Steam speed records including City of Truro and Mallard

My take is that you could schedule class 8Ps with XL limit loads on the basis that they could run at 90 on favourable sections day in day out. That's the practical limit.

 

Nor do we know what would have happened to British steam development either. From what I've read, Gresley was looking at going for higher speeds than Mallard's record.

 

The 05 hauled a train of 197 tons, I think, off the top of my head, at least one or two vehicles lighter than Mallard's 240 tons. So I think there's a strong argument that Mallard's achievement, which included an astonishing acceleration up Stoke Bank, sits just a tad higher, but I don't think anyone would argue against that it is a close run thing between these two excellent pieces of locomotive design.

The 05s were in use until 1958 as I recall, so they were pretty long lived. They are, agreeably, a small class with three non identical members, and the A4s were 35 locomotives in everyday service from 1935-1968 or thereabouts.

Gresley's intention was to prove the use of streamlined, short form trains, operating up to 130mph. He didn't quite manage it with Mallard, 126mph was an instantaneous speed calculated from the dynamometer roll, and he accepted 125mph as an average over recorded 5 second intervals.

I would argue that the A4 Pacific is part of a wider story about the LNER's and Gresley's aims towards regular high speed trains operating on long distance services, whereas the 05 class is considered something of a pet project for the ruling party of the time in Germany.

The interesting part of the German high speed rail story is the what if question, but it wasn't towards developing high speed rail in the manner Gresley and the LNER were imagining it. The high speed trains stopped operating in 1939. This leaflet gives an interesting insight to streamlined trains in Germany of the 1930s. https://retours.eu/en/27-schnelltriebwagen-reichsbahn/#11

 

It must be more important than life and death,like football,or we would not use time here.

We do not know what speed Mallard ran but dynamometer car gave non-physical values and they were evaluated by enthousiasts.
Let me refer to letter 273.
The blue curve comes from analysis of roll done by NRM.
The Mallard train needs active braking and superpower to come within Newtonian mechanics.

The red curve is made from roll by LNER and was five second averages.
Numerical values on graph from Bryan Benn 2005/Gresley 1938?
Numbers written on roll for going down 200:1 ( mp92/122.5 ) ( mp91.75/122.25)(mp91.5/123)(mp91.25/124.5)(mp91/124.25)
Shutting steam of can almost make it conform to classic mechanics but
during a speed record?

In my youth I made a cheap fifth wheel at university and it distorted signal likewise because of a not quite central shaft
I believe in mr Andrews black curve but will maybe hoist it .25mph.
If wonky gearwheel theory holds water the true,black curve curve shall run relative as mean of the wobling red.

In my world Mallard most likely ran 124.25 mph that is 199.91kmh/55.53mpsec.
The aim of german crew two years earlier was to go faster than 200kmh and many believe they did and longer on less than 1000:1 gradient

The three 05 pulled hospital trains close to frontline and Mallard broke down three times when being compared to other british locomotives in 1948

Real high speed german steam locomotive was finished around 1939 and they wanted diesel trains .

 

I dunno folks, soon you're going to be calculating how many Duddingtons and Brays can dance on a pinhead.

If you're going to call a figure. 'authenticated' it really does at least need to be a speed over a reasonable distance or time interval, and one long enough to average out potential issues with the machinery.

It would, of course, also be appropriate to subject the original dynamometer trace of the DRG record run to a similar level of scrutiny if it still exists.

 

Indeed. At least the one thing you can say for the German loco is that within a few days, it was (as recounted by Holcroft) again running at over 100mph. Which is more than can be said for Mallard!

Being less combative, I'm sure there is an interesting thesis about the development of high speed rail, but ultimately I don't think it will be about arguing the toss whether Mallard did 125.9 or 126.1 mph, which was irrelevant in practical terms. I'd be looking at the economics of the services, and how they were promoted - and also what the alternatives were. You can promote a train service on frequency, reliability or speed. I've seen an LNER poster promoting the reliability of its Liverpool Street service (in terms of how many trains ran to time); and an SR poster promoting the frequency of its Brighton service. The question is where was the greatest cost / benefit ratio. The LNER high-speed services have always looked to me as being expensive relative to the benefit - not just the direct operating cost, but also the timetable adaptations needed to run a high speed train on a low speed network. Some study to confirm or refute that hunch would be interesting.

Tom

 

A former colleague described a journey from Bristol to Newquay by car in the 1930's, a 10 hour journey for about 160 miles.

Clearly you would not need a particularly 'cutting edge' steam hauled Inter City service to be very competitive with anything apart from air travel in the pre war period which was what teh Southern was doing, and with electric trains to boot.

 

Both the Silver Jubilee and the Coronation turned in significant profits. Virtually sold out throughout their runs in the late 1930s. Despite the disadvantage of double blocking (the practice of putting an extra signalling block between the high speed trains and everything else running), the LNER board recorded their success both in terms of the profit and in the PR.

There is no doubt, in my view, based on the evidence I collated for the Gresley book, that the two streamlined trains were an absolute success.

They were part of a larger movement towards a true high speed railway and whilst I need to do more research into the archives, the big thing for me is that the research is pointing towards a full systems integration of train, track, signalling and braking by the LNER. Gresley was so close to a genuine high speed railway: close but no cigar thanks to the war in part, and, one suspects, the high capital cost of electrification that, happily, he did live to see a portion of before he passed.

 

Am I the only one captivated by the idea of EM2s swishing out of the Cross on an electric service to the North?

 

How far did they need to clear the tracks in front of a fast train? It's not just double blocking: that sets the minimum distance between a slow train and a fast one following, not the distance needed when the fast one starts. If you start with only two blocks clear, it immediately runs into distant signals at caution. So the train may have met its direct operating cost, but what about cost of the loss of capacity on the line caused by trying to mix fast and slow trains together?

Tom

 

That’s a very good question. I don’t know the answer, but I am trying to answer that as part of my PhD. When I know what I think is the answer, I will share it on this thread.

That’s the fascinating thing for me about researching high speed railways. You can see patterns in speeds, development of technologies, but the one thing which really comes across is that mixed traffic railways are not as efficient in scheduling as a single use railway (i.e. freight only, metro, suburban or high speed segregated lines).

However they have been a fact of life on railways since the beginning of the passenger train.

I think Tom it is likely that the loss of capacity to any one high speed train running is quite minimal, in respect of the overall schedule of the LNER (bear in mind it was in the case of the Coronation and Silver Jubilee, only two sets running a day in opposite directions).

But I could be wrong. It will be fun finding out!

 

There I suspect we hit the limits of cost accounting from that period.


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Perhaps a bit harsh? The LNER drawing office's inability to design an adequate inside big end isn't a condemnation of the whole locomotive, which as I heard was otherwise good to run. And the complacency that led them to accept the inadequacies of the design certainly wasn't unique to the LNER.
Of course we whose allegiance lies elsewhere may certainly gain a little quiet amusement from the incidence of failures at very high speed, and maybe even gloss over certain suspicions of our own. In my case, for example, there's a suspicion that had it not been for a similar complacency about superheater passages that restricted steam flow at high rates, my own favourites might have attained a fair few more mph.

 

Something that is of course very much a live issue today and perhaps needs to be better understood by or at least explained to politician and public alike.

 

I would say - my obvious bias aside - that when researching the middle big end issues for the Gresley and the Thompson books, it was very specifically poor by way of record in those classes which frequently exceeded 65-70mph for sustained periods. These were the A4, P2 and V2 classes.

In a weird twist, the original A1 and the later A3 records are better than these later classes, and my only anecdotal evidence I have to explain this, is mostly in relation to the high intensity service provision the A4s had, the P2s had other issues that compounded this weakness, and the V2s were a very large class that did a wide variety of work, thus producing at times a range of speeds and intensity that may have impeded their maintenance provisions.

The middle big end is, based on the mileages and availability evidence, absolutely fine for the other conjugated valve gear classes that were not achieving high speeds regularly.

I accept that this is speculative on my part but it does go some way towards explaining why a V1/V3 was so good, mileages and availability wise, when compared with a V4 that is of a similar size but expected to be achieving top higher speeds on work that it was doing.

 

Absolutely agree and I continue to bang this drum elsewhere for HS2.

 

Cook was of the opinion that inadequate lubrication was the primary cause. It might be interesting to consider length of runs and nature of duties (stop start or continuous) in an analysis. I fear I'm not remotely qualified to comment on what sort of usage would most expose inadequate lubrication but it would be interesting to have an informed opinion.

 

I was being deliberately mischievous, but in pursuit of a wider point, which is that extremes of performance are generally of very little practical benefit. What matters is the level of performance you can extract day-in, day-out - since that is the level that you can base a service design around. In the case of A4 pacifics, that day-in, day-out performance required was not remotely near 126mph.

Tom

 

But there was the kudos of being a record breaker. Speed sells even if it’s not 126 in daily service.

 

That's true Tom, but the Mallard record did a lot for knowledge in terms of the engineering on the L.N.E.R. for high speed trains.

126mph is what we remember of the day but there were lots of other things besides that were learned, wider lessons about the permanent way requirements, the usefulness of the streamlined casing for both locomotive and train, the braking tests, and of course the limits of the Gresley A4 at speed.

I don't believe that Gresley ever intended to run steam trains regularly over 100mph (though the Silver Jubilee and the Coronation both did at varying times), but the intention by Gresley was to develop a high speed railway. How that would have been accomplished is probably left to imagination as WW2 curtailed all development in that way. I don't think the V4 being the next big design to be put together by Gresley is fully indicative of his thoughts on the future of rail.