Can anyone tell me if and what impact and influence the ideas of Andre Chapelon (e.g. very high superheat, adequate drafting with double exhausts etc, importance of good exhaust porting from the cylinders) had on American steam?
Chapelon was the ‘god’ of French and European steam, and through the adoption of his ideas very significant increases in horse power and economy were achieved from quite modestly sized machines in the 1930s and 40s.
It is my percpetion as an Englishman’s that he sadly had little influence in the US, with the possible notable exceptions of double exhausts to UP’s Challengers and possible poppet valves on the Pensy T1s.
Chapelon put a lot of other peoples ideas together and did refining. US railroads operated under different circumstances, for one thing they were trying to make money, in that era Britain was the only European country which hadn’t yet nationalized their railways. In Europe coal was expensive and the railways were employment. In the US coal was cheap, and railroads were trying to cut costs. The B&O tried watertube boilers and both Giesl, and Kylchap Exhaust nozzles. The Delaware and Hudson tried very high superheat and high-pressure boilers, and even triple-compounding in a non-articulated locomotive. Several railroads tried Caprotti Poppet valves, and the improved Franklin Poppet valves, but in the end simple to build and maintain won out.
In terms of the “what could have saved steam” discussions, the Andre Chapelon and his disciple Livio Dante Porta were pursuing a middle ground between steam as it was and all of the “exotic stuff” which I would include turbines, water tube boilers, condensing tenders, much higher steam pressures, and so on.
I think the exhaust arrangements along with the steam-passage streamlining and perhaps some of the firebox mods are a just-plain no-brainer. It is like tuning a car engine for more horsepower by putting on “headers” or otherwise having a low restriction exhaust as well as induction system. The advantages for steam for such “tuning” are huge because the steam cycle at 200-300 PSI pressure is so low-efficiency to begin with that anything you do will give large gains. I fail to see how streamlining the exhaust passages would increase maintenance costs, especially when a lot of subscale live steam builders are doing it these days.
The bit about boosting the superheat temperature is also straightforward, but you run into limitations with cylinder lubrication. But the reason you need the higher superheat is that you are also going to increase the expansion ratio since you have that lower exhaust back pressure, and doing that needs the superheat to avoid condensation in the cylinders. And how are you going to increase the expansion ratio?
One way is compounding, and I believe Chapelon was doing that along with Porta, although not all of Porta’s designs were compounds. If you have something better than Walschaerts and piston valves (poppet valves?), you could probably do something about higher expansion with simple engines. But while poppet valves didn’t work out in American practice, they are not in the “exotic” category as water tube boiler, ultra-high pressure, and so on.
The thing about Super Power steam is that it was doing what you had been doing but just do more of it. Mayb
Thank you. Actually Chapelon succeeded in increasing the power output with the rebuilding of the E class Pacifics and the 240Ps by about 50%, and got the same horse power out of a 40 sq ft grate as an K4 Pacific with a 79 sq ft grate. That’s why I asked the question - could more have been achived in the US?
Does anybody have anymore info as to which US designs incorporated Chapelon principles?
IIRC, Chapelon visited several US railroads in the late 1930’s, including N&W. He had good things to say about our designs and incorporated several US ideas into his proposed group of modern designs for French railroads. Unfortunately, SNCF decided to electrify, and only one of his designs even got started, something like the frame casting.
I’ve been curious if N&W paid attention to his ideas, because their addition of the “booster” idea to the Y6’s was something that Chapelon did on one of his non-articulated locos (2-10-0 or 2-12-0 experimental with reheater). On the Y6, the booster valve allowed the engineer to add a small amount of superheated steam to the LP receiver while operating in compound, raising the temperature and degree of superheat without switching the loco back into much less efficient and slower simple operation.
I believe UP’s double exhaust locos (4-8-4 to 4-8-8-4) incorporated some of Chapelon’s ideas in the 4-nozzle twin stack configuration, although it was still basically a Master Mechanics front end.
Doesn’t Grand Canyon’s 2-8-2 have a Lempor exhaust, which has some of Chapelon’s ideas in its configuration?
Watch out for 3985. Very interesting mods to the exhaust system being installed there. We may find out what benefits will result from more advanced exhaust systems on a large loco
I’m writing this from memory, an increasingly dangerous method as time goes by. Will see if I can find anything more in all the books around here re: Chapelon and the US.
I don’t consider the PRR K-4 Pacific in any way a superior design for comparison. It was successful, and built in large numbers, but within a few years PRR had to double head all their principal passenger trains because the K-4 wasn’t powerful enough to do the job even on flatter lines. The NYC had much more advanced designs.
Chapelon noted in his book, La Locomotive a Vapeur, that he rode on N&W Y6 2122 on Nov 2, 1938. Based on a footnote, there is further information in Chemins de Fer, May/June 1939. This may be the French equivalent of one of our railroad magazines of the era (e.g., Railway Age, RME, etc.). How long he was here in the US and what other railroads he visitied, I don’t know. His designs in 1938 ranged from a 4-6-2T through 4-6-4’s, a 4-8-4 to a 2-10-4.
The experimental loco I was thinking of earlier was the 160A1, a 6-cylinder compound 2-12-0 (2 HP and 4 LP cylinders). It had a reheating circuit between the HP and LP cylinders. Although built in 1940, it wasn’t tested until 1948, after the end of WW2. Whether N&W knew anything about this is unknown. I’ve looked through the available files of locomotive information at the N&W archives in Roanoke many times, but so far found nothing from the 1938 era regarding his visit. Although there is considerable information regarding the modifications incorporated into the Y6’s from 1948 on, I’ve seen no reference to Chapelon. I do know this, however. The “boys from Roanoke” were not as insular as some think they were. The motive power people were constantly comparing their locomotives to others in the US. They were very conscious of what was going on in the industry.
No one is talking about Pennsy’s crusty old Pacifics in this discussion. The Pacific in question was a French locomotive, and it was able to produce more HP with 1/2 the grate area of American Pacifics. Even the “advanced” NYC designs you mention are not much to brag about from a mechanical engineering perspective.
pure speculation on my part but…i would think that in places like the hollowed halls of the Eddystone Works or Lima’s huge complex in its hometown were diagrams and notes of/on people like Chapelon and what ideas could be used short of infringement would be used
Admittedly there probably is some infringement. But keep in mind, locomotive designers around the world were working on improving their products. In short, someone may have gotten credit for it becuase he happened to publish his idea/complete his product first but doesn’t mean that others weren’t working in it.
The American school of thought for steam locomotive design and French school of though is worlds apart. American steam essentially was rugged, simple, easy to operate. Sure we tinkered with some stuff but in terms of design, we never really strayed from it in the heyday steam. French had more complex machines and their drivers were engineers (not promoted firemen) to understand how to operate them. Chapelon is a product of that environment and therefore some of his ideas probably wouldn’t make it onto a locomotive class for a US railroad. And also, think of this, some of the last steam locomotives to run of the French railroads was order by the French government to US companies to augment the locomotives that survived WWII. One of the reasons was lower operatiing costs.
I admit I do like the Pennsy approach to steam design (and the look of the Belpaire firebox) and the ATSF approach after 1912: simple, two-clyinder, and nothing fancy.
and the bottom line is… US: labour costs sky high, fuel costs low, coal quality doubtful (that accounts for the firebox difference, by the way), work load very high; Keep It Simple, Stupid. France: labour costs very low, fuel costs very high, coal quality good to excellent, time to do lots of fiddly maintenance. Chapelon/Porta wins in the latter environment, hands down. Lima, Alco, Baldwin win in the former.
One could extend the analogy to cars, as someone did above: say what you like about a pushrod V8 with a good Carter 4 barrel in terms of efficiency and whatever – but you could tune one with a dollar bill and a good ear, and whatever broke you fix under the backyard tree, and they ran forever if you took care of them a little bit. Try that with a modern, double overhead cam computer controlled four valve per cylinder screamer. Right… different solutions for different problems.
IIRC, Chapelon made a considerable improvement in those US-built SNCF 2-8-2s by the equivalent of porting and polishing their steam passages - certainly within the capabilities of US shop forces and by no means exotic in concept.
It’s interesting to note that the 141-R’s were the last operating steam in France, well after all of the indigenous French designs were removed from service.
Chapelon’s influence on American steam locomotive design may have been minimal because it came so late. If most of the data produced by the test runs of 160A1 and 242A1 came after 1948, it was too late for any influence on North American steam since only Roanoke was still building steam by that time, and not much longer at that.