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Assymetrical tail wing

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Created by Pierre74 > 9 months ago, 11 May 2023
Pierre74
32 posts
11 May 2023 6:05PM
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Hi all,
I recall from my R&D days in the snowboard industry that toeside and heelside pressures were measured to be significantly different.
Partially due to bindings (rigid spoiler vs. soft straps) but also due to anatomical differences.
Applying toeside pressure seems much more progressive and precise whereas heel side pressure appears harder to adjust.
In snowboarding, measured pressures where higher under the heels and as a result heelside carving turns radiuses where measured to be way shorter than toeside ones.

In that perspective I'd be interested in trying asymmetrical tail wings.
From intuition I'd put a virtually shorter fuselage on the toeside but I might be wrong.

Just a thought, as tail wings appear to be one of the ? tuning ? parts of a foil (along with shims.)
What's your thought? Has anyone tried it already?

J_foil
NSW, 128 posts
11 May 2023 8:19PM
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snowboarding / skiing and even surfing to some extent, the edge not engaged is in the air doing nothing, in foiling everything is immersed and contributing to the balance, that said maybe there is some merit.. try it hahah

Piros
QLD, 7211 posts
11 May 2023 8:48PM
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Just back from Indo on a foil trip with Misterbennetts , perfect waves for a week foiling and all of sudden half way through the trip I preferred my backhand. So I like this topic , my take is toeside on the balls of your feet , heel side on your heels , completely different pressure on the foil. I found it easier to drop in on my backhand on a steep wave and rotate my upper body (right hand back) and uncoil back in the bottom turn , bringing the left hand forward in the top turn . Just surfing 101..... but Pierre's tail , I much likey and will bulid one in the Von Piros chop shop.. Let's see how it goes



eppo
WA, 9686 posts
11 May 2023 7:32PM
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Sending it piros

Pierre74
32 posts
11 May 2023 8:21PM
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Select to expand quote
Ju_foil said..
snowboarding / skiing and even surfing to some extent, the edge not engaged is in the air doing nothing, in foiling everything is immersed and contributing to the balance, that said maybe there is some merit.. try it hahah


Good point, the pumping ability might also be modified

cornwallis
156 posts
11 May 2023 8:49PM
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Cool idea. It's going to pull to one side when you're flat I guess. Or maybe induce roll to one side.

I find toeside I breach more frequently or cannot recover from breaches. Also find pitch instability worse on toeside.

I imagine there might be something to this as the "engaged side" will have higher loadings, eg in Piros first pic the heelside wing of the foil under his heels is much more loaded than the bit poking out the water. I would imagine the same would be true for the tail to some lesser but non trivial extent.

Maybe rather than asymmetrical shape you could have one side with a more or less aggressive foil section. More aggressive lifty foil section for the heelside and a smoother faster one for your toeside?

Pierre74
32 posts
12 May 2023 2:40PM
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Select to expand quote
cornwallis said..
Cool idea. It's going to pull to one side when you're flat I guess. Or maybe induce roll to one side.

I find toeside I breach more frequently or cannot recover from breaches. Also find pitch instability worse on toeside.



So a longer fuselage on toeside would make more sense to you.
Worth a blind test!
It's funny that assymetrical sidecuts have allmost disappeared in the snowboard industry. Costly molds and marginal pure carving practice I guess.
At the time (20 y. ago) we came to the conclusion that the ideal snowboard should be torsion-stiff and flexion-soft on toeside and vice-versa. But it was hard to combine with keeping the base plane...

Piros
QLD, 7211 posts
12 May 2023 8:24PM
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One of my old favourites I've screwed to the wall the Burton PJ6 asymmetric. This thing just shredded .



Pierre74
32 posts
12 May 2023 11:21PM
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Piros said..
One of my old favourites I've screwed to the wall the Burton PJ6 asymmetric. This thing just shredded .



Classic!

jondrums
186 posts
13 May 2023 3:54AM
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I think you want a little higher angle of attack on the foil section of the two sides. That way you get a little more downforce on the side that is further forward to counteract that it is further forward.

I do the same thing when I go to a shorter fuse - a little more shim in the tail to get more downforce to counteract the shorter lever arm of the short fuse. your concept is really interesting as drawn.

I hope you try it.

How about a tail that is angled and has continuously varied foil section angle to make up for it. That way it doesn't induce roll moment, but performs better in a turn to the preferred direction?

Fishdude
315 posts
13 May 2023 9:29PM
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Maybe not the same thing but, It might be easier the start with just shortening the stab by a few centimeters on one side and see how that works?

Pierre74
32 posts
14 May 2023 5:05PM
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Fishdude said..
Maybe not the same thing but, It might be easier the start with just shortening the stab by a few centimeters on one side and see how that works?


That's right.
Idealy one should find two identical tails, one chopped on the toeside and the other on the heelside and blindtest it with a bunch of regular and goofy footed riders.
If no difference gets noticed>>>> chop more!
At some point this type of assymetry might be hard on the screw heads or more likely damage the fiber around the mounting holes.
Or pressure levels aren't that high? No idea.



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"Assymetrical tail wing" started by Pierre74