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Strength V weight for holding down power.

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Re: Strength V weight for holding down power.

Postby pj sofine » Fri May 13, 2016 1:03 pm

I also lost weight before our season started.The only change I noticed was on the low end,i weigh 210 now and notice I don't need my big board as often.And on the high end haven't noticed any difference.Seems like once the wind hits 20 or so everyone is on same size kites,except the wankers that are foiling now :nono:

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Re: Strength V weight for holding down power.

Postby Faxie » Fri May 13, 2016 1:11 pm

Westozzy wrote:Depends on kite to. A kite with some aspect can be driven to the edge to spill power more so that a lower aspect kite.

Yeh technique, strength and weight in that order. But weight can really help with bigger kites when shit really hits the fan. But even then, someone real heavy will eventually 'fold' the canopy in really overpowered conditions. The more waves, more chop involved the more weight can help given all other variables the same.
A kite with higher aspect will keep driving forward when you edge and move the wind window forward (in fact, all kites will get further away from the edge when you hit the brakes) and generate more power that way than a low aspect kite. It's a pretty persistent myth that you drive it to the edge and thus lose power.... it just doesn't work that way with a variable wind window. You're not behind a cable.

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Re: Strength V weight for holding down power.

Postby alamos_kiter » Fri May 13, 2016 2:06 pm

Faxie wrote:... It's a pretty persistent myth that you drive it to the edge and thus lose power.... it just doesn't work that way with a variable wind window. You're not behind a cable.
When you hit the brakes, you reduce apparent wind. Kiter not moving through the water -> shorter apparent wind vector -> less power.

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Re: Strength V weight for holding down power.

Postby Faxie » Sat May 14, 2016 6:59 pm

alamos_kiter wrote:
Faxie wrote:... It's a pretty persistent myth that you drive it to the edge and thus lose power.... it just doesn't work that way with a variable wind window. You're not behind a cable.
When you hit the brakes, you reduce apparent wind. Kiter not moving through the water -> shorter apparent wind vector -> less power.
True -but- when you hit the brakes you reduce (or maintain actually in this case) speed, wind window moves forward, but you go upwind too a bit, wind window increases a bit, kite flies forward to the new edge, generating power, especially the high AR kites. Forward momentum can be pretty much neglected too because of this. When you're stationary on the beach, and the wind increases/decreases by the same percentage as you would get hitting the brakes when riding, it doesn't make that much difference for the size of the window. But start running, and kites moves back quite a lot (even though the windspeed increases)

Low projected AR kites can be depowered better by edging than high AR kites too btw.

Say if you are actually braking in stead of maintaining because you are getting too much speed, and you're going from 25 knots to 15 knots boardspeed on a halfwind tack in let's say 20 knots, then your apparent wind is going from 32 knots to 25. Say if you're on the beach in windgusts from 25 to 32, how much does that affect the kite? Not so much.

But you window is going forward 15 degrees when you decelerate (not counting going upwind with the board, which would make it even more) and on 24m lines that would be a distance of 6m the window moves forward on the kite end (approximately) That's 6 meters the kite will travel generating power at the same time.

The shorter the lines, the less that effect will be... and guess what, shorter lines help you hold down power better. (19m equals 5m at the kite end for example)

One other thing that helps too when you feel you're getting overpowered and it's counter-intuitive.... pull the bar while edging hard. Keeps the brake on the kite and kills a lot of power instantly. But only works when the strap is close to full power. And after that you do have to depower but keep edging. Try it sometime :thumb:

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Re: Strength V weight for holding down power.

Postby alamos_kiter » Sat May 14, 2016 9:56 pm

Faxie wrote:Low projected AR kites can be depowered better by edging than high AR kites too btw.
Not sure why you would say that. The power produced by a kite is first and foremost of function of apparent wind and AoA.
Faxie wrote:Say if you are actually braking in stead of maintaining because you are getting too much speed, and you're going from 25 knots to 15 knots boardspeed on a halfwind tack in let's say 20 knots, then your apparent wind is going from 32 knots to 25. Say if you're on the beach in windgusts from 25 to 32, how much does that affect the kite? Not so much.
I would rather say, reduce your kiter's speed through the water from 20kn to 5kn. This reduces the apparent wind from 28,3kn to 20.6kn, which is a reduction in power of 47%. That is quite something.
Faxie wrote:One other thing that helps too when you feel you're getting overpowered and it's counter-intuitive.... pull the bar while edging hard. Keeps the brake on the kite and kills a lot of power instantly. But only works when the strap is close to full power. And after that you do have to depower but keep edging. Try it sometime :thumb:
True, stalling kite and board for sure kills the power. It works well with a small kite, or in stall turns where I use it all the time to pivot my kite. A big kite you won't be able to hold in stall though when overpowered :D

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Re: Strength V weight for holding down power.

Postby Westozzy » Sun May 15, 2016 12:36 am

Pfff however you spin the science, given the same weight a kite with more aspect allows you to control the power much better. To a point though. Given to much aspect in really powered conditions the efficiency afforded by the aspect can cause the kite to move to fast and try to hit the edge of the window (or whatever explanation you gave) ... Can get real jerky, on/off type power delivery.

Low AR can be better depowered than high ... My experience tells me otherwise given the ability to work your edge and throw.

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Re: Strength V weight for holding down power.

Postby Faxie » Sun May 15, 2016 1:01 am

alamos_kiter wrote:
Faxie wrote:Low projected AR kites can be depowered better by edging than high AR kites too btw.
Not sure why you would say that. The power produced by a kite is first and foremost of function of apparent wind and AoA.
Faxie wrote:Say if you are actually braking in stead of maintaining because you are getting too much speed, and you're going from 25 knots to 15 knots boardspeed on a halfwind tack in let's say 20 knots, then your apparent wind is going from 32 knots to 25. Say if you're on the beach in windgusts from 25 to 32, how much does that affect the kite? Not so much.
I would rather say, reduce your kiter's speed through the water from 20kn to 5kn. This reduces the apparent wind from 28,3kn to 20.6kn, which is a reduction in power of 47%. That is quite something.
Faxie wrote:One other thing that helps too when you feel you're getting overpowered and it's counter-intuitive.... pull the bar while edging hard. Keeps the brake on the kite and kills a lot of power instantly. But only works when the strap is close to full power. And after that you do have to depower but keep edging. Try it sometime :thumb:
True, stalling kite and board for sure kills the power. It works well with a small kite, or in stall turns where I use it all the time to pivot my kite. A big kite you won't be able to hold in stall though when overpowered :D
Because lower aspect kites create less power in a straight line.

47% Is quite something indeed, but since when do you come to an almost complete stop when you're getting overpowerd? And during braking, the kite will increase power at first. Because your window will go forward by 31%, resulting in an almost 13 meter forward flying of the kite to the new edge with 24m lines, creating it's own apparent wind. That creates a lot of pull on fast kites.

Works on big kites too as long as the aoa is high enough. But better on small kites, true. Boots will help a lot though.

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Re: Strength V weight for holding down power.

Postby alamos_kiter » Mon May 16, 2016 8:43 am

It's true that a high AR kite has the ability to produce more power than a low AR kite, but this has IMO nothing to do with the wind window shifting: it's kite speed. A low AR kite usually has lower l/d, in the (real world kite) range:
AR=3,5 -> l/d=3,0
AR=6,0 -> l/d=5,5.

This means two things:

- the high AR kite sees a bigger wind window, as it flies farther forward than the low AR kite. 90º-tan(l/d) = the angle off the apparent wind.
So, low AR with l/d=3 means, your kite sits 18º off apparent wind, whereas l/d=5,5 means 10º off apparent wind.
These 8º difference translate in 3,3m farther forward with 24m lines (2 x 24 x (sin(8º/2)) . Bigger window = more way to accelerate.

- the maximum speed a kite can achieve is l/d x true wind speed. A high AR kite with l/d=5,5 can achieve 45% more speed through the air than a low AR kite with l/d = 3, which translates in a power burst three times as large compared to the low AR kite.

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Re: Strength V weight for holding down power.

Postby Faxie » Mon May 16, 2016 1:32 pm

alamos_kiter wrote:It's true that a high AR kite has the ability to produce more power than a low AR kite, but this has IMO nothing to do with the wind window shifting: it's kite speed. A low AR kite usually has lower l/d, in the (real world kite) range:
AR=3,5 -> l/d=3,0
AR=6,0 -> l/d=5,5.

This means two things:

- the high AR kite sees a bigger wind window, as it flies farther forward than the low AR kite. 90º-tan(l/d) = the angle off the apparent wind.
So, low AR with l/d=3 means, your kite sits 18º off apparent wind, whereas l/d=5,5 means 10º off apparent wind.
These 8º difference translate in 3,3m farther forward with 24m lines (2 x 24 x (sin(8º/2)) . Bigger window = more way to accelerate.

- the maximum speed a kite can achieve is l/d x true wind speed. A high AR kite with l/d=5,5 can achieve 45% more speed through the air than a low AR kite with l/d = 3, which translates in a power burst three times as large compared to the low AR kite.
We're kind of saying the same thing. But you're saying it's kite speed and not the window shifting... but when you're are going 20 knots like in the previous example, either high or low aspect kite is going just as fast at that moment. The speed (and thus power) difference comes into play when the window moves forward. Difference in the size of the window is irrelevant for the distance each kite will travel when the window shifts. Think of unhooking too btw... and the different behaviour you get between high/low l/d kites and high/low windspeed.

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Re: Strength V weight for holding down power.

Postby North_Wind » Wed May 18, 2016 10:34 am

Both are a factor.

I have lots of guests at my kite house. For sure the 6ft 2" / 90 kgs guys can hold down more than the 5' 4" / 60 kg. gals, even if the latter are fitter.

But I have been going to the gym lots over the last year and converted a lot of fat to muscle (same weight). And I can definitely hold down more wind now (kite low!) and stay out for longer.


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