Subject: Steam engine timing

From: Matti Marttinen <[email-masked]>
Date: Mon, 22 Apr 1996 09:36:51 -0700

I'm trying to draw plans for small (bore 50 mm) double-acting one-cylinder steam engine with 
Stephenson valve gear.

I think that for lowest possible steam consumption and smooth
running there must be four "cycles" in the process:
Steam inlet, steam expansion,steam exhaust and also some compression
before piston reaches T.D.C. Steam inlet must begin just before T.D.C.

Now the questions for the steam gurus:
What are the best values (in degrees crank-angle) for opening
/closing inlet and exhaust ports? How many degrees should the valve cam
be ahead of piston crank?

And the final question: Is there any simple formula for calculating
horsepower when main dimensions of the engine and steam pressure are known?

Thanks in advance

M.Marttinen
Finland