CNJ Blue Comet Measurements - Model Railroader Magazine

dave hikel

Hi Frank,

I will look up or measure some of the dimensions when I get home this evening.  If you haven't purchased the USRA Pacific engine you might consider another engine as your starting point.  The Baldwin G3/P47 Pacifics were MUCH larger than the USRA heavy Pacifics.  In fact, they even had larger grate area and firebox area than a J1e Hudson in spite of the single axle trailing truck.  This ended up giving them more weight over the drivers than a J1e as well.

From looking at the specs side by side from steamlocomotive.com, it appears to me that the G3's, both from an appearance and design standpoint, owe much to the USRA Heavy Pacific and both owe much to the Pennsy K-4.. It's quite possible to put a different firebox on an engine. The Pennsy modified its USRA Heavy 2-10-2's to have Belpaire fireboxes, replacing the original equipment USRA radial stay fireboxes.

Total weight of USRA Heavy original: 306,000 lbs. The G3's were about 20,000 lbs heavier, some of which can be accounted for by the larger Wooton firebox and the additional weight of the feedwater heater as well as possibly heavier gauge steel for the higher (230 PSI vs. 200 PSI) boiler pressure.

Weight on drivers, USRA Heavy: 197000 lbs, G3: 197660 lbs.

Evaporative heating surface USRA: 3824 sq. ft, G3:  3849 sq. ft. I'm a bit surprised the difference isn't greater given the larger surface area of the Wooton firebox.

Driver diameter is identical.

The G3 used 26x28" cylinders vs the 27x28" cylinders on the USRA, but carried 230 PSI boiler pressure. The B&O P-7 carried the 230 PSI pressure, but used 27x28" cylinders with 80" drivers. The Pennsy carried 205 PSI pressure, used 27x28" cylinders. Most of the difference in tractive effort of the aforementioned locomotives can be attributed to the difference in boiler pressure. One inch larger diameter cylinders on the G3 would have upped the tractive effort to be marginally above the 50.,000 lbs of the B&O P-7 (due to the 1" smaller drivers on the G3).

I wouldn't place too much emphasis on engine weight as a criterion. When SP's P-1's and a P-3 class 4-6-2's were rebuilt into class P-4, the engine weight went from 222,000 lbs. to 265,000 lbs (greater than the weight difference between the USRA engine and the CNJ G3). In the rebuilding process, they got booster equipped Delta trailing trucks, a Worthington BL feedwater heater, the cylinder size went from 22x28" to 23x28".  Incidentally, after the rebuild, the weight on drivers was only 7,000 lbs less than a USRA light Pacific and the total engine weight was only 12,000 lbs less.

The only railroad that got USRA Heavy 4-6-2 orginals was the Erie. When they got additional copies in the 20's, the weight went up by 17,000 lbs, making them closer to the CNJ engines in engine weight.

Andre

It's really kind of hard to support your local hobby shop when the nearest hobby shop that's worth the name is a 150 mile roundtrip.