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How to turn a hydrofoil - and what is YAW ?

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nothing2seehere
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Re: How to turn a hydrofoil - and what is YAW ?

Postby nothing2seehere » Wed Dec 20, 2017 11:12 am

Interesting. I always assumed that the most tight turns (like the stuff Greg from BRM demonstrates) uses pitch to make the turns. He appears to roll the board into the turn but then his weight shifts back to use the pitch axis to fly the wings all the way around (kind of like that mtb on a bern / wall of death idea).

I realise its gone all theoretical and everyone is probably describing the same thing depending on how they experience the sensations during a turn.

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Re: How to turn a hydrofoil - and what is YAW ?

Postby Peter_Frank » Thu Jan 25, 2018 8:24 pm

HOW you create the yaw impulse, can be different, or a number of factors, countersteering using your body inertia like a cat turning midair to land on its feet, or like flying grandpa has explained, use the bar and lines as a "counterweight" push the bar in the opposite direction (outwards of the turn) - this will help give you the yaw impulse for tight easy carves, and it works :thumb:

8) PF

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Re: How to turn a hydrofoil - and what is YAW ?

Postby Jefe » Wed Jan 31, 2018 9:34 pm

I'm still new to foiling, but it seems to me the second you bank the board, your front foot/ back foot weight distribution starts apply not only pitch moment but also yaw about the mast to keep the turn coordinated.

If you somehow initiate with yaw only, the effect of the sideslip on the mast would probably overpower any sideslip effects on the foils anyway, but my guess is that slight anhedral and leading edge sweep balance out to give the wings a slightly positive dihedral effect, and that having any dihedral angle would be too much and just give you roll/ yaw coupling issues and make it easier to cavitate a wingtip in a turn (and increase spanwise flow/ induced drag).

Fun to think about, I've got a reasonable background in aircraft stability and control, but throwing another giant foil (the mast) and moving the CG up a ridiculous amount makes things interesting. Now I'm going to have to figure out how to instrument the foils with AoA and sideslip telemetry.... actually I think I just need to figure out how to tack and gybe the thing first :)

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Re: How to turn a hydrofoil - and what is YAW ?

Postby Jzh_perth » Thu Feb 01, 2018 1:41 pm

Wow. This topic - 8 pages on how to turn a Hydrofoil ? TLDR but for me carving the foil (after 3 years of foiling) is no different to carving a skateboard / snowboard. It’s all hips and knees and looking thru the turn to the exit. You can’t stamp down on the tail because that will just breach the frontwing. Who remembers dropping in on a skateboard ramp first time ? If you lean back you fall off the back, but if you keep your weight centered over the wheels - you’ll make it. Same thing applies here : lean into the turn keeping the weight centered (which implies hips fwd, knees bent , shoulders and chest rotated facing direction of travel) and you’ll ride out the other side as fast as you went in. If you lean too far fwd you touch down (no biggie) , too far back and you breach. (Splash)

All this talk of yaw and pitch and when to do what ? Guys. The foil is the most intuitive, beautifully responsive thing to ride. If you bank it over and commit to the turn it will cut a beautiful arc thru water and spit you out the opposite direction. Heavenly. If I get wobbly I always and try remind myself to look thru the turn (my motorcycle instructor would be proud) because your body naturally follows your head. Don’t look down. (Splash)

I appreciate it’s quite different to how we are used to riding our TTs and SBS but I don’t think over analysing it helps. Don’t overthink it and give it 50-100 attempts(sessions/hours)and you will be charging thru gybes with the best off them. Just do it !! :)

———
Short version :
Grab yourself a longboard and helmet and go skating.Skating / foiling have a lot in common.

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Re: How to turn a hydrofoil - and what is YAW ?

Postby Jefe » Thu Feb 01, 2018 9:43 pm

Jzh_perth wrote:
Thu Feb 01, 2018 1:41 pm
Guys. The foil is the most intuitive, beautifully responsive thing to ride. If you bank it over and commit to the turn it will cut a beautiful arc thru water and spit you out the opposite direction.
This is the most awesome thing about it! A foil is complex, but the human mind can learn so quickly that you just have to fall somewhere between 10-100ish times to unconsciously figure out all the minuscule weight and balance inputs and how to make the turn work. Why it works on the other hand... People are awesome.

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Re: How to turn a hydrofoil - and what is YAW ?

Postby TomW » Fri Feb 02, 2018 4:49 pm

Jefe,
It's totally addictive! It blows my mind that I've actually learned to gybe heel to toeside flying ( 70% success rate on one side), at 58yrs old. I'm 60 hours in.
Dropping into a 4ft bowl on a skate board took me 15 minutes to learn and 4 brutal falls at age 45. Foiling is way more difficult to learn than basic bowl riding.

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Re: How to turn a hydrofoil - and what is YAW ?

Postby jeromeL » Fri Feb 02, 2018 5:28 pm

Jzh_perth wrote:
Thu Feb 01, 2018 1:41 pm
Wow. This topic - 8 pages on how to turn a Hydrofoil ? TLDR but for me carving the foil (after 3 years of foiling) is no different to carving a skateboard / snowboard. It’s all hips and knees and looking thru the turn to the exit. You can’t stamp down on the tail because that will just breach the frontwing. Who remembers dropping in on a skateboard ramp first time ? If you lean back you fall off the back, but if you keep your weight centered over the wheels - you’ll make it. Same thing applies here : lean into the turn keeping the weight centered (which implies hips fwd, knees bent , shoulders and chest rotated facing direction of travel) and you’ll ride out the other side as fast as you went in. If you lean too far fwd you touch down (no biggie) , too far back and you breach. (Splash)

All this talk of yaw and pitch and when to do what ? Guys. The foil is the most intuitive, beautifully responsive thing to ride. If you bank it over and commit to the turn it will cut a beautiful arc thru water and spit you out the opposite direction. Heavenly. If I get wobbly I always and try remind myself to look thru the turn (my motorcycle instructor would be proud) because your body naturally follows your head. Don’t look down. (Splash)

I appreciate it’s quite different to how we are used to riding our TTs and SBS but I don’t think over analysing it helps. Don’t overthink it and give it 50-100 attempts(sessions/hours)and you will be charging thru gybes with the best off them. Just do it !! :)

———
Short version :
Grab yourself a longboard and helmet and go skating.Skating / foiling have a lot in common.
So basically you are saying that to turn on foil it's just muscle memory after all ;)
I guess except for first couple of session then everything else just flows and your brain takes over.

that's a good way to put it and true.
Though it's still interesting to understand mechanics. Just started working on late frontroll on twintip and looking back at video it's interesting to see what i am doing with bar, head, body and legs to initiate rotation but you just got to try a few times and it kind of works out. Teaching must be tough, a lot of it is just muscle memory and experience at the end of the day...

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Re: How to turn a hydrofoil - and what is YAW ?

Postby Peter_Frank » Fri Feb 02, 2018 7:04 pm

I strongly disagree...

Our natural impulses and experience from other boards does not work right away, in fact wrong, is my claim - thus the first times one wants to carve, it goes all VERY very wrong for most, or all new hydrofoilers.

For many, even after very long time, it is still a challenge.

And here the very thought and knowledge of creating YAW, instead of pushing the edges when leaning, really makes a huge difference.

So no, it is (IMO) not about "theoretics" and understanding how things work - it is much more real and something that can change the carving learning curve hugely for most hydrofoilers IMO.

Those who HAS learned, just do it and never think about it nomore, so makes sense they can not see it...
Those who has NOT learned, dont understand anything, so they dont know...

My point was to help those who are trying to make good carves, as it really makes a difference to "think" that you have to twist/yaw to turn tight :thumb:
All the other impulses, whether you lean into the turn, use the kite line pull to lean, or use countersteering, or push the bar "outside" the turn, are just different ways and something that will come natural pretty fast :D

But the very idea of "twist" to turn, is not natural for almost everyone is my statement, so I hope that it can help those who likes to "turn" and are just at the level where they experiment and crash a lot without turning much :naughty:

8) PF

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Re: How to turn a hydrofoil - and what is YAW ?

Postby plummet » Fri Feb 02, 2018 8:43 pm

Hehehe. And I still disagree with Peter. Yaw input is not primary when i'm carving the foil. Sure, some yaw is used but for me its more about roll and pitch with a small amount of yaw. At very low speeds you can use yaw more to manhandle the foil around. But when up to speed and carving there's less yaw and more roll. To me its so similar to riding a bike. At very low speeds you can turn the handle bars a lot to do tight turns. This is the yaw input on a bike. But as you speed up and ride on burms or banked corners You lean and roll into it with a small amount for steering input.

Since Peter loaded up this thread I've specifically taken note and done tests at low and high speeds and my conclusion is that yaw input is not primary for me.

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Re: How to turn a hydrofoil - and what is YAW ?

Postby Peter_Frank » Fri Feb 02, 2018 9:41 pm

plummet wrote:
Fri Feb 02, 2018 8:43 pm
Hehehe. And I still disagree with Peter. Yaw input is not primary when i'm carving the foil. Sure, some yaw is used but for me its more about roll and pitch with a small amount of yaw. At very low speeds you can use yaw more to manhandle the foil around. But when up to speed and carving there's less yaw and more roll. To me its so similar to riding a bike. At very low speeds you can turn the handle bars a lot to do tight turns. This is the yaw input on a bike. But as you speed up and ride on burms or banked corners You lean and roll into it with a small amount for steering input.

Since Peter loaded up this thread I've specifically taken note and done tests at low and high speeds and my conclusion is that yaw input is not primary for me.

But you also ride waves with a TT/Mutant only, right ?

Nough said, explains a lot....

PS: Sorry, not being rude, but it really makes a huge difference in how you feel when riding and carving, two different worlds.

8) PF


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