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 Was DPM's March 1961 editorial, Impressive But Not Convincing, on the H F Brown paper the last shot of the old steam-diesel debate? Or is it a sleeping dog that has lain far too long? After listing several of Brown's contentions and leaving specific rebuttal to "more qualified pencil pushers" DPM rested his case largely on this one paragraph: "We regard Mr. Brown's paper as impressive but not convincing. For example, the merits of 'modern steam power' are better illustrated in specific applications than in over-all comparisons. It is true that Missabe Road 2-8-8-4's moved ore trains of almost 18,000 tons gross off the range and that N&W 2-6-6-4's managed 14,500-ton coal drags in flatland running. The equivalent, say, of perhaps three six motor, 1750 h.p. diesels. Driver axle loadings in this example range from slightly less than 50,000 pounds for the diesel to 70,600 pounds for the 2-8-8-4 and on up to 107,525 pounds for the 2-6-6-4. Clearances favor the diesel, too, as does the fact that the articulateds are indivisible. Put it this way: How many roads possess N&W's physical plant? Again, even N&W found it necessary to manufacture two basic types of steam locomotives (simple 2-6-6-4 and compound 2-8-8-2) to operate in mountain and flat terrain on the merchandise trains that are now handled by multiples of a single type of diesel, a unit of which is also at home, say, on the Abingdon Branch, where formerly a 4-8-0 was the largest type of power assignable." DPM's pencil pushing is pretty much straight arrow on the DMIR application, judging by his own Steam's Finest Hour, p57, listing 565,000 WOD for the 2-8-8-4, and the November 1959 TRAINS on DMIR. Figure six motor units of the time commonly had 50,000 lb axle loads. Re the N&W application, however, he is strictly pencil pushy. His own SFH, p67, lists 432,200 WOD for the Class A, which, divided by six, is actually less that the 2-8-8-4 figure. Figure also the "single type" of diesel on the N&W was four motor units from two builders. Further, that four motor mainline freight units ran from 120 to 130 tons, or 60,000 to 65,000 lb. axle loadings, whatever the specific N&W figures were. Three SD9s would have replaced the A? Again, his own SFH, pp61, 66, says it averaged over 30 mph start to top with those 14,500 ton trains and did twice that with 125 cars of merchandise. By EMD figures relayed by  LeMassena, January 1974, the 3600 hp SD45 could haul a 5000 ton train on level tangent track at 35 mph, two at 51 mph, three at 62 mph, and four at 70 mph. By these figures, it would have taken three SD45s to make those 14,500 ton hauls, twice the hp of the DMIR units. But figure the 125 cars of merchandise averaged 60 tons each, for a train weight of 7500 tons. That is almost half again what three SD45s were hauling at that speed, or four and a half units. There is a lack of record what the Class A could haul at 60 mph. By Ed King's not quite complete account of the A, on test the A hauled 7500 tons at 64 mph, he reports without elaboration. This figure has since been questioned as a misprint by Le Massena, Mainline Modeler, July 1993. On freight runs they cruised at 60 mph, often with consists filled out to 8000 tons. On one run they covered 92 miles in two hours. The conditions could be a bit more wonderfully completely described, however.Impressive, and maybe even convincing, by DPM's own words then, is that the diesel is not quite the all-around motive power he thought. Actually, he did notice in the Oct 1956 issue that steam seemed to last longer on high speed flatland operations than on mountain pikes. And a footnote in the Lima diesel article, Nov 1963, referring to Brown's paper, said Lima could hardly be blamed for taking the diesel's fast freight performance as less than impressive. Rather than deprecate N&W's superb realization of the different requirements for slow and high speed power, DPM might have better questioned why PRR did not order 25 Y-6bs for the mountains and 100 As for the flatlands, instead of the redoubtable but not quite equal C&O T-1. What if it had not ordered the 25 Q-2's, a possibly superb 80 mph machine with proper attention to detail, but Class As instead? The Q-2 had no significant advantage over the J-1 under 50 mph, but significant disadvantages. Staufer and Pennypacker, Pennsy Power, pp196, 210, bemoans the order of 100 K4s instead of M1s, a better explanation of why it was not so much steam, but rather  its implementation, that failed. The N&W was the notable exception, of course, its 2-8-8-2 coming within a whisker of the four unit souped up 7000 hp F7 on 1% grades, performance and cost-wise, and at a much lower capital cost. Actually, as far as that goes, that same F7 came within a whisker of the A's performance on those 14,500 ton coal trains, leaving me to wonder where all that extra hp of the three SD45s goes. Actually, I have been wondering for about 35 years, since moving a block from the C&NW mainline, observing three unit SD40s on both 12,000 ton unit trains and fast piggybackers, and reading SFH on the A's exploits. And that Nov 1959 article on the DMIR noted the three unit diesel could start a heavier train, but the Yellowstone could pull a train it could start faster than the diesels. And that same issue has DPM's own observation on a PRR T-1 cab ride, that the great racer literaly SURGED when the throttle was opened at 70 mph, his emphasis. Contrast that with the May 1986 article on the Super C, the diesels crapping out at speed. The closer analysis should be impressive and convincing both. That is, if it is properly expressed in accounting terms, not merely performance figures. Does anyone know, then,     1) how big a train the A could haul at 60 mph? What happened to N&W fast freights after dieselization?   Figure this is the more critical figure today than the decade of dieselization, when the diesel's advantages on slow, heavy trains and fast light trains were more decisive. The speed limit today comes from the expense of fuel on fast freights. It is well documented in the pages of TRAINS if little realized that diesels are very, very expensive on fast, heavy trains, 5 hp/ton being about the economic limit. July 1970, January 1974, May 1986, April 1990. The Niagara was both more powerful at 60 mph than a 6000 hp E7 and cost less to operate, on the other hand, per March 1984 article. Too bad one was never tried on a Flexi-Van.   2) How fast could a 2400 hp SD24 or 2500 hp SD35 haul 5,000 tons?
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