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

https://www.alamy.com/stock-image-1930-illustrated-london-news-lner-w1-class-steam-locomotiv-no-10000-167039585.html


(If you open image in new tab and then zoom in it becomes readable)

This article (1930 Illustrated London News) does say "Stream-lined Boiler Casing"

 

Zooming the web page doesn't work well here but here it is as a JPG which is easily zoomed.
Edit: or perhaps not so easily. Try saving the JPG locally.

 

Definitely not streamlined. There are too many areas of air resistance.
The front wedge between the deflectors.
The ducting does not allow smooth air flow around the front of the loco.
The foot plating outside of the smoke deflectors.
The cylinders and motion.
The design of the lower third of the casing.
The design of the lower third of the casing.

 

I think on reflection it’s best to let the writing do the speaking on this occasion. I feel pretty confident with my research, mind, that others with an open mind might be more convinced.

However we should address one thing: the W1 was streamlined at the front end for three purposes: smoke deflection (obvious), reducing drag (pretty obvious actually) and the third, less obvious one - three separate ducts for the pre-heating air for draughting to the grate (less obvious).

For those unconvinced, read William Brown’s book on the W1 and then read Tim Hillier-Graves biography of Gresley.

For my part, I intend to cite the primary evidence I have accordingly.

 

The article i shared mentions only the boiler casing as being stream-lined, and in the text mentions the work involved with lifting the steam and smoke.

It's hard to judge how much of the shape is dictated by fitting the boiler in the loading gauge, and how much is shaped for reducing resistance. Coupled with experimental nature of the W1, access (to motion etc) may have been an important factor preventing stream-lining of the entire locomotive, along with parts that weren't able to be changed.

The A4 could be argued does not allow smooth airflow around the front of the loco, the wedge shape instead pushing the air up, rather than around( albeit smoothly!), The W1 funnels air into the ducts, and then is smoothly shaped curving towards the top.

It's interesting to compare the seemingly similar P2 original front to that of the W1.

 

I've been biding my time on entering what has so far been a quite interesting discussion to watch develop. Whilst I can't offer any particular insight into the process or thoughts behind the locomotives in particular I can offer insight from the perspective of someone involved with the design of aerodynamic vehicles in the 21st century.

'Streamlined' to me is a very particular way of describing the overall shape of a vehicle (or object) and describes an aesthetic more than it does a particular technical design process. In fact, my company has a 193 page document on the design of bodywork for high performance vehicles, it does not use the word 'streamlined' or any of its variations once in the entire thing. The words; 'airflow, drag, aerodynamic, air/fluid resistance', do pop up quite a lot though. In fact our specific document on virtual and practical wind tunnel testing is the only place I could find a use for it and that was as 'streamlines', being something you add to a virtual or physical model to show the routing of a fluid.

The reason I have quoted the post above is because for something to be 'streamlined' in the context of this discussion i.e. designed to reduce aerodynamic drag, does not mean completely forgoing any engineered surfaces. We can't say specifically what the ducting will do because we haven't seen the specific data for it in the wind tunnel, but it has lots of precedent in modern vehicles. Many modern cars have very aerodynamic front ends, but they still incorporate ducting or winglets to direct air to the brakes or into the engine bay. As another example, I've worked on a helicopter that has steps and squared edges for standing to access the top of the main rotor, that certainly wasn't un-streamlined.

To me, the design of the lower casing is probably one of the areas that looks most modern in it's design. One of the greatest causes of turbulence in high speed machinery is caused by how airflow falls over it's edges. By rounding it you have a better chance of keeping that flow laminar and preventing turbulence.

Is the W1 streamlined? As an engineer right now, I would say yes, simply because removing the smoke deflectors and looking at the shape, it looks streamlined. Is it aerodynamically designed? Well yes, we have pictures of it being developed in a wind tunnel. Is the design effective at reducing air resistance? I have no idea, it stands to reason it might be better in that regard than a conventionally shaped locomotive because at least some consideration was given to it. I can't help with the dates either I'm afraid but I hope the above makes some sense as to why someone could consider the W1 a 'streamlined' locomotive, without having to qualify that by stating it has also been aerodynamically designed to reduce drag.

 

Do you ever feel like the answers are more obvious when they’re right in front of you?

 

This is a superb post, thank you for responding.

Absolutely nails it in my opinion.

If I may, this is how the ducting works:

The three ducts intake air which is forced into the boiler casing, over the water tubes. This air is forced back to the grate in the air space between, pre heated by the water tubes.

Pretty ingenious bit of design quite frankly. Not a million miles away from the principles we have seen in road cars, albeit for cooling purposes and not pre heating air.

 

Can quite agree with elements of the last couple of replies about 10000s "streamlining". As to how much was dictated by a[ the shape of the water tube boiler, b] the overall loading gauge [13' 1" tall by 8' +/- wide] of the network and c] the ability to lift the smoke and steam clear of the locomotive.

 

Amazing really, I've got a lot of respect for any of the previous generations that were having to plan and imagine compound curves, ducted internally while only being able to plan in a 2D space.

Interestingly, looking at that image and comparing it with the side profile of an A4 you could speculate that it is actually the more purely aerodynamic of the two shapes*. Whilst the bodywork of the A4 has a much nicer continuous flow (and is definately more aesthetically pleasing) I would predict that you're going to get a good deal of high pressure at the nose of the engine, where the tangent from the curve of the smokebox cover would be almost vertical. Partially because air can't flow underneath the loco in the same way in can over the top. That probably works in your favour to delaminate the flow going over the engine, and prevent smoke wanting to flow along the smooth lines of the boiler casing and in turn lift above the cab.

On the equivalent spot on the W1 you have a vent. The high pressure can't build up because the air is being ducted away. I wouldn't suggest that it makes it more aerodynamic overall than the A4 style casing as a whole but hopefully it's an example of the subject matter being slightly more complicated than stating any ducting will abolish smooth air flow. Maybe it's one of the reasons the W1's shape required deflectors, and the A4's didn't? Without them you'd be ejecting smoke straight into your lovely laminar flow until it crashed into the cab.

*A very big speculation and only considering the absolute frontal aerodynamic drag, don't ask me to defend it in court.

 

My new respect and understanding of the W1 is partially why my respect for Gresley has soared in the research stages of this project. The W1 has been completely misunderstood for decades. William Brown gave us a lot of the primary evidence, and was really close with his book to the whole truth, Tim Hillier-Graves has given us some more of the story by way of Bert Spencer’s archives, and revisiting the W1’s file and looking at the drawings has given me a new understanding.

It’s a bit more complicated than that I think. The A4 does in fact funnel air below its casing (it is rounded below the front, thereby directing air under the train too) whereas the W1 is more about trying to suck in as much air as possible for pre-heating purposes, and also channel it up and around the single chimney for smoke deflection - which, unsurprisingly, given the shapes involved, it was really good at in its single chimney format.

But not in its double chimney format. With the softer Kylchap exhaust, smoke deflection was more difficult. Frustratingly, history confirms to us that the solution picked for trying to fix this was to add smoke hood, which didn’t help particularly (one of Bulleid’s ideas that he would later take to the Southern Railway for his Pacifics).

However in all formats, the W1’s boiler casing is actually really cleverly designed to minimise drag across the casing, and the overall profile of the locomotive’s casing is not quite so wide in the same areas as the A4, B17 and P2s with the streamlined nose. Just look closely at the cab…

That is somewhat true in my view, the front of the W1 with its three intakes actually encourages a good air flow around the front end.

So the A4 was intended to have W1 or P2 style deflectors on multiple iterations of its design, even in the final stage of the process deflectors were still going to likely be fitted for smoke deflection purposes. It’s just that Gresley had recognised that lifting the chimney higher than the boiler casing actually encouraged better smoke deflection - the second stage of this was Eric Bannister’s fortunate mistake in accidentally modifying the plasticine on the chimney to leave an indent at the rear, making it more effective.

I personally think a lot of writers have got it on the W1 for many years. It absolutely wasn’t a failure. Its work as a prototype was a success and encouraged the development of other locomotives. It absolutely fundamentally proved one thing: streamlining and wind tunnel testing was the way to go for high speed train development. Gresley changed his approach to design significantly after the W1.

It is in my view a crying shame that we lost the original locomotive by way of rebuilding, the water tube boiler machine has so much incredible design and potential in it.



One thing that should be noted. The W1’s casing and the A4’s have remarkable echoes of each other. The front end of the frame design for the A4 appears to have been lifted from the W1’s original design, something made more obvious when you have the streamlined casing off the A4. The evolution of chimney and smoke deflection design from the first streamlined loco, the W1, to the more conventional but retaining the deflectors, P2, to fully streamlined design, the A4, is quite remarkable.

 

An evolution much ignored in modern times with lessons from the APT programme assisting the designs of classes 90 and 91 whilst the Pendelino tilt mechanism was developed from that of the APT by the Italian firm who bought the system from BR after the APT project was abandoned as a "failure".

 

Were there not problems with that kind of boiler maintaining its integrity on a railway locomotive? Could those have been overcome if there had been more will to do so? How much did the very high boiler pressure, the compounding and the preheating of the air for combustion improve the thermal efficiency over conventional locos?
Even if it had survived in its original form until the outbreak of war, could it have continued to operate in that form during the war?

 

What about W1's boiler on the Turbomotive's chassi?

 

The turbines would need some redesigning to allow for the much higher boiler pressure.

 

So, in addition to the discussion on the question of whether or not the W1 was considered to be "streamlined", I have been lent a copy of Train Aerodynamics, which is suggested reading for high speed train design by a number of university courses on railway engineering.

Page 8, photograph - "wind tunnel testing on LNER steam locomotive" - on the chapter regarding train drag and streamlining - surprise surprise, the W1 wind tunnel model is held up as the first example of reducing drag and incorporating streamlining!

So with that, I'm calling it a day on the discussion from my end - the W1 is and was intended to be streamlined. If it's good enough for the text book on train aerodynamics, it's good enough for me. End thereof!

 

The loco the NER built that looks like it was designed with an Etch-A-Sketch?

 

What did HNG have to say on the matter?

 

Although we don’t have a direct quote from SNG to state (for the purposes of the naysayers) “the W1 was streamlined”, we do have his correspondence with Professor W.E. Dalby and Frederick Johannsen, from the National Physical Laboratory. We also have the later’s paper to the iMechE when he goes through streamlining of locomotives. We have clear photographic evidence of the W1 being wind tunnel tested in addition, and William Brown’s excellent book gives us many photographs of the locomotive under building, showing how the streamlined casing was built up.

(As a side note I am grateful to Tim Hillier-Graves for sharing with me aspects of his research from his work to this end to find the answer).

Johannsen’s personal archive has shown that the W1 was always intended to be streamlined, by virtue of the work he was asked to undertake in 1928 towards the W1 project. The W1 itself when tested had to be multi-functional by way of the design Gresley was undertaking with the boiler grate and design.

In any event, Gresley himself endorsed the following in 1936 that Johannsen stated:

“The streamlining of steam locomotives calls for aerodynamic study of the machine as a whole, attention being paid simultaneously to air resistance, the deflection of the exhaust away from the driver’s vision, access of air to the fire grate and bearings, and the design from the standpoint of accessibility and operating convenience.

Maybe it’s because I have been so close to the material, poring over drawings, letters, photographs, even a model of the W1 I have gone out of my way to build (!) but it was really, painfully obvious from the moment I realised that the front of the locomotive is basically a big air intake, that it had to have been designed and built with aerodynamic principles in mind.

It’s a curious thing; when I started work on the Thompson book I was basically saying that he wasn’t as bad as he was made out, and there was (still is from some quarters) a lot of push back on the ideas presented. Here’s I’m actually saying Gresley may have been far more ingenious and prescient than other locomotive engineers of the time with the W1 in particular, and I am still getting a lot of push back. Maybe I’m the problem…!

 

Or perhaps people dislike their prejudices being held up to examination and subsequently dismissed as being wrong.