Edward Thompson: Wartime C.M.E. Discussion

I am interested in how you calculated that. Could you show your working? I am not questioning your answers only looking to see the method and understand how you arrived at your figures.

It is a pity that the Eastern Region never did more comparisons between their locomotives, though can I say for the record that I think the comparisons between the A2/1, A2/2 and A4 are not particularly fair or conclusive, and here is my train of thought as to why.

We have in these locomotives three different sizes of grate and boiler, two different wheel diameters and two different sets of controls in addition to other advantages or disadvantages including streamlining and the kylchap double chimney.

The crews used are of course going to be more familiar with the A4 which has been in service for longer, and the Thompson Pacifics though similar at the front end are totally different beasts towards the rear, particularly due to the smaller V2 type boiler on the A2/1 compared with the larger 50ft square grate of the A2/2.

The higher coal and water consumption figures are quoted from British Pacific Locomotives by Cecil J Allen, and I agree they do not at first glance look favourable for the Thompson machines. There is a line of thought which suggests that the higher boiler pressure of the A4 compared to the 225psi of the Thompson machines might also be a factor in the results in addition to all of the above.

Allen states a second test, sans the A4, brought the coal consumption figures down to 62.8lb per mile for the A2/2 and 60.2lb for the A2/1 (page 103 of my copy of his book). A minor improvement but still quite clearly below the A4.

The third test gave the coal consumption figures for passenger working as follows, A2/2 was 46.1lb, A2/1 was 43.3lb and A4 was 40.5lb, on the freight working the A2/2 was 45.4lb to the A4's 45.2lb but the A2/1 was better at 41.4lb per mile.

Two things strike me here. The 6ft 2in engines are described as starting better than the 6ft 8in driver A4, but the A4 was more economical at high speed. That seems reasonable: the A2/2 and A2/1 were both designs intended for mixed traffic work. The A2/1 in particular was effectively a new build "conversion" from the V2 which as we know was intended for fast heavy freight and mixed traffic work.

So by saying the mixed traffic Pacifics were inferior on the fast passenger work to the express passenger Pacific, are we not missing the point? The criteria from which the three classes were conceived were different to each other and intended for different traffic requirements. One poster made the excellent point of traffic needs changing rapidly over the coming years from pre-war into the war and post-war.

It makes sense to look more closely at the A1/1 and A4 comparison for they were both 6ft 8in Pacifics and shared the same boiler type and most of the chassis type too, from the front driving wheels rearwards, the big difference being of course the Thompson front end compared to the Gresley's, the lack of streamlining and the advantage of the Kylchap double chimney. Comparing apples with slightly different apples as opposed apples and pears perhaps.

We do not know what context the visits were made in so how is it fair to state that merely visiting the works for attention X number of times equals a poor locomotive? We do not know how long it was in works each time either or what required fixing? More context and information is needed and comparisons with Gresley and Peppercorn machines required.

That is not to say I don't accept that the A1/1 may have been to works more times in its life than any other locomotive, but the comment regarding "well above average for even a prototype locomotive" - well, what is the average for a unique prototype locomotive in the LNER fleet then? Do we know the rebuilt W1's attendance record? It's the only other comparable unique locomotive we can mention on the LNER at the same time. I'd suggest that statement to be used as a crutch to beat the A1/1 is if not flawed certainly isn't strong enough to beat it down just because...

Any pointers in sources I am always grateful to follow up on and I'd be happy to share my contact details with anyone who would be willing to pass them on.

Quoting "fourth choice" again when on previous pages this has been quashed doesn't really lend your view to one of balance to be fair. Repeating something shown to not be true is unfair to the man in question.

I am happy to settle for the theory that he was third choice (but note that the sources which state are not from the highest ranked LNER officers but from those outside the organisation or in and around a similar level of seniority with Thompson) but if he was third choice 19 days after Gresley's death to appoint the man who was on a technical level the most experienced across a range of departments and most senior engineer seems a fair length of time.

He was not Edward Thompson locomotive engineer, but Edward Thompson CME and as such had duties beyond just the most talked about and obvious subject.

I'm not sure it is as clear cut as that Sheff. I am reminded of something I was told by a well known A1 Trust member a few years back - the emphasis in the W1 development being not to produce a more powerful locomotive than an existing A1 but a more efficient one. I am not certain looking at my notes and sources that Thompson looked necessarily to outright replace the existing fleet but to supplement them with locomotives (in theory at any rate) easier to maintain.

 

One thing I think I have to argue - simply based on the evidence as I can see at the time - is that Thompson was arguably following trends set by other contemporary CMEs here and abroad. Look at the original form of 6201 Princess Elizabeth and then compare it either the A2/2 or the A1/1's overall form. The similarities are truly astonishing on an aesthetic level, moreso on an engineering level. Extremely similar cylinder placement, short connecting rods of equal length. In Rowledge's The LMS Pacifics, one of the proposed Pacific designs by Stanier is a three cylinder locomotive whose dimensions and statistics are very close to the A1/1's. Coincidence? Could have been, but many sources have stated Thompson was an admirer of Stanier's work. Looking at contemporary engineering trends and ideas is worthy of examination.

The trouble is - and perhaps I am being trite and unfair myself - but it has seemed to me for some years that the biggest problem with discussing Thompson was change itself. LNER fanatics and followers vigorously defend Gresley - rightly so for his period in office and in the conditions he lived in - but conditions changed. Was Gresley's work still viable? Many sources state the Peppercorn A1 is the locomotive he would have built. How can that be so? His last locomotive design before his death was made with high grade materials and using the conjugated valve gear.

Nothing had changed in his engineering ethos despite an increasingly different set of working conditions, and I feel looking at the V4 specifically is evidence that Gresley could not have designed the Peppercorn A1. If we should be grateful for anything, it is perhaps that this most excellent locomotive class was developed on the back of a big change in the engineering ethos which was (whether we like it or not) implemented by Thompson.

 

Wasn't it the case, though, that the V4 was initially conceived & designed specifically for the West Highland line, where you had the problem of requiring high power but with low axle loading? The logic of using lighter but stronger materials can be followed in that situation; however the problems of both cost (always an issue with the LNER) and material availability during wartime then works against it.

 

What was the point in the A2/1s? Same boiler, wheels and cylinders as a V2, but I can't see the advantage of a Pacific over a Prairie, especially not when the 4-6-2 ended up with a reputation for very rough riding. Thompson must've had his reasons for the conversion, but I can't fathom out what they might be.

 

Obviously, but my comment was related to S.A.C. Martin implying that it was a factor related to coal and water consumption.

 

Oh, come on. The Lizzies were based on Stanier's GWR knowledge. They are often called LMS Castles.

 

Fair enough.

 

Oh come on. One minute you quote Townend to justify support for the A1/1 but when someone else quotes Townend that shows the same loco in less than favourable light you dismiss it. Cake and eat it comes to mind.

 

The V2s were doing all that was asked of them - the soubriquet "the engines that won the war" was well earned in the case of the LNER - so why introduce a small class of V2 conversions in wartime?

 

And of course Stanier's 3-cylinder Pacific never got off the drawing board.

 

I don't believe I have said that they weren't? Or even mentioned the GWR at this point?

Merely that Thompson may have been inspired by them and other similar Pacific designs in the creation of his own designs. (In no way am I saying the Thompson Pacifics are as good, I am saying their overall format is remarkably similar, and contemporary).

There are several sources stating Thompson was an admirer of Stanier and in some ways the development of line makes sense. It is worthy of further study and exploration I think.

That's a bit unfair - you do have to put statements into context with evidence.

I've no issue with the statement itself but would like to know what this was measured against.

Do you know what the average number of visits to works was for comparable locomotives on the LNER? I've never seen any stated anywhere so how can we take that specific statement on its own without knowing fully what it is being measured against?

It's fair to ask questions when things are not qualified. Townend's other comments I have quoted are either personal reflections or stats that are measured against others (as I did with Allen, above).

Absolutely, a still born project.

 

The streamlined front end does at high speed reduce the horsepower required to attain high speeds, does it not? This was proven in comparisons between the A1 and A4s pre-war, the A4 as a result being more economical on fuel than the A1.

So it stands to reason that when comparing the express runs, the advantages of the A4 front end should be taken into some consideration, surely?

 

My last post for the moment as will be in work shortly, but the A2/1 appears to have been part of the overall project to create a standard mixed traffic Pacific, and also perhaps experiment with fixing the pony truck problems of the V2s by fitting a bogie, as on the P2s. Happily a replacement pony truck was all that was required on the V2, and the A2/1s were not perpetuated.

 

Standard? So how come ET created A2/1, A2/2 and A2/3 subclasses?

 

I believe Peter Townend is still alive so perhaps you should ask him.

 

That's my point. During and after the war, the speeds that trains ran were much reduced compared to the late 1930s. The experimental wind tunnel data showed that at 60mph the A4 streamlining saved only 40HP.

 

The information on the tests is in P Townend's Top Shed 2nd Ed p148. The tests between the two A4s were carried out over 5 days on the 8.20 am KingsX to Doncaster and back. After problems with the double kychap loco running wildly ahead of time, a set of results which compared the locos fairly was obtained. Coal was used in weighed bags but the dynamometer car wasn't available to allow a measure of coal useage per drawbar hp hr. It is assumed that the same formation was used each day, so the load would be nominally equal to provide a direct comparison. When the double kylchap loco was reigned in to match the single chimney loco's ability the saving was 7 lb per mile; I assume a load of 350 tons so the saving per ton per mile would be 7 / 350 lb per ton mile ie. 0.02 lb per ton mile. Now, it is possible the train weighed more, it is possible the loco should be included ( I don't know if it was or not in the 1945 results) but using say 450 tons of coaches and 150 ton of loco totalling 600 tons leads to a saving of 0.012 lb/ton mile, which when applied to the results for 4466 to try to show the effect of the kylchap still produces savings of between 17 and 10% over the A1/1. I agree it's rough calculation, but the benefits of the kychap are well known and when two locos give such close results as 4470 and 4466 when one has a kylchap and the other doesn't, it seems fair to assume the non kylchap loco is at a significant disadvantage. Why Thompson didn't test his new A1/1 with kylchap against a kylchap A4, I have no idea....

OK, rechecking the info on the 1945 trial the total coal usage/mile is also given, which thus provides a train weight of around 475 tons - exactly half way between my two examples, though I still don't know if this includes the locos

Edit - and rereading the text I find that it did include the locos....

Well, the man who said "well above average for even a prototype locomotive" worked for the LNER and ran Top Shed, so his opinion is not something to be taken lightly. As he's still alive, perhaps you should interview him. In fact I think his books are a pretty fair commentary on the pacifics.

 

I remember seeing one W Bremner Esq scoring a goal at Hillsborough which put an end to Manchester Utd's FA Cup ambitions, and this seems to have subsequently become a regular occurrence!

 

No, he built a class of proper ones, the big uns.