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Weight of LEI kite sizes ?

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plummet
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Re: Weight of LEI kite sizes ?

Postby plummet » Thu May 19, 2016 10:12 pm

Why? What conclusions do you intend on making?

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lovethepirk
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Re: Weight of LEI kite sizes ?

Postby lovethepirk » Fri May 20, 2016 7:09 am

joriws wrote:But mass of air probably increases as kite size increases. And there was comparison of kite weight by area+projected area. And a note that weight by area goes down as kite size increases. But actually it has more air in it thus being heavier in usage condition so weight per area is not going that fast down.
The mass of air does increase, but in essence you would add the mass of the air then subtract the mass of air displaced. Without subtracting the displacement you're looking at maybe 15-40 grams of weight so either way not material.

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Peter_Frank
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Re: Weight of LEI kite sizes ?

Postby Peter_Frank » Fri May 20, 2016 7:24 am

Peert wrote:I own two OR cyphers but the biggest one has a repair. That has added some weigth. This would spoil your correlations.
That would still be great if you could weigh these, as I will know the big one might have a tad extra weight - but it is the rough numbers that are interesting.

I got a 7 myself with a repair, and a 9 without, both 5 struts same model/year - but will also weigh these when at home one day.

The OR Cyphers are 4 strut kites I can see.

The one or 3 strut lighter kites are those I lack somewhat now, as the normal 5 strut kites are covered pretty well now, but the more the merrier (the more reliable output of it all) :rollgrin:

WHY ?

To understand the relationship between sizes and weight, and being able to easily transfer one size to another, regarding how much it will weigh and share it with you afterwards as a tool, as you can get pretty close this way :thumb:

Of course also basically because I like to understand precisely how everythings works, and this very issue has always been interesting and useful, but have never looked much into it (there are many other things I dont want to understand at all ha haa.... :naughty: )

8) Peter

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Re: Weight of LEI kite sizes ?

Postby ronnie » Fri May 20, 2016 8:16 am

lovethepirk wrote:
joriws wrote:But mass of air probably increases as kite size increases. And there was comparison of kite weight by area+projected area. And a note that weight by area goes down as kite size increases. But actually it has more air in it thus being heavier in usage condition so weight per area is not going that fast down.
The mass of air does increase, but in essence you would add the mass of the air then subtract the mass of air displaced. Without subtracting the displacement you're looking at maybe 15-40 grams of weight so either way not material.
That is true in terms of the kite floating, as the volume of air displaced is actually air that is floating in the air around it.

Atmospheric pressure is 14.7 psi. Add on 8 psi for inflation and you are increasing the weight of the air by 54% and 10 cubic feet of air at 1 bar weighs about 0.37 kg, so an increase of about 0.2 kg in terms of weight (so the 0.37 kg of the 0.57 kg weight would still be 'floating' in the air). These are just rough figures to get a ballpark idea of the weights. In terms of inertia, then you have to move the whole 0.57 kg of weight around with the kite.

It also helps explain why the ram airs 'float' so well. in that there is almost no increase in the pressure of the air inside the kite. but a bigger mass of air to move around, so they have more inertia and slower response times.
Last edited by ronnie on Fri May 20, 2016 12:02 pm, edited 1 time in total.

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Re: Weight of LEI kite sizes ?

Postby foilholio » Fri May 20, 2016 9:53 am

kite weights excel.zip
(9.8 KiB) Downloaded 45 times
I inputted some Switch and Flysurfer numbers. Using small variations of a kite scaling formula,("value to scale"*(SQRT("size scaling to")/SQRT("size scaling from))) I could not get it to universally apply, but it roughly does so. Interestingly the formulas that most apply to the inflatables is a bit different from the foils. It's seems each kite model needs a custom adjustment to calculate the weights accurately so I don't hold much hope a universal formula can be found, but maybe different formulas that can get pretty close for the particular style of kite say foil or inflatable. Also some basic facts about the kite like strut or cell count could be used to make the formula more accurate.

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Re: Weight of LEI kite sizes ?

Postby Peert » Fri May 20, 2016 2:09 pm

Peter_Frank wrote:
Peert wrote:I own two OR cyphers but the biggest one has a repair. That has added some weigth. This would spoil your correlations.
That would still be great if you could weigh these, as I will know the big one might have a tad extra weight - but it is the rough numbers that are interesting.

I got a 7 myself with a repair, and a 9 without, both 5 struts same model/year - but will also weigh these when at home one day.

The OR Cyphers are 4 strut kites I can see.

The one or 3 strut lighter kites are those I lack somewhat now, as the normal 5 strut kites are covered pretty well now, but the more the merrier (the more reliable output of it all) :rollgrin:
Ok, I will put them on the scale for you (I am obliged to, since you are always so helpfull to everyone who is asking questions on this forum). As I repaired it myselve and have additional repair material available I will even calculate/estimate the weight I have added. Expect my findings not earlier than monday.

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Re: Weight of LEI kite sizes ?

Postby foilholio » Fri May 20, 2016 4:48 pm

kite weights excel 0.2.xls.zip
(10.2 KiB) Downloaded 69 times
updated excel sheet

using kite scaling formula but changed the square root to root to the Nth. Each kite seems to need a different Nth.

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Kamikuza
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Re: Weight of LEI kite sizes ?

Postby Kamikuza » Sat May 21, 2016 5:58 am

plummet wrote:Why? What conclusions do you intend on making?
Well that explains a lot.

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Re: Weight of LEI kite sizes ?

Postby proletariat » Sun May 29, 2016 4:33 pm

Mostly slingshot stuff. Respectively, 2012 Rally, Wave, Wave, 2014 RPM. Bars are various years of the compstick from 2014 to 2016.

Board - 10.7 pounds + 0.3 (screwdriver) - 11.0 

14m = 7.6 lbs.
12m = 7.8 lbs.
10m = 7 lbs.
8m = 6.3 lbs. 

17" Bar = 2.4 lbs
20" Bar = 2.7 lbs.
23" Bar = 3.0 lbs.

Pump = 1.9 lbs. 
Compression bags - 0.3 lbs * 4 = 1.2 lbs.

North Face Giant Bag = 14 lbs. 

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Re: Weight of LEI kite sizes ?

Postby Peter_Frank » Sun May 29, 2016 6:30 pm

So your 12 and 10 are the same model and year, 5 strut kites ? 7.8 and 7.0 lbs. 3,5 and 3,175 kg.

Thanks, as not interested in different models only the very same series.

I weighed my 9 and 7 same model/year and 5 strut kites: 3,2 kg and 2,85 kg.

8) Peter


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