No. 9's horsepower

[Jock Ellis]

Does anyone know how much HP No. 9 should have when completed? Traction effort?

[Keith Taylor]

It depends....do you want to know the boiler horse power, or indicated horsepower?
Either one can be figured by formula. Roughly the boiler horse power can be determined if you know the heating surface as each ten square feet of heating surface is equal to one boiler horse power. Indicated h.p. is p.l.a.n. / 33.000 Where P = the mean pressure in the cylinder, l= the length of stroke, a= the area in square inches being acted upon by the steam and n. = the number of strokes per minute. The length of stroke is actually double the length of the cylinder as the No.9 is double acting.
I am just making a wild guess.....but I think the boiler horsepower might by somewhere around 75 or 80 boiler horsepower. I'm sure Jason has the exact figure, and I would be interested to know how close my wild guess is!
Keith

[Tom Casper]

Keith,  Are you correct on your boiler hp to square ft?  Seems rather high to me.  To get 80 hp, would need 800 sq feet? 

Tom C.

[Keith Taylor]

One boiler hp is roughly 10 sq. feet of heating surface....that includes not only the firebox, but also the tubes and the front tube sheet. The surface area adds up quickly when you figure the area of all of the tubes. My guess was based on the size roughly compared to a 75 hp Case tractors boiler. In retrospect I'm thinking more along the lines of 65 to 75 bhp.
Keith

[Keith Taylor]

You can read a nice description of boiler horse power at this site: http://www.sizes.com/units/horsepower_boiler.htm

Keith