Dear Lars,
Thanks for these comments. Where should I look out for the private message?- this is new to me. I would be very intertested to see the Big Boy data when we have established direct contact
Dear NM Coot,
Thanks- understand and largely agree with what you write. Will check out the reference if I can get it. One of the first books I bought on US railroading was Duke and Kistler’s photographic treatise on the Santa Fe in California, and I remember being very struck by the fact the 4-8-4s ran the 1765 miles from Kansas City to Los Angeles, over as many obstacles as you would care to mention. Inspired by the photograph of 3777 climbing Cajon Pass with 11 vehicles unassisted, I had a go at producing the power map for a 29xx class, again using guesses for many key parameters (Seems I can’t post this Excel graph)
I then got a crew with a miraculous ability to work at a constant 65000lbs/hr to the cylinders to drive 2926 all the way from Seventh Street, San Bernadino to the Summit, using this map. This is what I got:
On the index page, where all the trains.com forums are listed, nearer the top you’ll see a clickable post from anyone who wishes to start a conversation with you. Similarly, if you click on the bold username in any text message posted here, a page will open and one of the options will be to start a conversation.
Crandell
Thanks for all your replies. I’m now getting some data, and have reports on the PRR T1, Q2, NYC S1a S1b and S2a, and C&O H8 to hand, and have ATSF and UP references on order. It will take me some time to digest and analyse everything, several weeks, if not months I would have thought. I will report back then for those who are interested.
An initial look see at the data says that on Porta’s critique ‘US exhaust design could not have been worse’ there is a case to answer; at top steam rates of 125000lbs/hr the PRR Q2 had an exhaust pressure of 31 psi, blastpipe area about 58 sqins; the Niagara already a back pressure of 10 psi at 52500lbs/hr, 44 sqins blastpipe, which means that at the quoted rating of 6000IHP the blastpipe pressure would be approaching 40psi! If it were possible to reduce that figure to 5 psi at the same steam rate (and I’m not claiming it is), you would get about another 1200IHP for ‘free’. The T1 had a back pressure of 25-29 psi at 100000lbs/hr which implies a blastpipe area of less than 50 sqins; star of the show so far is the C&O H8 which showed around 13psi at the same steam rate.
Now these backpressures look horrendous to European eyes, but there are mitigating factors. Firstly the % loss of efficiency you get from high back pressure decreases as MEP rises, and US MEPs it seems were higher than elsewhere. Secondly, these figures, apart from the H8, are probably at steam rates, whic
@ Dreyfusshudson
A few more notes
quotes in >> French Croissants <<
In all the discussion on this topic I’m really surprised to so rarely see the name Chapelon mentioned. His designs and performance standards really exceeded everything being discussed in this thread. The ultimate steam locomotive, 242.A.1, was a rebuild of a poor performer and comfirmed Chapelon design principles and showed what could be possible in the future. Both his original designs and his rebuilds of poorly performing engines gave dramatic increases in power with significantly reduced fuel and water consumption. In North America, compounding had a horrific history and would never be accepted. That left 1, free exhaust clearance, 2, soft but effective exhausting, and 3, relatively high super heat to increase steam fluidity. I previously mentioned Chapelon’s own book but there have been others that give considerable detail for both test bank and field trials of his locomotives.
Imagine a steam locomotive capable of continous output of 4000 hp at the drawbar at 50 mph on the test bank and 4000 to 4200 hp on service trains. Total weight was 148 tons and adhesive weight was 84 tons. Boiler pressure was 292 psi and a triple klychap exhaust was fitted. The grate was 54 sq ft. Because of the three cylinder configuration the locomotive showed no tendency to slip even at maximum outputs.
if you want dream steam imagine a Chapelon-designed 4-8-4 to the North American loading gauge. (Or better yet, a Chapelon-designed Garratt 4-8-4+4-8-4…) No North American locomotive would even come close either performance or economy.
Three men, two and one valiant Mikado
Ok, NM Coot, you put attention on André Chapelon – and rightly so: no discussion on steam locomotive efficiency could be complete without due consideration of his work. So far, I for one had kept my comments strictly limited to the initial topic of this thread, more precisely: the question in mind if locomotive performance and efficiency can be ‘predicted’ (questionable wording in view of ol…erh, classic! engines) respectively, can it be assessed closely enough and with tolerably correct correlations between various types of engines? So far, I didn’t want to extend discussion onto ‘how to optimize classic steam loco efficiency?’
Hello All
It wasn’t my intention to divert the thread. It was my intention to indicate that you can’t consider either predicted or actual performance without taking Chapelon’s work into account. North American practice has always differed significantly from the rest of the world. The rest adopted some of the best NA practices, but it seems to me the converse is not true. I did try to indicate that what Chapelon achieved with 242.A.1 was simply a starting point for what could be achieved. Other engineers offered changes with considerable potential improvements. For example, Bulleid’s concept for oil-bath valve gear was a massive conceptual leap but was let down by very poor detail work. Having said all this, the classic Stephenson steam locomotive could never compete with either electric or diesel-electric performance or operational benefits. But it is interesting to speculate on what could have been…
It’s time to throw a bomb into this discussion. Chapelon’s 242.A.1 may have pointed the way to improved efficiencies and performance, but that won’t mean too much if such locomotives spend an inordinate amount of time being maintained. French steam was alloted a lot more shop time than would be tolerated by a North American CMO, so the fuel/maintenance trade-off needs to be considered in any discussion of efficiency. Vernon L. Smith, longtime Superintendent of Motive Power of the Belt Railway of Chicago, opined that North American steam locomotives were the best at what a locomotive should do by producing more ton-miles and passenger-miles with less down time than anywhere else.
Well , I see what you mean . I agree with you as regards virtues of American Super Power steam . Yet , may I kindly invite you to read my paragraph on why the 141.R out-lasted the 141.P on the SNCF ? In a nutshell :as far as decisions were taken upon technical reasoning – there were numerous other considerations playing a part in which steam on which lines of which sheds etc had to go first – it was not regarding matters thermal efficiency in any which way , it was b
J: I believe that N&W retired their big steram last Switchers were first to go in my area… I think that a “Y” was the last to drop its fires under regular service. Anyone more info?
An S1 or S1a was the last to drop its fire. Sorry, don’t have the exact engine # at my desk, however, it was written up in “Classic Trains” mag a year or two ago.
Just for the record, N&W diesilization started with the Harrisberg Lline and its 4-8-0’s. Plus, of course, replacement of J’s by run-through Southern Ry E-Units Monroe - Bristol.
Last operating steam on NKP was an 0-8-0 at Calumet Yard.
No it did not!
Nor is it topical.
Crandell
Great discussion, turning into a full time job to keep up!
I am in sympathy which most of what is written.
I do agree with CJ Hegewisch (12/04/11) that the perspective of operators was different to that of the gurus running testing stations. Our test stations were interested in cost savings from efficiency, because that is what they were designed to measure. Their work led to a few, trivial improvements to efficiency, all of which were ignored by the operators and not implemented. The only things they did that were accepted were to narrow the blastpipes of some designs, which made efficiency a bit worse, but improved the reliability of steaming. The basic philosophy (not well executed) of latter day UK designs was low maintenance. Efficiency was pretty good, but draughting stone age, because of the predilections of those in charge of design. Clearly if any feature which improves efficiency adds to maintenance costs, that needs to be factored in.
So, as Juniatha so eloquently puts it (13/04/11) efficiency is one thing, operating a railway another, and operational needs win out over efficiency if they are in conflict.
“I’d like to understand; exactly how hard and for how long were US designs worked?”
Have a look here…
Volumes have been written on this! North American freight service, with a few exceptions, is NOT the place to look for continuous performance capabilities. Here are a few passenger examples. ATSF 4-8-4 classes worked 1791 miles, Kansas City to Los Angeles, 12 crews, Raton, Glorieta, continental, Cajon passes. Average engine worked 18 to 20 thousand miles per month. (2900 class 4-8-4 on freight service via Belen cutoff, only averaged 8000 to 9000). NYC 4-8-4 S-1b, in field tests, consistently produced 6600ihp at speeds of 75 to 85 mph and were capable of accelerating a 1000 ton train to 75 mph in 19,400 feet. They averaged over 20,000 miles per month. Kiefer was never able to optimze them because of dieselization taking place and bumping them from passenger service. SP GS3 regularly handled 925 ton trains up compensated 1.0% grades at sustained speeds in excess of 55 mph, which I believe is equivalent to about 5500ihp. NYC J-3a Hudsons worked the 20th Century, usually about 1000 tons, from Harmon to Chicago, 925 miles, in 16 hours with 7 intermediate stops. In practice the J-3a boiler, in line with most modern boilers, could produce more steam than the engine could consume. What made the J-3a so much more powerful and efficient was the care taken with the dimensions of live and exhaust steam passages and the high degree of superheat (about 750 degree F). J-3a’s on average worked about 12,000 miles per month.
Not sure if this what you wanted. In any case it is just a sample.
NM_Coot
Whenever I see a thread like this I usually do a quick google for the challenger freight video.
It puts it all into perspective. The fact that you have so much black smoke shows that there is a lot of unburned fuel/inefficiencies, but she is a beaut.