WW&F No. 9 - Official Work Thread

[Hansel Gordon]

Since there seems to be confusion,

The wider the whistle, the louder it gets.

The longer the the whistle, the deeper it gets.

Short & chubby= high pitched (#9's whistle)
Long & skinny= deep pitched

[Keith Taylor]

Since there seems to be confusion,

The wider the whistle, the louder it gets.

The longer the the whistle, the deeper it gets.

Short & chubby= high pitched (#9's whistle)
Long & skinny= deep pitched

Not quite Hansel....width does not make it louder. It affects the timbre or "character" of the sound. The whistle's "loudness" is a function of pressure.
The length of the resonator determines the musical note played. The longer the bell the lower the note. Long and skinny will give a low pitch.....but a thin nasal sound. Long and a wide bell gives the deep resonant note. Short and wide gives a high pitched but resonant note.
But to return to your premise...the diameter of the bell doesn't affect how loud it is. The reason you can "quill" a whistle to change the volume is because you are changing the pressure admitted to the whistle by limiting the amount of steam entering the whistle.
Keith

[Keith Taylor]

Here is an example of a long bell small diameter whistle.
https://www.youtube.com/watch?v=Mfl3hAveRoE
You can hear it is playing a low musical note....but it has a thin nasal sound.
Not the deep rich sound you might hear in a steam boat.
Keith

[Dwight Winkley]

AHHH!  A old time trolley car whistle.

dwight

[Keith Taylor]

AHHH!  A old time trolley car whistle.

dwight

Yes...a Westinghouse "trombone" whistle. Interurbans and MU cars like the Pennsylvania RR's MP-54's used these whistles.

Keith

[John McNamara]

What I think has been missing so far is a discussion of harmonics, i.e. multiples of the fundamental frequency of the whistle. If the fundamental frequency is 1000 Hertz, there are also some other frequencies present, such as 2000, 4000, etc. These are all pressure waves that need some space to do their thing - i.e. resonate. A wider whistle will provide the space for more pressure waves of varying harmonic frequencies and hence a "richer" tone. A narrow whistle will only provide space for the fundamental frequency without any overtones - hence a shrill sound. The foregoing is a bit of a hand-wave, but I believe it is correct.

Indeed, as Hansel says short and stubby = high pitched, and long and skinny = deep pitched, but I'll add that wide = rich and skinny = shrill.

-John

[Wayne Laepple]

Here's a perfect example of what John is saying above. It's Norfolk & Western No. 1281. The N&W's standard freight "hooter" was made from a piece of superheater flue -- just a hunk of steel pipe. But check out the overtones and undertones demonstrated by the engineer's wrist action on the whistle lever. And as a bonus, listen for the Doppler Effect as the engine passes.
https://www.youtube.com/watch?v=zBm-ONvNhS4

[Keith Taylor]

Here's a perfect example of what John is saying above. It's Norfolk & Western No. 1281. The N&W's standard freight "hooter" was made from a piece of superheater flue -- just a hunk of steel pipe. But check out the overtones and undertones demonstrated by the engineer's wrist action on the whistle lever. And as a bonus, listen for the Doppler Effect as the engine passes.
https://www.youtube.com/watch?v=zBm-ONvNhS4

Wayne....you are not hearing overtones and undertones; you are hearing pitch modulation when the engineer quills the whistle. There certainly are a LOT of harmonics in that whistle and that comes from the steam sheet hitting the mouth of the resonator. A smoother surface would reduce the harmonics. In organ pipes when you want to eliminate the harmonics they glue leather to the lip of the pipe to eliminate the "bite."
 Again my area is pipe organs and having a bigger cross section doesn't necessarily mean more harmonics. A 6" diameter diapason is full of harmonics, yet the same 6" diameter in a Tibia Clausa has virtually no harmonics.
Keith
P.S. I think we are getting a little far afield of the topic No.9! I suggest that Ed move the whistle topic elsewhere. It is a very interesting topic....but not really on topic here.

[Ira Schreiber]

Besides, who gives a hoot...........(ducks again)

[Hansel Gordon]

Hey Keith,
I was just trying to dumb it down for those who aren't into whistles.

[Jason M Lamontagne]

There is a topic in work and events called new whistles for 9 and 10... Perhaps it should move there. 

I look forward to hearing no 9's whistle- Eric basically finished it up today.  Really, with the work that went into it and the fact that it reproduces the historical sound (as much as we know how anyway), it'll have to be REALLY bad to deserve any drastic changes.

See ya
Jason

[Stephen Piwowarski]

I'm looking forward to hearing this historic sound recreated in all its glory. I've been enjoying this topic from afar and love all of the good information that has gone into it. One thing that I believe has yet to be mentioned is the height of the cut up- that is the distance of the bottom of the bell away from the windway. The higher this cut up is the lower the fundamental frequency or pitch of the whistle. This whistle appears to have a fairly high cut up. That, paired with a relatively short, stout bell should produce a sound rich in overtones, that can be feathered with great variation in pitch. I can't wait.

[Stephen Hussar]

Not meaning to derail the whistle conversation, these are just a few shop pictures around No 9.

[Dave Crow]

Forgive my ignorance, but what holds the tapered wedges in place?

[Keith Taylor]

Forgive my ignorance, but what holds the tapered wedges in place?

Friction....just like a Morse Taper holds a drill chuck onto a drill press or a Jacobs taper holds the drill chuck in place on a portable electric drill.

Keith