Kiteforum Wiki Recent Changes FAQ How To Gear Useful Tips Safety Rules Schools Shops

 All times are UTC + 1 hour

 Page 2 of 3 [ 26 posts ] Go to page Previous  1, 2, 3  Next
 Print view Previous topic | Next topic
Author Message
 Post subject: Re: Beaufort scale is useless.Posted: Wed Jun 20, 2012 12:37 pm
 Medium Poster

Joined: Sat Apr 30, 2011 11:26 pm
Posts: 110
Location: Europe
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!"

Top
 Post subject: Re: Beaufort scale is useless.Posted: Wed Jun 20, 2012 1:07 pm
 Medium Poster

Joined: Tue Feb 03, 2004 12:08 pm
Posts: 140
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.

Top
 Post subject: Re: Beaufort scale is useless.Posted: Wed Jun 20, 2012 1:49 pm
 Frequent Poster

Joined: Wed Mar 11, 2009 9:57 pm
Posts: 258
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.

Top
 Post subject: Re: Beaufort scale is useless.Posted: Wed Jun 20, 2012 4:07 pm
 Very Frequent Poster

Joined: Tue Oct 12, 2004 5:10 pm
Posts: 771
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?

Top
 Post subject: Re: Beaufort scale is useless.Posted: Wed Jun 20, 2012 6:35 pm
 Rare Poster

Joined: Mon Apr 27, 2009 4:27 am
Posts: 9
The Beaufort scale is a wonderful thing.
To all wind junkies like myself I strongly recommend
"Defining the wind" by Scott Huler e.g.

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

Top
 Post subject: Re: Beaufort scale is useless.Posted: Wed Jun 20, 2012 8:06 pm
 Medium Poster

Joined: Tue Apr 17, 2012 3:27 pm
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

Top
 Post subject: Re: Beaufort scale is useless.Posted: Wed Jun 20, 2012 9:12 pm
 Frequent Poster

Joined: Tue Jan 02, 2007 11:50 pm
Posts: 243
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

Top
 Post subject: Re: Beaufort scale is useless.Posted: Wed Jun 20, 2012 9:32 pm
 Very Frequent Poster

Joined: Mon Mar 16, 2009 4:35 pm
Posts: 903
Location: Southwestern Ontario
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....

Top
 Post subject: Re: Beaufort scale is useless.Posted: Wed Jun 20, 2012 9:34 pm
 Very Frequent Poster

Joined: Thu Jun 05, 2008 1:52 am
Posts: 1065
Location: Thailand
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.

Top
 Post subject: Re: Beaufort scale is useless.Posted: Wed Jun 20, 2012 9:37 pm
 Very Frequent Poster

Joined: Thu Jun 05, 2008 1:52 am
Posts: 1065
Location: Thailand
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.
They are not very useful when wind speeds can be assessed in terms of kite size.

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

Top
 Display posts from previous: All posts1 day7 days2 weeks1 month3 months6 months1 year Sort by AuthorPost timeSubject AscendingDescending
 Page 2 of 3 [ 26 posts ] Go to page Previous  1, 2, 3  Next

 All times are UTC + 1 hour

#### Who is online

Users browsing this forum: BudhaNl, zob and 22 guests

 You cannot post new topics in this forumYou cannot reply to topics in this forumYou cannot edit your posts in this forumYou cannot delete your posts in this forumYou cannot post attachments in this forum

Search for:
 Jump to:  Select a forum ------------------ Sports    Kitesurfing    Snow / Land Info    Special Offers    User News    Reviews    Safety    Info    Second Hand    Lost & Found    Events & Demos    Kids Club    New Members    Tricks and Moves    Polls    PDF Files    Weather    Contests    Help Me Board Styles    Kiteracer    Airstyle    Wakestyle    Wave Kite Groups    Board Builders    FKA, RickI column    Women's Forum    Flamer's Paradise Travel    Travel Instructors    Instructor Discussions    Africa       South Africa Instructors    North America       Florida Instructors Europe    Portugal    Spain    Germany    France South America    South America    Argentina Middle East    Israel