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Foiling stall?

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kitenight11
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Foiling stall?

Postby kitenight11 » Fri Jul 26, 2019 10:56 pm

Hello,,

I read often about a foiling stall, what does this mean?
Thanks for answers.

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Re: Foiling stall?

Postby tkaraszewski » Fri Jul 26, 2019 11:14 pm

Same as an airplane wing. Flow separates from the foil and so stops generating lift and you fall. It happens when you go too slow.

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Re: Foiling stall?

Postby Whattheflock » Sat Jul 27, 2019 12:00 am

I was playing with this the other weekend, finding that stall speed. Keeping the foil slifhtly pointing up with back pressure but keeping the kite almost at noon. The board just drops like a stone.

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deniska
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Re: Foiling stall?

Postby deniska » Sat Jul 27, 2019 4:57 am

stall speed greatly depends on the weight. You can slow down any wing to almost 0mph and it will not stall if you hang your weight on a kite

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Re: Foiling stall?

Postby Foil » Sat Jul 27, 2019 6:40 am

deniska wrote:
Sat Jul 27, 2019 4:57 am
stall speed greatly depends on the weight. You can slow down any wing to almost 0mph and it will not stall if you hang your weight on a kite
your right,
and that feels so weird,
using my foil kite i sometimes come to a complete stop in a turn as i spin the board round, when it happens I give a smile and a little Wow!

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Re: Foiling stall?

Postby OzBungy » Sun Jul 28, 2019 2:44 am

Image

I think that technically a stall is simply the wrong angle of attack for the current conditions affecting the wing. It applies to all kinds of wings. Kites, aeroplanes, hydrofoils etc.

Speed is a factor, so is loading, profile shape and depth, chord, water flow, control inputs, possibly junk in the water.

You can also stall parts of the wing. In a tight turn the inside tip can stall while the outside keeps flying.

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Re: Foiling stall?

Postby alowishus » Mon Jul 29, 2019 6:20 am

My hoverglide used to make a kind of groaning sound :o . What's the explanation for that?

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Peter_Frank
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Re: Foiling stall?

Postby Peter_Frank » Mon Jul 29, 2019 7:42 am

alowishus wrote:
Mon Jul 29, 2019 6:20 am
My hoverglide used to make a kind of groaning sound :o . What's the explanation for that?

This is pretty normal for many wings, especially for the lower aspect ones.

As they can easily ride "semistalled", meaning at a very high angle of attack (a lot higher than the high aspect wings), without suddenly loosing all lift (full stall), but only losing a tad of lift at parts of the wing, but still riding.

When doing so (same goes for airplanes), there will be generated loads of turbulence and eddies at (and after) the trailing edge, and also tip vortices, one can almost see this in OzBungy's post with the gif animation.

In many scenarios, low frequency resonance will occur in this turbulence - meaning a deep groaning or humming sound.

It can be so pronounced that you can feel it as a vibration in your feet, easily :wink:

This can be enhanced a lot, as if you can hear the sound, you will feel it a lot more than it really is - human nature :roll:

I once thought I had a "faulty" wing, the first time I got one that "groaned" ha haa :rollgrin:

But found out, it was me not riding "perfectly" - as soon as I got more experience, and rode the wing more, it magically dissapeared.

If this sound comes, you are riding too slow or with too much pressure on your rear foot, so easy to stop.

But it will very often happen when doing tight carves and you push too much.
Still, with time you will avoid this, as your body will find the precise limit so this does not happen anymore.

Having said that, there is no problems in riding like this, apart from being very draggy and close to a full stall.
Being able to ride semi-stalled like this is the very reason we use low aspect wings in waves so you can push the wing more in turns, also "over" the limit and still fly, apart from their faster turning of course.

8) Peter
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kitenight11
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Re: Foiling stall?

Postby kitenight11 » Mon Jul 29, 2019 10:42 pm

so stall means, that you are riding too slow and falling down on the water Surface, Right?

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Re: Foiling stall?

Postby jumptheshark » Tue Jul 30, 2019 2:04 am

yup


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