Sir Nigel Gresley - The L.N.E.R.’s First C.M.E.

Yes, aerodynamics works at any speed. But the lower the speed, the less the gain, and at typical steam railway speeds, the gains are not sufficient to make the effort worthwhile. After all, BR(S) seemed quite happy to build 90mph EMUs with slab fronts, presumably realising that the advantages in construction (and I suspect driver visibility) outweighed the small gains to be made from aerodynamics. (Look at VEPs, CIGs etc)

Reducing weight (which has to be carried uphill, and then dissipate all that energy through the brake blocks on the way down) is of more benefit to fuel efficiency that aerodynamics; it also helps with acceleration and braking which is of more benefit in timetable terms: rapid acceleration gains you more than a higher ultimate top speed that takes you a long time to reach.

That rather makes my point: the LNER couldn't achieve the benefits of streamlined trains without a system-wide improvement, encompassing timetable design, upgrades to track and signalling, braking performance etc. That was unrealistic to achieve in the 1930s on anything other than a handful of services, and pace @huochemi that in turn could "only be achieved in ways that seriously interfere with much of the ordinary passenger traffic and freight traffic."

In other words, for the conditions of the time, it was a dead end.

Tom

 

Well fuel saving is always a benefit if you can make it without increasing other costs. But for a reasonably contemporary viewpoint here's an extract from "Next Station", a 1947 GWR publication in a section headed "Streamlining":
"...Today the streamlining of railcars is standard GWR practice. The streamlining of locomotives is not."
"...But most of all the decisions rested on a consideration of the overall length of the trains concerned. The railcar body is sixty-two feet long. The full length steam train is between nine hundred and one thousand feet long in all. The difference in length is important, because a vehicle running on rails has to overcome not only the head resistance to the front end, but also the less obvious effect of a sideways wind. In the railcar, headwind is a factor to be taken seriously; in the steam train it is negligible in proportion to the side thrust. ... A streamlined locomotive might be good to look at, but the train went no faster because of it and the coal bill remained the same."

 

You may want to consider the cost/benefit equation. London Underground experimented with streamlining in their 1935 stock, but omitted it from the production build of 1938 stock because the trains did not achieve enough speed to deliver the gains that would have justified the extra expense and lost capacity (this, I add, in stock that would be the first to have underfloor traction equipment).

It's an extreme case, but I think an important one about costs and benefits.

As for modern units, I suggest that the Electrostars are not obviously more aerodynamic than the VEPs and CIGs they replaced, or the Desiros than the variety of units that they replaced.

 

Those were all worthwhile improvements that were needed for fast running, so they were associated with the streamlined trains, but not consequences of the streamlining per se.

 

It may not be obvious to you, but the Electrostars and Desiros are definitely more aerodynamic than the trains they’re replaced. Look at the edges, look at the roof, look at valances, look at the windscreens. Sorry but what you’re saying doesn’t track into modern train engineering at all.

This is the same GWR whose own streamlining attempts were locomotive only and aesthetic, rather than scientifically produced. I am sceptical that you can take that seriously given the GWR made no serious attempts at streamlining (what serious streamlining concepts are the railcars based on? What testing?)

Particularly as Johannsen’s wind tunnel testing does take cross winds into account amongst other things. That’s how we get the different data for an “ideal” streamlined train. This proved the concept of a fully streamlined train and gave us the valuable theoretical data that led to actual streamlined trains.

But it was the high speed streamlined trains that pushed the need for this investment. Otherwise - why bother with any kind of innovation?

Tom, I think you’ve missed the point. The LNER were in the process of making all of these upgrades - then WW2 happened.

The LNER under Gresley were running the first scientifically designed, fully streamlined high speed trains anywhere in the world. And at that - they were running three services. The Silver Jubilee, the Coronation and the West Riding. Newcastle, Edinburgh and Leeds as the main destinations invoking high speed intercity running, non stop.

Sounds familiar? That’s exactly what happens today on the modern LNER. We just don’t have the train names, we do have the services.

Someone had to be first. Gresley recognised the benefits of the fixed formation, shorter trains running at high speed. Couple that with streamlined, articulated coaches with a premium service, and the obvious results of the LNER’s great success in running these trains.

***

I cannot help but feel there’s a level of missing the point here across the board. What exactly is being argued against?

• Aerodynamics - we appear to be arguing that modern trains are no better than those they replaced in aerodynamics. That’s wrong. Fundamentally wrong - the aerodynamic differences between a 4VEP and an Electrostar is stark!
• Aerodynamics has no benefits except in the highest of speeds - this is also wrong, the gains become greater as speeds increase.
• The LNER didn’t succeed in high speed running and it was an engineering dead end - fundamentally wrong. The LNER proved the concept and their trains were scientifically developed over many years. Were it not for WW2, this would have improved. That much is clear.

At the end of the day I think the results speak for themselves where the LNER is concerned.

I haven’t even mentioned yet the in cab signalling experiments on the A4s in Scotland yet, which would have produced faster running with single block signalling at high speed, when married with the new braking systems from Westinghouse on the streamlined trains. Sadly curtailed by the war.

Gresley was so far ahead of his time it was unreal.

 

The key word was "obviously"; I don't dispute some improvements (not least, losing all those door handles on a VEP), but not enough to undermine the truth of the original observation comparing some modern units to Crabs.

 

Just responding to a couple of points:

What I am arguing is only that the streamlining and the improvements in other areas were all required for high speed running; rather than the other improvements being due to the streamlining.

 

I don't believe I was arguing that streamlining was responsible for those benefits: but the high speed streamlined services helped Gresley and his department heads argue for better infrastructure as a result of those services.

Sorry, but you are wrong on the Crab.

There is no way that any modern unit is more draggy than a Crab, or as draggy, in isolation or on a non streamlined passenger or freight train. Shape and surface are incredibly important to aerodynamics and the Crab doesn't conform to any of the required shapes for optimum aerodynamic effects. Please stop making that comparison.

The Crab > 4VEP > Electrostar line of development shows obvious improvement in design towards the reduction of drag.

If it didn't, we'd be in trouble as a nation in train engineering.

 

I would be quite interested to know what modern units you would compare to a crab? Barring things like a Sprinter, which were purposely built to be as cheap and no thrills as possible to suit conditions at the time of their design, doing a quick image search on a 4-VEP makes me wonder how you could fit in more clutter on the front end to make it worse than it already its.

Going back a point, even the slab fronted end of a Sprinter has some consideration. Flush headlights, flush windscreens and windows, rounded corners between the front and sides, the great massive air dam in front of the wheels. Going back to my original point on terminology in modern practice. Objects can look streamlined, aerodynamics are designed in starting with a base knowledge and the developed through experiment and validation.

A good analogue might be the modern HGV. You can't do anything to the rear end or the length, in Europe you have the disadvantage of most units being cab over to suit maximum length regulations and your top speed is limited to 60mph. However you don't need to spend very long looking at a modern tractor unit to see the little gains that have been applied to improve the aerodynamics. Air dams to the trailer, fully curved windscreens, tapered rounded corners at the bodywork. It is true that the changes won't make as much of a difference as if the truck could do 100mph, but doing a 100 miles of driving at 60 the aerodynamics will mean that it uses less fuel.

The benefits of aerodynamics lie outside of gains solely related to top speed and fuel consumption too. Even basic considerations can make a vehicle significantly less noisy for the occupants. Properly directed air also aids stability and reduces the tendency for something tall and slab fronted to rock as the air pressure fluctuates from one side to the other.

 

I'm not claiming anything. I'm merely reporting what was said in a contemporary publicity document which I happen to have.

My own belief is that the whole subject is too long on emotion and short on fact. Streamlining was a very live subject at the time. Of the UK rail companies the LNER certainly put the most effort in. The GWR PR booklet is, I submit, correct in stating that short one or two car units can have proportionally greater gains from streamlining than full length trains, I think basic science can take us that far. I don't think I'm competent to evaluate whether it's correct in going on to claim that no savings were evident for full length trains.

Logically there must be decreasing benefits on the spectrum from railcars through short high speed trains using dedicated low drag coaching stock and at the other extreme normal speed service trains using standard carriages. But to analyse how well individual historical streamlining exercises worked, and to what extent they were successful is somewhere I'm not knowledgeable enough to go.

As for evaluating the success of the various implementations on the bottom line as a result of reduced expense and increased ticket sales, well again that would be a very hard thing to do and I don't believe I know enough to offer an opinion.

 

That doesn't feel fair. I am at least citing my sources and providing the reasoning.

I don't think you have to be "competent" to recognise that streamlining a full train gives greater benefits than streamlining just a portion. Gresley had proved this beyond any reasonable doubt between the W1 in 1929 and 4 July 1938.

Which is why I've provided the relevant information from the Johannsen reports (happy to pass you a copy if you would like it Jim).

Fair, and I have felt similarly. William Wilson did I feel a good job in his 2020 paper on the investment dilemmas of the LNER, but I disagree with him on some of his conclusions.

Further reading here: https://rchs.org.uk/wp-content/uploads/2021/03/FINAL-Wilson-LNER_2.pdf

For those interested, it's really well researched and cited throughout. Highly recommended reading if you like that sort of thing (I do!)

 

Interesting paper by Wilson, thanks for that. A rudimentary revenue/cost analysis of the Silver Jubilee is on page 43. The scale of investment in widening schemes and passing loops is also noteworthy. The paper is strong on the context in which Gresley was working.

 

I deliberately said the whole subject, I didn't intend to pick you out individually. I'm sure your sources are the best available, but I have my doubts as to whether they are really adequate. The whole discipline of aerodynamics and aerodynamic testing was in its infancy pre WW2, and continues to develop.

If I may give a parallel example in racing sailboats, where I have a slightly wider knowledge, much work was done on the subject of mast aerodynamics in the 70s and 80s, and all sorts of highly sophisticated innovative designs were produced. However adopters - and I was one of them - were disappointed that the actual results in competition on the water didn't seem to produce the sort of performance gain in practice that the testing had predicted. It wasn't until the advent of CFD at the turn of the century that we finally learned something of what was really going on, and why a simple round stick seemed to perform pretty much as well as the most sophisticated shapes the wind tunnel development could devise.

So that's why I fear the data we have is inadequate to evaluate the success of the various streamlining exercises. No doubt the technology applied to modern train design could be applied to the historic vehicles, but an expensive game unless someone needs an example to train a new batch of students... There are interesting questions, there's no doubt about it, but are they serious research money interesting?

 

Sometime ago I made a train horsepower calculator that somehow gives reasonable results.
Using the front area for locomotive and Cd from a car is not very realistic for trains.

https://www.national-preservation.com/threads/steam-train-power-calculator.1193201/

 

I don't disagree Jim, that's why the whole area is fascinating to me. The results of the original W1 streamlining exercise informed the further testing in the 30s, and when retested it was found more lacking in some areas. Understanding had changed and the science was better. Significantly better, actually.

All I have tried to emphasise is that it was a development process which started in the mid 1920s and by the emergence of the A4s was becoming better understood, the science was better, and many of the principles we see now in modern train design were actually in place.

(on a side note, I have been comparing the measurements and calculations done by Johannsen to modern day thinking and my findings confirm that he was an exceptionally intelligent young man who was also quite ahead of his time and thinking. The optimum train design work is not at all far off how we look at aerodynamics on modern trains today).

I think I need to be clearer. I am not saying, for example, that the W1 was a successful exercise. It was a partially successful exercise, this is backed up by the later 1930s retesting of the W1's shape.

The understanding of aerodynamics evolved from 1926 through to the emergence of the A4.

However, by the A4's introduction, the science being applied actually isn't too different to what we do today, we just have more tools and theoretical modelling to be able to produce better results. The calculations take more into account today, and are incredibly extensive. Computer modelling has allowed us greater insight into how trains work in relation to aerodynamics.

If I may hazard a comment, the subtleties of modern train design in aerodynamics are where you need to look more closely to see the marginal gains in different areas that add up to significant gains fuel economy and similar.

 

For sure. I bet that there's a measurable difference between external door handles and push buttons for instance.

 

I have not failed to be surprised to see that what are perceived as small changes on the surface add up to overall better aerodynamics in the context of a full train.

 

I recall this situation in reverse with the designers of a racing boat who were upset about the handicap we'd allocated them:
"How come our handicap is so severe: the boats based on a so and so which is only rated xxx"
"Indeed, and you've made quite a number of little improvements haven't you?"
"Well yes, but only little ones"
"So how come you're surprised that ten 1% improvements add up to 10% overall?"

 

It has been quite interesting reading all the toing and froing with regards to 10,000 and her "streamlining". What with the is it/isn't true streamlining. I've developed the view that she was the modern [being 100 years younger] take on Messrs Stephenson's and Booth's Rocket. Insomuch as the first steps down the streamlining road. As when you look at the "production" order for 10 locomotives based on Rocket. They all had re-arranged cylinders which were angled lower than Rocket's 45 degrees and in turn had more and more tubes fitted in the main boiler barrel.......

 

On the earlier point of why the Coronation Scot was not reintroduced, yes this is partly for the same reason that the LNER did not reintroduce their streamlined trains, in that speeds all over the UK system were restricted.

The wider context was the whole railway system was run down after years of heroic and under-resourced efforts carrying massive traffic during WW2. Track, trains and signalling equipment were no longer in good enough condition, hence the speed restrictions.

A still wider context is that low-capacity, premium priced streamlined services were no longer in tune with the zeitgeist. Britain had just elected the reforming Attlee government with a significant majority; and in a time of continuing food rationing and bomb-damaged housing. The national priority was surely seen as providing better services and living conditions for ordinary people, and doing so right across the board. So trying to re-introduce a few streamlined services only accessible to an elite might not have been seen as a good commercial or PR move. Especially as with the signalling and braking abilities of the time, making space for the streamliners would probably have limited the capacity available for expanding ordinary expresses, commuter services or freight.