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 Post subject: Re: DIY Home Made wooden Hydrofoil fins
PostPosted: Thu Nov 21, 2013 3:21 am 
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don pitcher wrote:
Thanks. I imagine just using one wing in the center would be better, but I need to improve pitch control.
...


You would Still need some sort of stability for the person to balance
on , ( like the Tail on a normal design) ; without TWO foils to balance
against, i don't think the design would work ?
Your design is sound, with the Two foils, it should work after you
come up with the proper aria and airfoil.

I'm Kinda thinking that Flat is NOT optimum ? And Yea, the single strut
would be Better for Drag reduction !!

Bille


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 Post subject: Re: DIY Home Made wooden Hydrofoil fins
PostPosted: Thu Nov 21, 2013 12:55 pm 
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don pitcher wrote:
zfennell wrote:
don,
whats the material list and dimensions for your twin-tip prototype?


The fuselage is 1" 6061-T6 square stock. I made it very strong because of the cantilever with the wings at the end but also wider than I like because the moment on the weld gets ridiculous with a small width (this is a weakness with this design). If the wing is placed with little to no cantilever, then a lighter square tube could be used.

The wings are 1/8" 7075-T6. They are way too big. 6" x 24"

The frame is made of 1/8" x 3" 5086. 24" tall. I think closer to 30" would be better except the frame would likely buckle at that height unless more draggy bracing was added. Also, if welding aluminum and not heat treating afterword, 5086 is nicer than 6061 because it has a much higher annealed strength.

I really think an extrusion riser, square tube fuselage, a wing under the riser, and bolted together would be better and easy.

Image

Edit: originally wrote 5068 but meant 5086.


There is this FoilSim program you can download. (version 1.4b)
https://www.grc.nasa.gov/www/K-12/FoilSim/index.html

I have fiddled around with it a bit using an eclipse shape with camber underneath. You can vary the thickness/chord ratio and the angle of attack using sliders and it helps you find the highest lift/drag ratio as you just keep moving the sliders around until you find the optimum.


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 Post subject: Re: DIY Home Made wooden Hydrofoil fins
PostPosted: Thu Nov 21, 2013 1:08 pm 
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Billie, you are a piece of work! (but we all are really) You are repeating what I have already stated.

don pitcher wrote:
I knew it would not be near as efficient as a directional; but, it is not as efficient as I would like. It needs to get better and I think it has potential...

...I then moved the wings together. This was better, but pitch control needs to be improved. I have been too busy to progress this further.

My next step would be:

*remove the draggy frame with a streamlined riser.

*to have one wing in the middle and two small stabilizer wings at the end.

*use a long square tube as the fuselage to move the stabilizer wings further away from the center wing. This will allow for a smaller stabilizer wing which will have less disruption of flow to the middle wing.

With the extrusion i mentioned previously, this could all bolt together. It doesn't get any easier than that!


Thanks Ronnie!


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 Post subject: Re: DIY Home Made wooden Hydrofoil fins
PostPosted: Thu Nov 21, 2013 3:36 pm 
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don pitcher wrote:

Thanks Ronnie!


Hope its useful.
It would help to know what angles of attack you would like to use as the best ones seem to be quite shallow.


Once you have got a shape with the best lift/drag ratio, you can 'fly' it in water using the flight section to get an idea of what area you would need to generate the lift needed.


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 Post subject: Re: DIY Home Made wooden Hydrofoil fins
PostPosted: Thu Nov 21, 2013 5:00 pm 
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Location: Chile/Brasil
ive started my wooden foil this is what ive done so far.
first pic is keel profile


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2013-11-18_20-14-26_212.jpg
2013-11-18_20-14-26_212.jpg [ 2.4 MIB | Viewed 255 times ]
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 Post subject: Re: DIY Home Made wooden Hydrofoil fins
PostPosted: Thu Nov 21, 2013 5:07 pm 
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Location: Chile/Brasil
second pic are the wings


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2013-11-18_19-14-03_150.jpg [ 1.62 MIB | Viewed 249 times ]
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 Post subject: Re: DIY Home Made wooden Hydrofoil fins
PostPosted: Thu Nov 21, 2013 5:09 pm 
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Location: Chile/Brasil
special thanks hawwaii for the inspiration to get off my butt and do something with my spare time!


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 Post subject: Re: DIY Home Made wooden Hydrofoil fins
PostPosted: Thu Nov 21, 2013 5:49 pm 
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cool, windfreak, that is a good looking wing!
Are you cutting it with a router sled?
If so how did you calculate the shape of the jig?


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 Post subject: Re: DIY Home Made wooden Hydrofoil fins
PostPosted: Thu Nov 21, 2013 6:21 pm 
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Location: Chile/Brasil
Hello BWD,
yes i used a sled jig. to make the profile.
i printed the wing profile i wanted on paper.
epps 836 for the keel.
Naca 0012 for the wing
glued and i cutted the pattern with a bandsaw.
and did a copy on the router.
bolted them together with a rod to make proper distace for the router.
adjusted the profile with sander an adjusted depth to get the desired chord.
voila instant wings and reproduceble.
i will post a picture of the gig.
thanks for the comment! :thumb:


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 Post subject: Re: DIY Home Made wooden Hydrofoil fins
PostPosted: Thu Nov 21, 2013 6:26 pm 
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Location: Chile/Brasil
i will post the specs too so every one!
with some woodshop experience and some tools
you can build this in a afternoon.
i have spet about 500 dolars in all the tools and materials like carbon and fiberglass and resin to finish the Project.
the rest is time to figure out construction methods and excecution.
ive logged about 8 hours in execution and about 500 hours in thinking it over!!:) 8)


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