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 Post subject: how big a role doe density of the air play?
PostPosted: Tue Feb 01, 2005 4:41 pm 
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how big a role doe density of the air play?

i have noticed that in cold denmark 12knots is more than in cabarete.

or is that just in my head and the differences are marginal?
how many % difference can it make?


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 Post subject:
PostPosted: Tue Feb 01, 2005 6:11 pm 
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its a funny thing, in my experience 20mph in the winter is a 15m kite day, 20mph in the summer is an 18m kite day.

now i know that all the sums say that air density difference between say 0oC and 20 oC is only about 5% (thats a bullshit example but it's of that order). where as my windmeter and my ability to hold on tells me its good for about 3-4m difference in kite size.

so i'm guessing that there is more going on than just air density in terms of wind power. wind gradients shouldnt make much difference as we only ever fly at about 15m altitude.

the man to ask is peter frank, he did some sums on it a year or two ago.

but the answer for me at least is a definate yes, colder winds and colder weather has more punch.


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PostPosted: Tue Feb 01, 2005 8:06 pm 
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I agree with this, and am very interested to see a more detailed explanation of how this works, and how wind strength is relative to altitude etc. Anyone out there who can explain all this ???

Thanks


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PostPosted: Tue Feb 01, 2005 8:16 pm 
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i know its a pretty big factor because where i kite we get coldwinds from cool fog and people ride 6's in about 25mph winds. whereas other spots i may be on a 10 or 8 in those conditions.

I especially see its effect when i travel, what i think is totally kitable 12 weather will turn out to be 15 weather.


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PostPosted: Tue Feb 01, 2005 9:32 pm 
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The easy way around this issue is to use a windmeter that measures the
power available in the wind ( such as the Hall Brothers wind meter ...
http://www.hallwindmeter.com/wind.html ) rather than one that measures
the spped of passing air molecules ( such as all those meters with little
propellers)

That way the measurement you get will always indicate the same size
kite, no matter what the temperature and pressure.

Steve T.


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PostPosted: Wed Feb 02, 2005 5:11 am 
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I've had this thought for a while, that there should be two scales for wind measurements. ie

Engines are measured by Power (hp/kw) and Torque(nm)

Electricity has Volts and Amps

Wind should have speed but also *power* ... shouldn't it?

Something to think about anyway!


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PostPosted: Wed Feb 02, 2005 5:19 am 
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Steve youre a genius i love ya,


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 Post subject:
PostPosted: Wed Feb 02, 2005 9:37 am 
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Quote:
The easy way around this issue is to use a windmeter that measures the
power available in the wind ( such as the Hall Brothers wind meter ...
http://www.hallwindmeter.com/wind.html ) rather than one that measures
the spped of passing air molecules ( such as all those meters with little
propellers)

That way the measurement you get will always indicate the same size
kite, no matter what the temperature and pressure.

Steve T.



A great example of K.I.S.S.!

I am surprised that they do not offer the windmeter in Knots. Does anyone here have a good answer to this?


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 Post subject:
PostPosted: Wed Feb 02, 2005 10:48 am 
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Quote:
Steve youre a genius i love ya,


Thankyou K ;-)

Steve T


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 Post subject:
PostPosted: Wed Feb 02, 2005 11:10 am 
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Hope this help:

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