Shape of the RR engine smoke stacks

[Glenn]

What is the reasoning behind the shape of RR engine smoke stacks?

 

 

Why is the stack tapered.

Why is the stack enlarged several times the diameter at the top.

 

Is this to improve air flow, decoration, or what? Will this imporve the chimney of the forge?

[locustman]

Newbie and first post. I can answer some of your questions as I had to make one similar to the Diamond. They're spark catchers or arrestors. Designed so that large ash or embers fall down between an inner and outer flue, smaller embers or sparks caught usually by a mesh screen. Used on wood burners and more popular on your side of the pond, as coal was fuel used over here and we don't have vast areas of prairie to set on fire.

 

The Taper will be shaped to improve draw on the fire.

 

Not much relevance to forges, unless your some how sending vast quantities of sparks up the chimney and sending the neighbourhood up in smoke! 

[Nobody Special]

The spark arrestor thing, definitely.  But there was also something about using larger diameters to prevent back pressure on the steam exhaust blastpipe. Been awhile since I read it somewhere. Someone on here will know the details.

 

And for no good reason at all, here's a pic of one of my favorites, The General, with it's "balloon" smokestack. A beautiful train, located about 8 miles down the road from me. It was stolen during the Civil War by Union soldiers, leading to the first issues of the Medal of Honor. The museum also has big chunks of a foundry that built engines, including the wooden molds, and a Westinghouse generator turned belt system to a number of "power" tools. And also, possibly the largest anvil I've seen locally. The cutoff hardy in it probably weighs 20 lbs.

 

One of the trains that chased the General was the Yonah, which serviced Etowah, Ga, possibly the largest iron producing area in the South before Sherman burned it to the ground. Another was the Texas, which is very similar, and located in downtown Atlanta, manufactured in the same town as the General. I've been to where Etowah was, great area to scrounge for ore.

 

http://upload.wikimedia.org/wikipedia/commons/6/67/W%26A_No3.JPG 

[notownkid]

The Bradley & Hunters were the wood burners and Glen if you look up logging RR's in your neck of the woods and their were a ton of them, you'll see the Shays, Climax's and Hysler all gear drive engines used the spark arresters to keep from burning up their own woods as long as they burned wood but once converted to coal or oil up went the tapered stacks. 

 

There is a Currier & Ives print of an early American type 4-4-0 wood burning engine (Like the General) highballing across the plains somewhere at night and the stack is just blasting red sparks out of it lighting up the night.