Could Jubilees have performed as well on the Cheltenham Flyer as Castles?

[2251]

1 hour ago, LMS2968 said:

The snag here is that the independent loco builders had obtained an injunction preventing one railway company from building engines for another. This was obtained after Crewe built several engines for the Lancashire & Yorkshire Railway in the Nineteenth Century; to the best of my knowledge, it was still in force in the mid-1920s, and wasn't broken until the Southern built LMS 8Fs for the LNER (confusing, I know, but that's what happened!).

 

The battles between the builders and the railway companies in the latter part of the nineteenth century were far more complex than that.   

 

As for the Southern-built 8Fs, I think the power to build them came from the wartime emergency legislation, so it was not really a case of an established rule being "broken" but rather something being allowed under the exigencies of wartime conditions.

[Chris M]

Did I read somewhere that the castles used were specially picked for the Flyer? One thing which is perhaps impressive is that the Castles appear to have been able to do this run day after day without major issues. I think this says something about the loco being a good design and precision built. To me this running is more impressive than achieving a record speed but breaking in the process. I expect there are quite a few classes that could have kept to time on the Cheltenham flyer but would they have been able to do again and again without damage?

[Steamport Southport]

3 hours ago, KingEdwardII said:

Well, the LMS had a loan of "Launceston Castle" in 1926 and it was so good on LMS duties including the Cumbrian banks that the LMS asked if the GWR could make some Castles for them...

 

...which the GWR refused. I suppose they got an alternative when they headhunted Stanier from Swindon to become their CME in 1932...

 

Yours, Mike.

 

Well before the Jubilees were even thought of though. They were comparing the Castle with locomotives that were basically 4Ps, the ex MR people thought the solution to the motive power crisis was more 4Ps working in pairs.

 

The Castle experiment proved that large 4-6-0s was the solution and the LMS decided to rebuild the Claughtons with bigger boilers of a similar type to what the L&Y had used with obvious MR tinkering, which led to the Royal Scots and Patriots. The Patriots were officially rebuilt Claughtons, but only the first two actually were.

 

The Jubilees were virtually a Patriot with a taper boiler. All would have been rebuilt with the 2A boiler in the early 1950s but by then the Britannias and Clans had appeared. Then the Modernisation Plan happened so no more Jubilees or Patriots got the new boilers.

 

This is a rebuilt Claughton. It was more cost effective to build new locomotives than rebuilding them so only a few were rebuilt.

 

Nominal Tractive Effort of 29,570LB so according to the BR era power classification a 7P!

 

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

 

 

Jason

[Compound2632]

54 minutes ago, KingEdwardII said:

It is said in the book "British Steam: GWR Collett Castle Class" by Keith Langston, on p12, that the LMS first made a request for a batch of Castles and when that failed, asked for the Castle drawings - which were also refused.

 

I'm afraid that isn't supported by Hunt et al., which is now the definitive work on the subject. Does Langston give a source for his information? Launceston Castle was tested on the West Coast Main Line in October and November 1926; what actually happened then was that in December 1926 the LMS board approved an order for 50 "Improved Castle" engines with the North British Locomotive Co. (as being the only firm with the capacity to complete at least some in time for the Summer 1927 timetable). It was then that the Great Western declined to provide drawings either to Derby or to Springburn, so work was immediately started on designing the Improved Castle at Derby, with the outline design sketched out by early January. Detailed design was carried out at NBL under the supervision of staff from the Derby LDO [Hunt et al., pp. 14-15, 17]. 

 

2 hours ago, LMS2968 said:

The snag here is that the independent loco builders had obtained an injunction preventing one railway company from building engines for another. This was obtained after Crewe built several engines for the Lancashire & Yorkshire Railway in the Nineteenth Century; to the best of my knowledge, it was still in force in the mid-1920s, 

 

This would have been perfectly well-known to all parties concerned, which makes Langston's version absurd.

[melmerby]

2 hours ago, LMS2968 said:

it was still in force in the mid-1920s, and wasn't broken until the Southern built LMS 8Fs for the LNER (confusing, I know, but that's what happened!).

The GWR, Southern & LNER also built them for the LMS. The LNER & GWR ones for the LMS were on loan to the building company, until after the war

2 hours ago, 62613 said:

Wasn't that during the exceptional event which occurred between 1939 and 1945, though?

Ministry of Supply war rules would've been in force, overiding any restrictive legislation.

 

As a curious twist, the Southern built 8Fs for the LNER (were 'loaned' to the LMS at the end of 1947, getting sequential LMS numbers (8705-8772) in the process.

 

A very complicated history

[Compound2632]

1 hour ago, Steamport Southport said:

They were comparing the Castle with locomotives that were basically 4Ps, the ex MR people thought the solution to the motive power crisis was more 4Ps working in pairs.

 

The Castle experiment proved that large 4-6-0s was the solution and the LMS decided to rebuild the Claughtons with bigger boilers of a similar type to what the L&Y had used with obvious MR tinkering, which led to the Royal Scots and Patriots. The Patriots were officially rebuilt Claughtons, but only the first two actually were.

 

As shown in my previous post, the loan of the Castle led directly and within a couple of months to the LMS Improved Castle, aka Royal Scot. This was the culmination of the LMS management's efforts to solve the West Coast Main Line locomotive problem inherited from the LNWR. In practical terms, the Royal Scots took the place of Claughtons and Dreadnoughts, both class 5P; it might be the case that in practical terms neither of these engines were as good as a Compound 4P and certainly resort had to be had on occasion to Claughtons in pairs, but that was certainly not seen by anybody in the LMS management, whatever their previous company, as a good or desirable way forward! There was a lot of work going on in the Horwich and Derby LDOs in 1923-26 towards four-cylinder Pacifics, which was brought to a halt by the demonstration that a 4-6-0 could do the job; the Improved Castle had three cylinders, as being cheaper to build and maintain, with higher boiler pressure to compensate for the smaller cylinder volume, 95% of that of the Castle; in fact the nominal tractive effort of the Royal Scot was 5% greater than that of a Castle.

Edited March 27, 2023 by Compound2632

[Compound2632]

1 hour ago, Steamport Southport said:

Well before the Jubilees were even thought of though.

 

Which reminds me that I don't think the point has been made in answer to the OP's question that a Jubilee could not have outdone a Castle on the Cheltenham Spa Express, since that train was introduced in 1929 and its heyday was 1932, whereas the Jubilees were built 1934-36. So they simply weren't around!

[rodent279]

22 minutes ago, Compound2632 said:

 

Which reminds me that I don't think the point has been made in answer to the OP's question that a Jubilee could not have outdone a Castle on the Cheltenham Spa Express, since that train was introduced in 1929 and its heyday was 1932, whereas the Jubilees were built 1934-36. So they simply weren't around!

No, I know, and I did mention that in my OP!

 

It's just a theoretical question-could a Jubilee have equalled the work of the Castles on the Cheltenham Flyer? A pointless question, one purely for  debate and entertainment. It doesn't matter when, or whether they were in double chimney form etc, and it's not "are Jubilees better than Castles", because I accept that they are different animals built for different purposes.  As I said in a later post, an equally valid question is whether a Castle could do the same work as Jubilees on Euston-Brum services, or over the S&C with the Thames-Clyde Express.

 

I suppose its a bit like asking whether Sir Matt Busby's Man Utd could have won the European Cup in 1999, or could the current England football team have won the World Cup in 1966- we'll never know, it's just interesting debate.

[Compound2632]

On 25/03/2023 at 22:38, Compound2632 said:

The tractive effort formula used to determine the power class, as used on the LMS and BR, was calculated at 50 mph for passenger engines. (Piston speed (rms) enters into it.)

 

On 26/03/2023 at 07:02, LMS2968 said:

The formula for Nominal Tractive Effort was Bore (squared) x stroke x number of cylinders x boiler pressure x 0.85 all divided by 2 x driving wheel diameter, all in inches. There is no reference to speed and is, by definition, an approximation of the T.E. at starting. Once moving, the time available for steam to flow to and from the cylinders reduces so the Mean Effective Pressure within the cylinder reduces. The shorter cut-offs used as speed rises also reduces the M.E.P. so Actual Tractive Effort falls exponentially as speed rises.

 

For the most part, power output is dependent on the boiler's ability to generate steam, never a reliable quality of the 5XPs right to the end. If all the parameters were good, they could be excellent, but if there was any problems they were mediocre to poor. 

 

Sorry, I'd missed this reply of yours to a post of mine; whilst your statement about the nominal tractive effort formula and its applicability is correct, I would draw your attention to my other observation quoted above, re. the calculation to determine passenger engine classification. (For freight, the calculation was for 25 mph.) This is all discussed somewhere on the Midland Railway Company topic by @Crimson Rambler, who has a thorough-going engineering background. As a physicist, and hence fond of simplification, the calculation is that the work done in the cylinders, pressure times change of volume (i.e. volume swept out each cycle of the engine) is equal to the work done in moving the train,  the force (tractive effort) times the distance moved in one cycle of the engine, i.e. the circumference of the driving wheels. One can only talk of power once one takes into account the speed, since power is the rate at which work is done.

 

The calculation of the work done in the cylinders given there is a simplest approximation; with the aid of indicator diagrams one can calculate the actual work done, as the pressure changes.

[LMS2968]

27 minutes ago, Compound2632 said:

 

 

Sorry, I'd missed this reply of yours to a post of mine; whilst your statement about the nominal tractive effort formula and its applicability is correct, I would draw your attention to my other observation quoted above, re. the calculation to determine passenger engine classification. (For freight, the calculation was for 25 mph.) This is all discussed somewhere on the Midland Railway Company topic by @Crimson Rambler, who has a thorough-going engineering background. As a physicist, and hence fond of simplification, the calculation is that the work done in the cylinders, pressure times change of volume (i.e. volume swept out each cycle of the engine) is equal to the work done in moving the train,  the force (tractive effort) times the distance moved in one cycle of the engine, i.e. the circumference of the driving wheels. One can only talk of power once one takes into account the speed, since power is the rate at which work is done.

 

The calculation of the work done in the cylinders given there is a simplest approximation; with the aid of indicator diagrams one can calculate the actual work done, as the pressure changes.

Hmm, you're a physicist while I'm an engineer; basically, engineering can be considered as applied physics and we both work to the same formulae.

 

There has been a lot of talk in this thread about tractive effort (a force) when the poster is actually talking about power, which as you intimate is Force (T.E.) x Velocity (say speed for simplicity). With a steam engine, maximum tractive effort occurs at zero m.p.h., while by definition power output is none (Tractive effort x 0 m.p.h. = zero h.p.). At zero m.p.h. full boiler pressure is available in the cylinder as at least one valve will be permanently open to admission so the boiler's ability to generate steam doesn't come into it; once moving - and at speed - the boiler's steam-raising ability then becomes the major factor to keep up the demand from the cylinders. If it can't, pressure falls and power output falls with it.

 

By the way, Compound, that wasn't aimed at you: I know that you already know all this!

[Compound2632]

15 minutes ago, LMS2968 said:

once moving - and at speed - the boiler's steam-raising ability then becomes the major factor to keep up the demand from the cylinders. If it can't, pressure falls and power output falls with it.

 

Indeed, and what I've glossed over is that the LMS power classification scheme included a boiler-related element (based on grate size I think, from memory) so an engine had to meet both the tractive effort and the boiler capacity threshold for the power class. 

 

It's interesting in this respect that Dugald Drummond and others of his generation under-boilered their engines, by later standards, to prevent them from being thrashed - by limiting the supply of steam, the driver was forced to operate the engine economically at short cut-off, and not waste coal.

[Flying Pig]

1 hour ago, Compound2632 said:

As a physicist, and hence fond of simplification, the calculation is that the work done in the cylinders, pressure times change of volume (i.e. volume swept out each cycle of the engine)

 

If you were a proper physicist, you'd look at an indicator diagram and invent a constant to account for the variation in pressure through the stroke. 😁

Edited March 27, 2023 by Flying Pig

[Compound2632]

23 minutes ago, Flying Pig said:

 

If you were a proper physicist, you'd look at an indicator diagram and invent a constant to account for the variation in pressure through the stroke. 😁

 

No, I'd integrate the area under the curve. It's the engineers who introduce fudge factors like that 0.85.

[LMS2968]

11 hours ago, Flying Pig said:

 

If you were a proper physicist, you'd look at an indicator diagram and invent a constant to account for the variation in pressure through the stroke. 😁

As engineers, we use indicator diagrams a lot, including for internal combustion engines. But you can also measure the TE on a rolling road or at the drawbar with a dynamometer car.

Edited March 28, 2023 by LMS2968

[LMS2968]

9 hours ago, Compound2632 said:

 

No, I'd integrate the area under the curve. It's the engineers who introduce fudge factors like that 0.85.

We have to deal with the practical, not the theoretical!

[rogerzilla]

Cox and Holcroft had a gentle argument about the SR influence on the Royal Scot for years, but what both agree on was;

 

1. GWR refused Castles or Castle drawings

2. SR happily sent Lord Nelson drawings, and parts of the firebox design were used.  Holcroft said it was more than that, Cox said that was all.

 

So the LN had bits of its firebox reused in the Royal Scot and the Q1- impressive for a loco with a notoriously long and narrow box.  Bulleid was probably just saving money by reusing pressing dies.

[LMS2968]

The LN and Scot fireboxes show similarities in profile but are very different in end view. Eric Langridge, a draughtsman at Derby, a was equally adamant that the Scot owed nothing to the LN design.

[rodent279]

10 hours ago, Compound2632 said:

 

No, I'd integrate the area under the curve. It's the engineers who introduce fudge factors like that 0.85.

Digressing a little, isn't the 0.85 a kind of "safety margin", an allowance to take account of varying boiler pressure and wheel diameter?

Edited March 28, 2023 by rodent279

[kevinlms]

54 minutes ago, LMS2968 said:

The LN and Scot fireboxes show similarities in profile but are very different in end view. Eric Langridge, a draughtsman at Derby, a was equally adamant that the Scot owed nothing to the LN design.

How can they have much in common? The LN was a 4 cylinder design, the Royal Scot only 3.  The boiler had some similarities, but the chassis, was closer to an enlarged Fowler 2-6-4T and the loco had some standard LMS fittings based on the Midland ones.

[LMS2968]

I don't think there is any suggestion of similarity below the running plate, and the boilers were very different also. Attention was mostly on the firebox, and as I said, there is a similarity in profile but not cross-section.

[Compound2632]

Again as Hunt et al. say, resemblance between the Lord Nelson and the Royal Scot is due to the two being engines designed to meet similar requirements and constraints. There is a bit more to it than that, though, because the Lord Nelson has Derby LDO heitage through the person of Maunsell's Chief Draughtsman, James Clayton. Fowler and Maunsell were friends and I think we can be in no doubt that the question of design isuues for a large 4-6-0 were discussed between them; all these locomotive engineers met at the ARLE meetings and would have been well aware of what each other were doing. No locomotive was designed in isolation!

[DCB]

On 25/03/2023 at 23:02, Compound2632 said:

The Jubilees and Castles had driving wheels of virtually the same diameter and boilers pressed to 225 psi. What makes the difference in the tractive effort formula is the total cylinder volume, which is 18% greater for the Castle. The work done in the cylinders is the pressure multiplied by the volume swept out in each cycle; since the drivers are the same diameter, both locomotives travel the same distance in each cycle. Hence, since work done equals force times distance moved, the tractive effort (force) is 18% greater for the Castle than the Jubilee, at the same speed. (There is a fudge factor related to piston speed but since the engines have the same 26" stroke this is the same for both.)

 

Of course, all sorts of real-world factors to do with the detailed engineering come into play...

It would be more interesting to compare a Jubilee with a Castle over the South Devon banks where the bigger cylinders should enable the Castle to be operated on shorter cut offs and use steam more efficiently, but the evidence seems to suggest Castles with 30% more TE than a Saint were not that much better hill climbers. Slipping being the limiting factor, the loco with the highest axle loading would probably win if sanding arrangements were the same . 

 

The outstanding high speed runs by locos with low TE were the Gresley rebuilds of Ivatt atlantics with massive superheaters on the ECML in the 1930s,    

 

The old singles were exceptionally light on repairs, It was just they were unreliable as they could be disabled by a sudden rain shower, and train weights per passenger just about doubled circa 1900       Aspinall on the L&Y  sussed the TBO   Time between Overhauls in miles  was linear with driving wheel diameter and went with 7ft 3" on his 4-4-0 and Atlantics, 

Churchward was after 2 tons pull at 70 mph when he went for the 6ft 8" ish wheels,  maybe 7ft 3" on a King  wheelbase would have been better for the Cheltenham Flyer,   The Castles seemed to be able to do high 90s on the level 98 for Clun on the Somerset levels 1964,  but very little more down hill.  Its said an attempt to flog Earl of Ducie downhill at 35% cut off the same day still didn't achieve a ton   A King holds the record for speed on a regular service train (not a special) in the UK at 107/108 MPH on the Athelney Marshes on the CRE but that's  BR era high superheat king.    The only way to settle this is a race,  Swindon to Paddington, Jubilee vs Cheltenham Flyer schedule!

[melmerby]

25 minutes ago, DCB said:

maybe 7ft 3" on a King  wheelbase would have been better for the Cheltenham Flyer

The trouble with bigger wheels is that it starts to impact boiler diameter and also overall height of the loco.

 

[LMS2968]

14 minutes ago, melmerby said:

The trouble with bigger wheels is that it starts to impact boiler diameter and also overall height of the loco.

 

And limits wheel size. This was the problem encountered when designing the later Stanier Pacifics: The biggest boiler possible was specified along with 6' 9" coupled wheels, and the top front corners of the firebox had to be drastically cut back to achieve it.

[The Johnster]

3 hours ago, DCB said:

The only way to settle this is a race,  Swindon to Paddington, Jubilee vs Cheltenham Flyer schedule!

 

It would need to be done over a period, say a week, and be free from Per Way or signal checks, and account for the faster line speed through Reading station.  And then you'd have to repeat the exercise with a Castle, then with a double-chimneyed Jubilee and a double-chimneyed Castle.