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 Post subject: Re: Eletric Kite Inflation
PostPosted: Fri Apr 15, 2011 10:47 pm 
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C Johnson wrote:
I was told by a PHD physical therapist / kiteboarder who has written her own kiteboarding fitness book that it is a great way to warm up.


Unless she has MY back, she's not the expert.

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What are your credentials to say it's not healthy?


I don't think I personally said anything about whether or not it's healthy. I can tell you my credentials for confirming that it hurts... it fucking hurts.

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If you are going to live your life according to an ergonomics manual you probably shouldn't kiteboard at all.


Hold on there - I thought you were the one telling us about the book. I'm telling you about my back. And for the record, I have no trouble kitesurfing, snowboarding, skydiving, riding motocross, hang gliding, paragliding, running, jumping, or lifting heavy objects. I do have trouble sitting, lying down, and pumping kites.

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I find it hard to believe the amount of exposure would constitute an ergonomics issue.


Understood - but I think we've already established that you're not all that bright.

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if you are that concerned about it I would highly recommend stretching and doing a prewarm up before you pump your kite.


I stretch and exercise my back and abdominal muscles every morning and every night. I'd suggest you worry about how you pump up your kite.


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 Post subject: Re: Eletric Kite Inflation
PostPosted: Fri Apr 15, 2011 10:58 pm 
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spork wrote:
I do have trouble sitting, lying down, and pumping kites.


sounds like classic sciatica, irritation of the sciatic nerve

I hope you get to rig a compressor, love to see pictures of it, if you do decide that route.


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 Post subject: Re: Eletric Kite Inflation
PostPosted: Fri Apr 15, 2011 11:06 pm 
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edt wrote:
I hope you get to rig a compressor, love to see pictures of it, if you do decide that route.


I've used the BST pump for years. For me it's the perfect solution. I don't pump up next to the car, and I even travel with my 12V pump.


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 Post subject: Re: Eletric Kite Inflation
PostPosted: Sat Apr 16, 2011 1:30 am 
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Yo Spork - I think most of C J's last comments were directed at me.

I'm not big on internet arguments, I'll just say that the majority of people pump up their kites like they're lifting a heavy object using mostly their back, and even a PhD/PT would acknowledge that's not good for you.

I gotta say the one time I was able to completely fill my kites all day with a mechanical pump was launching at landing at Kitty Hawk Kites ($5 all day with grass rigging) in Hatteras which was pretty awesome.


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 Post subject: Re: Eletric Kite Inflation
PostPosted: Sat Apr 16, 2011 2:27 am 
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Kevin123 wrote:
Yo Spork - I think most of C J's last comments were directed at me.


That's what I suspect, but I found them to be uninformed and insulting.

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I'm not big on internet arguments...


Sadly, it's all I live for.

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I'll just say that the majority of people pump up their kites like they're lifting a heavy object using mostly their back, and even a PhD/PT would acknowledge that's not good for you.


Agreed. Here's a pic of the last hand pump I used. I added a telescoping shaft and a foot-hold so I could pump standing up and straight in line with the foot that's holding it down. Also added a pressure gauge. It was dubbed Franken-pump by my "friends".


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 Post subject: Re: Eletric Kite Inflation
PostPosted: Sat Apr 16, 2011 6:40 pm 
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Spork you need to work on reading everything someone says before jumping to conclusions. If you had you might have read something about having a bad back.

Thank you for throwing insults my direction. That seemed necessary.

For the record. A small nitrogen bottle has been the best non-pumping setup i have seen. Small light, portable, requires no batteries or power.

Nitrogen is important because it does not expand or contract the way air does with temp. Gas coming out of a bottle will always be freezing cold because of the rapid expansion. If you just use air you run the risk of an exploding kite once it reaches ambient temp.


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 Post subject: Re: Eletric Kite Inflation
PostPosted: Mon Apr 18, 2011 2:48 am 
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C Johnson wrote:
Spork you need to work on reading everything someone says before jumping to conclusions. If you had you might have read something about having a bad back.

Thank you for throwing insults my direction. That seemed necessary.


I'm sorry if I misinterpreted your words. It seemed to me that you were claiming your friend could be more of an expert on my back than I am because she wrote a book - but you seem to claim that you shouldn't worry about what it says in books.

In any event, back issues are notoriously complex. My back gives me real pain almost 100% of the time. But some things bother it and some don't. I'm lucky that most activities don't. And you should know that I've *never* missed work or failed to carry the heaviest loads when there is work to be done.

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Nitrogen is important because it does not expand or contract the way air does with temp.


I'm no chemist, but I find that hard to believe. I would think that at the pressures we're dealing with, both Nitrogen and air (which is about 80% Nitrogen) would act very nearly as an ideal gas and therefore follow: P*V = n*R*T

So it seems hard to believe there would be any significant difference. But I'm all ears if someone can explain it to me.


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 Post subject: Re: Eletric Kite Inflation
PostPosted: Mon Apr 18, 2011 7:04 am 
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Ah, we've had this argument with putting N in bike tyres ... compressed air contains water vapour which of course expands and contracts with temperature changes. 100% N is dry, doesn't have the water vapour so doesn't change volume.
How much difference it would make at 8psi in a LE? Probably not a whole lot ... perhaps :lol:


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 Post subject: Re: Eletric Kite Inflation
PostPosted: Mon Apr 18, 2011 7:05 am 
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spork wrote:
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Nitrogen is important because it does not expand or contract the way air does with temp.


I'm no chemist, but I find that hard to believe. I would think that at the pressures we're dealing with, both Nitrogen and air (which is about 80% Nitrogen) would act very nearly as an ideal gas and therefore follow: P*V = n*R*T

So it seems hard to believe there would be any significant difference. But I'm all ears if someone can explain it to me.


Air is actually about 79% nitrogen, but it has a lot more water vapor by comparison to 95% nitrogen. High % nitrogen gas will be more stable than "air" because of the absence of vapor. Nitrogen also does not permeate thru tire rubber and will not cause oxidation that air does as it permeates rubber material.

For the purpose of inflating kites and very low psi and for relatively short periods of time the advantage of using nitrogen is rather negligible.

Compressed air usually has a lot of vapor in it unless the compressor system has a dryer included in it. I thought about using a compressor, using scuba tanks, etc...but the Scoprega pump seems to be perfectly sufficient for inflating a few kites every day. If you are inflating over 10 kites/day a compressor would be nice though. But compressors require a fair amount of electricity to run and scuba tanks need to be refilled by someone with proper equipment. The Scoprega pump battery charges off your cigarette lighter, or an optional AC charger. Seems like the simplest and most cost effective solution in the long run.

I cannot imagine going to the trouble or expense of keeping a bottle of nitrogen handy for inflating kites. Seems a bit excessive.


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 Post subject: Re: Eletric Kite Inflation
PostPosted: Mon Apr 18, 2011 7:17 am 
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Kamikuza wrote:
compressed air contains water vapour which of course expands and contracts with temperature changes.


Not the compressed air in my SCUBA tanks. You're talking apples and elephants. Whether the gas contains water vapor doesn't depend on whether it's Nitrogen or air, but rather whether or not you dry it.

Yes water vapor expands and contracts with temperature changes - much like Nitrogen, Oxygen, etc.

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100% N is dry, doesn't have the water vapour so doesn't change volume.


Of course Nitrogen changes volume with temperature at the pressures and temperatures we're talking about it's very nearly an ideal gas. That means its pressure change is almost exactly linear with temperature.


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