Author Topic: A little is a lot  (Read 1228 times)

SUPeter

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A little is a lot
« on: October 08, 2018, 06:22:46 AM »
I'm not really sure who said this first with regards to foiling but find it to be the perfect  descriptive phrase for foiling. .  Dave Kalama comes to mind though it could have been a number of other early adopters of this addictive sport.  Finally finished my 6' x 29" Fugly and other than the need to move my tuttle back 3" , it worked quite well.   
    Now to get to my point.  Over the years I have spent a considerable amount of time reviewing the research having to do with surface skin drag reduction on hulls moving through water.  Anything from polymer infusion, air bubble infusion, super hydrophobic surfaces, riblets of varying size and texture, Earl Pedersons "Jet Bottoms",  Jick Mebane "Jick Bottoms"  and various other methods. 

    My hypothesis being that if we could lessen the surface skin drag by only a small amount we may be able to create a board that lifts free of the surface that much sooner and with greater ease.  To do this I used the same carbon fiber tow strips to create a rippled surface that would decrease the laminar flow, adding a slight bit of "confusion to the water, thereby decreasing the drag coefficient.  Of course, this is not easy, having to vacuum bag the glass over these strips to maintain the ribbed and pleasurable feeling.  Well, it got done and with a bit of cabinet scraping of the valleys there is a noticeable ripple to the bottom of my board. 

     Now, I have only tried this board once and on a very big day which is not ideal at my experience level but here is what I found.  Maybe Kalama type Fuglys do this automatically, but compared to my 7' 4" Simmons inspired SUP, this board got up to speed and flying almost immediately. Of course, I have no control group to compare with but I was impressed.  Maybe it's the Placebo Effect but at least I'm satisfied with the fact that all this work trying to texture the hull did not slow it down any.  It is going to take some getting used to but so far so good.   

     I definitely would appreciate any one else's experience or knowledge pertaining to the subject of "Skin Drag Reduction"  But I will continue with the notion that in all aspects of foiling--------------------A Little is a Lot!

   

SUPeter

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Re: A little is a lot
« Reply #1 on: October 08, 2018, 06:23:30 AM »
another pic

SUPeter

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Re: A little is a lot
« Reply #2 on: October 08, 2018, 06:24:09 AM »
Another.  This pic is taken from the middle of board, looking forward.  To lessen the need for a ventral fin, I made the lower bevels vertical to prevent yaw..  So far works as intended.  There is also a transverse "lifter in nose of hull.  Not sure how this works at this time.  Maybe if only to initiate water confusion.  Who knows?
« Last Edit: October 08, 2018, 06:49:55 AM by SUPeter »

Beasho

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Re: A little is a lot
« Reply #3 on: October 08, 2018, 06:57:01 AM »
Fantastic Stuff!

Any chance you can upload higher resolution pictures?  Those shots are like Instagram thumbnails.

Your search for lower drag brings me back to my windsurfing days.  At 30 mph the skin friction on a windsurfer exceeded everything we are talking about.  I remember all sorts of tricks being used from sanding with 320 grit to applying Vaseline to 'Phaser' dimples.  The reality on the foil is "The foil is what matters." 

The initial push from the wave gets us up to 7 or 8 mph whereupon skill can take over to get you flying.  I keep hearing of guys that can flat water fly.  Derek Hama come to mind. 

To do this requires 1) Skill 2) Strength to Weight and 3) Equipment

Keep on testing but at the same time keep on practicing.  Nothing inspires like the ability to fly. 
« Last Edit: October 08, 2018, 06:58:44 AM by Beasho »

SUPeter

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Re: A little is a lot
« Reply #4 on: October 08, 2018, 07:21:23 AM »
Practice! yes!  Can not get enough.  Its funny, but a buddy had a board with Phazer dimples on the very same day I tested this one.  My goal is to create a board which can take off on those really flat bumps with greater ease since once flying, it is those very flat bumps which are perfect for foiling.  All in all I find the Kalama shaped Fuglies alone increase the range of wave types available.  Anything that may help beyond that will only get me on that many more waves.  Jury is still out.

SUPeter

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Re: A little is a lot
« Reply #5 on: October 08, 2018, 09:53:56 AM »
hope these images post .

SUPeter

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Re: A little is a lot
« Reply #6 on: October 08, 2018, 09:54:31 AM »
another

SUPeter

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Re: A little is a lot
« Reply #7 on: October 08, 2018, 09:55:03 AM »
This pic is taken from front of board, facing the back of board.  If that makes sense.  My original description was wrong.
« Last Edit: October 08, 2018, 10:22:12 AM by SUPeter »

SUPeter

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Re: A little is a lot
« Reply #8 on: October 08, 2018, 12:25:27 PM »

Here is some recent research using ripples shaped like Barchan sand dunes to effectively decrease skin surface drag in moving water.



https://www.hindawi.com/journals/mpe/2017/6212605/

SanoSlatchSup

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Re: A little is a lot
« Reply #9 on: October 08, 2018, 04:24:51 PM »
Very cool!! Great graphics, and great shape.

I'm hoping to pick up mine that's very similar later this evening...fingers still crossed, and exercising as much chill pill patience as possible. Lol...

I went with really beveled rails (20" bottom to 28" width so 4" bevels on each side...was supposed to be 29" wide, but that's for a different story, ugh) with the idea of reducing "bottom drag" as soon as I start lifting it, and hoping that it will "release" or lift the board a little bit quicker as more, and more of the board comes out of the water...sort of like adding "wings" to each side of it.

Mind just be mental gymnastics, and an exercise in futility...but sure is fun to play around with, and hopefully it works just a little bit as planned...fingers crossed again. Hahahaha... :D
Me: 6'1"/200...6'0" Chelu Foil Boards...9'6" Bob Pearson "Laird Noserider"...9'6" Costa Azul Wide Body...14' Lahui Kai "Manta"...8'0" WaveStorm for when proning urges still hit, and 7'3" Chuck Glynn foil board backup.

PonoBill

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Re: A little is a lot
« Reply #10 on: October 08, 2018, 04:32:43 PM »
I have no idea how effective your ripples might be, but I have experience on Mr. Fugly, and the very first thing I noticed it that it gets off the water very quickly. So quickly that I went over backwards the first few times doing much less to get the board flying than with my previous board.
Ponohouse is for sale: http://www.ponohouse.com
Foote 10'4X34", SIC 17.5 V1 hollow and an EPS one in Hood River. Foote 9'0" x 31", L41 8'8", 18' Speedboard, etc. etc.

SUPeter

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Re: A little is a lot
« Reply #11 on: October 08, 2018, 04:48:19 PM »
"I have no idea how effective your ripples might be, but I have experience on Mr. Fugly, and the very first thing I noticed it that it gets off the water very quickly. So quickly that I went over backwards the first few times doing much less to get the board flying than with my previous board. "

I know exactly what you mean Pono.   The board just wants to be out of the water. 
« Last Edit: October 08, 2018, 04:50:06 PM by SUPeter »

TallDude

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Re: A little is a lot
« Reply #12 on: October 08, 2018, 04:52:38 PM »
I love the R&D SUPeter. Glenn Curtiss invented the 'Step' hull which allows sea planes to break free of surface tension and become airborne. I'm surprised no one has incorporated a step hull into their foil boards?

https://history.nasa.gov/SP-468/ch8-2.htm

SUPeter

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Re: A little is a lot
« Reply #13 on: October 08, 2018, 05:02:14 PM »
There is a step!  Just beyond the mast, there is a release edge created after the board is glassed.  Mine is 1/2" high and allows the water to cleanly break free of the bottom with little or no suction. I just used epoxy, aluminum powder and milled fibers.  If you notice, there is a gray band behind the mast in one of the photos.  That's it.
« Last Edit: October 08, 2018, 05:05:25 PM by SUPeter »

PonoBill

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Re: A little is a lot
« Reply #14 on: October 08, 2018, 05:14:46 PM »
Yup. the Kalama boards--at least the newer ones, all have a step. Mr. Fugly has a pretty big one. That and the deep chamfer on the tail makes the board leap off the water. Once I got the leaping under control I realized that the sharp undercut of the rails does the same thing if you're keeping the board flat and not doing missile shots off the water. I'm up and flying while I still think I'm surfing. The transition is something I had to get used to. If I leaned on a rail a little to turn while I thought the board was still on the water it would do the typical foil trick of pushing hard up against the rail pressure.
Ponohouse is for sale: http://www.ponohouse.com
Foote 10'4X34", SIC 17.5 V1 hollow and an EPS one in Hood River. Foote 9'0" x 31", L41 8'8", 18' Speedboard, etc. etc.