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Chapelon and related Matters

Discussion in 'Steam Traction' started by Big Al, Oct 25, 2023.

  1. Big Al

    Big Al Nat Pres stalwart Staff Member Moderator

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    Raised a smile. Not certain about Rule 6 . Where would some of our English designers be without the expertise and engineering know-how of the French - i.e. Chapelon?
     
  2. S.A.C. Martin

    S.A.C. Martin Part of the furniture

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    Hmm…:)

    For another thread I think…
     
  3. Big Al

    Big Al Nat Pres stalwart Staff Member Moderator

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    Indeed so. It all fits into the category of 'X' = good, 'Y' = bad where you insert your designers of choice. Learning is a two way process and I've always been of the view that the best designers do not close their minds to anything from their peers. That said, selectivity is wise!
     
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  4. 242A1

    242A1 Well-Known Member

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    However Chapelon was a bit of an outlier - his relationship with some of the railway hierarchy wasn't exactly smooth. Prove people wrong and they will resent you for it rather than learn from your example, or examples in Chapelon's case. So for those outside of France rule 6 might well not apply in his case. It could be said that this exception proves the general rule.
     
  5. S.A.C. Martin

    S.A.C. Martin Part of the furniture

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    We need a new thread, tbh. I was initially sceptical ahead of my Gresley research and I found in writing that book that there was an awful lot Gresley taught Chapelon, and not the other way around. He benefited, certainly, from some aspects of Chapelon's work (the Kylchap derives, arguably, as much from Kylala as it does from Chapelon) but the evidence points towards Gresley as a fully fledged locomotive engineer and Chapelon as an improver, rather than the full C.M.E. role of the former.

    We had an interesting debate on the Gresley thread before, I recall. I still remained unconvinced of the clamour for Chapelon.
     
  6. Romsey

    Romsey Part of the furniture

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    I don't think it's so much the engineers or designers but the political elements meddling or trying to score political points.

    Cheers, Neil
     
    Last edited: Oct 25, 2023
  7. 242A1

    242A1 Well-Known Member

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    Gresley and Chapelon were very different people. Gresley was born in 1876, attended Marlborough College, served an apprenticeship at Crewe and became a pupil of Aspinall. He quickly rose through the L & Y before joining the GNR.

    Chapelon was born in 1892 and was a graduate of the Ecole Centrale in Paris, official name Ecole Centrale des Artes et Manufactures, a very notable institution. Levassor and Panhard graduated from here as did Georges Darrieus, Rorbert Rillieux, Eiffel and thousands more. Chapelon served in the Artillery in WW1 returning to the Ecole in 1919 to graduate in 1921. He joined the PLM but found it unscientific and offering poor prospects so he left to work for the Societie Industrielle des Telephones before joining the PO in 1925. He jointly worked with Kylala on the now famous exhaust system and it was 1929 before 3566 appeared as a one off he was permitted to do to test his theories. Was it testing theories or just putting his knowledge to use? He predicted 3,000 ihp at speed and achieved it. A little later with a few adjustments 3,400 ihp and then 3,700 ihp. His modifications were not particularly costly at the time, only a few hundred pounds per engine and much cheaper than building new machines. More power was needed and so eight coupled rebuilds came about giving at first 4,000 ihp. This progress was driven by a number of factors including the growth of electrification. He didn't need to build new engines to prove that established accepted thinking was less than well founded. But this thinking was a part of the Railway Establishment and like any institution members reacted to maintain their position or justify them. He developed ideas, proved further established notions to be incorrect, set efficiency records, left research which benefitted the TGV. But never got to build the engines he really wanted to do or could do.

    It took a long time for Gresley to develop his Pacfics into something which could approach 3566. He could have done better than he did, he took some poor advice from Dalby which delayed things on the valve gear development side but he had a good team and got through it, he was responsible for more than just locomotives and there was the financial issue. Gresley was undoubtedly good, he wouldn't have progressed so quickly if that were not the case. But Chapelon's academic background gave him the edge when it came to locomotive development. It is interesting that those who came after him never produced locomotives which could equal those he produced unless they followed his template. Even DeCaso's famous U1 Baltic fell short even though it was an outstanding achievement.

    In 1952 the building of the prototype 152P was underway, the first of the 6,000 hp engines made possible by the creation of 242A1. Then the decision was made to end all steam development work. He had waited a long time to get his engine, his fusion of ideas. But it was not to be.
     
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  8. S.A.C. Martin

    S.A.C. Martin Part of the furniture

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    This is why we need a separate thread really and have that discussion elsewhere, because fundamentally focusing on just the horsepower aspect of Chapelon’s locomotive work and comparing that in isolation to Gresley’s work, who was running an entire railway system as CME, with locomotive design as just one aspect, is academically questionable.

    Not to mention that, as has been pointed out on the Gresley thread, there were thousands of Gresley locomotives doing actual work and a very much smaller proportion of Chapelon locomotives in service.

    Playing Top Trumps on one aspect of locomotive design isn’t a great basis for an academic debate, in my opinion.
     
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  9. martin1656

    martin1656 Nat Pres stalwart Friend

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    I have to agree, this, as interesting as it is, has nothing to add to the Tornado story, and this needs a separate thread, People who see a new post on this thread, are hoping for news, an explanation maybe, an update on how the overhaul is going, they don't want to read more about French designers, or what Gresley had for breakfast[/QUOTE]
     
  10. Jimc

    Jimc Part of the furniture

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    And if Gresley had modified his locomotives to give much more horsepower, then wouldn't the result have been appalling reliability due to his staff's apparent inability to design adequate big end bearings?
     
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  11. LMS2968

    LMS2968 Part of the furniture

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    You mean like 4472 wit a 250 p.s.i. boiler? Although in that case it was the whole engine, including the frames, which suffered.
     
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  12. S.A.C. Martin

    S.A.C. Martin Part of the furniture

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    Loath to keep pushing this off topic, but many A3s were fitted with the A4 type boiler in BR days but reduced the boiler pressure to 220lb. There were not, as far as my research has shown, the same issues that Scotsman had in the preservation era, which are probably a combination of other factors (including cylinder reboring, for example).
    Probably not, as the issue was one of sustained high speed and overrun and not fully the big end design, which for freight, mixed traffic and banking engines fitted with the conjugated gear was perfectly serviceable in normal operating conditions.
     
  13. Jimc

    Jimc Part of the furniture

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    And if you upgrade all the structure, bearings and everything else to cope with the extra loads then you are tons over the weight budget, so the boiler has to be reduced in size to get the weight down and...
     
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  14. MellishR

    MellishR Resident of Nat Pres Friend

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    I agree that this discussion deserves a separate thread but I am not opening one because I am not at all sure what the title or exact scope should be.

    Meanwhile continuing here for now; Simon is right that Gresley's reputation should rest on all of his achievements, good and (sometimes) not so good, whereas Chapelon's rests on power output. However the latter was not a figure in isolation. It was power output in relation to the size (and therefore weight) of the locos and the amount of coal and water consumed in delivering the power. It has often been observed that efficiency was less important in Britain where we had plenty of relatively cheap coal, but that didn't stop a lot of our CMEs putting a lot of work into improving efficiency, so it does seem strange that the adoption of Chapelon's principles was so half-hearted.
     
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  15. MellishR

    MellishR Resident of Nat Pres Friend

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    That doesn't seem to have been a problem for Chapelon.
     
  16. 30567

    30567 Part of the furniture Friend

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    title-- are russet apples better than comice pears?
     
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  17. S.A.C. Martin

    S.A.C. Martin Part of the furniture

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    I can't see why a title just titled "Andre Chapelon" isn't usable, to be honest.
     
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  18. LMS2968

    LMS2968 Part of the furniture

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    I'm not very familiar with things across the Channel but what was the maintenance / overhaul mileages, and the annual mileages, for these high power Chapelon machines?
     
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  19. Jamessquared

    Jamessquared Nat Pres stalwart

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    How big was the French loading gauge? There are features of Chapelon's locos (such as feed water heaters) that seem to benefit from having generous width outside (and above) the boiler, without having to compromise the boiler down to a smaller diameter. An extra foot of width or height makes quite a significant difference in packaging all the equipment needed for a complex loco.

    Tom
     
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  20. S.A.C. Martin

    S.A.C. Martin Part of the furniture

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    Something always conveniently left out whenever Chapelon is mentioned, actually.
     

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