Author Topic: Low wind foils  (Read 843 times)

biggins

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Low wind foils
« on: May 14, 2020, 06:02:42 AM »
Question for you foil gurus...

Iím looking at gong foils and was wondering which would be better for lightest wind.

1. new veloce xxl is 107 wide but only 1800cm projected surface area and perceived 1900, not sure what perceived means. Very thin high aspect but not much area.

2. Curve XXL 120cm wide with a projected area of 2610cm and perceived 2800. Still pretty high aspect but not like the veloce.

So Iím wondering for ultimate low end do I go with the big curve or pump and hope to get low end with speed. Seems like veloce has range but might be harder to get on foil in really low winds.

Any thoughts as I see axis and others going high aspect as well but obviously surface area comes into play as well.

Thanks,

D


Phils

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Re: Low wind foils
« Reply #1 on: May 14, 2020, 09:46:25 AM »
My understanding of low end lift is that SA and volume (or thickness) are what matter the most.  Aspect ratio affects glide-to-drag mostly.  The bigger, thicker wing will get you going sooner in low winds.  Once either wing is up, the thinner, higher AR wing will tend to stay up better in low winds.

PonoBill

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Re: Low wind foils
« Reply #2 on: May 14, 2020, 07:40:03 PM »
So here's the thing, the biggest factor in lift is velocity. Area and foil profile are linear, velocity is exponential. Double the area and you perhaps double the lift (actually less because of greater drag, but let's not gag at gnats). Double velocity and lift is four times greater.

So when high aspect decreases lift to drag ration it also lets you get the foil going faster for the same power (paddle, wave or wing). Beginning foilers have a hard time getting the speed up, but as soon as you master that the huge draggy wing becomes, well, huge and draggy.

I'm 225+, and a 101 Axis, which is about 1400 sq cm is plenty. When I started out the only thing I could reliably fly on was the GoFoil 280, which is about the size of a Cessna wing.

Which is a long way around to tell you that where you are in your progression has more to do with what you need for a wing than any other factor. I'm reasonably sure that when I get better I'm going to think the 101 is a ridiculous monster and it will be resting in the pile of crap in the back seat of my truck.

I'm not sure any of this is helpful with your question other than to say whatever you have will work sooner or later in less and less wind.
« Last Edit: May 14, 2020, 07:42:42 PM by PonoBill »
Foote 10'4X34", SIC 17.5 V1 hollow and an EPS one in Hood River. Foote 9'0" x 31", L41 8'8", 18' Speedboard, etc. etc.

Phils

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Re: Low wind foils
« Reply #3 on: May 15, 2020, 01:18:49 AM »
So here's the thing, the biggest factor in lift is velocity. Area and foil profile are linear, velocity is exponential. Double the area and you perhaps double the lift (actually less because of greater drag, but let's not gag at gnats). Double velocity and lift is four times greater.

So when high aspect decreases lift to drag ration it also lets you get the foil going faster for the same power (paddle, wave or wing). Beginning foilers have a hard time getting the speed up, but as soon as you master that the huge draggy wing becomes, well, huge and draggy.

I'm 225+, and a 101 Axis, which is about 1400 sq cm is plenty. When I started out the only thing I could reliably fly on was the GoFoil 280, which is about the size of a Cessna wing.

Which is a long way around to tell you that where you are in your progression has more to do with what you need for a wing than any other factor. I'm reasonably sure that when I get better I'm going to think the 101 is a ridiculous monster and it will be resting in the pile of crap in the back seat of my truck.

I'm not sure any of this is helpful with your question other than to say whatever you have will work sooner or later in less and less wind.
This is really good.  You could also throw in pumping into the mix.  Higher aspect should also pump better, correct?

surfwingsteve

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Re: Low wind foils
« Reply #4 on: May 16, 2020, 08:58:51 AM »
So here's the thing, the biggest factor in lift is velocity. Area and foil profile are linear, velocity is exponential. Double the area and you perhaps double the lift (actually less because of greater drag, but let's not gag at gnats). Double velocity and lift is four times greater.

So when high aspect decreases lift to drag ration it also lets you get the foil going faster for the same power (paddle, wave or wing). Beginning foilers have a hard time getting the speed up, but as soon as you master that the huge draggy wing becomes, well, huge and draggy.

I'm 225+, and a 101 Axis, which is about 1400 sq cm is plenty. When I started out the only thing I could reliably fly on was the GoFoil 280, which is about the size of a Cessna wing.

Which is a long way around to tell you that where you are in your progression has more to do with what you need for a wing than any other factor. I'm reasonably sure that when I get better I'm going to think the 101 is a ridiculous monster and it will be resting in the pile of crap in the back seat of my truck.

I'm not sure any of this is helpful with your question other than to say whatever you have will work sooner or later in less and less wind.

Thank you PonoBill. Don't you just LOVE the physics of this sport?  SOOO important in truly understanding and figuring out what you must do with your gear and your body to adjust the variables to get flight.  I totally nerd out on it.  I, at 200lbs, am on the Maliko 280, can't imagine dropping to a 1400, but Bill you give us all hope at 73 and 225lbs!  Keep rocking it!

PonoBill

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Re: Low wind foils
« Reply #5 on: May 16, 2020, 03:31:10 PM »
Steve, we're the same age and you're 25 pounds lighter. You'll get there in a hurry.
Foote 10'4X34", SIC 17.5 V1 hollow and an EPS one in Hood River. Foote 9'0" x 31", L41 8'8", 18' Speedboard, etc. etc.

biggins

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Re: Low wind foils
« Reply #6 on: May 16, 2020, 10:46:11 PM »
Good info Bill, thankyou. Thatís kind of what I figured...HA can be amazing if Iíve got the skills. Iím not sure if I do but Iíll give a whirl and see what happens.

Thanks again

D