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 Post subject: Re: HeliumPosted: Mon Jul 02, 2012 2:57 am
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Joined: Sat Aug 29, 2009 11:25 pm
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Location: The Naki
William Munney wrote:
stakas wrote:
The lifting power of helium is roughly 1 kg/m3.
The strut volume of a large kite is probably 0.5 m3 the most.
So the weight difference would be 4 kg versus 3.5 kg.
A huge amount of air is also carried with the kite while moving thru the sky.
The only way to make it really matter we would need a sealed, double surface kite.
Made from very light material and filled with Helium.
(Let say a 15 m2 kite with an average thickness of 0.15 m has a volume of 1 m3. If you can make it 1kg heavy (roughly the third of a current kite's weight) then it would float in the air and would be incredibly faster to move it around.)

Let's try hydrogen!

oh yeah and fly the kite through a fire!

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 Post subject: Re: HeliumPosted: Mon Jul 02, 2012 9:19 am
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Joined: Sun Mar 20, 2011 6:52 am
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dyyylan wrote:
plummet wrote:
We did the maths a while back and it doesn't stack up. the impact would be negligable.

ps taut helium molecule too small\?... thats the whole point. less weight!.
but your would get permiation through the bladder. but not enough permiation to worry about in an average 2 - 3 hr kite session

but if the molecules are smaller, wouldn you need more of it to pump it to the same psi? i have no idea, i was an art major :p

PV=nRT, to achieve the same PV you need the same n, the same n in different molecular weight elements leads to different total weight so, yes, negligible or not, the weight of the gas would be less for a a lighter (smaller) molecule. Or so I think anyway, it's been a looooong time since school!
PS Let's try H2S, it would be fun to see the faces of bystanders upon deflation!

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 Post subject: Re: HeliumPosted: Mon Jul 02, 2012 10:50 am
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Joined: Sun Oct 05, 2008 5:47 am
Posts: 37
I could be wrong but I'm pretty sure helium is heavier when under pressure.

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 Post subject: Re: HeliumPosted: Mon Jul 02, 2012 12:13 pm
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Location: The Naki
Ned Divine wrote:
dyyylan wrote:
plummet wrote:
We did the maths a while back and it doesn't stack up. the impact would be negligable.

ps taut helium molecule too small\?... thats the whole point. less weight!.
but your would get permiation through the bladder. but not enough permiation to worry about in an average 2 - 3 hr kite session

but if the molecules are smaller, wouldn you need more of it to pump it to the same psi? i have no idea, i was an art major :p

PV=nRT, to achieve the same PV you need the same n, the same n in different molecular weight elements leads to different total weight so, yes, negligible or not, the weight of the gas would be less for a a lighter (smaller) molecule. Or so I think anyway, it's been a looooong time since school!
PS Let's try H2S, it would be fun to see the faces of bystanders upon deflation!

now if we are going to make a stink about it why do things by halves? might as well inflate the kite with undiluted ethyl mercaptan.

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 Post subject: Re: HeliumPosted: Mon Jul 02, 2012 12:13 pm
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Joined: Wed Jul 11, 2007 2:09 am
Posts: 518
Pretty sure that Taut was referring to the molecule size with regard to the porosity of the bladder material. You would have to make sure the bladder was sealed with some kind of sealant as not to let the helium simply diffuse out.

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 Post subject: Re: HeliumPosted: Mon Jul 02, 2012 4:48 pm
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Joined: Wed Jun 18, 2003 2:35 pm
Posts: 86
I love helium posts

Here's an idea for light wind race kites. Make a sealed twin skin kite with mylar foil and fill it with helium oxygen mix to make it basically nuetral in boyancy so that they do fall out of the sky when the wind "holes" out to zero.

Almost garanteed Kite racing in the olypics.......Maybe (hang on maybe i should stop this )

Ciao,

Mike

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 Post subject: Re: HeliumPosted: Mon Jul 02, 2012 5:38 pm
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Joined: Sun Mar 20, 2011 6:52 am
Posts: 623
tino wrote:
I could be wrong but I'm pretty sure helium is heavier when under pressure.

Helium is heavier under pressure than when not under pressure But Helium weighs less than air (for any given pressure and volume) so a kite inflated with helium will indeed be lighter, in exactly the same way that a balloon is. Not a lot lighter, but lighter.

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 Post subject: Re: HeliumPosted: Mon Jul 02, 2012 5:48 pm
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Joined: Sun Jun 12, 2011 12:47 pm
Posts: 1638
Ned Divine wrote:
tino wrote:
I could be wrong but I'm pretty sure helium is heavier when under pressure.

Helium is heavier under pressure than when not under pressure But Helium weighs less than air (for any given pressure and volume) so a kite inflated with helium will indeed be lighter, in exactly the same way that a balloon is. Not a lot lighter, but lighter.

It sure is fun to revive this original 10 year old topic (7/1/2002)

Let's all learn from this video

Thank you........................class dismissed

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 Post subject: Re: HeliumPosted: Mon Jul 02, 2012 7:51 pm
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Joined: Sun Sep 04, 2011 5:37 pm
Posts: 962
William Munney wrote:
...

Let's try hydrogen!

YEA -- Excellent Idea !!!
And you can use a lit-candle to find Leaks .

Bille

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 Post subject: Re: HeliumPosted: Tue Jul 03, 2012 11:00 am
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Joined: Sun Oct 05, 2008 5:47 am
Posts: 37
Ned Divine wrote:
tino wrote:
I could be wrong but I'm pretty sure helium is heavier when under pressure.

Helium is heavier under pressure than when not under pressure But Helium weighs less than air (for any given pressure and volume) so a kite inflated with helium will indeed be lighter, in exactly the same way that a balloon is. Not a lot lighter, but lighter.

I inflate most of my kites to 10 psi.... is this enough to make it heavier?

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