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Home Built Infusion Foil.

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max
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Re: Home Built Infusion Foil.

Postby max » Tue Jan 17, 2017 5:02 am

GrantL wrote:This being the case I choose to glue the 2 halves together.
Such awesome work.

Do you think that the wings could be built in this same way . . . glueing two halves together from two separate half moulds?

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Re: Home Built Infusion Foil.

Postby GrantL » Tue Jan 17, 2017 5:44 am

max wrote:
GrantL wrote:This being the case I choose to glue the 2 halves together.
Such awesome work.

Do you think that the wings could be built in this same way . . . glueing two halves together from two separate half moulds?
Hi Max. The short answer is yes. I will get to them after the fuselage.

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Re: Home Built Infusion Foil.

Postby GrantL » Tue Jan 17, 2017 6:06 am

So to make it possible with gluing l must stress that the infusion resin is vinyl Ester infusion specifically for infusion. The glue also is a vinyl Ester. You can't use any old epoxy glue.
One reason this works on a mast is the fact that you have an extremely large bonding area to deal with.
Once you have removed the mast scrap off the flashing around the edges carefully of course.
With a foam block gently sand the front edge. I recommend wet with 180grit. Watch the slurry from the block, if it is black stop immediately! You are now sanding into the twill which is only 0.15mm. Repeat for the trailing edge sand always at +-45deg. Avoid sanding length ways. REMEMBER THAT YOU DON'T NEED TO SAND VERY MUCH. you don't need to create a tapered trailing edge or correctly formed front edge, your mould took care of that.
OK so mast is fully sanded Lightly with 180grit, any residual glue gone.
Almost done.
To protect the mast from UV and abrasions a coat of Vinyl ester clear coat will do. This will also give you a high gloss finish. I tinted mine black as l wanted to. But underneath the carbon looked exactly the same as my fuselage and wings

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Re: Home Built Infusion Foil.

Postby GrantL » Tue Jan 17, 2017 6:42 am

Deflection of mast.
Rigid mount 850mm from bottom of Tuttle mount with 5kg load. 13mm result.
Torsional stiffness about center of mast 300mm 5kg. Deflection 7mm.
So pretty happy with the stiffness of my mast

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Re: Home Built Infusion Foil.

Postby TomW » Tue Jan 17, 2017 10:40 pm

Ok, I understand. Thanks. Really appreciate your time. I know it takes some time to describe it.
Sorry for a few more questions. What specific carbide scraper and what high bond glue.

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Re: Home Built Infusion Foil.

Postby GrantL » Wed Jan 18, 2017 12:19 am

TomW wrote:Ok, I understand. Thanks. Really appreciate your time. I know it takes some time to describe it.
Sorry for a few more questions. What specific carbide scraper and what high bond glue.
http://www.linbide.com 50mm carbide scraper.

Glue
Derakane 8084 resin is an elastomer modified Bisphenol-A epoxy vinyl ester resin, that offers very high toughness, elongation, impact and fatigue resistance, with exceptional adhesion. It is the resin of choice for demanding structural applications .

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Re: Home Built Infusion Foil.

Postby GrantL » Wed Jan 18, 2017 3:45 am

Fuselage Construction.
The fuselage I laminated the same , 70/30 ratio a thickness of around 4mm using infusion again. Due to the deep shape of the fuselage I only decided to infuse this deep. The remaining cavity in the center is so small , I tossed up whether I should fill with foam or laminate full. I decided to wet laminate with carbon fiber. So now I have a bullet proof fuselage.
20160803_081404.jpg
Fuselage imbeded in first mould
As the fuselage is supporting quite high impact loads from the front wing due to Me grounding on the beach and the possibility of falling onto the wings I also strengthened the joint. The glue area of contact is extremely small compared to the mast.
Starting at the nose I laid 600gsm double bias on top all the way to the rear wing cradle and the same on the underside 100mm past the mast trailing edge. These strips of carbon are the width of the mast stopping at the corner radius. Over this is the standard twill. The gives me the added torsional strength supporting the wing and mast if subject to any excessive loading.
Cosmetically stopping the fiber twill on the corner radius blends its pattern nicely.
20160908_203645.jpg
2 fuselage halves
I made a tapered end on my mast to fit into the fuselage , and screw from underneath, but I decided to glue this one together. I still had to machine the fuselage to fit the mast so there was no time saved. I just considered the bashing ahead this foil connection was going to get being a novice. Therefore I choose the glue option. When I build a second one this winter I will make the fuselage removable for easy transporting.
Again the fuselage was sprayed with clear to protect it from UV.

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Re: Home Built Infusion Foil.

Postby GrantL » Sun Jan 22, 2017 12:29 am

Front wing building.
After reading many online methods of quick solutions of how to produce wings I took a step back. I looked into the different hydrofoil profiles being regularly used an soon discovered that any profile will work. As a "newbie" not fully understanding what is good and bad, l took a stab in the dark and started drawing a front wing.
I was going to use the eppler 817 but was a little concerned with the reflex, and how successfully I could mould it. So instead I used an airfoil profile Aquila 9.3% which would be a whole lot easier. I decided on a size of 58cm^2 and added anhedral and tapered the front leading edge. I finally committed to a wing shape and created a 3d model.
The issue I have is what ever you draw, trying to produce an accurate wing which is symmetric in all respects is impossible. Even creating a mould on a cnc router or machining center is difficult unless you have 3 axis interpolation. So I designed a curved jig which I could build my plug on. What I did was slice my 3d profile up every 15mm from the center. So I produced multiple 2d profiles right to the wing tips. I laser cut these profiles out of 1mm steel, which I positioned on my jig in exactly correct position and angle. I epoxyed them in place. By using a jig I had an xyz datum and knew exactly the position of each piece. The final result ended up looking like a aeroplane wing waiting for a membrane.
You might ask why I did this. My reasoning for using a thin steel ribs was that my profile was correct in all respects. The steel ribs every 15mm controlled the final profile. I basically filled the skeleton with bog fairing as close as possible to the ribs. Finally I sanded the top of the wing down to the ribs until I hit steel.
When the sanding was completed I laid some carbon fiber on top to strengthen my wing. I could now remove from the jig
20160921_075216.jpg
Front wing with 150gsm of twill wet laminated on top side
You can see some of the ribs under the carbon. A little sanding with A Foam block and spot filling would smooth out these. The under side was easy as it was flat. So no laminate required
I started my rear wing next knowing exactly what to do, using eppler 817 and doing a much better job. The rear wing needed laminating top and bottom. I used some light glass for this
20160929_080302.jpg
2 wings ready to paint with primer
So I ended up with my 2 wings which I new were exactly correct to the profiles I choose.
After priming, wet sanding and polishing l produced my wings ready to mould.
20161012_064425.jpg
Front wing primed

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Re: Home Built Infusion Foil.

Postby Kamikuza » Sun Jan 22, 2017 3:04 am

:o

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Re: Home Built Infusion Foil.

Postby GrantL » Sun Jan 22, 2017 6:00 am

Wing moulds.
Probably one of the most difficult parts to mould are the wings especially if you have a curved anhedral shape. But any thing is possible. Like my mast and fuselage I needed to make a 2 piece mould splitting on the trailing edge and the center of the leading edge radius. I created a splitter plate using MDF to form a basic curve, matching the wing anhedral. Bog was required to get the exact curve and exact center line of the wings. Once I was happy with my plate I was able to start molding the wings, same method as previously.
20161020_103342.jpg
First halves of molds
After molding the 2nd halves I was ready for the fun part, actually making the wings
20161029_093551.jpg
4 halves, front and rear wings
As always the first layer of laminate is the 150gsm twill to protect the uni carbon. 3 x 300gsm uni running right across the wing, 1 double bias 600gsm same direction.
I repeated this a second time. Also a bit more double bias around the middle of the wings for the fasteners. This I repeated on both halves.
20161102_073823.jpg
20161102_073831.jpg
Infusion same procedure as before. Laminate around 3mm thick top and bottom
20161102_073837.jpg
Ready to infuse.
I shaped high density foam to fill the cavity and sandwiched the assembly together with glue in the molds
20161108_082818.jpg
Mold clamped while gluing.
After removing from the mold I had 2 wings exactly the way I wanted, profile accurate all over and importantly symmetrical. All I had to do was clean off the excess glue, sand lightly and spray with clear coat to protect carbon fiber.
I mounted the front wing with an AOA 2deg. The rear wing is sitting at - 2deg relative to the front wing.

And that is how I made my first carbon fiber kite foil.
Thank you for reading. If you have any questions don't hesitate to to ask.


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