Blowing machine

[david_h]

You could try it.

[Terry McGee]

Yes, I was coming to the same conclusion. If I put just two input tubes in parallel, it should double the output deviation, proving or disproving the point.

Sigh, I feel I'm back with Isaac Newton, writing his Philosophiæ Naturalis Principia Mathematica, while locked down in London by the plague. His laws of motion entirely conjured by thought experiments. I had to do something similar in the early Covid days, when I couldn't travel up to Canberra to diagnose an issue with the carillon there. Fortunately, I had Newton's equations rammed into my head back in High School, so I could feed off his genius.

[david_h]

The clue is in the term "millimeters of water". One problem is that the illustration looks too much like a hydraulic jack, which we learn about in physics or engineering at school, but in order to illustrate something different.

I am wondering if a cheap digital aneroid barometer in a jam jar would work at the low pressure end of the range.

[stringbed]

The clue is in the term "millimeters of water". One problem is that the illustration looks too much like a hydraulic jack, which we learn about in physics or engineering at school, but in order to illustrate something different.

I am wondering if a cheap digital aneroid barometer in a jam jar would work at the low pressure end of the range.

How do you think organ pipes are tuned and voiced? One example of the employed measuring tools can be seen here.

Of similar relevance to this discussion are things like this.

There are numerous further instances of both.

[david_h]

I was suggesting a low-cost device for measuring small pressure differences that someone may even have around for other purposes. I may try it later.

[Terry McGee]

Hmmm, in my 10 tubes in, 1 tube out thought experiment, continued long after bedtime last night, I realised that opening up the additional 9 tubes would send water levels scooting up the out tube, even at balance. Might need to rethink that one!

[Terry McGee]

I've been meaning to get on and test the resistance of one of the heads with the very non-linear windways. I settled on the old Generation head.

Here are its vital statistics:
Old Generation D
L D W
0 1.64 8.25
4.25 1.65
11.29 1.62
14.78 1.54
16.49 1.5
19.16 1.43
22.86 1.37
24.28 1.26
24.69 1.14
24.79 1.0 7.85

And here are the Resistance test results:
Old Generation
MM H20 SQ RT A/P Flow
113 226 15.0 30
53 106 10.3 20
12 24 4.9 10
0 0 0.0 0

Resistance factor = SQRT(P)/Flow 0.501109879279097

Note a pretty high resistance value. Collating it with the others, and setting them in diminishing resistance order, we get:

Killarney: 340mm H20, Resistance = 0.615
Old Generation: 0.501
Tweaked Mellow D: 170mm H20, Resistance = 0.435
McGee 1/2" bore: Resistance = 0.408
Feadog Mk 1: 134mm H20, Resistance = 0.388

Like with the Killarny, I couldn't run to 40L/Min for risk of running out of manometer and spilling blue water everywhere.

I'm imagining the high resistance of this one is due to the dramatic plummet in height over the last few mm of windway. This is almost an example of a moderate sized windway terminating in a narrow orifice.

[trill]

Terry McGee, the testing machine !
Cranks out the data like you’ve never seen
It’s been a hard road, with duct-tape + sweat
But when we get done, we’ll have the best whistles yet !

Plus, thanks especially for such a *complete* data set for the Gen !

[Terry McGee]

Ha ha, cheeky young whipper-snapper....

Yes, hopefully it is all leading us in the direction of better whistles. That hopefully comes a little later after we have assimilated and capitalised on what we've learned!

We have I think made some good progress over the last little while. I can bring to mind:
- a measurement technique for windway heights (the little drill bits facing backward approach)
- subsequent exploration of some of the various height profiles makers have used in their windways
- a workable blowing machine set up where we can explore the issues and test our theories
- a better understanding of how flow and pressure work in the whistle, and their relationship to airspeed.
- the discovery of the strange wafty behaviour below the first regime
- evidence that resistance is pretty much just a windway thing, independent of what's going on further down the whistle
- a proposed approach to defining and measuring resistance
- 5 very different windways measured to indicate their resistance
- confirmation that we don't really need to measure pressure and flow, apart from perhaps at the outset to identify their relationship (the resistance) of the whistle-under-test
- a developing protocol for taking data and measurements
- what have I forgotten?

There's still plenty to explore and improve. I can think of these:
- being able to calculate Resistance from the physical data
- a way to measure the windway width of curved windways (or is straight across near enough?)
- do we need to log both Frequency and Pitch at every event? Tunborough needs Frequency for his modelling, but it's pretty meaningless to we humans. 903Hz is A6+45cents, we shouldn't have to note both. I do have an app which translates but I also don't want to have to enter the data and transfer the answers. It would be nice to have a column in the spreadsheet to enter either of these data, and for the spreadsheet to automatically fill in the next column with the other form of data. Probably easier to log Frequency and calculate Pitch? (It would be pretty straight forward to calculate pitch as a deviation from A440 of 1244.67 cents, but that's not very user friendly either!)
- the Protocol for testing can probably do with a bit more work. Running a full set of tests is quite a bit of work - we want to make sure to capture all the data with a minimum of backtracking.
- I need to go through the spreadsheets, making the records of various whistles consistent in format, to avoid misinterpretation.
- I should use the system to test my McGee 1/2" Bore whistle with a range of tapers, starting off with a new stopper offering no taper, and slowly milling and testing increasing tapers until I feel it's gone too far.
- I'd still like an agreed way of measuring "voicing", or at least stopper to blade vertical offset, or whatever!
- The system is possibly at the point where I should do a complete run on a whistle, under Tunborough's stern superintendence, to hopefully give him good data, but also to throw up any remaining deficiencies.
- Transferring data to this forum is a bit tedious, especially given its limitations in formatting tables. Perhaps we need to investigate a shared spreadsheet approach? The discussion of the data could still take place on the forum.
- And we haven't really answered the question that started this topic, how to make a budget blowing machine!
- And, as usual, the hardest question of them all, what have I forgotten? Where do we go from here?

[trill]

. . . Here are its vital statistics . . .

Wow !

Made a graph : Auto + equal-scale. Guess at recirculating flow under the swoop.

[Terry McGee]

Yeah, so unfair on the poor old air molecules. They spend a lot of time wriggling down this shaft, only to bang their heads on the roof on the way out.

In another discussion, stringbed linked us to this image of an organ pipe with two windows (left and right in the left-hand image).


Air coming up from the bottom, diverted to left and right, and then entering the two vertical windways. Again, note the shape of the two windways. Same sort of profile.

Minimising drag (resistance) along the way but then building up airspeed at the last moment?

Or is it a fiendish plan to give the air jet a bit of down-tilt at the last moment?

Or both? Or other?

[trill]

. . . only to bang their heads on the roof on the way out. . .

I'm wondering:

1) Do the 2 windows give more volume ?

2) Is the "jet-switching" synchronous ?

So, who would be qualified to make a prototype 2-window whistle ?

Might be easier to make a low whistle first. Wouldn't need such tiny files . . .

But seriously, on the subject of the diagram:

1) note the "protrusion" of the floor, like so many of our whistles, but no chamfer shown.
2) the floor looks "level+parallel" with the bottom of the blade.
3) I'm really wondering why it has the swoop at the end. My current guess is that it minimizes skin-friction losses leading up to orifice/slots.
4) Also, by having the slot height controlled by the swoop, if a slot-height change is needed, all you have to do is replace or adjust that one rectangular piece.

Thinking about it now, that alone (replaceable piece to adjust the slot) makes it a great design for testing windway parameters!

(hint hint . . . )

[Terry McGee]

I'm wondering:

1) Do the 2 windows give more volume ?

That was the question I asked in viewtopic.php?f=1&t=114106

2) Is the "jet-switching" synchronous ?

I imagine if it works for the organ pipe shown, it should work for whistles.

So, who would be qualified to make a prototype 2-window whistle ?

Let's get to understand what one window (etc) does first! But it wouldn't seem too much harder. If it has any merit.

Might be easier to make a low whistle first. Wouldn't need such tiny files . . .

And it might assist bringing up the volume of low whistles. But it might also increase the flow too much, leaving our player deflated.

But seriously, on the subject of the diagram:

1) note the "protrusion" of the floor, like so many of our whistles, but no chamfer shown.
2) the floor looks "level+parallel" with the bottom of the blade.
3) I'm really wondering why it has the swoop at the end. My current guess is that it minimizes skin-friction losses leading up to orifice/slots.
4) Also, by having the slot height controlled by the swoop, if a slot-height change is needed, all you have to do is replace or adjust that one rectangular piece.

Thinking about it now, that alone (replaceable piece to adjust the slot) makes it a great design for testing windway parameters!

(hint hint . . . )

Heh heh, I've been wondering about that too.

It might be an idea that would work better at Low Whistle scale. Indeed, would the world be ready for a square Low Whistle? That would put it within the scope of people equipped for linear woodwork, but lacking a lathe. Sorry, Dear Reader, your range of excuses is evaporating.

[stringbed]

Indeed, would the world be ready for a square Low Whistle? That would put it within the scope of people equipped for linear woodwork, but lacking a lathe. Sorry, Dear Reader, your range of excuses is evaporating.

There’s nothing new with that: https://www.recorderhomepage.net/a-roun ... recorders/

[stringbed]

But seriously, on the subject of the diagram:

1) note the "protrusion" of the floor, like so many of our whistles, but no chamfer shown.

Chamfer makes it easier for a fixed voicing to function on a whistle of varying length and in multiple mode of vibration. Neither of those conditions apply to an organ pipe. The voicer’s challenge there is to give a rank of nominally identical pipes a coherent sound, scaling by some subjective criterion of uniformity from the lowest bass to the highest treble. That task is then multiplied by the number of differently sounding named stops on the instrument.