Wing foil sessions - beginner

[Dontsink]

Clay, you know WAY more than I do. I'm just basing that statement on the slingshot teaser video. They said the foil is designed to have a downforce in the wing tip at high speed.
Check out minutes 1:30 : https://blog.slingshotsports.com/hydrofoil-wing-performance-3-new-hover-glide-infinity-foil-wings/

I think that is a pretty standard design principle in foils,sails,airplane wings etc..some twist in the foil towards the tips.

I saw a Naish vid of a computer animation of their foil design software,low pressure areas in red and high in blue.

At cruise speed only the center third of the foil actually produces lift,the outer thirds sre "neutral" .They are actually doing a big job as endplates preventing the high pressure on the bottom moving to the low pressure on top.

If we push the foil past its design speed/angle of attack range the tips start producing downforce.I have gotten my Takuma 1210 up to 18kt but it becomes very squirrely,feels like a loaded spring trying to come out of the water and if you overdo a tiny bit he front foot pressure it drops like a stone.I think this is the tips biting down too far,removing all the low press on top and dumping the lift.

[PonoBill]

Clay, you know WAY more than I do. I'm just basing that statement on the slingshot teaser video. They said the foil is designed to have a downforce in the wing tip at high speed.
Check out minutes 1:30 : https://blog.slingshotsports.com/hydrofoil-wing-performance-3-new-hover-glide-infinity-foil-wings/

Apparently by magic. They might mean the wing has some washout, which would mean different amounts of lift at varied locations of the wing at various angles of attack. But saying it has downforce at higher speed without some kind of servos, shape-shifting, or a demon inside the wing is simply nonsense. It also means we're headed into the next level of marketspeak usually encountered with oddly-shaped fins.

[Dontsink]

Clay, you know WAY more than I do. I'm just basing that statement on the slingshot teaser video. They said the foil is designed to have a downforce in the wing tip at high speed.
Check out minutes 1:30 : https://blog.slingshotsports.com/hydrofoil-wing-performance-3-new-hover-glide-infinity-foil-wings/

Apparently by magic. They might mean the wing has some washout, which would mean different amounts of lift at varied locations of the wing at various angles of attack. But saying it has downforce at higher speed without some kind of servos, shape-shifting, or a demon inside the wing is simply nonsense. It also means we're headed into the next level of marketspeak usually encountered with oddly-shaped fins.

Not magic at all,washout or twist is used in just about any foil application you can think of.
Wings,propellers,turbines,foils etc...

And of course they create downforce if the angle of attack gets low enough (like going fast).
I remember pulling the bar full back when i flew Hang gliders and watching the tips go negative as the speed went up.

[flkiter]

Here's a vid I did on getting up switch stance. Helps with getting up regular stance also for those learning.. Basically get some speed, lift in the wing and get to your feet with them in a sup stance, not surf.  I did it on a 4'8 79 liter board in about 12 mph.
https://www.instagram.com/tv/CTKtZKvDJWh/?utm_medium=copy_link

[PonoBill]

Clay, you know WAY more than I do. I'm just basing that statement on the slingshot teaser video. They said the foil is designed to have a downforce in the wing tip at high speed.
Check out minutes 1:30 : https://blog.slingshotsports.com/hydrofoil-wing-performance-3-new-hover-glide-infinity-foil-wings/

Apparently by magic. They might mean the wing has some washout, which would mean different amounts of lift at varied locations of the wing at various angles of attack. But saying it has downforce at higher speed without some kind of servos, shape-shifting, or a demon inside the wing is simply nonsense. It also means we're headed into the next level of marketspeak usually encountered with oddly-shaped fins.

Not magic at all,washout or twist is used in just about any foil application you can think of.
Wings,propellers,turbines,foils etc...

And of course they create downforce if the angle of attack gets low enough (like going fast).
I remember pulling the bar full back when i flew Hang gliders and watching the tips go negative as the speed went up.

I'm pretty certain I mentioned all that, but downforce? You actually think there's enough washout to produce downforce in the tiny range of AOA on a foil with two feet of air space (at the most) between flying and not? I'll buy relatively less lift (and I still doubt that), but downforce--nope. Washout is twisting the wingtips so the trailing edge is higher than the leading edge. The aim of washout is to equalize lift at the wingtips at low angles of attack and low relative speed, like turning tightly where the inside wing is moving slower than the outer. Hang glider wings flex a lot and can change their washout when speed and therefore pressure on the wingtips increases. Foil wings don't flex.  I used to fly ultralights--mostly a pterodactyl, a fledge with a snowmobile motor. Other than flattening the wing which makes them prone to spinning, I have no idea what you're talking about when you say "go negative". And it certainly doesn't happen with a foil.

[ninja tuna]

Nice video Flkiter,

If you dont mind, a couple of follow up questions. 

What was the volume of that board to your weight?  It looks like you were doing good in the lighter winds, does that method get easier with more wind?  Can that be done with more of a sinker board (less volume)?

Thanks again

[Dontsink]

Clay, you know WAY more than I do. I'm just basing that statement on the slingshot teaser video. They said the foil is designed to have a downforce in the wing tip at high speed.
Check out minutes 1:30 : https://blog.slingshotsports.com/hydrofoil-wing-performance-3-new-hover-glide-infinity-foil-wings/

Apparently by magic. They might mean the wing has some washout, which would mean different amounts of lift at varied locations of the wing at various angles of attack. But saying it has downforce at higher speed without some kind of servos, shape-shifting, or a demon inside the wing is simply nonsense. It also means we're headed into the next level of marketspeak usually encountered with oddly-shaped fins.

Not magic at all,washout or twist is used in just about any foil application you can think of.
Wings,propellers,turbines,foils etc...

And of course they create downforce if the angle of attack gets low enough (like going fast).
I remember pulling the bar full back when i flew Hang gliders and watching the tips go negative as the speed went up.

I'm pretty certain I mentioned all that, but downforce? You actually think there's enough washout to produce downforce in the tiny range of AOA on a foil with two feet of air space (at the most) between flying and not? I'll buy relatively less lift (and I still doubt that), but downforce--nope. Washout is twisting the wingtips so the trailing edge is higher than the leading edge. The aim of washout is to equalize lift at the wingtips at low angles of attack and low relative speed, like turning tightly where the inside wing is moving slower than the outer. Hang glider wings flex a lot and can change their washout when speed and therefore pressure on the wingtips increases. Foil wings don't flex.  I used to fly ultralights--mostly a pterodactyl, a fledge with a snowmobile motor. Other than flattening the wing which makes them prone to spinning, I have no idea what you're talking about when you say "go negative". And it certainly doesn't happen with a foil.

It does go negative meaning it creates high pressure on top and low on the bottom,therefore downforce,because unlike a HangGlider or your Ultralight our foils are fully rigid and they cannot flatten out.

This downforce does not have to be big at all to create control problems.You are mixing low pressure in the root and high pressure in the tips on the same side of the foil,there is nothing stopping those pressures from trying to equalize.And they do.

[flkiter]

Nice video Flkiter,

If you dont mind, a couple of follow up questions. 

What was the volume of that board to your weight?  It looks like you were doing good in the lighter winds, does that method get easier with more wind?  Can that be done with more of a sinker board (less volume)?

Thanks again

Hey tuna,
It is a 4'8 at 79 liters. More wind always helps and yes you can do the same on a sinker board but it will need a good amount of wind to get you moving forward. Once you can get a board planning some then it's easier to get up on it. I was in some light winds with a small board to show that it'll be easier with a bigger board and more wind.

[clay]

Clay, you know WAY more than I do. I'm just basing that statement on the slingshot teaser video. They said the foil is designed to have a downforce in the wing tip at high speed.
Check out minutes 1:30 : https://blog.slingshotsports.com/hydrofoil-wing-performance-3-new-hover-glide-infinity-foil-wings/

Apparently by magic. They might mean the wing has some washout, which would mean different amounts of lift at varied locations of the wing at various angles of attack. But saying it has downforce at higher speed without some kind of servos, shape-shifting, or a demon inside the wing is simply nonsense. It also means we're headed into the next level of marketspeak usually encountered with oddly-shaped fins.

Not magic at all,washout or twist is used in just about any foil application you can think of.
Wings,propellers,turbines,foils etc...

And of course they create downforce if the angle of attack gets low enough (like going fast).
I remember pulling the bar full back when i flew Hang gliders and watching the tips go negative as the speed went up.

I'm pretty certain I mentioned all that, but downforce? You actually think there's enough washout to produce downforce in the tiny range of AOA on a foil with two feet of air space (at the most) between flying and not? I'll buy relatively less lift (and I still doubt that), but downforce--nope. Washout is twisting the wingtips so the trailing edge is higher than the leading edge. The aim of washout is to equalize lift at the wingtips at low angles of attack and low relative speed, like turning tightly where the inside wing is moving slower than the outer. Hang glider wings flex a lot and can change their washout when speed and therefore pressure on the wingtips increases. Foil wings don't flex.  I used to fly ultralights--mostly a pterodactyl, a fledge with a snowmobile motor. Other than flattening the wing which makes them prone to spinning, I have no idea what you're talking about when you say "go negative". And it certainly doesn't happen with a foil.

It does go negative meaning it creates high pressure on top and low on the bottom,therefore downforce,because unlike a HangGlider or your Ultralight our foils are fully rigid and they cannot flatten out.

This downforce does not have to be big at all to create control problems.You are mixing low pressure in the root and high pressure in the tips on the same side of the foil,there is nothing stopping those pressures from trying to equalize.And they do.

I would love to see some gopro slo mo video of a foil doing this.

I rode the infinity 76 for many moons and never experienced down force at speed, on the head+ days I resorted to a longer mast and a washer in the stab to try and take the lift out and keep the foil from breaching.

The Kujira has a speed range unique from other foils I've ridden and to flexy for me so I didn't go on a very deep test to figure why it rides differently.

[Dontsink]

Not much to see in a vid i think, pressure differences are invisible and i do not know if any cavitation is involved at our speeds.

Maybe with a CFD foil design software animation that showed pressure distribution it could be visualized easily.

There is some freeware foil design stuff but i have not played with it yet,they do require some techy learning.

Anyway,if a foil has washout it is inevitable that with increasing speed and decreasing AOA the tips will start pushing down at some point.

Why we loose control of the foil i am not 100% sure about, i like my theory of negative&positive pressures going nuts on each other but i cannot prove it is the main cause of what feels like a high speed stall.
It may be simply that at those speeds tiny changes in AOA create dramatic changes in lift and we are not quick enough to correct with weight shift.So we either overfoil and breach or get dumped down onto the water .

[surfcowboy]

Progression tracking. 38 sessions in year one. I can’t jibe yet but can handle pretty hairy conditions (3’ chop and chest high swell) comfortably regular stance and survival-level switch.

 I think gear has held me back as now with my new wing with more glide I’m feeling less pressure to rush a turn. Going to check some high aspect wings and also get some time on an efoil to get comfortable entering a turn at 10-12 mph. I think I forget sometimes that I simply haven’t spent much time on foil in waves. Maybe time to go back and SUP foil a bit more too. (Andrew 805, expect texts lol.)

Anyway, it’s good to take stock and check progress on any project. It also helps to stave off frustration. If you’re thinking of taking this leap, do it. Even just working on skills in a tiny lake feels great and is a blast and will lead you to meet great people. Also my arms and shoulders look better than they have in my whole life hahahahaa..

[Hwy1north]

Hwy1north: Thanks for the infinity 84 specific information. Really helpful. I'm riding the 84 and I've been working on pumping to get on foil. Seems like I can rise up on the foil briefly, but it won't stay up. I'm thinking about going back to my 99cm.
2 questions for you:
1) I have this setup:https://slingshotsports.com/collections/complete-foils-wing-surf/products/hover-glide-fsup-v3 . There is no way to move the mast forward/backward along the fuse. Should I buy a longer fuse?
2) Based on your experience, do you think there is a better foil for the beginner+ phase? The Infinity is HEAVY and other foils seem so light. I know everyone has their favorite foil, but the Infinity always gets moderate approval. Is it worth moving to a different foil?
Thanks!

The fuse is "switch" able.  Flip it around and the mast moves towards the wing or away.  Towards the front wing means run further forward in mast track, and you will get a more pitch sensitive foil, away from front wing, and more stable foil (theoretically...)  most beginners just need to make sure they have a fair bit of pull in the hand wing (so not under powered) then bear off and give a few pumps high to low and not side to side so that your feet get light as you pull on the hand wing.  The board will rise, stiffen your arms, and head up wind.... and don't stop weighting and unweighting your feet by pumping your legs until you are going fast.

Some foils are very athletic meaning you have to give them lots of input to get the most out of them.  The 84 is very smooth and suprisingly fast for how low aspect it is.  It just isn't very athletic.  You gotta row through the gears a bit before it takes off and make sure you are pointed in the right direction.  You probably have it in the mast to rear spot, so try switching the fuse to see if that livens it up.

[surfcowboy]

Solid day today. In a hilarious turn I actually watched an Alan Cadiz video on what I was going to work on. He talks about drifting downwind and just feeling that. I got good progress upwind and started turning and catching the chop for a few seconds and then powering back upwind. It was a revelation. At first I outran the bumps and felt that kick and dip when I hit the through. After I figured out I was running them over I started looking at the way they ran and turning into them and running down the line and it. felt. amazing. Holy sh@t I just want to do this all day. So yes, I did a maybe 100-200 foot downwinder on a 2’ chop but it still blew my mind.

Also did a touch and go foot switch which let me get to toeside a couple of times. Way to much back leg pressure but I remember when switch felt this awkward too. It’ll come. Overall I am seeing that I’m too back-footed in general. Gotta play with that too. I think PonoBill has a good idea with his “one foil only til I get it”. I need consistency more than anything at this stage.

[oakfish]

Hwy1north: this is great info! I had no idea I could "switch" the fuse. I'll give it a try. Thanks!

[Hwy1north]

No worries. Hope it helps. I'm no Slingshot expert, but I think the fuses are all the same and your 84 wing should have a removeable cover if you wanted to try the A position... 

https://support.slingshotsports.com/hc/en-us/articles/360057617412-Slingshot-Hover-Glide-Switch-Fuse-for-Hydrofoiling-

https://www.youtube.com/watch?v=3krRo2BfyII&t=93s