Hi guys,
... in general the steam locomotives are good , but not as realistic. At a certain stages and speeds the exhaust beats sound like a rolling drum ( too defined and thumpy ? ) instead of a tambourine effect if I may use that comparison. ...
A good many real steam locomotives sounded extremely "percussive". So yes, many of them sounded very much like a drum. Why? Because different types of steam locomotives sounded different. The laws of physics come into play, e.g., a smaller locomotives "smaller" sounds and larger locomotives sound "bigger". The "chuff" is produced in the smokebox (see image, below), so change the size/configuration in the smokebox, add a superheater, or make the smokebox bigger/smaller and the resulting sound will be different (see note #1, below). Some locomotive actually used mufflers in the smokebox which radically changed the exhaust sound, etc. U.S. steam sounded different that European steam largely because European locos smokebox configurations were typically designed for more efficiency, etc. A steam locomotive's "chuff" sounds different up close and personal than it does at a distance. They also sound different in different physical environments. If there is lots of reflective surfaces nearby, such as buildings, streets, or embankments, the sound will vary. The sounds also vary according to how hard the engine is working. Even water in the cylinders can affect the sound of the "chuffs" (see Note #2, below). Thousand of different factors may combine to change the character of the exhaust sound, in accordance with the laws of physics.
If you want to listen to some excellent examples of how different a given type of steam locomotive can sound, listen to the
O. Winston Link's sound recordings, made in the late 1950s of various N&W steam locomotives. Listen to how extremely percussive the N&W Yb Mallets sound in one track, then compare that to other recordings of a Y6b that sound extremely soft and mellow. The same can be said for recordings of the N&W Class Js. On some tracks, they're very crisp, on others there's very mellow, and on other tracks they really have a sharp, yet deep and gruff "bark" to them.
Why steam locomotives "chuff" -- an explaination from the 1911 book, A Text-Book of Physics, page 297
Note #1 -- Differences in exhaust sound, superheated vs. saturated steam
From:
Locomotive Engineers' Monthly Journal, 1913
In your answer to J.M. Logan in the February Journal I note you make the statement that the best proof of the absence of back pressure in locomotives equipped with superheaters is that the sound of the exhaust is much more clear and snappy. On the road on which I am employed they have a large number of Pacific type passenger engines that are alike in every respect excepting that they are about evenly divided between saturated and superheaters. As my duties often require that I ride these engines I soon noticed that the sound of the exhaust of the superheaters while free from slobbering or dragging was not as snappy or clean cut as the sound of the exhaust from the saturated steam locomotive. The mild exhaust of these engines is due of course to the fact that the superheater locomotives are using about 30 per cent less water consequently the volume of the exhaust steam is not great enough to fill the stack solid which is necessary in order to get a snappy exhaust. It is also partially due to the high velocity of the escaping steam account of the high temperature at which the steam is exhausted. On our saturated locomotives the stacks are quite frequently cut out just above the smoke arch while on the superheater engines there seems to be an entire absence of this.
Note #2 -- How water in (cold) cylinders affects sound
From:
Thermodynamics of the Steam-Engine and Other Heat-Engines, 1889
... water which collects in the cold cylinder of an engine when started quickly passes away as is indicated by the change of the sound of exhaust from dull and heavy to dry and short.
