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weight / projected area = onepossible light wind indicator

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Hansen Design
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Re: weight / projected area = onepossible light wind indicator

Postby Hansen Design » Fri Oct 23, 2009 7:38 pm

Peter:
Airborn weight requires lift which also creates induced drag. The lift expended in this regard subtracts from the total available for 'performance.' This is most notable in how far a kite will fly to the edge of the window (and remain there in a stable way) which is a direct measure of light air performance. Suggest you attach a 'few kg's' to your kite and try it. (actually a few tenths of a kg will make a difference.)

Peter_Frank wrote:The weight of the kites are interesting in other respects, but for "light wind" perfomance, I cant see any relevance whatsoever !
So a difference of a few kg's wont make any noticable difference at all !
I am 100% sure that the mass wont make much difference, regarding KITING in light wind.

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Re: weight / projected area = onepossible light wind indicator

Postby Peter_Frank » Fri Oct 23, 2009 8:34 pm

Hansen Aerosports wrote:Peter:
Airborn weight requires lift which also creates induced drag. The lift expended in this regard subtracts from the total available for 'performance.' This is most notable in how far a kite will fly to the edge of the window (and remain there in a stable way) which is a direct measure of light air performance. Suggest you attach a 'few kg's' to your kite and try it. (actually a few tenths of a kg will make a difference.)

Peter_Frank wrote:The weight of the kites are interesting in other respects, but for "light wind" perfomance, I cant see any relevance whatsoever !
So a difference of a few kg's wont make any noticable difference at all !
I am 100% sure that the mass wont make much difference, regarding KITING in light wind.


Why ?

More kite weight equals more lift needed, equals more AOA, equals more induced drag - thats basics yes.

And if the "weight" composant comes from the rider weight, it will be somewhat compensated by dynamic lift from the board, also true.

But still, if you got an equal force acting on the lines (equal to the reduced lift by a lighter kite so to speak) because of a lighter rider in motion, why would that be different from a lighter kite, when talking fully static behavior ?

As I wrote - the dynamic behaviour is usually by far the most important - and here low weight is by far the most important performance factor, I agree.

Kindly, Peter Frank
Last edited by Peter_Frank on Sat Oct 24, 2009 8:21 am, edited 1 time in total.

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Re: weight / projected area = onepossible light wind indicator

Postby FredBGG » Fri Oct 23, 2009 10:58 pm

Weight makes a significant difference becasue it affect your upstroke speed a lot.

A lighter kite will go up quicker that generating more power thanks to more apparent wind
effect.

Also a light kite will be more forgiving in the lulls or when you make a mistake.

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Re: weight / projected area = onepossible light wind indicator

Postby Peter_Frank » Sat Oct 24, 2009 8:43 am

Yes, a lighter kite will work better in all respects when you ride out there, no doubt at all - so the topic headline is correct :thumb:

But I cant see it as a direct performance booster, if talking static flight riding straight out !
On the upstroke, gust/lull handling, acceleration, relaunch, turning - everything "dynamic" - it has huge positive influence, as I said.

Almost the same as a windsurfer where the board and rig has to be as light as possible to perform especially in chop and gusts - so putting the kg's on the rider instead of the gear, will perform much better because of dynamic effects, by a huge margin.

If out in stable wind and flat water, it would not matter with a heavier board and rig, if the rider was equally lighter - but this situation hardly exists in reality :naughty:

Although - with a kite it is not at all a 1:1 mass conversion kite/rider, because of board lift - but that is another issue... Meaning, one kg difference on the kite, equals MANY kg on the rider 8)

Kindly, Peter Frank

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Re: weight / projected area = onepossible light wind indicator

Postby herculon » Sat Oct 24, 2009 9:03 am

i updated the list.
@DrLightWind: thanks for your data. but do you have the projected area of your Torque2 ?
whats the projected area of the ozone zephyr ?

thanks for all your input and discussions so far! i have added a column

UR - User Rating.

if you like, please post your subjective rating of the lightwind abilities of the listed kites. i will collect them and post the mean.

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Re: weight / projected area = onepossible light wind indicator

Postby Gigi;) » Sat Oct 24, 2009 12:16 pm

M2C - ligther is better... to some point.

In LW lighter is usually better... When wind picks up... well to some point it is still better... BUT in heavy/gusty winds less weight is not always better - lighter kite is not always as stable as heavier in gusts... assuming the same kite same size...

For LW I can say that lighter is better - performance gain in virtually all areas except in heavy gusts (which usualy is not issue in low wind). The problem of upstroke stall on the same but heavier kite is more noticeable than on lighter.

I will soon make some new comparisons for LW (mainly design/weight ones), but I need to finish my new 12m kite first ;)

:bye:

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Re: weight / projected area = onepossible light wind indicator

Postby Rorke » Sat Oct 24, 2009 2:56 pm

I can weigh my kites, but figuring out the projected area is beyond me. If my kite were a square or a circle or a triangle...maybe.
Wouldn't it be sweet if manufacturers provided this information?

I can't imagine there is any flying advantage from increased weight. (Durability is different)

I know this is about lightwind riding, and I don't want to redirect the thread too much, but...
When you are surfing in 20 knots of breeze and you catch a wave toward your kite at 10 knots, then you'll have around 10 knots of apparent wind in the kite.
So even on a 20 knot day, your kite will still experience lightwind.

Is this correct? Makes sense to me.

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Re: weight / projected area = onepossible light wind indicator

Postby jakemoore » Sat Oct 24, 2009 3:29 pm

Peter_Frank wrote:But I cant see it as a direct performance booster, if talking static flight riding straight out !


I gotta disagree. My last lightwind kite was a Flysurfer Speed 1 - not a dynamic flying turning kite but an excellent park and ride light wind kite. And I fly that kite in flat water, smooth wind conditions so very steady state. In lighter wind weight would make a huge difference for that kite even with the weight of water after getting the outside skin wet. After a relaunch the kite would fly really deep, backstall and not generate the same pull of the dry kite. And after it dries the pull is back.

For anybody who doesn't believe I suggest trying Hansens suggested experiment of putting an extra KG on the kite. Its easy and you will see the difference.

FredBGG wrote:In a LEI the air is pretty compressed rendering it heavier than the surroundine air.


Fred
You might be suprised how balanced many LEI kites are. But FS kites are still the light wind winner. FYI, If an LEI had 12.5 CF of bladder volume and was pumped up to 1 ATM psig (I would guess both of those numbers are a little high) then the air would give an extra pound of mass to the kite.

Long ago when searching for light-wind solutions I made a comparison of wing loading. At that time the clear winner was the PeterLynn C-Quad. I still doubt anything comes even close. But there is a usability issue there.

Jake

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jakemoore
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Re: weight / projected area = onepossible light wind indicator

Postby jakemoore » Sat Oct 24, 2009 3:32 pm

C-Quad 8.5m2 1.4 kg 0.164 kg/m2

I guess the silverarrow comes close then. :)

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Re: weight / projected area = onepossible light wind indicator

Postby DrLightWind » Sat Oct 24, 2009 4:14 pm

herculon wrote:@DrLightWind: thanks for your data. but do you have the projected area of your Torque2 ?

Not yet but it is 4.2 aspect ratio

DrLW


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