SR-72 canard H fin

What works and what doesn't. Share design ideas, references and contacts for paipo board builders.
CHRISPI
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SR-72 canard H fin

#1

Unread post by CHRISPI »

My best board in for overhaul and update
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Original board
Original board
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jbw4600
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Re: SR-72 canard H fin

#2

Unread post by jbw4600 »

Looks good!! I wish could I try one out. What this deck padding material you use?
CHRISPI
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Re: SR-72 canard H fin

#3

Unread post by CHRISPI »

The deck pad is a first time experiment that worked out ok, three layers of Polyethylene foam
SJB
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Re: SR-72 canard H fin

#4

Unread post by SJB »

I still dont get the concept...seems like built in drag and turn resistance. Color me skeptical. Need a test drive.
CHRISPI
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Re: SR-72 canard H fin

#5

Unread post by CHRISPI »

I can’t seem to explain how it works, the canard board has not been tested . It has the same lifting surface area as most surf boards but stacked into the zone in contact with the wave face. And only the left or right side is in contact with the water .And my explanation how it plains up on the wing tips does not seem to be understood .In the transition zone between displacement and plaining the foiled hull holds onto lift longer than displacement hulls that surfboard etc are off the plain, a car person would understand this as having lots of torque , my boards takes off quickly and holds onto speed in flat sections , takes off on small weak waves like a long board, but holds a horizontal line in the vertical zone on the wave face .The operating zone or parameter have been expanded hugely .
SJB
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Re: SR-72 canard H fin

#6

Unread post by SJB »

Hope to try it some day. I am no techie...i.e. everytime I get on an airplane I am skeptical it will get off the ground....but it works.
CHRISPI
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Re: SR-72 canard H fin

#7

Unread post by CHRISPI »

First test ride on Sunday ,very weak wave 1m at 8 sec , I expected increased drag was going to be an issue but there seems to be less drag than before , so confusing may be some sort of nozzling or focusing effect of the boundary layer ??. Lots more testing needed I LOVE IT . Coanda effect ??
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Ted
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Re: SR-72 canard H fin

#8

Unread post by Ted »

This reminds me of a prone board I saw that had a metal hydrofoil extending downward about 12 inches. As I remember, the builder said he paddled it upside down to get outside and flipped it over and kicked hard to take off. Seemed like it could get very exciting to run into anything.
CHRISPI
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Re: SR-72 canard H fin

#9

Unread post by CHRISPI »

Hi Ted
The fin tips extend 10 cm down from the deck, less than most surf board fins, riding flat over people is safe .But when turning around carelessly dangled legs in the wave face the fin extends horizontally outside my hip area. I have gashed a leg and some boards
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Re: SR-72 canard H fin

#10

Unread post by SURFFOILS »

Crisps, that's just the hottest looking board ever !
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CHRISPI
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Re: SR-72 canard H fin

#11

Unread post by CHRISPI »

Thanks Bret. Seems to be no down side to two wings, hard to understand why there seams to be less drag now than before. I haven’t had it in big conditions, but this one has been fun to test
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Re: SR-72 canard H fin

#12

Unread post by Wooddave »

Hi Guys,,
awesome work as always Crispi
I'm Just guessing of course but,I think that the decrease in drag (or lack of increase)may be due to the disturbance caused by the front wing, which may break up the water so to speak clearing a path for the rear wing.
CHRISPI
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Re: SR-72 canard H fin

#13

Unread post by CHRISPI »

Thanks Dave, I am pleased with the layered deck pad not perfect but for a first time experiment not bad. I like the idea (lack of increase in drag).It feels like it’s not as good as it was holding horizontal high lines. But take offs, bottom turns and making slow sections has improved significantly, maintains momentum well .This board makes mush fun .
CHRISPI
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Re: SR-72 canard H fin

#14

Unread post by CHRISPI »

I have just had the most amazing session in my life with this board resetting the my bench mark best waves ever
CHRISPI
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Re: SR-72 canard H fin

#15

Unread post by CHRISPI »

CHRISPI wrote:I have just had the most amazing session in my life with this board resetting the my bench mark best wave ever
Wooddave
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Re: SR-72 canard H fin

#16

Unread post by Wooddave »

Hi Crispi,
glad to hear you're enjoying your success with the latest model.
I'd love to see that thing in action.
I've been working on a few new designs. I've got three built and have two more configurations to build for more comprehensive testing.
I have only tested two of them in the pool but they have some pretty interesting characteristics even in there.
I took some (bad) video of the test and will post it on you tube when I get a chance to edit it.
IMG_2003.JPG
IMG_2001.JPG
the design is a continuation of my earlier designs in that before I was attempting to create the rear channels through flex.
these have the channels built into them, they're made from 3mm ply with carbon in between and on the bottom.
my prototyping capacity has expanded considerably since acquiring my laser cnc.
I can now easily produce variations on a theme, though as you know actually building them is a little more time consuming.
CHRISPI
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Re: SR-72 canard H fin

#17

Unread post by CHRISPI »

Dave WOW that is thought provoking .Very very interesting, I see a convex Mylar plastic sheet joining the two boom tails that is thin enough to go concave at speed
Wooddave
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Re: SR-72 canard H fin

#18

Unread post by Wooddave »

Thanks, funny you should mention the Mylar sheeting, I have toyed with that idea, I'm still researching the best material and method of attachment, but I have envisioned a foil that is only a minimal frame with interchangeable (fabric?) skin for varying conditions. That is at least three generations away. For now I want to work on figuring out a shape that has similar flight characteristics to conventional foils except with an improved turn radius....
I put the foils to board and gave them a try in the surf yesterday and :D :D :D :D
IMG_2025.JPG
It was small surf but the foils worked wonderfully,, especially the longer one
As you might notice the board is just a skimboard with a layer of 1 inch Sea Deck foam
IMG_2023.JPG
I also realized that I am in horrible shape and I need to work on that as well
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Re: SR-72 canard H fin

#19

Unread post by SURFFOILS »

Great work you two. Dave, what feeling did you get from the longer foils ?
CRISPI, do you think the two foils create a longer 'wheelbase' rather than a single, I'm using a length of 23 inches that's very stable.
Have you seen the current commercial foils with masts up to 3 feet deep ? Crazy.
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