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[quote user="MichaelSol"][quote user="Bucyrus"] This is the result I would expect to see:1)      Both locomotives would be producing their maximum horsepower at their maximum speed.  2)      The maximum speed for both locomotives would be the same.  3)      The diesel would accelerate the train to its maximum speed in less time than the steamer. [/quote]And that's the problem. You've defined a set of conclusions you want to reach, and designed a test ensured to reach them. But, the DE reaches its maximum hp at about 19 mph; Steam at around 40-50. The DE generates its greatest power where it can't use it (slip, etc) and where the train doesn't need it. The Steam engine power parallels the resistance increases of the train more "usefully." Nobody would buy a car based on its maximum hp rating; but rather at a standard that represents a useful measure, i.e., where is the train at in terms of speed and weight.The importance of the weight on the drivers, and using that as the standard is well established.  Older annual reports reported fleet data exclusively in terms of tractive effort, and purchasing decisions were based on that. HP offers a surrogate that most -- most -- people understand more intuitively, but it is an imperfect surrogate. There is "a" correlation between weight on drivers and TE, but because these motive power types produce power so differently, it is likewise imperfect and, because the power curves themselves are not linear, but in fact, curves -- and since the hp curves are different for Steam and Diesel-electric, your approach simply chooses two end points and assumes therefore a straight line between them. That generates misinformation, not useful information, aside from the fact that the endpoints you choose -- maxiumum hp -- are located at very different points on the scale even as you "define" them to be identical for the purpose of reaching a specific conclusion.From a tractive effort standpoint, a view similar to the hp chart earlier, shows key differences for these types throughout their operating range. The column on the right is the resistance of the train at different speeds. The TE ratings of the motive power types must exceed the resistance of the train and where the TE rating does not exceed the train resistance, that represents the speed limit of the train.<table border="0" cellspacing="0" cellpadding="0" width="366" style="width: 366px; height: 306px"><tbody><tr height="17"><td width="64" height="17"> MPH</td><td width="64">  Diesel</td><td width="64">  Steam</td><td width="83">  Resistance</td></tr><tr height="17"><td height="17" align="right">0</td><td align="right">100,000</td><td align="right">60,000</td><td> </td></tr><tr height="17"><td height="17" align="right">5</td><td align="right">60,000</td><td align="right">59,000</td><td align="right">14,825</td></tr><tr height="17"><td height="17" align="right">10</td><td align="right">42,000</td><td align="right">58,000</td><td align="right">17,939</td></tr><tr height="17"><td height="17" align="right">15</td><td align="right">32,000</td><td align="right">56,000</td><td align="right">19,924</td></tr><tr height="17"><td height="17" align="right">20</td><td align="right">28,000</td><td align="right">52,000</td><td align="right">22,194</td></tr><tr height="17"><td height="17" align="right">25</td><td align="right">22,000</td><td align="right">48,000</td><td align="right">24,749</td></tr><tr height="17"><td height="17" align="right">30</td><td align="right">19,000</td><td align="right">40,000</td><td align="right">27,588</td></tr><tr height="17"><td height="17" align="right">35</td><td align="right">16,000</td><td align="right">33,000</td><td align="right">30,713</td></tr><tr height="17"><td height="17" align="right">40</td><td align="right">14,000</td><td align="right">29,000</td><td align="right">34,123</td></tr><tr height="17"><td height="17" align="right">45</td><td align="right">11,000</td><td align="right">24,000</td><td align="right">37,818</td></tr><tr height="17"><td height="17" align="right">50</td><td align="right">9,000</td><td align="right">22,000</td><td align="right">41,798</td></tr><tr height="17"><td height="17" align="right">55</td><td align="right">8,000</td><td align="right">20,000</td><td align="right">46,062</td></tr><tr height="17"><td height="17" align="right">60</td><td align="right">7,000</td><td align="right">19,500</td><td align="right">50,612</td></tr><tr height="17"><td height="17" align="right">65</td><td align="right">6,500</td><td align="right">18,750</td><td align="right">55,447</td></tr><tr height="17"><td height="17" align="right">70</td><td align="right">6,000</td><td align="right">18,000</td><td align="right">60,567</td></tr></tbody></table>At 50 mph, the train would need the equivalent of five Diesel-electric units to move at the speed, but only two reciprocating Steam engines. And this is where the capitalization of the Diesel-electric weighs heavily on railroads seeking operating efficiencies by operating at higher speeds. To operate at 50 mph, the train needs five equivalent Diesel-electric units with a combined TE of 300,000 lbs. But at 5 mph, the train has therefore 300,000 lbs of TE to move 15,000 lbs of resistance! That is extremely expensive tractive effort.  Maybe it looks good to you on paper, but to me it says that this is a power type that generates its power on the wrong parts of the power curve and that represents an expensive misapplication, waste, of power and capital.A Diesel-electric that can substantially outpull a Steam engine at 1 mph loses its TE advantage pretty quickly, and by 30 mph can pull only half the train that the Steam engine is pulling. And yet the Steam engine had plenty of TE to start that train; it simply has substantially greater capacity to run that train at the higher speeds. Practically speaking, if the Railroad wants to run that train at 30 mph, it can only assign half the tonnage to the Diesel-electric that it can assign to the Steam engine. The higher TE of the Diesel-electric available at very low speeds is useless, meaningless, from that standpoint because that's not where it needs the TE. It's an utter waste of a perfectly useless statistic. And at that 30 mph speed, the Steam engine will still have slightly greater TE available per pound of train resistance, notwithstanding that it is hauling twice the tonnage.And so what is it that the Steam engine missing there? They can both start their trains just fine. The train is at its lowest overall resistance at the low speeds. High available Tractive Effort at those speeds is a meaningless statistic because that's not the range in which the train is going to develop its need for high Tractive Effort. It's the Diesel-electric that fails to carry its burden at the higher speeds, not the reciprocating Steam engine. And that is a fundamentally different characteristic of the motive power types.In this instance, even if these TE curves are adjusted in the fashion you desire -- maximum hp reached by each motive power type -- the adjustment still presumes, even by the standards of steam locomotives extant 60 years ago, a relatively small steam locomotive even by comparison with the average hp Diesel-electric road locomotive today.Is there a point in comparing a relatively large Diesel-electric locomotive with a relatively small reciprocating Steam engine? Yes, it is the only way to get the results you want because, ironically, the Steam engine at the identical "maximum" hp as the Diesel-electric has a substantially lighter footprint than the Diesel-electric at that horsepower, which limits its tractive effort to that of the Diesel-electric. But, that offers the "unfair" advantage to the Diesel-electric by limiting the Steam engine to the Diesel-electric's inherent limitations, by carefully setting the "maximum" hp at completely different points: 19 mph for the Diesel, 50 for the Steam, and calling them "equal" which yield's Steam's advantages of substantially higher hp, single units with greater TE per pound of locomotive on the driving wheels. In other words, your test is carefully calibrated to produce exactly the results you want, by eliminating all of the advantages of Steam power, and testing only on the advantages of the Diesel-electric. While that may be satisfying, it will not translate accurately nor usefully into meaningful economic data, and will in fact give false and misleading results. Testing both motive power types against genuinely common metrics yields completely different results. What that illuminates is that the reciprocating Steam engine, pound for pound on the driving wheels, delivers more power than the equivalent hp Diesel-electric. That is why, when the weight on the driving wheels is comparable, the Steam engine can generate a substantially greater hp and TE -- it is more efficient at producing power at the speeds where the power is needed and through the means that the power is applied: through the driving wheels at the rail.And of course, this underscores the point of the thread -- no matter how you slice and dice the data, the capital cost of reciprocating Steam likely remains substantially lower than equivalent Diesel-electric hp, and the operating costs of the Diesel-electric are now so high that it represents, by a substantial margin, the most expensive operating alternative for railroad motive power. [/quote]It was not my intention to design a test that will show the conclusions I want to reach.  I do not advocate one type of motive power over the other, but rather, I am only interested in the comparison as it relates to the question that titles this thread.  And I see that question as being primarily related to the quickly shifting economics of fuel.  So I am not trying to reach any conclusion.  I have no preference or stake in the matter whatsoever.My only objective in proposing the test that I did was to provide what seemed to me to be the fairest apples-to-apples comparison.  My prediction of the results is not a wish for those results.  It is only to test my understanding of the comparison by stating what I expect before the test is performed.    It seems to me that the test I proposed is basically the same as the comparison that you have offered in the combination of the above table showing tractive effort and your earlier one showing horsepower.  However my test includes the stipulation that both locomotives are rated at the same horsepower.  I know that horsepower is not the whole story of performance, but it seems like the most comprehensive characteristic for a fair comparison.  I keep thinking that a fair test must pit locomotives of identical power ratings, or some fair measure of capability, but maybe that is not the case for the point you are making.  If you are only trying to show the shape of the TE curve during acceleration of steam compared to diesel, the power or size of the two locomotives need not match.But still, both locomotives exhibit a similar rate of TE fall-off as speed increases.  The only difference is that the diesel TE falls off faster and is higher in the beginning.  As you point out, the diesel's high TE at the beginning is not useful, but is it really a penalty?  It seems to me that it is a consequence of the electric transmission that may or may not be useful, but is not a penalty assuming that the transmission is a necessary attribute for overall performance.So, setting aside the high TE of the diesel at very low speed, the two locomotives develop similar shaped TE curves.  The steamer shows a higher TE overall, but we are not comparing these actual amounts because there is no stipulation that the two locomotives are identical in power, size, or capability.  Indeed, the steamer, according to your first table of horsepower is considerably more powerful than the diesel, so I would expect it to produce higher TE where it is indicated by the second table.   So I am still a bit confused by your conclusions from the tables, and my confusion boils down to this:If you are comparing the actual performance of the two locomotives in the tables, it seems unfair that they are not matched in horsepower, size, or similar indicator.If you are not comparing the actual performance of the two locomotives in the tables, I don't see how you can draw any conclusions about which one provided more tractive effort at any given speed.In re-reading all that you have said about this issue, it seems that you are indeed comparing the actual performance of the two locomotives and concluding that the steamer's TE performance is superior to a comparable diesel even though the steamer has at least 2800 more horsepower than the diesel going into the comparison test.
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