Chapelon and related Matters

The whole system of maintenance in France was different so difficult to compare. Drivers were all qualified engineers and looked after their own engines, if an engine was stopped for a mechanical fault the driver would be involved in the repair work. I think they accompanied them to the works for general overhauls. If he changed to a different class of engine he had to be passed out on it before being allowed the drive unsupervised.
The position of fireman was a separate semi skilled job and there was no promotion route to driver. On a couple of visits to Calais before the end of steam I was quite surprised to see that in a lot of cases the fireman was considerably older than his driver.
Given the learn as you go approach in the UK, where a crew were expected to take on any engine allocated to the job, I doubt if such complex machines as Chapelon compounds would have been a success.

 

As ever I don't believe there was any one loading gauge, but here is the standardised Berne gauge (orange) against the GC loading gauge (cyan) and the smallest of the standard NR gauges (Gray shadow). There is a good bit more room. Note especially the extra space for cylinders, which in turn permits wider rod bearings and so on.

 

It would probably be impractical given availability of records, but it would theoretically be possible to look at this in terms of whole life cost to see how it would compare, given the nature of the differences. That feels like a PhD in economic history type topic though...

 

With thanks to the mods for moving the discussion across to a new thread.

 

Hard to say exactly. Chapelon in his own writings tends towards the performance as well, but there is a section on locomotive utilisation, covering about 5 pages. He was clearly very impressed by the results achieved in the US and writes enviously and at length about the methods employed and results achieved, but for French service I think you could approximately extract the following:

Up to 10,000 km/month for single-crewed locomotives on express service, rising to 15,000 km/month with double-crewing. Pool working apparently resulted in a reduction in total mileage (kilometerage?). He notes that for effective implementation of pooled working the maintenance organisation must be in place to adequately replace all the work historically done by the crews and considers this a solved problem in the US context with consequently much greater mileages. But, back to his commentary on French matters:

The very American 141Rs managed 2.4x the fleet average monthly mileage for the entire SNCF steam fleet, working out at 300 km/day (or 9,000 km/month) at a time when the electric fleet averaged 2.7x the steam fleet monthly mileage. He cites the 141R performance as being "equalled or even exceeded" by the entirely SNCF 141Ps, but with the caveat that this was for the Ouest region fleet. I might guess that the 141Ps in the Ouest did more express work than was typical for a mixed-traffic class, as apparently the 141Ps were preferred on fast work to the 141Rs, with no doubt favourable effects on their mileage. The superior availability of the 141Rs was uncontested. While Chapelon cannot claim any entirely new-build compound design to his credit, since I suspect neither of the post-war SNCF classes were entirely as he'd have done it, I get the impression he was much happier to be associated with the 141P than the 241P; he certainly cites a lot more of their performances.

The other interesting statistic cited is the 250,000km average distance between failure on route for the entire SNCF steam fleet; the period for this is claimed as "the early 1950s" in a footnote.

Sources not cited in the text, but well-sourced information on French locomotive matters is I suspect a challenge for a very doughty researcher indeed.

 

The 141P class numbered 318 engines and were produced by seven builders.
The 4-240A and 5-240P numbered 37 engines in total.

So far as Pacifics go, on the Est 231-051 to 231-073 were rebuilt PO series 3500 (later 1-231.C.51 to 72) total 22 engines
The Nord had rebuilds of the PO series 3500 3.1171 to 3.1190 ordered directly from the PO-Midi in 1934 later 2-231E.1 to 20. They also had two batches of Chapelon Pacifics newly built one in 1936 3.1191 to 3.1198 later 2-231E.21 to 28 and then one built in 1937 and 38 3.111 to 3.1130
for a total of 48 engines.

The PO had the rebuilt 3566 plus 3701 to 3721 produced in 1932, these were the first type of Chapelon rebuilds and 3722 to 3731 were produced in 1934 of a second type.

The experimental 160 A 1 was a rebuild of a PO compound 2-10-0 number 6030. It was produced between 1938 and 1940 at the Tours workshops and was taken to Brive on a 1,200 ton freight train with no running in whatsoever in order to be hidden away to reappear in 1946. This machine could develop 3,000 ihp at 25 mph. It was produced to prove that steam locomotives could produce high power outputs at low speeds and also to meet a PO freight loco requirement. It was also a testbed for his six cylinder compound ideas and had steam jacketed cylinders and an interstage superheater. The valves were Lentz poppet, the exhaust was double Kylchap and the first, fifth and sixth coupled axles had a lateral control mechanism.

The three cylinder compound was proposed in order to obtain a more robust construction in order to meet the demand for locomotives to develop 6,000hp and the opportunity to rebuild an OCEM design produced for what had been the Est system presented the chance to provide a proof of concept. 241B-101 was built by Fives Lille in 1932. It had come about as a result of a request by one Raoul Dautry and was a three cylinder simple fitted with Renaud rotary cam gear and it not only performed badly it also derailed regularly. Chapelon proposed rebuilding it in 1938 but he had to wait. During the German occupation he had been working on designs to be put into production once the war was over and was given his opportunity in 1942 with 242A1 appearing in service 1946.

Chapelon visited the USA. He went to Alco in Schenectady and rode on the N & W and he included a number of American ideas in his new designs. He gained power in his designs by making use of the application of thermodynamics. He didn't build bigger, the Pacifics were pretty well the same size as they had originally been but were far more powerful. The 4-8-0s were not much larger than the Pacifics they were rebuilt from but they produced far more power. Do you improve an engine by making larger or do you make it better?

 

So do we have totals for Chapelon’s actual builds?

It was a question I was struggling to answer when I was writing the Gresley book when it came up.

 

You need to add the 90 GELSA locomotives built for Brazil. So I think that there were 548 but I could be wrong. He produced a range of designs of the six cylinder school of thought and of the three cylinder but non were built apart from the two proof of concept machines. The 241P Class Built by Schneider of Le Creusot for the SNCF was based on a PLM design the 241C which was a poor choice seeing that this design was both less powerful and also less efficient than the smaller 231E. But much like BR and the LMS the ex PLM people were in control at the SNCF. They didn't want any input from Chapelon but Schneider got in touch with him. The SNCF had a requirement for a locomotive capable of 2,500 dbhp to haul 800 ton trains at 120 kmh on level track but the Chapelon 240P could haul such trains up a 1 in 125 at very close to this speed - they could sustain 3,600 dbhp. And where did these engines mainly work? The hilly sections of the PLM mainline. The PLM design needed attention paid to the steam circuit, strengthened frames and improved bearings. The end result could sustain 4,000 ihp and 2,900 dbhp (ish) and 35 were built. You should add these to the total but when you look at the 4-8-0 it makes you wonder if these 4-8-2s were worth the trouble. It appears that they only came into being because of political infighting. AXC did his work with Schneider, the PLM/SNCF got what it wanted but was it the best that Chapelon could do? Not really, far from it.

 

I’ll try again.

Do we have totals for:

• Total number of rebuilds/conversion
• Total number of new builds

Because from where I am standing, it looks like less than 600 steam locomotives affected altogether over the course of his career. As a reminder, Thompson alone affected LNER policy to the tune of 410 4-6-0s.

My challenge to those giving Chapelon the high status is can you prove that his engineering policies had a substantial affect on the railways he worked for?

 

The challenge with that, as previously discussed, is that Chapelon was working at a time in which modes were changing. Therefore the effect of his designs was reduced through factors that had nothing to do with his designs or the engineering, but simply through the transition away from steam.

 

How much (or how little) influence Chapelon's work had on the operations of the French (and other countries') railways is indeed one measure of his significance. How much increase in power he could get out of a single rebuilt loco is a different measure of his significance. We naturally tend to focus our attention on where he made a big difference rather than where he made less difference, but we should not ignore either.
His influence on the use of steam power to pull trains in France and elsewhere was limited first by WWII and then by the transition to diesel and electric traction. Even so, locos built in the 1950s such as the BR Standards could have delivered more power for their size and fuel consumption if more notice had been taken of Chapelon's holistic approach: we can argue about whether that would have been "better" for BR and for Britain.

 

I would argue strongly that there is again far too much emphasis on the performance/horsepower aspect of Chapelon's work.

Nobody's mentioned costs to convert/build his designs, were his designs simple/complicated to run, were they fuel efficient (evaporative rates and coal/oil consumed).

If you're moving over to diesel/electric traction then trying to build the ultimate steam locomotive looks like Canute trying to hold back the tide quite frankly.

The BR standards to me are the best compromise for continuation of steam power set against a desire to modernise and use new traction.

 

The French started experimenting with railway electrification in the early years of the twentieth century. At First came the phase of addressing technical questions plus development and then testing.

In the 1920s the 1,500 volt dc system came into use on the mainlines around Paris and in the Pyrenees. The reason for developments in the Pyrenees was the availability of cheap electric power, hydro electric. The P and O was the first electrified line out of Paris and the first section of this was completed in 1926. The Pyrenees (Midi) development got underway earlier and had locomotives capable of working at 120 kmh in 1922.

Chapelon's first rebuild appeared in 1929. This revealed that the established locomotive designers really did not know enough. This upstart upset the applecart and with just a few exceptions he was never forgiven for it.

Did Chapelon need to build new engines? And was it the right time to do it? If a locomotive was sound mechanically but lacking thermodynamically and the thermodynamic issues could be largely addressed at a modest cost there was no good reason to build new. The building of 3566 proved this and everything after this was a further improvement. The C1 Atlantics weighed a little under 70 tons and for that weight a Chapelon engine should produce well in excess of 2,500 ihp.

So the rebuilt engines had to deal with increasing loads and meet the challenge of electrification. Or in the case of 242A1 send it back to the drawing board. And if you think he was forgiven for that I know of a bridge that is up for sale.

It is rather pointless looking at the French situation and placing it under a UK overview. It is not about how many engines and it is far more complicated.

On the subject of complicated and engines. Compare a 231E with an R, you can do this at Mulhouse. It was Porta who thought that the French drawing offices were crazy. So many details that a crew can adjust if they understand what they are doing. The French crews were well trained, they could deal with their charges but it did demand skill and time, so back to the E and the R. Chapelon wanted and indeed needed to escape from the traditional French way of doing things. He wanted higher utilisation and higher mileages which the R could deliver. The French compounds were more complex but a large part of the complexity was the result of detail design practice.

 

The original Pacifics were costed at a few hundred pounds each at the time. They were complicated largely due to French drawing office practice. You don't get the greater power output within a very similar design envelope without being more efficient. Of course people mention these things, they also wrote things down.

When traction costs are calculated and everything is taken into account (i.e. the cost of catenary system maintenance not being deliberately omitted, or the cost for running old locomotive designs being used rather than the costs for current designs) there is next to no difference.

And as for the B.R. Standard designs, that is a very hard sell when you look outside the limiting shores of these islands.

 

I think it is naive to assume that there is a direct linear relationship between weight and power output.

For example, suppose you take a loco with a cylinder, say 10" diameter * 15" stroke.

Let's approximate the construction as being

• two discs of pi * d^2 * t in volume of metal
• a wrapper of pi * d * l * t

Now let's double all the dimensions. The amount of material constructing the cylinder will go up four fold, since it is essentially an area relationship of the size of the ends and the wrapper. But the power that can be generated will go up 8 fold, since that is related to the volume of steam ingested, all else being equal.

So doubling the size of the cylinder gives your eight times the power for only four times the weight of material.

Obviously in other areas the relationships are different, and would take a lot of calculation. (If you double the power of a loco, do you need frames that are double the weight? Probably not. Double the main steam pipe diameter gives you a different volume to wetted surface area (that causes friction to the steam flow) ratio etc.) But the point is you can't simply assume a neat linear relationship between mass of loco and expected power - saying that because a 140ton loco could do 5000hp, therefore a 70 ton Atlantic should make 2500hp is just silly.

Tom

 

I'm afraid I must respectfully disagree with your dimensional analysis. For both cylinders and circular flat plates, if you're designing to a constant stress (and why wouldn't you) the required wall thickness is proportional to diameter. So two discs, volume proportional to d^3 and a wrapper with volume proportional to l*d^2 Your port sizes have only come down proportional to d^2, so your steam flows are fantastic - in fact some work might need to go in to manage the clearance volumes. Now of course you may say that the foundry only does that wall thickness, and we insist on having x rebores of this dimension in the liners before new ones are needed, but those aren't fundamental scaling laws, those are choices.

In general with heat engines the small engines have fantastic power to weight ratios; think motorbike engines as opposed to car engines, because you can rev the living daylights out of them. Holcroft reckoned there was basically a piston speed at which all steam locomotives topped out (although I think this was influenced by valve events and porting too). But let's say they're all great; you have an eighth of the volume but you can go at twice the rpm before limiting piston speed, so your displacement per second is only a quarter. Where they fall down is thermal efficiency, because the surface to volume ratio is poorer. But actually, with steam locomotives, I'd argue smaller machines have another advantage, and that's that they're all built to the same loading gauge. A C1 boiler is practically an optimal design; it's like a Garratt; the boiler you would build if the rest of the engine allowed it. Short and stubby barrel, big combustion volume, you can get in a superheater with as many elements as a West Country. Now, I'm not suggesting that you build everything out to the loading gauge, Duchess style, but in general as designs get bigger within a specific loading gauge they get longer, and only extending in one direction is only going to make it harder to hit optimal proportions.

(To cover one of the more specific points raised, I will mention that the SNCF 141P had the lowest specific steam consumption of any steam locomotive recorded, at 11.2 lb/hp-hour, a hideous unit if ever there was one. Given the relatively soft exhaust of most compounds, I would not assume it was putting most of its fire up the chimney and ruining the coal consumption figures in the process)

 

Also remember that SNCF kept all their German 2-10-0 locos for heavy freight.

 

The Nord 4-6-0 SNCF 240D (we used to have one, it was located at the Nene Valley Railway) was a Du Bousquet engine and certainly not a Chapelon, weighed 70.8 metric tons, a little under 70 Imperial tons could be relied upon to deliver and sustain 2,000 hp and dated from 1910. The original PO Pacifics pre 3566 rebuild dated from 1910 in superheated form and their output went from 1,850 hp at high speed to 3,000hp and then more. So in the light of this what might the Du Bousquet engine be able to achieve if subjected to a full late 1920s/early 1930s Chapelon rebuild?

 

This is exactly what I’m talking about to some extent. For clarity, in 1929, Gresley had built over 1000 steam locomotives for the GNR and then LNER and then had a substantial hand in the development and building of hundreds of existing and carefully selected “standard” designs, together with one streamlined prototype (no.10,000).

We need more information and citations for this. Why was this the case? Who were these designers? What influence did they have on Chapelon’s career?

Secondary evidence presented as fact is always in danger of presenting a story that may not align with the primary evidence. Vague statements such as the above implying conspiracy don’t help us get to the truth either.

[quoteDid Chapelon need to build new engines? [/quote]

That’s the wrong question. Was he instructed to build new locomotives? Did the railway company he worked for ask for new locomotives or rebuilds? They’re running a railway company after all.

Treat each on its own merit, but I agree in principle, there may be good reason to renew rather than rebuild.

Examples?

A locomotive approaching 30 years old at the time that Chapelon was designing his first rebuilds are old technology based on older principles. They’re irrelevant in this context. Gresley was producing the W1 and the A3 Pacific in 1929, hardly slouches, the latter preforming very well.

We really need more context for this “forgiveness” thing. Not everyone knows Chapelons story: what is this about and who is involved, where can we find the evidence for all of this?

You can’t run a railway on a few prototype locomotives or rebuilds. Ultimately running a railway is down to rolling stock, infrastructure, fuel and staff. Assessing the relative worth of individuals work is all about the decisions they took and how it affected the actual railway operations.

But did that level of additional engineering complexity translate into actual performance by way of mileages and availability?

I’m an asset engineer in my day job and that last statement has no basis in fact, whether now or in the 20th century on the railway. If you look at the costs of a railway system, you will always find that newer traction will have lower operating costs, particularly steam to electric. It’s understanding the difference between capex and opex spending within the industry.

They weren’t built for outside of these shores, so that’s something of a moot point.

 

That’s the wrong question. Was he instructed to build new locomotives? Did the railway company he worked for ask for new locomotives or rebuilds? They’re running a railway company after all.



Treat each on its own merit, but I agree in principle, there may be good reason to renew rather than rebuild.



Examples?



A locomotive approaching 30 years old at the time that Chapelon was designing his first rebuilds are old technology based on older principles. They’re irrelevant in this context. Gresley was producing the W1 and the A3 Pacific in 1929, hardly slouches, the latter preforming very well.



We really need more context for this “forgiveness” thing. Not everyone knows Chapelons story: what is this about and who is involved, where can we find the evidence for all of this?



You can’t run a railway on a few prototype locomotives or rebuilds. Ultimately running a railway is down to rolling stock, infrastructure, fuel and staff. Assessing the relative worth of individuals work is all about the decisions they took and how it affected the actual railway operations.



But did that level of additional engineering complexity translate into actual performance by way of mileages and availability?





I’m an asset engineer in my day job and that last statement has no basis in fact, whether now or in the 20th century on the railway. If you look at the costs of a railway system, you will always find that newer traction will have lower operating costs, particularly steam to electric. It’s understanding the difference between capex and opex spending within the industry.



They weren’t built for outside of these shores, so that’s something of a moot point.[/QUOTE]


The answers to most if not all of this are to be found in books and papers that you can read. Also you might find some answers on the pages of this forum.

As for Gresley and his team bringing about the building of many engines for both the GNR and LNER this cannot be questioned. Some would argue about the standardisation aspect of the LNE though I would not fully agree with these arguments, the careful selection of new types and existing types to serve on the railway, to serve as standard types, was well thought out. It was a well balanced approach given all the circumstances.

Chapelon's first project was a proof of ideas, a proof of his understanding of the best science of the day applicable to his field. The P and O felt the need to improve its express passenger locomotive stock and they carried out a conversion of one of the 3500 class Pacifics fitting it with Lentz valve gear. As far as we know Chapelon was not involved in this but this work was not sufficient to provide significant improvements. Chapelon's boss on the railway was one M. Billet and it is largely thanks to him that he was able to conduct the work on 3566. Once the locomotive had shown its capabilities the railway agreed to further rebuilds. The introduction of the Houlet superheater allowed the maximum sustainable horse power to rise to 3,400 ihp and a modest enlargement of the cylinders took the figure to 3,700 ihp and engines of this third development went to the Nord railway too. They produced the power that it wanted and needed.

The speeds of mechanical transport in France was limited to 120 kmh (75 mph) because of a decree of Napoleon III and this decree largely remained in place until WW2. This made the running of high speed passenger services difficult the only way that this could be achieved was with high acceleration and little or no slowing on the grades so as to deliver high point to point averages. So schedules calling for a 70 mph average speed needed engines of unusual capacity and these had to be designed by someone. Or you can accept double heading or increase journey times. Neither option is particularly attractive.

On routes where heavier loads needed to be worked the more powerful 4-8-0 type was used. The Pacifics could not work the loads to schedule and the 4-8-0s were also more efficient. The SNCF came into official being on 1st January 1938.
Before long WW2 was making life very difficult. Chapelon kept working but was officially attacked for demonstrating a passive attitude in front of the enemy. As a result he was demoted from his senior engineering position. There was a paper presented in 1992 as a result of work carried out by the National Center of Scientific Research. At the National Conference in the September this work by B. Escudie, J. Payen and J. Ramuni was read and reveals much of what was going on.