[steam_tech] Re: TRAINS.com latest- can steam make a comeback?

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Let's try this again.  I posted most of this before, but I believe it will answer at least one or two of the questions posed here.

The best I can do on an estimate of a Class A's capacity on level tangent track, at the total evaporation and firing rate N&W expected, is about 4,200 trailing tons at 60 mph. This reflects a maximum of about 5,550 DBHP at 40 mph, the usual high point on an A's DBHP curve.

It is highly unlikely that an A every pulled 7500 tons at 60 mph on level track.  I believe that would take over 10-11,000 drawbar HP.  AnA is good, but not that good!

Now if you give 1218 about a 0.2% downgrade and enough distance.....

N&W rated its locomotives very conservatively, and the often quoted 5,300 DBHP is usually considered at the rear of the aux. water tank. Toward the end of steam, the A's were developing slightly more than this in order to get 16,000-18,000 ton trains from Williamson to Portsmouth in something less than 4 hours. That's where the 5,550 figure comes from.

There are many examples of A's running a steady 60 mph on time freights nos. 84 and 85 (some of O Winston Link's recordings), but I've not been able to directly relate a trailing tonnage figure to this speed. As a result, the above estimate is derived from Davis equations commonly used by the RR industry during the 1950's.

Using the same estimating method as above, I changed the tonnage to 4500 and the grade to -0.022%, the average downgrade grade from Williamson to Portsmouth. The estimated maximum speed was 60 mph. An A didn't average this speed from point to point. This is the best guess I can make as to why the A was rated at 4500 tons Wmsn-Ptsmth.

I also agree with John, please sign your posts.  We would like to know who we're talking to.  Based on the Steam_Tech site I have a pretty good idea, but other on this board likely won't.

Dave Stephenson

> 

>> > Let's see if 1218 can do 60 mph or more with a

> 7500 ton train, as the Class A has been reported to do since an early test, and numerous times since> then.

> >

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