WTT - Daylight Visible Beneath The Blade

[Daniel_Bingamon]

I don't like to exceed 7/16" dia. on a Low whistle either. Anything above that is just too large. (That doesn't count on the basswhistle though).

The non-Javascript Windows Flutomat can also be used. You can use it with any number of toneholes.

[fearfaoin]

I just tried your url and I didn't have any trouble.

I found my problem. Had to use Internet Exploder instead of Netscape. Hate when that happens.

The non-Javascript Windows Flutomat can also be used. You can use it with any number of toneholes.

And where would I find this creature, Daniel? Google's giving me no luck today.

Thanks.

[syn whistles]

FWIW-- due to their design, the bottom of my whistle blades is exactly the same height of the fipple top, but you can still see a sliver of daylight in there.

Probably similar designs, but same comment and observations apply to Syn Whistles.

[GaryKelly]

And where would I find this creature, Daniel? Google's giving me no luck today.

Thanks.

Ron,

I think this is what you're looking for (I hope!):

http://www.gjk2.com/fluto.zip

The zip file contains an html page which has the flutomatic calculator in it...worth a try I reckon. Can't for the life of me remember the URL where I downloaded it from though

Hope this helps

[dkehoe]

Fellow whistlers -

I've got a few comments (for what they're worth) on this thread.

1. Back pressure is entirely due to air friction in the windwayand the air velocity. The more surface area per unit volume in the windway, the more backpressure. Backpressure also goes up by the square of the velocity, so if a windway/blade combination requires greater velocity than another one, the whistler will experience higher backpressure.

2. The length of the windway is almost immaterial, except for the above explanation, where the longer the winway the greater the air friction and pressure drop.

3. The ratio of the windway heigth to the window length matters, as this (and the air velocity) is what determines the frequency of the edgetone oscillation. The frequency is determined by the Strouhal number (I've posted on this before).

4. The eddies that are created as the air leaves the windway are bisected by the blade. These eddies oscillate above the blade and below the blade. The eddies below the blade start the pipe vibrating. This is why having the blade in approximately the middle of the windway is best, at least scientifically, aesthetics are anyones call.

5. the pipe can only vibrate at certain frequencies (the notes) so it does. The edgetone described above is not necessarily at the frequency of the note (it probably isn't) but that doesn't matter, the pipe vibartes at its natural frequency, and this is what we hear.

[serpent]

Fellow whistlers -

I've got a few comments (for what they're worth) on this thread.

1. Back pressure is entirely due to air friction in the windwayand the air velocity. The more surface area per unit volume in the windway, the more backpressure. Backpressure also goes up by the square of the velocity, so if a windway/blade combination requires greater velocity than another one, the whistler will experience higher backpressure.

2. The length of the windway is almost immaterial, except for the above explanation, where the longer the winway the greater the air friction and pressure drop.

3. The ratio of the windway heigth to the window length matters, as this (and the air velocity) is what determines the frequency of the edgetone oscillation. The frequency is determined by the Strouhal number (I've posted on this before).

4. The eddies that are created as the air leaves the windway are bisected by the blade. These eddies oscillate above the blade and below the blade. The eddies below the blade start the pipe vibrating. This is why having the blade in approximately the middle of the windway is best, at least scientifically, aesthetics are anyones call.

5. the pipe can only vibrate at certain frequencies (the notes) so it does. The edgetone described above is not necessarily at the frequency of the note (it probably isn't) but that doesn't matter, the pipe vibartes at its natural frequency, and this is what we hear.

There are so many differences in theory and practice - while the totally technical aspects are perfectly correct on paper, they fail to take into account the vagaries of imperfections and little things like chamfered fipple plugs, which alter the behaviour of the air (Coanda effect) as it passes over the curve, curves in the profile of the blade, which alter the behaviour of the air as it passes over the airfoil, droplets of moisture in the airstream, so many variables.

As a purely practical matter, I can say with no chance of contradiction, that, should I place the edge of my blade in the precise middle of the theoritically-correct (but practically, imperfect) airstream coming from the windway on one of my instruments, the whistle will be hissy and airy as hell. The airstream is further perturbed by little things such as sharp edges on the insides of the fingerholes, the fact that the fingerholes actually exist, and the odd bit of pocket-lint that got into the fipple plug glue.

I do believe that pure aerodynamics have also proven that bumblebees can't fly.

Not to start a "Tech War" - just to hint that there are practicalities involved in the construction of whistles that are not addressed by the "pure" physics. To my knowledge, nobody out there has ever built a technically perfect whistle for us to try, though... hmmmmm...
Cheers,
serpent

[Jerry Freeman]

I concur with Serpent on what happens if you put the soundblade exactly in the middle of the windway height.

That "bumblebees can't fly" thing is an old urban legend. Physicists have figured out the aerodynamics involved, and it's pretty interesting. The trailing edge of the front wing creates a vortex that whirls like a horizontal tornado directly above the back wing, creating an astounding amount of lift. The four-winged scheme is a masterpiece of aeronautical design.

Best wishes,
Jerry

[serpent]

I concur with Serpent on what happens if you put the soundblade exactly in the middle of the windway height.

That "bumblebees can't fly" thing is an old urban legend. Physicists have figured out the aerodynamics involved, and it's pretty interesting. The trailing edge of the front wing creates a vortex that whirls like a horizontal tornado directly above the back wing, creating an astounding amount of lift. The four-winged scheme is a masterpiece of aeronautical design.

Best wishes,
Jerry

Jerry! Cool! I didn't until this minute know that someone had figured out that bumblebees really could fly! (Well, I had some personal evidence given to me by one that landed in an armpit while I was pointing directions to someone... I dropped the arm, and..... ) But that vortex thing is truly fun to know!
Cheers,
serpent

[Jetboy]

I would like to add my two penn'orth here.

Without the staggeringly technical and scientific knowlege displayed by Serpent (is this a hinderance ......?) I have arrived at the same conclusion as he. The fipple blade should be pretty much level with the base of the windway floor. In my whistles, this produces the purest tone with little chiff. A slight bevel on the trailing edge of the plug helps improve the volume. I have had some success with a curved blade a la Clarke, this seems to improve the richness of the tone but also like the clarke, gives a slight breathyness to the note.

Jetboy
Weston Whistles UK

PS Serpent, deep repect, your various posts on the technicalities of whistle design have been invaluable. Maybe when I have one that comes clost to yours, we could do a swap.

[Zubivka]

That "bumblebees can't fly" thing is an old urban legend.

Is not. It's a practical joke, of sorts, at the Paris Académie des Sciences, end 19th century. There was a scholars' battle about "lighter-than-air" (crafts, i.e. balloons) vs. heavier-than-air. While someone was demonstrating ex cathedra that "heavier-than-air" couldn't fly, some Academist released a live maybug from a matchbox, which of course took off bumbling in the respected auditorium, and made its point.
Hence, the poor conferencer remained in history as the man who tried to prove that "bumbleblees can't fly"...

[Jerry Freeman]

Hi, Zoob.

No! Wait! We're both right!

That's a funny story. Apparently bumblebees have participated in aerodynamical debates for quite awhile. Here's the source of the "urban legend" I was talking about (I've lifted the whole comment, including the poster's intro):

"The following was posted to an entomological discussion list by Paul C. Johnson at UNH. I include it (without the authors permission), because it is an oft heard story which is, of course, nonsense in its ususal context.

Bumblebees CAN fly! The oft heard ridicule of scientists that say a bumble cannot fly because its wings are too small, in spite of the evidence of their own eyes, is based on a misrepresentation of an incident that occurred in the 1930s. McMasters (in the Amer. Sci. 77:164-169) reports that a noted Swiss professor of aerodynamics at a dinner party with biologists was asked about the aerodynamics of wasp and bee wings. He performed some calculation for the bumblebee based on a smooth wing and got a low Reynolds number "proving" the bee incapable of flight. He obviously knew that the calculations were simplistic, and later (after examining a wing under a microscope and noting the bent and folded nature of the wing), corrected his error, but like the news media of today, the correction received little notice."

http://www.asa3.org/archive/evolution/199602/0059.html

Best wishes,
Jerry

[Daniel_Bingamon]

How the windsheet (3D duct of air the comes out of the windway to flow across the wind) see the edge is what's important. Some whistles have straight windways while other have inclined windways - while the inclined windways cause air velocity changes to take place, the flowing out can take an uphill or downhill arch based on the design of the windway - thus line of sight cannot be the judging factor of whether light in the bore should be seem through the windway.

[serpent]

How the windsheet (3D duct of air the comes out of the windway to flow across the wind) see the edge is what's important. Some whistles have straight windways while other have inclined windways - while the inclined windways cause air velocity changes to take place, the flowing out can take an uphill or downhill arch based on the design of the windway - thus line of sight cannot be the judging factor of whether light in the bore should be seem through the windway.

Daniel, Thanks for showing us the light!
cheers,
serp

[Zubivka]

4. The eddies that are created as the air leaves the windway are bisected by the blade. These eddies oscillate above the blade and below the blade. The eddies below the blade start the pipe vibrating. This is why having the blade in approximately the middle of the windway is best, at least scientifically, aesthetics are anyones call.

Something is wrong here.
If the air flow is bisected by a blade, and this blade's edge is about flat (see for instance Alba's Q1, or a Shaw, or Clarke original), or just symetrical, then the pressures above and below the blade will be about equal. If they are, then the oscillation of the pressures (depression, surpressure cycle) can't start. A hiss is all you get.

Like the bumblebee, a Clarke can't whistle...

The conditions for the whistle to "start" calls for a first depression to form inside the fipple chamber. This will in turn "suck in" the air stream to fill the depression, starting the cycle again. The blade can be flat (Alba Q1) positively sloped (most whistles, recorders) or reversely sloped (NA flutes), which will change the height of the blade leading edge in the airstream, but some initial unbalance is necessary to start the "air reed".

[Jerry Freeman]

thus line of sight cannot be the judging factor of whether light in the bore should be seem through the windway.

Daniel, the theory you present makes sense, but this statement does not. Without playing it, I can tell you 99% of the time whether a Generation type whistle will be a good player or whether a whistle I've tweaked is ready to play by looking into the windway and observing the position of the soundblade in relation to the windway floor. (I may still have to adjust the window length and soundblade edge, but the position relative to the windway floor is critical, in my experience.)

The part of your statement that is useful is your explanation of why different whistles require more or less or no space below the soundblade. That explains why Shaws require more room than Generations, which require more room than whistles of the type that play best when the soundblade is even with the windway floor.

However, with any given type of whistle, there is an ideal position for the soundblade relative to the windway floor. Experimenting with different soundblade positions to determine the ideal position and then sighting into the windway and checking the amount of daylight under the blade of other whistles of the same type is a very useful technique. It shouldn't be necessary with whistles where all of the same type are more or less identical (e.g. whistles made by craftspeople using precise lathe settings, etc.), but with mass produced whistles that vary from lot to lot, and craftsperson whistle prototypes still in an experimental stage, it is useful.

Best wishes,
Jerry