Steam speed records including City of Truro and Mallard

Duke and V2 diagrams at same speed and power can be compared in BR test repports

http://users.fini.net/~bersano/english-anglais/english-anglais/BR-tests/

The V2 diagrams looks stranger and stranger with speed and the highest are still only at ca half the rev per second that Mallard did at 126.
Mass forces grow squarely with rounds per second so the hypothetical Mallard 126 diagrams is everybodys guess.
When LNER had got a lesson from GWR and elongated valve travel and port width,Gresley ordered max cut of reduced.
Conjugation had problems working fast.

 

I think that’s a bit harsh. I personally welcome @Hermod ’s input, and I think this discussion would lack much of its depth without it.

 

Can I just second that. Please don't do ad hominen stuff the likes of which we see from others on the forum. Play the ball, not the man.

Hermod's entitled to his views on Gresley (even if I don't ultimately agree with him).

 

The world would be a poorer place without a bit of humour. Keep posting your usual stuff Mr Hermod.
And to Mr Buchanan, your post 'wins you no credit'.

 

Coming back to this thread after a day or two, Big AL has picked up a very important point on running a mixed traffic railway. It's not the absolute 3 or 4 minute headway which matters but the spacing of trains over long distances and different acceleration and braking. Just as an example outer suburban (Waterloo - Basingstoke or Euston - Northampton) trains run with 100 mph stock will average somewhere around 50 mph over 20 or 30 miles. So for a class 6 freight (up to 60 mph) once up to speed will let the passenger train get away, then start getting double yellows approaching each station stop of the passenger train. A wise driver on the freight will hang back a bit and ensure he doesn't need to brake and accelerate.

For class 6 freight read steam special - trains timed at 75 mph rarely get a clear road for any appreciable mileage. Before computerised section running times, custom and practice for timing steam at 60mph was to pick the point to point timings of a heavy class 6 (1200t) or a light (say 500t) class 7, 45 mph freight as the acceleration was pretty close to a steam special.
(Winchester to Basingstoke is roughly 19 miles and pass to pass running time for a 75 mph freight is about 25 minutes.)

Incidents like Big Al's run from Grantham are a wonderful example of a "can do" attitude between signalling staff, train crew and control plus faith in the ability of the steam loco on the day. Of course, careful specification of a service and examination of the timetable can sometimes open up such opportunities. Such initiative is in the hands of the organisations who bid the service specification or timings to Network Rail. With increases in service frequencies and standard hour timetables, the chance to look for one off gaps in the service is decreasing year by year.

Cheers, Neil

 

Did it have cut back casings compared to pre-war mallard? Also the drag of the train as a whole was presumably different, with mk1s? Aerodynamic drag seems likely to have been higher, but improvements that unlocked power seem potentially greater at that point, but then was the permanent way better or worse? really a minefield, especially given the lack of scientific rigor given to railway speeds.

 

Aerodynamic drag would have been definitely worse. Removal of casing plus the lack of smoothed sides to coaches.

 

In contrast to the detailed discussions of Mallard's speed record, there seems to be very little in English railway literature about the German Class 05 record from 1936, beyond that it was heading from Hamburg towards Berlin and topped 200 km/hr. There is no doubt much more in German literature. Below is a Google auto-translate from the German Wikipedia entry on the Class 05:

"During the journey, the train had to stop at the entrance to Wittenberge station for 2½ minutes. In order to keep to the timetable to Berlin, people were forced to drive over 180 km/h on the following route. As it continued, the train accelerated as quickly as possible. The locomotive crew (engine driver Oscar Langhans and fireman Ernst Höhne) had already determined that 05 002 was running well that day. The speed was reached faster than usual at 150 km/h, which was maintained until the slow speeds at Zernitz train station. The locomotive crew was then allowed to fully extend the locomotive. The 05 continued to accelerate until the speedometer needle reached its stop. It was at 200 km/h. This speed was reached and slightly exceeded on the section between Friesack and Vietznitz. The performance measured while driving was 3,400 PSi. It was only because of the curves at Paulinenaue that we had to brake to 170 km/h. The locomotive was able to maintain a speed of 200 km/h that day. You had to use the distance/time measurement to ultimately determine the speed. Direct driving speed values could no longer be measured. It was found that 5 km was covered in less than 90 s, resulting in a record of 200.4 km/h. Within these 5 km there was a section of 558 m, which was traversed in 10 s, which suggests a maximum value of 201 km/h; a value that was also published in the press in 1936."

The 05-002 speed record was apparently measured over a 5km distance, so Gresley may have been keen to demonstrate Mallard's speed over a certain distance, rather than claim any possible instantaneous speed.

05-002 is stated to have had a device for measuring steam consumption, which may have been used in deriving the stated power output of 3400 PSi. (PS = Pferdestärke = 735 watts. British horse-power usually quoted as 746 watts, so = 3350 iHP). That figure is comparable with the figures estimated for Stanier Pacific No 6234 Duchess of Abercorn in a 1939 Crewe to Glasgow trial. The Stanier Pacific and DRG 05 both had grates of about 50 sq ft (4.7 sq m), so would be expected to have similar maximum sustained power.

It is interesting to look at the design features of the Class 05 (diagram attached). It was a special experimental design for high-speed trials, with drivers of 2.30m (7ft 6in) in place of the usual DRG express engine standard of 2.00m (6ft 7in). Something similar had occurred in 1896 when the North Eastern Rly built two engines with 7ft 7in wheels (Class Q1 - LNER D18) for a possible resumption of the 1895 "races to the north", which did not happen.

The 3-cylinder layout had divided drive and 3 separate sets of valve gear. The Reichsbahn did not perpetuate the conjugated valve-gear mechanism that had been used on some Prussian and Saxon 3-cylinder designs.

The Class 05 had a round-topped firebox and parallel boiler barrel of 1.90m (6ft 3in) diameter. There was no combustion chamber (not adopted in Germany until after WW2), so the tubes were very long at 7m (23ft), and correspondingly large, with 70mm small tubes and 171mm flue tubes. There was only a single blastpipe and chimney; the Germans never appeared to favour multiple-jet exhaust systems. No doubt partly due to the long boiler barrel, the 05 was a heavy loco at 129t, and hauled a 10-wheel 85t tender. So the engine and tender were heavier than the 197t 4-car test train.

The Class 05 was never multiplied beyond 3 units, but the Germans developed the Class 01.10 and 03.10 streamlined 3-cylinder Pacifics, which were just coming into service as WW2 erupted and put an end to high-speed running. During the war, the streamlining became increasingly seen as a nuisance that hindered maintenance, and started to get removed. After the war, all were de-streamlined. In addition, the Class 05s had boiler pressure reduced from 20 bar (284psi) to 16 bar (227psi), which had remained standard for the DRG Pacific classes. After the war, these 3-cylinder classes all had a normal maximum permitted speed of 140 km/hr (87 mph).

 

I have understood that the Germans had the same trouble as the LNER with big ends after a really high-speed run and that they
solved it on the basis that while there was steam on the compression of the piston at the end of the exhaust stroke cushioned the inertia
forces of the connecting rod, piston rod, cylinder head etc. as the load on the the piston reversed. Keeping the regulator open and some
pressure in the steam chest obviated this and worked.

In the UK I have barely known this mentioned and it seems clear that this was not known to the LNER.
I think if you attained 112 mph down Stoke the big end went all right through to Kings Cross.
(Notoriously Silver Fox after 113 mph did make it through to Kings Cross but with the big end breaking up decidedly. The strap on the
end of the connecting rod held but without white metal or much of the brasses the inside piston overran, doing no good to the cylinder covers.)

What I did not have the wit to think to enquire about was whether it was the inside big end that went in Germany, as under the A4s.
My conjecture is that the information could well have come to be known or confirmed here via Giesl who had wide contacts and particularly 50s, 60s in East Germany where they fitted his ejectors to burn brown coal and of course with some care kept one of the high speed locomotives as an unstreamlined Pacific passed for 112 miles an hour/180 kilometres an hour - which it still formally is.

The cushioning effect is demonstrated by the effect of a four row superheater on a King: extended steadily with full load the relief valves in the cylinder covers would lift visibly every stroke releasing the compression.[/QUOTE]

 

Good points. The specially authorised recent trip by The Bristolian did very well, with long-sustained running at 75 mph. The lack of frequent braking and re-acceleration gave an easier trip for both loco and crew and a saving in fuel.

These considerations were what the 5AT design was intended to tackle; being both an easier fit into modern high speed traffic, and a more fuel-efficientl and greener day out. Such a shame that idea could not be progressed due to lack of interest - and lack of funding for the high development costs. (It would probably have needed at least two builds - one as a test engine to prove concepts and find ways to tackle weaknesses; then building a second loco to be the “production” model.

No chance of resuming this idea now. The best we might hope for might be very occasional high speed specials, maybe with specially fettled-up A4s, as with the 90 mph Bittern trips.

 

Yes. Not likely this would be an everywhere, every time thing. But one might hope for an occasional steam-enthusiasts fast service, on selected less busy routes, with the scarcity value of such trips meaning that seats would be filled.

 

We can always hope.

 

I think its a well-known fact that lead steam provides a significant amount of cushioning to the inertia effect of the piston, piston rod, and conrod, as does compression, and I'd be pretty certain that it was known to the LNER and probably its predecessors.

 

Thanks for that. It struck me with some surprise that the boiler had the same 23ft length barrel as the GWR Great Bear, which surprised me, since those are generally held to be too long - the notorious Union Pacific Big Boy has only 22ft tubes for example and the A4 I think 19ft. However the DDR design has larger diameter fire tubes - 2.75 as opposed to 2.5in and flue tubes 6.75 as opposed to 4.75. Its also got 4 rows of 6 flue tubes as opposed to 3 rows of 7 on the original GWR boiler. For comparison the A4 has 2.25in fire tubes and 5.25 flue tubes and if I worked it out right I think 3 rows of 11 and 1 row of 10 flue tubes.

So I used your drawing to sketch the general outline of the DDR05 to (reasonably close) scale against the drawing of the Bear I already have and its quite evident what a huge machine the German locomotive is. Also that the vast increase in size is achieved with a relatively low increase in cross sectional area. An A4 drawing would have been better of course, but I didn't have one readily available*, but although its obviously bigger than the much earlier GWR locomotive I doubt its that much bigger, so I hope the comparison useful.

The German locomotive doesn't come across as especially sophisticated to me. My own feeling is that if you could combine an LNER style tube and superheater arrangement with a Duchess style firebox you'd have a better boiler than any, but I'm no expert in steam locomotive design, so treat that opinion with *considerable* caution.



*If someone can provide me with an A4 drawing to scale of 1mm to the inch I'll provide the comparison.

 

It does not make sense to evaluate steam locomotives without considering the revolution caused by Chapelon in a paper published februar 1935 .

Prof Nordmann made a speech on 17 april 1934 where he shows a complete drawing of what became the 05 001 and 002. Streamline and long pipe boiler.

He mentions a recent (feb 1934) french paper that describes some modern french compound locomotives that made an ihph for ca 5.2 kg of steam,but it sounds as he did not really believe it and hopes that the 05 to be ,will use between 5 and 5.5 kg.

In 1941 he express a certain regret that it did not come below 6.25 and that Chapelons 1935 paper had been a chock for german complacency.
He then goes on describing a Norwegian (designed and buillt 1935-36) 4 cylinder compound that had beaten all recent german locomotives on test plant and the road
Only the very big simple cylinders from the 06 locomotives had bettered steam consumption sligthly at plus 5 rps and half load.

The LNER V2 was designed post the Chapelon earthquake and never got below 6 kg during test in the fifties.
For comparable cylinder size the belgian type 12 atlantic(1938) had 12 inch piston valves where V2 had 9.
On Mallards record try there was almost 50 lbs pressure drop between boiler and steam chest.
Somebody had not understod what was possible.
From a recent picture of Tornado without pistons and valves it seems that others have not either to this day.

 

Where is this revolution?

The big issue I have with the whole Chapelon debate is that everyone on the pro-Chapelon side makes big, bold claims about his influence and changing the engineering of others.

Yet the actual effects seem relatively small worldwide - there isn't the evidence for this revolution other than in an enthusiasts capacity when talking specifically about IHP and efficiencies.

Far more wide reaching were the developments of streamlining on trains, continuously welded rail, 25kV overhead line configurations, signalling developments and the use of welding in rolling stock.

The obsessive nature of the Chapelon claims just don't add up to much in the wider context of the development of the railway.

Add to that, given everyone dumps on Mallard's run and praises the 05, the revelation (at least to me) that it is quite a simple machine in setup probably says a lot about the German opinion of Chapelon's work.

 

Regarding Chapelon and Germany, you need to make allowance for “not invented here syndrome” and the political situation at the time.

 

I mean sure, but I asked this question before in terms of "evidence" and the response was really lacking in specificity of what that evidence was.

 

Surely there is evidence that locos built or rebuilt according to Chapelon's principles achieved substantially better thermal efficiencies and power-to-weight ratios than any other steam locos before or since. Opinions may differ as to how important those improvements were for the overall business of the railways that used those locos, and also as to how much trade-off those improvements demanded in other aspects such as the costs of building, maintenance and servicing.