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

[rodent279]

At the risk of starting all-out warfare between lovers of red engines and those who follow the One True Faith of green engines with lots of copper & brass bling, here's a question.

 

We all know of the exploits of Collet's Castles on the Cheltenham Flyer in the early-mid 1930s.  Leaving aside the small matter that they weren't built until 1934, and when they were, they were on the wrong railway and had some teething steaming troubles, could Stanier's Jubilees have achieved the same levels of performance?

 

(I suspect the answer is yes.)

 

I wasn't quite sure where this should sit, Prototype Discussions seemed the best fit.

[LMS2968]

The 5Xs ran the Euston - Birminghams - the fastest scheduled expresses except the Coronation Scot on the LMS - for many years. But each was on its home railway, built to suit those conditions: coal type signal sighting (from which side of the footplate), familiarity to similar types of engine, etc.

 

They were happier were they were.

[JeffP]

Weren't Castles class 7?

And Jubilees 5XP?

 

[JohnR]

Quite a difference in tractive effort though - Castles had 31,625 lbf while Jubilee's only 26,610lbf

[rogerzilla]

I think the Cheltenham Flyer was a short train, so TE wouldn't have been too important.  There is only a difference of one in power classification, as BR incremented everything above 5 to get rid of the X half-classification.  A rebuilt Royal Scot would have been a fairer Castle substitute but I think a Jubilee would have managed it.

 

In practice, a V2 was found to do almost anything an A3 could, with the same difference in power classification.

Edited March 25, 2023 by rogerzilla

[Compound2632]

2 hours ago, JeffP said:

Weren't Castles class 7?

And Jubilees 5XP?

 

1 hour ago, JohnR said:

Quite a difference in tractive effort though - Castles had 31,625 lbf while Jubilee's only 26,610lbf

 

The power required to move a train rises very rapidly with speed. To average 70 mph+ over a distance of 65 miles requires a more vigorous acceleration than is needed to average 58 mph over a distance of 113 miles, also the maximum speed has to be proportionately greater than the average speed, since the length of time available for cruising at speed is rather shorter.

 

So apart from the fact that it's all downhill, the Cheltenham Flyer was the more demanding of the two tasks.

 

For myself, I wonder what a Johnson spinner of the 115 Class - highest recorded speed 90 mph - could have done in the place of Duke of Connaught with the Ocean Mails on 9 April 1904: Shrivenham (pass) to Westbourne Park (pass), 70 miles, at an average of 80 mph (71.3 mph start (Pylle Hill) to stop (Paddington)). To my mind, that puts anything done by a 4-4-0 at the time or by a great lumbering 4-6-0 a quarter of a century later firmly in the shade!

Edited March 25, 2023 by Compound2632
grammar tidy

[The Stationmaster]

17 minutes ago, Compound2632 said:

 

 

The power required to move a train rises very rapidly with speed. To average 70 mph+ over a distance of 65 miles requires a more vigorous acceleration than is needed to averaging 58 mph over a distance of 113 miles, also the maximum speed has proportionately greater than the average speed, since the length of time available for cruising at speed is rather shorter.

 

So apart from the fact that it's all downhill, the Cheltenham Flyer was the more demanding of the two tasks.

 

For myself, I wonder what a Johnson spinner of the 115 Class - highest recorded speed 90 mph - could have done in the place of Duke of Connaught with the Ocean Mails on 9 April 1904: Shrivenham (pass) to Westbourne Park (pass), 70 miles, at an average of 80 mph (71.3 mph start (Pylle Hill) to stop (Paddington)). To my mind, that puts anything done by a 4-4-0 at the time or by a great lumbering 4-6-0 a quarter of a century later firmly in the shade!

I thing it was an accepted wisdom - backed by solid evidence such as you have quoted - that singles were in most cases very free running engines and could attain and sustain high speeds in the right conditions.  Their big problem until the arrival of steam sanding was getting heavier trains underway and no doubt heaier trains also taxed their speed ability for obvious reasons.  But in their day for sheer speed and fast running they were not easily beaten and that helps explain their relatively long life as a wheel arrangment on some railways.

[Compound2632]

14 minutes ago, The Stationmaster said:

I thing it was an accepted wisdom - backed by solid evidence such as you have quoted - that singles were in most cases very free running engines and could attain and sustain high speeds in the right conditions.  Their big problem until the arrival of steam sanding was getting heavier trains underway and no doubt heaier trains also taxed their speed ability for obvious reasons.  But in their day for sheer speed and fast running they were not easily beaten and that helps explain their relatively long life as a wheel arrangment on some railways.

 

I singled out the 115 Class as they were the first Midland engines to have piston valves - Johnson being encouraged to try these out by his old friend W.M. Smith, at the time Chief Draughtsman at Gateshead. The result seems to to have been an even more free-running engine than Johnson's earlier slide-valve engines, as one would expect the large valve volume led to a less constricted steam circuit - higher pressure at the cylinder inlet. As far as I'm aware, the Achilles class singles were slide valve engines.

 

The Midland singles worked over a road with some long stretches of 1:200 in both directions and in the 1890s the Nottingham non-stop was the longest non-stop run in the country - 124 miles - so they were very capable engines for their day, though loads were not what they were to become in later days, with corridor carriages, and indeed were rather less than was routine on the expresses out of Euston. This was, of course, all with the benefit of steam sanding, the development of which at Derby was the precursor to the re-introduction of singles in 1887.

Edited March 25, 2023 by Compound2632

[pH]

Possibly (probably?) the last ‘high speed’ steam-hauled service to be introduced on British railways were the A4-hauled Glasgow-Aberdeen 3 hour expresses in the early 1960s. Earlier, the LMS had run a 3 hour service on that route from the summer of 1938 until it was stopped in wartime. The power for these 3 hour trains? - Jubilees. Members of the class were shedded at St Rollox, Perth and Ferryhill.
 

[rodent279]

12 hours ago, JohnR said:

Quite a difference in tractive effort though - Castles had 31,625 lbf while Jubilee's only 26,610lbf

Agreed, but that's only starting tractive effort.  What matters to sustain a high speed is the ability to develop power at speed, and starting TE doesn't tell us much about that.

 

[Compound2632]

33 minutes ago, rodent279 said:

Agreed, but that's only starting tractive effort.  What matters to sustain a high speed is the ability to develop power at speed, and starting TE doesn't tell us much about that.

 

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.)

[Compound2632]

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...

[melmerby]

How about the Jubes (or Patriots) with the 2A boiler?

That pushes them up to 7P with 29,950lb TE, although 10% down compared to the Scots with the same boiler.

Edited March 25, 2023 by melmerby

[LMS2968]

7 hours ago, 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.)

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. 

[DCB]

On 25/03/2023 at 10:28, rogerzilla said:

In practice, a V2 was found to do almost anything an A3 could, with the same difference in power classification.

A good V2 could do anything a A3 could pre war but after they churned out 180 odd of them and fitted self cleaning screens they were very different beasts to the post KJ Cook tuned up kylchap double blastpipe A3 pacifics, despite a very similar boiler . 

 

On 25/03/2023 at 10:28, Compound2632 said:

 

 

The power required to move a train rises very rapidly with speed. To average 70 mph+ over a distance of 65 miles requires a more vigorous acceleration than is needed to average 58 mph over a distance of 113 miles, also the maximum speed has to be proportionately greater than the average speed, since the length of time available for cruising at speed is rather shorter.

 

So apart from the fact that it's all downhill, the Cheltenham Flyer was the more demanding of the two tasks.

 

For myself, I wonder what a Johnson spinner of the 115 Class - highest recorded speed 90 mph - could have done in the place of Duke of Connaught with the Ocean Mails on 9 April 1904: Shrivenham (pass) to Westbourne Park (pass), 70 miles, at an average of 80 mph (71.3 mph start (Pylle Hill) to stop (Paddington)). To my mind, that puts anything done by a 4-4-0 at the time or by a great lumbering 4-6-0 a quarter of a century later firmly in the shade!

 

Its more about Driving Wheel size, superheat, boiler pressure,  valve numbers and sizes and valve timing and the lack of interruptions to steam flow than tractive effort.  I can't find the right books but I believe Jubilees have 9" piston valves and (3) 17" cylinders and Castles 8" valves and (4) 16" cylinders  Kings 9" Valves  and (4)  16.25"(Nominal) cylinders. The valve timing was very even on the Castles front stroke to back and all the cylinders had equal length connecting rods,  The Jubilees had North British Loco Co valve gear essentially pretty good but had one short and two long con rods which might have made a slight difference to optimal cut of between middle and outside cylinders, and smoothness of the action as 90 was approached , Lots of reports of Rebuilt Scots rocking and Rolling)   The Castle had better "Safety Valves" and tended to run at 225psi blowing off slightly where Jubilees Ross Pop abruptly lost 5 to 10 psi if the valves were allowed to lift, but the Jubilee had higher superheat which helped steam flow through the steam passages.
Thing is though from the way "Rooke" performed over the S&C the LMS 3A boiler should have been well up to providing steam enough for the long Downhill with a following wind Cheltenham Flyer record runs.   Plus the line was quiet when the Flyer ran and a lot of people timed it so I have no doubt a Jubilee could have timed the Cheltenham Flyer with the standard load, as could a Star, more similar TE wise to a Jubilee but a much smaller diameter boiler.
I always suspect its the North British Chassis which kept the Scots, Jubilees, Patriots and B17s speeds down. That long wheelbase between middle and trailing wheels, The Kings had to have their rear axle side play restricted because of bad riding and they were shorter, 8ft 3" against 9ft(?)     I suspect Jubilees could have run as fast as Castles, they had a better racing ground past Ashchurch but the highest speeds seen to have been high 90s Caprotti class 5s, similar to Stars and Black 5s elsewhere.    

As regards singles, they would probably have got to Wantage road by the time they should have been passing Didcot, the 14XX with similar valve events were timed at 85 on 62" wheels so with 90" wheels you are looking at 120...

The Jubilees, Scots, Black5s, 2ps etc all ran fast on the WCML south of Rugby but the trains were tightly scheduled, several nose to tail at 70 plus MPH, gain a minute and catch a distant signal and they could lose a couple of minutes, catch a stop signal. lose 5 minutes. Fast runs needed a late start but not late enough to lose the path, which gave little chance for making up significant time.  Apart from Summer weekends the GW main lines were much quieter.   The CRE turned up something like 20 minutes early when they tested a Castle against a Gresley A1 1925(?).   It was horses for courses.  In the final and my totally unbiased opinion as a GWR fan The Castle was the better loco but wouldn't squeeze between the LMS Platforms, but the Jubilee could have timed the "Flyer." 

Edited March 27, 2023 by DCB

[rodent279]

What sort of loads did Jubilees have on the Euston-Brums? I'm guessing nowhere near as light as the 6 or so on the Cheltenham Flyer?

 

I suppose to be fair, one should also ask would Castles have been up to that job, or to slogging over the Long Drag with the Thames-Clyde Express?

[Compound2632]

5 hours ago, DCB said:

Its more about Driving Wheel size, superheat, boiler pressure,  valve numbers and sizes and valve timing and the lack of interruptions to steam flow than tractive effort.   

 

The things you mention certainly affect performance in practice, but not the nominal tractive effort, which was what I was discussing, which is about the physical limit to the power the locomotive can develop.

[rogerzilla]

Sam Ell at the Swindon test plant fixed the V2 steaming problem at some point after the self-cleaning screens were fitted, so it depends when you make the comparison!

[KingEdwardII]

6 hours ago, rodent279 said:

would Castles have been up to that job, or to slogging over the Long Drag with the Thames-Clyde Express?

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.

[melmerby]

10 hours ago, DCB said:

That long wheelbase between middle and trailing wheels, The Kings had to have their rear axle side play restricted because of bad riding and they were shorter, 8ft 3" against 9ft(?) 

Jubes were 8' 0", Castles 7' 9"

Incidentally, the boiler on a Jubilee is the same as a Black 5 but has a bigger firebox, I would say they were under-boilered.

[2251]

On 25/03/2023 at 10:50, The Stationmaster said:

I thing it was an accepted wisdom - backed by solid evidence such as you have quoted - that singles were in most cases very free running engines and could attain and sustain high speeds in the right conditions.  Their big problem until the arrival of steam sanding was getting heavier trains underway and no doubt heaier trains also taxed their speed ability for obvious reasons.  But in their day for sheer speed and fast running they were not easily beaten and that helps explain their relatively long life as a wheel arrangment on some railways.

 

I am sure the Stationmaster is more than aware of this, but it is worth noting that that that acknowledged free-running was a function of both the lower frictional losses and considerably lower piston speeds. On  the latter point, at 60 mph, a Castle's drivers (with a circumference of 21 ft) are turning at 250 rpm, whereas those of the single (with  a circumference of 24.2 ft) are only at 218 rpm. With valve-events and steam-circuits more the product of intuition and experience than science, that made an important difference.

 

[LMS2968]

1 hour 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.

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!).

[62613]

2 minutes ago, LMS2968 said:

 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!).

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

Edited March 27, 2023 by 62613

[Compound2632]

2 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.

 

This is not correct. A set of Castle drawings was requested and refused. [Hunt et al., LMS Locomotive Profiles No. 15.]

[KingEdwardII]

40 minutes ago, Compound2632 said:

This is not correct.

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.

 

Yours, Mike.