Chapelon and related Matters

This is a thoroughly frustrating response and needs addressing.

If you make a statement with no citations or no references, how can we examine this and understand it better?

One of the unspoken (but very much agreed and followed) rules on the Thompson and Gresley threads is that people need to give evidence for their statements when challenged. I think for academic purposes that really needs to be the case.

Making a series of vague statements and then saying "it's in books and papers" isn't good enough. You need to be specific. If you look elsewhere on this forum I have made it possible for those who want to continue their reading to look at a single thread for sources of information, separated out by topic.

That's really what we are looking for.

But again, we're missing some details here. What were the modifications? If it's limited to just the superheater, that's a change that many locomotive engineers have done to older locomotives across the globe. What made this one a particularly potent rebuild, and how did this somehow affect Chapelon personally in a negative way?

That is more of what I am asking for, I will look up that source. Interesting to note the forced reduction in the speeds, that would certainly skew development quite markedly.

All I am asking for is that when someone makes a statement, they can back it up with a reference, citation or source so that it can be analysed further.

 

Perhaps, but the choice of a GNR C1 4-4-2 by 242A1 was I assume considered. The C1 boiler had a total
evaporation area of2450 sq.ft married to a 31sq.ft grate. ( the various special locos eg compound, 4
cylinder etc.had even larger evap. areas.

( Compare SR Schools 2049 and 28.3. They consistently on the 9.15 ex Charing Cross delivered EDHP between
1300 and 1400 between New Cross and Knockholt, probably IHPs of 1500-1600. I do not have to hand a
max for the Class but I think 1800-1900.)

I think the C1s regularly developed EDHPs of 1200-1300, possibly more in the late 1920s to 1930s after various
minor adjustments. ( they had lower boiler pressure than the Schools, 2 cylinder vs 3 etc). i.e. a C1 designed
in the 1930s could reasonably be expected to produce 2000IHP . Although the increased boiler pressure and
cylinder volume would lead to an increase in weight, ( 69tons 12cwt to 72tons ? )

I have no doubt that if a rebuild utilising the thoughts of Chapelon and his acolytes were undertaken that
2500IHP could be extracted from a C1 Atlantic. As 242A1 says it’s thermodynamics.

Thompson when he was i.c. Stratford works oversaw the rebuilding of the Holden 4-6-0s, essentially
a larger boiler. The resultant B12/3 were marginally more powerful than the B17 Sandringhams but
suffered from frame problems etc induced by the added stresses.

The C1s with their large boilers were undoubtedly conservatively designed but they had a long life and
it was only the lack of maintenance in WWII and the advent of the B1s that brought their demise.

Stating the obvious French and British practice were very different, particularly wrt footplate manning,
overall speed limits, maintenance and the move to electrification. (eg comparatively few Maunsell locos
compared with Gresley, Stanier and Collett ) However, in no way wishing to denigrate British Engineers
Chapelon was a major influence not only in France but around the World, arguably a genius.
Whether less locos were built to his designs in France than were built to Gresley’s in the UK is
irrelevant to Chapelon’s standing as a locomotive designer.

Michael Rowe

 

With respect Michael, your main focus is again purely on power output. Locomotive engineers do not just consider power output, there's a huge range of different factors to take into account, not least the needs of the operational railway.

I do hope you can quantify the statement of Chapelon being a "major influence around the world" - I cannot see this to be true. Minimal locomotives built to his designs abroad (metre gauge locomotives for Brazil).

What were his "innovations" that were used abroad? We can see the Kylchap is listed - but this is jointly with Kylala, arguably the more important side of the design given it was his design that Chapelon subsequently modified.

"Genius" is used without quantifying why he is a genius. If Chapelon's actual innovations are used minimally, and his actual sphere of influence is small, the argument can be put forward that he's not as important a figure as the secondary sources claim in railway history to date.

So for me, the discussion is interesting - but what's been put forward is not convincing me of Chapelon's genius.

 

While we are talking about French stuff (which I know virtually nothing about) what is, or was, a 230B? I ask the question as two of them featured in the brilliant 1964 film The Train

 

Yes I agree wrt power output. I was responding specifically to the various IHP claims, specifically
as related to power/weight ratios. I also suggested ( using the B12/3 s as an example) that high
power/weight ratios might result in greater risk of mechanical failure.

Chapelon’s writings ( some with Sauvage) and specifically the 1938 “Locomotive a Vapeur”, were
very influential. The “arguably a genius” epithet was based IMHO on his recognition of draughting,
complete combustion, minimising external heat loss and pressure drops, maximising heat
flux allied with a sympathetic water treatment regime.i.e. increasing overall efficiency ( as per

second law of thermodynamics ). All of this contributed to the high power outputs.

I appreciate that this does not constitute a data set. The 1100 pages of Locomotive a Vapeur
reward perusing. The shortened 1952 version ( English translation available ) contains the
essence.

His influence I suggest can be seen in the post WWII designs in Germany, Eastern Europe,
China and the Indian sub Continent.

Michael Rowe

 

As a relatively small thing its recorded (Durrant, Swindon Steam) that in the 1930s the GWR changed their steam chest design to increase the internal volume as a result of Chapelon stating that greater steam chest volume meant less pressure drop when valves opened for admission.

 

Which particular designs in China were influenced by Chapelon? The Giesl (an unlicensed version) was relatively common.

 

The SNCF classification system sometimes allowed the same class name to be given to different types on different SNCF regions - a bit like the situation on our SR! There were at least two 230B classes. Not being familiar with the 1964 film, I'm unsure which one you want!

Firstly, there was a PLM express passenger class with 2.00m (6ft 7in) wheels:

https://fr.wikipedia.org/wiki/230_PLM_2601_à_2760

But SNCF gave the same class designation to an ex-Etat mixed traffic type with 1.75m (5ft 9in) wheels:

https://en.wikipedia.org/wiki/État_3701_to_3755

Both types were 4-cylinder compounds dating from the early 1900s. But apart from the differences in role and coupled wheel diameter, note the cylinder positions. Whereas most French railways followed the de Glehn model for 4-cylinder types, the PLM placed the outside cylinders over the bogie centre, similar to L&Y Dreadnoughts and SR Lord Nelsons.

 

But in what manner Michael? I am still no clearer on what direct influences he has had on any of those areas of the globe.

There's a lot of talk of him being the foremost steam locomotive engineer, I note from some of the books (one Colonel Rogers included - for which I have deep misgivings given the atrocious tome on Thompson he wrote) - how has he achieved this accolade?

From where I'm standing, I can name a good number of locomotive engineers I would put ahead of Chapelon, two of which are GWR engineers, two LNER engineers, one LMS assistant engineer responsible for locomotive design, another Frenchman who produced some locomotives which affected, in particular, British locomotive policy, an Austrian who produced some excellent exhausts, and an Argentinian (who probably produced one of the world's greatest locomotives, now tragically lost to scrap and vandalism in the 2000s).

Of those engineers, one of them has a significant number of world firsts and records to his name, and actually influenced (I would argue) far more than Chapelon did in railways generally, not just locomotives. Certainly, Chapelon was influenced by him in streamlining terms.

There's an air of over egging the pudding here for me. I'm not convinced. I am open to being convinced - but so much of this is so vague. We need stats, we need evidence, we need direct citations and some better explanation than "he influenced a particular country" without explaining what his influence was, and what the effects were. Sorry to say.

 

Not being very familiar with those country's locos, I'd be interested to know how.

The locos held up as his best designs seem to be exercises in complexity in the interests of thermodynamic efficiency - the ultimate being a six cylinder compound 2-12-0 with an intermediate re-heater between high and low pressure cylinders. That's a long way from a German class 50 / 52 Kriegslok for a loco designed to do a similar job!

Look at the way loco design was going in the UK, US and Germany before - and especially after - the war. The prevailing design philosophy seems to have been about utilisation and cutting labour in servicing. Hence you get rugged two cylinder simple designs with (in the UK) labour-saving features like rocking grates, self-cleaning smokeboxes and the like: in the US a degree of gigantism fed by mechanical stokers. The ethos is to recognise that labour is the significant cost in operating steam locos, not fuel, so designs are optimised around minimising labour (and improving time between overhauls, which cuts capital investment by means of reduced fleet size to cover a given work).

Given that, in what way was Chapelon influential? Robert Stephenson was influential: "Planet" formed what was the basic template for British steam loco for the next half century. In the twentieth century, Churchward was influential: a BR standard is essentially the same template as a Churchward loco being built fifty years earlier, with a nod to Urie / Maunsell ideas of access.

Evidence of influence to me is for later designers to be copying your ideas. But Chapelon's designs in the 1920s onwards didn't lead to large numbers of complex high thermodynamic efficiency compounds in the subsequent years: the road travelled was entirely different because designers saw the problems of steam locos in entirely different terms to those perceived by Chapelon. I can't help thinking that in the absence of much evidence of his influence on later designers, there is a tendency for acolytes to say he was influential because they wished it had been so, rather than because it objectively was so.

Tom

 

Eloquently and perfectly put Tom, thank you for saying what I have been struggling to say.

 

Thanks for the interesting reply. The engine in the film was 230B517, and it looked very much like the Etat version, it definitely wasn't the PLM one

 

Simon, I strongly suggest that you read La Locomotive a Vapeur, which I am sure you will find an interesting read in the broader sense, but in particular Chapter 10, in which Chapelon lays out what was done in the first PO Pacific rebuild. The headline is really the opening up in the steam circuit, from 1/10 of piston area to 1/5. If any pre-Chapelon express passenger locomotives in the UK approach that figure I don't know which they are, yet if you look at a Bulleid or an A4 (both post Chapelon) you will notice the almost exaggerated size of the main steam pipes compared to something like a Castle. They also had Lentz poppet valves driven by long lap Walschaerts gear, high superheat (up to 400C), and englarged valve chests. But he also lays out the incremental modifications tried on subsequent locomotives and how much effect they had, building up to the complete package. The net result is that the original locomotive had a rated drawbar horsepower of 1440 hp (and this from a pre-war Pacific) while the final modified version (of the Pacific) had a rated 2650 dbhp (I will not quote ihp except in very specific circumstances, ihp never pulled a train). Now, I know you're saying: "But what about the things that weren't the power?" The power was the point, I'll return to that in a moment. They were efficient too, each incremental version had a lower coal consumption per dbhp than the predecessor, and was also more efficient across the working range, even when not working at full power. There are graphs and many of them to illustrate the point.

So, back to why the power (and efficiency) was the point. France got into Pacifics earlier than the UK, there were several pre-war classes and far more Pacifics existed in France pre-Chapelon than in the UK, where only the LNER had taken to them in any significant way. But more power was required; train loadings were heavy, uphill speeds needed to be high and a lot of them were somewhat disappointing in performance compared to the Atlantics that had gone before (they had not scaled up well). Some lines had tried Baltics with little return, others were getting into 4-8-2s. So more power was definitely needed, electrification was on the way (because coal was expensive), investment in new types would be avoided if possible. And then Chapelon demonstrated that the existing Pacifics (of which there were many) could be improved substantially. The PLM alone rebuilt two hundred and more of their Pacifics. The PO Pacifics, dispersed by pre-war electrification, ended up all over the SNCF network and the Nord had even more built new to the modified PO spec (231E) when they ran out of examples to rebuild, despite the Nord Pacifics being among the best of the pre-Chapelon types. So perversely, his influence was to quell the need for new high power machines to be built. The Pacifics were already there, they could be and were made more powerful and more efficient instead. Nothing to any comparable extent happened in the UK; the A1 to A3 evolution or the rebuild of the Royal Scots being about as extensive as it got when it came to rebuilding of top link power for greater performance.

The largest new built class following his influence was, of course, a set of mixed traffic 2-8-2s. The post-war influx of 141Rs came into a different world, ordered under Lend-Lease, they were never going to be a typically French design.

 

There's an apples and oranges debate going on here, a little.

Cutting it down, SAC Martin is of the quantity matters, whilst 242A1 is of the quality matters camp.

In terms of getting 3rd party sources, there is very little available unfortunately.

 

But arguably Gresley and his team including Bert Spencer were already doing what you’ve described in the refinement of the streamlined internal passages for the Pacifics and up to the A4 development (and including the W1 and P2 developments). In my research I came across several interesting letters between Gresley and other members of the LNER design team and it was pretty clear they believed they were first to make these incremental improvements to the overall steam circuit.

Chapelon’s first rebuild appeared in 1929: in that same year Gresley had A3s being built, the W1 emerged in its three cylinder compound, and high boiler pressure setup, and the P2s were just coming onto Bulleid’s drawing board. All of these classes had improvements to the basic steam circuit setup.

One thing to note though - Gresley took on the Kylchap exhaust for the P2s (minus one) and one A3 first, followed by the W1 and then four of his A4s before he passed in 1941. It wasn’t until Thompson took over that all new Pacifics would be built with the double Kylchap setup, and in Peppercorn’s day, it was only applied en masse to the A1s, the A2s having a mixture of single and double chimney fittings. So there was still room for examining the costs and looking at the compromises between other tech (like self cleaning smokeboxes) that might be more desirable.

Gresley was, as far as I can see, the first in the UK to use that exhaust type but the LNER were also the only ones in the UK to use it in any great number. I know it was mostly a great success, particularly when applied later in BR days (the late Peter Townend having them fitted to some V2s and a significant amount of the A3s, together with all of the A4s), but in the grand scheme of things Chapelon’s influence looks very limited here. If anything, he was following Gresley’s lead on some details.

 

A bit simplistic, Tom has summed it up well above - we need to qualify what Chapelon's influences were and then quantify them to see what effect he actually had elsewhere.

 

There are also two further dimensions. One, interesting but lesser, is over the correct sequence of events (where it would be interesting to know which way round the influences worked) - for example on steam passage work.

The second is about degree. To judge by some comments, a suggestion that either Chapelon or Gresley was not the best engineer since Archimedes is being interpreted as a suggestion that they are a complete non-entity. For this layman, I don't think there is any question that both were in the first rank of steam locomotive engineers; understanding significance is then a much deeper and more challenging task given their overlapping careers and the wider circumstances affecting both their working lives and the future of their designs.

 

To me there are separate questions - is the designer any good, and were they influential?

Chapelon was good, in the sense that his designs worked and had high efficiency. But to be influential, you need to see others following the same design philosophy, and that is what I am struggling with.

It’s possible to be influential but not actually much good. Thomas Crampton was an example: he had a very specific design ethos that he hoped would solve problems as he saw them; and locos to his design philosophy were very widely used across both the UK and in Europe. It just turns out that in the main they weren’t very effective and were, in the main, quickly rebuilt or replaced. But I think he was undeniably more influential than Chapelon, just his designs were less effective.

Tom

 

Just on the "good" point, I would also suggest that this has to be assessed in context. And there the interesting question is whether Chapelon's designs, good as they were in the specific context of the French railways, would have been correspondingly beneficial in the significantly different environment of the UK. I suspect that the combination of loading gauge, readily available coal supplies and cheap labour would have made Chapelon's designs unaffordably expensive for use in Britain. For example, there's been mention of the adoption of Kylchap chimneys - my recollection is that this was very delayed in the UK, despite proven financial payback, and that Townend was not allowed to complete the work due to some very tight cost management decisions.

That is an assessment that has nothing to do with the quality of his engineering, and everything to do with the trade off between cost and benefit.

 

E.S.Cox. WORLD Steam in the Twentieth Century. Ian Allan 1969.p.15

QUOTE. “ Whilst these lineaments have also in their way spread into some
other countries around the world, although to a lesser extent than those of
America and Britain, it is not in externals that France has had an almost
universal effect, at least over the last thirty years or more, but rather
from the technical work of one of the giants of the steam world, André
Chapelon. His work on the opening out of the whole main circuit, directed
especially towards freeing the compound engine of its internal restrictions,
has been picked up in many other countries and has greatly enhanced the
performance and efficiency of simple expansion engines as well END QUOTE

p.69. QUOTE “In the concluding years up to 1939 increasing attention was
paid to the work of Chapelon in France, who by opening out the steam circuit
all The way from regulator intake to blastpipe tip, had disclosed new vistas of
performance and efficiency not only for compound but the simple expansion
as well. Gresley and Stanier in particular took note in a practical manner of
the possibilities involved and in their Pacific designs paid close attention to
the ease of passage for the steam through the cylinders END QUOTE

Stanier to the Institution of Locomotive Engineers in 1939

QUOTE “The work of Chapelon has drawn to the attention of Locomotive
engineers all over the world the importance of the internal stream lining
of the steam passages all the way from the regulator to the blastpipe, and
there is no doubt the importance of smooth steam flow has been ignored
in the past. END QUOTE


Michael Rowe