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Sneak peek new Kook 2 piece foil

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tahoedirk
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Sneak peek new Kook 2 piece foil

Postby tahoedirk » Sat Oct 15, 2016 5:35 pm

Getting close, maybe this week. It's taken many hours of head scratching to get this far. I suspect my rear wing is still too big but that will be easy enough to change later.
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First you have to make the part.
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Next, get it smooth and shiny.
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Build a crazy box, embed it in clay, raise the box 3/4" for flange and have Storm cover it with thickened epoxy. Glass the crap out of it.
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Flip it over, ditch the clay, clean it up, repeat.
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This is the hardest part. Select mast profile. This is between NACA 01234 and NACA 01264 100x12.5 (I hope)
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Try for perfection with table saw and sandpaper.
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Cut a Tuttle box in half and fasten it to the mold halves.
There's more still to do.
Try not to think about how much money you "could" be making.

Mossy 757
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Re: Sneak peek new KOOK 2 piece foil

Postby Mossy 757 » Sat Oct 15, 2016 5:54 pm

That's the highest performance looking home made foil I've seen on here so far. You might enjoy playing around with where you mount your strut, a lot of really fast foils are starting to position the strut further back on the fuselage, it gives better stability.

Did you copy your wing designs from another foil?

tahoedirk
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Re: Sneak peek new KOOK 2 piece foil

Postby tahoedirk » Sat Oct 15, 2016 6:37 pm

Thanks mossy,
I think you are right, so I am moving the strut back for starters, where I had it before, about 1" back from the front wing. I plan to keep it changeable until I/we find the sweetest spot, same with the pitch on rear stab. There is nothing copied on this except the concepts. The wings are two of my current favorites which I have tweaking, mostly unsuccessfully, over the last year and a half.

I've decided if one out of five alterations are improvements then I'm doing well. Tough R&D

Sadly it just turned to winter here and I ran out of travel money, I'm always a year behind though.

ahhh, anticipation.....

revhed
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Re: Sneak peek new Kook 2 piece foil

Postby revhed » Sat Oct 15, 2016 7:11 pm

I am unsure the benefits of STRUT further back from F wing T E as the load on the fuse there is great concerning D I Y.
One would need to be sure of strength there!
Have seen breakage there more than once.
Have strong feeling your T bar will be "loose" meaning yaw will be sensitive and fast due to less R wing (stab) up swept surface area.
And more stab vertical surface area can compensate for Strut L E mounted very close if not directly above F wing T E.
It seems logical that the Strut will act as a "rudder" or long vertical fin and further back should add "tracking" and yaw stability, but turn less sharp.
The relationship between the distance between Strut L E and F wing T E AND the amount of surface area, shape, up swept (if any) of a stab, wing tip angle and area is quite a challenge.
Very interesting to see some builds with completely flat wings and Strut mounted L E directly over F wing T E, talk about sensitive and responsive again depending on surface area relationships, but still a quick fast fly!
P1190003.JPG
P1190003.JPG (38.84 KiB) Viewed 1440 times
Credit to Christoff South Africa for this design if I recall OK. He also had a dedicated K B H F forum at one time.
This always interested me and sure wish I could have test flown it as flat wings are SO much easier to fabricate using thick glass as a mould base.
But note the vertical surface area.
Gotta go eat...
R H

tahoedirk
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Re: Sneak peek new Kook 2 piece foil

Postby tahoedirk » Sat Oct 15, 2016 10:06 pm

Yup, hats off to Christoff his website was informative and inspirational

Rev , I remember you thought I was onto something with my first fuselage profile because it had lots of vertical surface area, I ended up going the other direction with a nearly round fuse and I like it better. Gunnar also thought I would need more vertical, or rudder like component. I tried it and I prefer the loose, turny nature of the direction I have gone. An older version of mine with an unlikely front wing has the mast mounted an inch rearward and it rides superbly. Since I have been changing more than one thing at a time, it is hard to know exactly what factor is responsible. I aim to find out and have myself a grand old time discovering. There is a fine balance between locked in stability and yawing loosness and especially personal preference. The other subjective factor is that one learns to ride whatever they are on , eventually well, so it is hard to compare unless you gave each model equal time on the water, not gonna happen. The one thing I have yet to eliminate is cavitation under load, it has been my nemesis. The good part is now I can ride these crazy gizmos and discern the differences.

Some of the new foils ride so well, like perfect and you can buy them for not so much money. However, I am so pleased that I started this journey , it has been very satisfying and I'm right in there with my favorite new production models which I have tried. I have decided that I don't think I am after the fastest foil , rather the most fun surfy feel with the least drag I can achieve. Currently I'm stuck at 33MPH. In the end however, the least drag probably does equate to the fastest. We will see...

I really hope some more readers/craftsmen are getting inspired right now and will soon join us and try their hand at this creative endeavour.

Thanks for your input, again. Dirk

bigcane
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Re: Sneak peek new Kook 2 piece foil

Postby bigcane » Sat Oct 15, 2016 11:06 pm

How are you confident that you have the correct rear wing angle before you mold it?

tahoedirk
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Re: Sneak peek new Kook 2 piece foil

Postby tahoedirk » Sat Oct 15, 2016 11:44 pm

I'm not,
I set it at 3 degrees after much deliberation. I have to make one first and ride it. The mold is made to adjust and it is easy to measure after I test drive it. I have found that even a couple of tenths makes a big difference. I can barely ride some foils that I sold , even recent ones, I've offered to reset them but the owners decline, they are used to them. I am used to being out of the rear strap more often than not now, except for jumping. This is huge though because properly setting both wings on three different axes has gobbled up hour after hour. I am hoping to shaves these hours down significantly, and still sell them for 1000$ I do believe that there is almost a perfect angle for speed ,drag ,pitch stability and foiling transitions. I currently like about 3.4 but I shortened my fuse by an inch and added a bit of camber in the TE mid section of the rear stab. It will take some luck or work to get it perfect.

I have been either vacuum bagging or clamping in the past . By bolting together my molds instead, I hope to be able to tweak it mildly and visualize/measure it, if needed while it cures.

Great question BC

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downunder
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Re: Sneak peek new Kook 2 piece foil

Postby downunder » Tue Oct 18, 2016 5:35 am

Dirk,

you are making your wings with a fiberglass and sanding it after?

tahoedirk
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Re: Sneak peek new Kook 2 piece foil

Postby tahoedirk » Tue Oct 18, 2016 7:13 pm

So far only carbon, hoping for minimal sanding, just the edges hopefully. Did I say hopefully?

tahoedirk
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Re: Sneak peek new Kook 2 piece foil

Postby tahoedirk » Tue Oct 18, 2016 7:31 pm

Actually......I was thinking about going for a little colored fiber glass bling on my new prototype. I know carbon is way sexier but...

What do you think?
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6oz colored fiberglass /carbon tape


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