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[quote]QUOTE: Originally posted by GP40-2 [quote]QUOTE: Originally posted by oltmannd [quote]QUOTE: Originally posted by feltonhill The grade from Portsmouth to Williamson on the N&W is descending westbound at about -0.016% for the first 100 miles (range - level to -0.058%), upgrade 0.30% at Kenova over the Ohio River and -0.012% for the last 30 miles or so into Portsmouth. Train weight varied depending on the mix of 50-ton and 70-ton cars. At a train length of 160 cars, trailing weight would be about 12,000 to 15,000 tons. Ultimately, a single A was expected to haul 180 cars over the division, a trailing weight of up to 17,000 tons. According to GP40-2's figures, a CW44AC could develop 4,305 DBHP. To match the A's performance, it would need between 5,300 and 5,400 DBHP, so it would not match a single A's performance overall. The GE's operating economy would obviously be much better. Again according to GP40-2's figures, a CW60AC would have about 5,895 DBHP. This is beyond the range of an A in daily service. I've found no data for an FEF-3 above 75 mph, so I don't know what it would do with any certainty. Existing information indicates that they were very capable performers in regular service and could reach their design speed (100-110mph) easily. However, they were not record-breakers in the DBHP department according to the small amount of test info available. Don't know why. GP40-2's figures for the P42 indicate that it would develop 3,850 DBHP at 100 mph. This would be pretty rarified atmosphere for steam and is likely well beyond the range of an FEF-3. My guess is that an FEF-3 would develop about 2,500 to maybe 2,700 DBHP at 100. Since I don't have access to much diesel information, I find the relatively high percentage of rated HP making it to drawbar HP unusual. I didn't think they were that efficient from prime mover to rear coupler. [/quote] I think the diesel numbers being thrown around are net traction HP which is elec power out of the main gen headed for the traction motors. You'd have to factor in losses in the traction motor and gear set plus some allowance for HP to move the loco itself. My recollection is that the overall eff. from engine shaft into generator (traction HP) to drawbar is about 80%. [/quote] Try in the neighborhood of 93% to 96% of the actual crankshaft horsepower for the latest designs. Even the orginal EMD FT's were 82% to 84% efficient, and that was with using unsophiscated DC generators/ DC traction motors. Nominal Horsepower rating is the minimum HP available to the alternator. This is a conservative number, and actual crankshaft HP into the alternator is usually several hundred HP higher than the Nominal rating. Currently I am not a liberty to discuss the latest tests on the new ES44DC's, but they have eye popping efficiency from crankshift to drawbar, especially for DC traction motors. [/quote] Of course, to compare this to a steamer you would have to take into account the efficiency of the prime mover--"chemical horsepower" in vs. drawbar horsepower out. Internal combustion engines are much better than boilers, but they have never been great. Sincerely, Daniel Parks
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