomad's DIY foil build

Postby kitexpert » Tue Aug 09, 2016 9:09 pm

NorCalNomad wrote:You must not have seen too many mast as a 2 axis symmetrical foil shape isn't as efficient as say a symmetrical naca shape. I have yet to see a carbon mast with a 2axis symmetrical foil.
Actually what I've seen have not been completely symmetrical 2 axis, but however thickest point is quite near at the center. Look how Denisesewa's mast profile has changed to that direction. For my eye your mast hydrofoil looks a bit too blunt at front area. But if you have finished your mast its ok, no doubt it works.

Of course mast profile must be symmetrical chordwise, so no cambered. There might be some cavitation or stiffness related reasons why generally used mast hydrofoils are what they are. I have seen four hf's at close range and many more in forums, no big differences in that relation.

Thinking dragwise and based on aerodynamics I agree what you wrote about efficiency - but is this so much different world that this knowledge is not valid?

Big differencies to aerodynamics are: 1)water is over 800 times as dense as air 2)used hydrofoils are very small by their size.
NorCalNomad wrote:It's pretty easy to make a laminated structure far stiffer than an alum. one as long as you know some basics of your forces, lamination, and layup processes. Should even be not that hard with a male mold that also adds stiffness to your part.
I am not sure that Alu vs. carbon stiffness in DIY practice. Some aluminium alloys are very stiff, when heat treated etc., in every direction. Laminating on male mold (wooden core, foam core etc) doesn't add stiffness much, because the surface takes most of the loads. That is why foam core is at all reasonable.

Easiest way to increase stiffness is to add diameter. I read from kbhf forum calculation of decreasing mast thickness some mm's (about from 20mm to 15mm) would give knot or two benefit over 20kn speeds - for a beginner these speeds are too much... Of course for racers it is a big difference. Here local hydrofoilers fear high speeds (or crashes) they can reach with their hf's.

NorCalNomad
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Re: Nomad's DIY foil build

Postby NorCalNomad » Sun Aug 14, 2016 3:31 am

Ordered up my carbon since TAP Plastic's carbon is stupid expensive compared to compositeenvisions.com.

Predrilled all my screw and insert holes larger and backfilled them with epoxy to seal up the wood. Wanted to do this before I started laminating so that I could keep my centers better without having to measure off of my lamination's.

Now I have to figure out where I'm going to do my mast/ fuselage lamination's since my kitchen probably won't be big enough to work easily :-? #apartmentlife sometimes is a real bitch.

NorCalNomad
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Re: Nomad's DIY foil build

Postby NorCalNomad » Mon Aug 22, 2016 6:20 am

Updated photos and words about putting in my inserts, attaching the fuselage to the mast, and starting to laminate the wings.

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Re: Nomad's DIY foil build

Postby rynhardt » Sun Dec 25, 2016 8:00 pm

Hey dude. What happened? Still building this?

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rynhardt
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Re: Nomad's DIY foil build

Postby rynhardt » Sun Dec 25, 2016 8:02 pm

NorCalNomad wrote:Updated photos and words about putting in my inserts, attaching the fuselage to the mast, and starting to laminate the wings.
Let me do a quote.. This way you should get a notification ;-)

NorCalNomad
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Re: Nomad's DIY foil build

Postby NorCalNomad » Mon Dec 26, 2016 9:33 am

Sorry, work, GF, and skiing picked up. But I just injured my knee skiing, and she's back home with family so I should be jumping back on the project in the next few days.

Also, for everyone thinking about doing one of these.
1. Vacuum system is worth it (wasting so much time and $ sanding right now)

2. If you aren't using a vacuum system be patient with your layups and don't try to do too much at once
3. For most stuff since there is a good deal of curvature don't use really thick fabric. lots of thin layers are way easier to work with

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rynhardt
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Re: Nomad's DIY foil build

Postby rynhardt » Mon Dec 26, 2016 8:33 pm

Knee injuries suck. Hope it's not too serious.

NorCalNomad
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Re: Nomad's DIY foil build

Postby NorCalNomad » Tue Dec 27, 2016 3:10 am

Yeah it's feeling better today, but I'm not going to push it.


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