rehess Loc: South Bend, Indiana, USA

As a result of discussion in another section, I went through some old images of mine relating to smoke emanating from steam-driven equipment. The purpose of these images is to demonstrate what is true of this smoke, and how it should be depicted if smoke is added {or enhanced} for artistic reasons. All of these are scans from film, the first two quite old. I realize these have no great technical merit, but they are the best of mine I can find right now to demonstrate my points.

The first two are from 1971 of a coal-fired locomotive. The first image shows the locomotive at rest, with smoke shooting out of the stack at high velocity. The "draw" generated by the stack is what pulls air into the firebox and allows the fire to burn efficiently, so that velocity should be there even if the locomotive {or any other steam device} is at rest. The second image shows the same locomotive on the same day, but now it is moving, perhaps 20 mph. Motion causes the smoke to be dispersed in a way that it is much thinner, and you can see that it covers a substantial area, but we still see a stream rushing out the stack.

The second two are from 2006 of wood-fired equipment at a local museum. Wood should be a "dirtier" fuel, but although each of these pieces of equipment was in use at the time I took the pictures, we don't see any smoke at all. Smoke is a result of incomplete combustion; allowing smoke reduces efficiency of operation and makes the neighbors grumpy; a good operator can often reduce, or even eliminate smoke, so while it adds a nice artistic touch to an image, excluding it can also be realistic.

Linda From Maine Loc: Yakima, Washington

Thanks for the interesting info, rehess! The eclectic knowledge we gather on UHH every day is pretty darned cool.

magnetoman Loc: Purbeck, Dorset, UK

Living close to a heritage railway, I often see engines 'over-smoking' - as you say, efficiency of burn is critical to clean running. Sometimes the engine stands in the station and almost disappears under the smoke then, suddenly, everyone jumps as the safety valve blows-off and steam clears the air! I think the amount of smoke varies with the experience of the fireman, but I may be wrong. Interesting shots you have posted - don't see many steam cranes in action nowadays, even at the Great Dorset Steam Fair - I shall look out for one this year and post a pic if I find it.

rmalarz Loc: Tempe, Arizona

Very interesting bit of insight and information.
--Bob