Author Topic: Angle of Attack of foils  (Read 6238 times)

surfcowboy

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Angle of Attack of foils
« on: January 06, 2018, 09:02:16 AM »
Foil owners and observers, let's talk AOA.

I'm using the chord line for my 0° mark. However it got me to thinking. Although that's the easiest way to guess without having a way to easily measure true zero lift I'm curious as to how other foils are set up.

For instance, the Naish looks to be set with the bottom flat from videos and pics. Is that not the case?

Other folks, what do your foils have for AOA?

https://en.m.wikipedia.org/wiki/Angle_of_attack

supuk

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Re: Angle of Attack of foils
« Reply #1 on: January 06, 2018, 09:31:55 AM »
if you put a straight line between the two point were your feet are in foiling stance your cord line wants to be approx. parallel to this. Its doesn't really make any difference if the fuz also runs parallel to this but it defiantly make life easier when setting things up on the board and with the tail. If you don't have a digital level don't forget if you have a nice straight edge you can down load a digi level app for most phones

Interestingly I  bumped into a friend today and noticed he was running crazy amount of incidence on the rear wing which was interesting, he seam to think it was working well for him  so will have to experiment with that a little more with that. Curently I'm running 1.6deg incidence but would be keen to hear what others are set at. 

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Re: Angle of Attack of foils
« Reply #2 on: January 06, 2018, 09:39:03 AM »
if youre using a cambered foil make sure the lowest point at the front is just a hair lower than the trailing edge, in my opinion you want a degree or two on the wing to keep the fuse level on take off. of course depending on the final result youre after, if its top end speed run it on the zero lift line (make a model of your foil section and drag it through the bath) and take the drag hit for take off.
alternately make the foil butt join onto the fuse instead of a socket, then youre free to chose
alternately alternately put tubercles on the leading edge and crank up the AOI to 5+ degrees, the induced vortices will sort out the extra lift at speed

surfcowboy

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Re: Angle of Attack of foils
« Reply #3 on: January 06, 2018, 06:14:43 PM »
Container, I hoped you'd show up.

I have my chord line worked out pretty well, also have my mast and fuselage at right angles. I checked my mount today and think I have that deal straight as well.

I did wonder about putting a slight positive angle on the wing just to be safe. I figure risk a little extra drag just to make sure I have early lift. (This is my beginner foil so I'm actually hoping for slow.)

My tail wing will be mounted flat on the fuselage with screws so I can shim it easily but the front will be hard mounted. (But hey, it's only glass, right?

I'd love to see the butt joint, that sounds like something I might try so I could experiment with it, if I ever make another one of these lol. This is a tough one. Lots of staring at things and thinking.

starman

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Re: Angle of Attack of foils
« Reply #4 on: January 07, 2018, 09:41:38 AM »
Here is a very good video from Alex Aguera (Go Foil) on installing a tuttle box for hydrofoil surfing.

https://www.youtube.com/watch?v=i7PfoZW_Ivo

surfcowboy

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Re: Angle of Attack of foils
« Reply #5 on: January 07, 2018, 05:12:53 PM »
Thx starman, I'm actually talking about mounting the wing to the foil for those of us who are building these things as well as those who are just geeky, that angle between the wing and the fuselage.

Looking at the Naish and Takuma wings they looked to be level (0° AoA) from the front. It seems as if that's not the case from what folks are saying here.

On my foil the trailing edge is raised about 5/16" above "flat" and as I type that I realize that it's hard to see a quarter inch from a distance so of course those foils could look flat on the bottom from a casual video on the internet.

Also I wanted to flush out a few more of the foil heads here. ;)

supuk

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Re: Angle of Attack of foils
« Reply #6 on: January 08, 2018, 12:09:32 AM »
With a plate mount it really is not that critical as you can just use a shim underthe plate. You could build in AOA to account for rocker but if you use a board with less rocker at any point you will have to shim the front which is a little less desirable. Like I say go level with the fuz and it make it easy to put a level on when setting it up and the use shims to change the AOA and ether adjustable rear or shims to change the incidents, that’s the benefit of a plate mount.

surfcowboy

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Re: Angle of Attack of foils
« Reply #7 on: January 08, 2018, 03:59:36 AM »
That's where I've landed but I was careful to err to the side of a slight positive instead of negative. The iPhone level is really handy.

My fuse is actually really level, I'm surprised and somewhat proud of that one.

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Re: Angle of Attack of foils
« Reply #8 on: January 08, 2018, 10:05:32 AM »
its a tough one surfcowboy, too much angle and you spend your days flying round nose down, as you can see in this photo. not enough and you drag the fuse at an angle half the time. surely dragging the fuse a bit would be better in the long run nose down riding is terrible for your back knee. at the end of the day you own a grinder and some fibreglass, thats as good as CAD isnt it?

surfcowboy

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Re: Angle of Attack of foils
« Reply #9 on: January 08, 2018, 07:53:05 PM »
Container, you have my strategy laid out. Burn while you learn. ;)

So far things are looking pretty good. I'm getting way more optimistic as time goes on.

I'm pretty sure that I'm gonna be within 1° of flat and I'm errring to the up side.

surfcowboy

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Re: Angle of Attack of foils
« Reply #10 on: January 13, 2018, 05:03:27 PM »
Got to checking my levels today before I lay a layer of glass and get this thing sealed up.

Here’s my chord line and mount angle. This is my custom paddle shaft wing mount.



And here’s the foil line. Both were checked with the iPhone level all but hilariously you can’t take a pic of that while using it. ;)

It’s a little off axis but you get the idea.


 


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