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 Post subject: Re: Beaufort scale is useless.
PostPosted: Wed Jun 20, 2012 12:37 pm 
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Erlend M B wrote:
Pump me up wrote:
plummet wrote:
But we NEVER measure velocity across the ground. We measure the FORCE the wind imparts on the impellers of our measuring devices.


I beg to differ. Most handheld windmeters measure the speed of the air. There is almost no resistance in the impellers, so it's rotating speed is determined by the speed of the air, not the force.



Soooo... is there any handheld measuring tool actually measuring the FORCE of the wind, instead of just the speed? Maybe its time to come up with one, if it does not already exist. Some sort of "mini-sail" working like a scale, basically measuring the "weight" (force) of the wind hitting it. Auto-pivoting to always be at a correct angle to the wind, reducing user error..

Then we can start talking pressure (force over area) instead of speed, like N/m2.
http://www.knmi.nl/samenw/hydra/faq/press.html

"Hi, what kite are you using?"
"well, its around 120 N/m2, so im powered with my 10m, boosting nicely!"


Then, on that note, we should change from talking kite-size to talkin kite force. No kite is true to stated surface area, the number is more a guideline to the force of the kite. Different shape of kites have a huge impact on the force it can generate, so why not create a test facility somewhere with very constant and steady winds, and then just simply measure each kite models and sizes force at max power and max depower at 12o'clock, power generated throughout a "hotlaunch" etc..

Then, you know what to use and you can get a more realistic windrange.

Also, we can start neerding about forces and pulls, much like when talking about cars!

"woaahh my kite has a hot-launch maximum of a 1000 N at windforce 120N/m2! It's much cooler than yours!"


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 Post subject: Re: Beaufort scale is useless.
PostPosted: Wed Jun 20, 2012 1:07 pm 
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Location: Scunthorpe
Bft 4 or less = Cable Park
Bft 5 + 6 = 10m kite
Bft 7 = 8 = 7m kite

The scale works perfectly well for me.


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 Post subject: Re: Beaufort scale is useless.
PostPosted: Wed Jun 20, 2012 1:49 pm 
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Vinny wrote:
Bft 4 or less = Cable Park
Bft 5 + 6 = 10m kite
Bft 7 = 8 = 7m kite

The scale works perfectly well for me.

Agreed, I have a kite for each of the forces from 4 to 8, Also if you read the beaufort scale descriptions for sea state then you can make a good judgement of what the conditions are actually like on the water.


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 Post subject: Re: Beaufort scale is useless.
PostPosted: Wed Jun 20, 2012 4:07 pm 
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I wasn't aware that it actually measures force. Although, it's a little obscure - it is the force measured on a the sails of a British man-of-war - wow that's useful.

Why not measure force in standard units of N? or better yet in Pa?


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 Post subject: Re: Beaufort scale is useless.
PostPosted: Wed Jun 20, 2012 6:35 pm 
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The Beaufort scale is a wonderful thing.
To all wind junkies like myself I strongly recommend
"Defining the wind" by Scott Huler e.g.
http://books.google.com/books/about/Def ... NRAAAAMAAJ

You will find all kinds of things you didn't suspect including about Beaufort's
personal life.


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 Post subject: Re: Beaufort scale is useless.
PostPosted: Wed Jun 20, 2012 8:06 pm 
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Posts: 155
Location: The New Old West
I think Mr. Beaufort took his wind seriously...and so...

Like any of us, after a while he / you create your very own wind scale....we sit down and look at sea, lake whatever, notice the very same things as Mr. Beaufort did..

then Bam...!!!

You know exactly what size sail or kite you need to rig...

Don't be jealous, Mr. Beaufort was the first, you can diss him but you ain't going to beat his system

especially with a little whirly gig you hold out and wonder at...

(Tap tap, is this thing stuck? blow blow, tap tap shrug---Hmm, I guess I'll ??? tap tap etc.)

When it comes to the sea, Sailors have always put their trust in their eyes...

Here's to looking good
fokiten


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 Post subject: Re: Beaufort scale is useless.
PostPosted: Wed Jun 20, 2012 9:12 pm 
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Someone better educate me. Isn't force from wind proportional to speed squared? Where do we see that in the Beaufort scale? We don't. And also, where is the temperature used in the Beaufort scale? I don't see how this is a measure of wind "force."

As far as I can tell it is a measurement of speed, with a very large step between numbers. I'm working on one to name after me. It is more of a binary scale. "Enough to ride" and "not enough to ride". Or maybe a 5 step measure, for "not enough", "Too much" and 3 kite sizes in between? :)

I can't see the attraction of using the old beaufort scale.

Peter


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 Post subject: Re: Beaufort scale is useless.
PostPosted: Wed Jun 20, 2012 9:32 pm 
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foam-n-fibre wrote:
Someone better educate me. Isn't force from wind proportional to speed squared? Where do we see that in the Beaufort scale? We don't. And also, where is the temperature used in the Beaufort scale? I don't see how this is a measure of wind "force."

As far as I can tell it is a measurement of speed, with a very large step between numbers. I'm working on one to name after me. It is more of a binary scale. "Enough to ride" and "not enough to ride". Or maybe a 5 step measure, for "not enough", "Too much" and 3 kite sizes in between? :)

I can't see the attraction of using the old beaufort scale.

Peter


The descriptions of which indicate what level the wind is at is about the effect of the winds force on objects (except 1 and 2 when it refers to its effect on smoke), I don't think it would hurt for a beginner to pay attention to the winds effects on objects around and the water. Not to sure if temperature would play a role in this or not, as everything is cold, the wind may produce more force but the objects it effects may require more force to be effected....


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 Post subject: Re: Beaufort scale is useless.
PostPosted: Wed Jun 20, 2012 9:34 pm 
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Vinny wrote:
Bft 4 or less = Cable Park
Bft 5 + 6 = 10m kite
Bft 7 = 8 = 7m kite

The scale works perfectly well for me.


Bft 2 to 3 = FS Speed3 21

Works perfectly for me.


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 Post subject: Re: Beaufort scale is useless.
PostPosted: Wed Jun 20, 2012 9:37 pm 
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consumer wrote:
I appreciate the tradition, but the beaufort scale is about as useless as my slanted pump base idea. It is dated and not very useful when wind speeds can be reported in m/s ,mph, or even knot.
I'm intrigued by the irony that there are countries that had enough foresight to adopt the metric scale, but still refer to wind speeds using BFT's.


"m/s ,mph, or even knot" are units derived from tradition or convention. :lol:
They are not very useful when wind speeds can be assessed in terms of kite size. :jump: :jump: :jump:

PS look at the history of units. The knot is interesting.
http://en.wikipedia.org/wiki/Knot_(unit)#Origin


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