Edward Thompson. Good or Bad

[Tom F]

Gee Simon, it's Christmas morning and your on here talking about Thompson!

Go play with your new L1 and Suburbans, and ignore the nay sayers! Merry Christmas!

[S.A.C. Martin]

Gee Simon, it's Christmas morning and your on here talking about Thompson!

Go play with your new L1 and Suburbans, and ignore the nay sayers! Merry Christmas!

I am Tom

67717 is running on the layout behind me. I've got both turkeys in the oven, and the potatoes to do next, with my Dad on the spuds and various bits and pieces before the Martin clan descend on us again...!

Merry Christmas Tom, hope it's a great day.

[Blink Bonny]

Ay up!

Mrs BB know the best place for me while there's kitchen activity. In the computer room with the occasional cup of coffee pushed through the slot in the door. Maybe a biccie if I've been good.

Hang on - the door's locked. Excuse me while I hammer on it and bellow for release, wouldya?

[60800]

Brown Jack's busy running in, Silver Link is awaiting a repair next week (broken wire straight out of the box ) and a lovely new thompson coach is sitting behind Union of South Africa

[strang steel]

Gee Simon, it's Christmas morning and your on here talking about Thompson!

Sorry, that was my fault. I had a few minutes to spare while waiting for the stuffing to cool down, before I delighted the turkey with my soft hands.

I can thoroughly recommend a Waitrose Organic free range specimen.

I have left my 4 Gresley suburbans for next week, when my credit card is less stressed and I may even succomb to a Hornby 61138.

Lovely.

[Hatfield Shed]

... Where did he go wrong with the L1 though? Why did they knock themselves to bits like they did? Basically they should have behaved like a tank version of the K1...

Tractively they did. An L1 in good nick was a very good performer for its size. Rather the same as the Gresley K4 which is the precursor design to the K1. Apply high loads with large static thrusts and the frame strength must increase in proportion to resist the racking forces generated. If the strength is too small, because the weight of steel possible is insufficient because a low all-up weight for high route availabilty is required, and nothing other than steel can be considered, 'something has to give'.

In engineering, there's always a price to pay for enhanced performance, and unless it is possible to use a (near inevitably) more expensive 'unobtanium' to overcome the effect of higher forces using a given weight of structural material, then accelerated flexing and wear of that structure will be the result. That's how they won the 'Concrete Mixer' tag! Read D.W. Harvey's assessments of this attempt to get a quart of performance out of a pint pot of structural strength, for confirmation. This problem might have been avoided had Thompson had more time in which to test the design in a year or more of ordinary service, before placing the build order. Quite how he would have revised it, now that is quite a question...

(Tangent here: this by the way is why the 5AT project is a predictable failure, unless they are proposing building the frame and rods from titanium or similar; and that will cost a packet. For sure you can get a lot of power from a loco that size, but the forces in the structure will rack it apart in short order if built to typical UK practise. Look at the dimensions of the frames and rods of US machines exerting equivalent thrust forces per unit weight.)

The boiler was a shy steamer too, never a characteristic to win a design friends among footplate crew. On the main line suburban services out of Kings Cross they were heartily disliked by KX loco men used to the GN and GE tank locos which 'steamed all day long'. Moving much of the allocation to Hitchin apparently helped, they got a more sympathetic reception there. Anecdotally, I had this explained to me as "The Hitchin men had regular exposure to Derby loco designs; by comparison the L1 was a decent machine".

P2s? 96lbs of coal a mile? I just hope the enthusiasts who are considering building a new one will take that into account when they do their sums.

There's not a lot of doubt that the P2s were mismanaged in service, often driven with regulator part open on long cut offs, rather than by the full regulator short cut off method. That will degrade the thermal efficiency. Tested at Vitry the fuel efficiency was as expected for a Doncaster wide firebox machine. At bottom, the P2 boiler is the basis of the unit that went on to be fitted to the A1 and A2, and no fuel efficiency troubles there. The slipping seen on Blue Peter, and to which the A2s were generally prone as a result of their relatively low adhesion factor, is dealt with by the extra coupled wheelset. It is a better format than a pacific if very high speeds are not the aim, and secure traction for lifting large loads on gradients is required.

I hope a P2 does get built, and in further developed form too, for example with the Caprotti gear used on DoG to such effect.

[S.A.C. Martin]

... Where did he go wrong with the L1 though? Why did they knock themselves to bits like they did? Basically they should have behaved like a tank version of the K1...

Tractively they did. An L1 in good nick was a very good performer for its size. Rather the same as the Gresley K4 which is the precursor design to the K1. Apply high loads with large static thrusts and the frame strength must increase in proportion to resist the racking forces generated. If the strength is too small, because the weight of steel possible is insufficient because a low all-up weight for high route availabilty is required, and nothing other than steel can be considered, 'something has to give'.

In engineering, there's always a price to pay for enhanced performance, and unless it is possible to use a (near inevitably) more expensive 'unobtanium' to overcome the effect of higher forces using a given weight of structural material, then accelerated flexing and wear of that structure will be the result. That's how they won the 'Concrete Mixer' tag! Read D.W. Harvey's assessments of this attempt to get a quart of performance out of a pint pot of structural strength, for confirmation. This problem might have been avoided had Thompson had more time in which to test the design in a year or more of ordinary service, before placing the build order. Quite how he would have revised it, now that is quite a question...

(Tangent here: this by the way is why the 5AT project is a predictable failure, unless they are proposing building the frame and rods from titanium or similar; and that will cost a packet. For sure you can get a lot of power from a loco that size, but the forces in the structure will rack it apart in short order if built to typical UK practise. Look at the dimensions of the frames and rods of US machines exerting equivalent thrust forces per unit weight.)

The boiler was a shy steamer too, never a characteristic to win a design friends among footplate crew. On the main line suburban services out of Kings Cross they were heartily disliked by KX loco men used to the GN and GE tank locos which 'steamed all day long'. Moving much of the allocation to Hitchin apparently helped, they got a more sympathetic reception there. Anecdotally, I had this explained to me as "The Hitchin men had regular exposure to Derby loco designs; by comparison the L1 was a decent machine".

May I just say, that is a very insightful and interesting read, thank you for sharing. I'm reading up on the L1s and it appears the prototype was the best of the bunch, though why this is so, is put down to it being maintained carefully.

P2s? 96lbs of coal a mile? I just hope the enthusiasts who are considering building a new one will take that into account when they do their sums.

There's not a lot of doubt that the P2s were mismanaged in service, often driven with regulator part open on long cut offs, rather than by the full regulator short cut off method. That will degrade the thermal efficiency. Tested at Vitry the fuel efficiency was as expected for a Doncaster wide firebox machine. At bottom, the P2 boiler is the basis of the unit that went on to be fitted to the A1 and A2, and no fuel efficiency troubles there. The slipping seen on Blue Peter, and to which the A2s were generally prone as a result of their relatively low adhesion factor, is dealt with by the extra coupled wheelset. It is a better format than a pacific if very high speeds are not the aim, and secure traction for lifting large loads on gradients is required.

I hope a P2 does get built, and in further developed form too, for example with the Caprotti gear used on DoG to such effect.[/quote]

So, just to go back to the argument "The P2s were heavy on coal" - the locomotive itself was not thermally inefficient, but was driven badly?

Ergo, if they had been handled better, that part of Thompson's argument for rebuilding would have been void?

The A1 Trust is looking to use British Caprotti valve gear on no. 2007 - all the information towards the current proposal is on the A1 Trust's website under "The P2 Project". The results of the first study are expected back soon, if the other covenator I know and have spoken to is correct.

[Hatfield Shed]

The first L1 suffered from a common syndrome which I think of as the 'precious prototype problem'. Basically it doesn't actually get tested in real conditions, it is a 'pet' that is trialled as a demonstrator. The people involved in the design are all over it, compensating for its deficiencies. They 'know' it is a splendid design with great potentialities, and are out to demonstrate the fact; the problems that do show up are promptly rectified by the specialists to hand, and are passed over as no more than teething troubles to be sorted out by small redesigns and adjustments.

It never gets worked day in, day out, as a general user unit by the regular operating staff, with the minimal attention required to get it off shed on time in the 'rough and tumble' of the service environment. For a year or more. With no-one from head office regularly present and ensuring careful treatment. It's when the loco isn't receiving any special care beyond that typical of the service environment that the robustness or otherwise is really exposed. The L1s literally went to pieces in the standard environment, and an experienced engineer like Bill Harvey tells it like it is "Inferior to the (thirty years older) A5 design by Gorton".

The P2 design was probably not ideally balanced for the reality if its intended service route. It almost certainly needed the higher 250 psi boiler pressure (at least - Bulleid who knew this design well and had a not dissimilar route problem on the SR went to 280psi) that arrived with the A4, to help compensate for the operating conditions effect on the superheater performance. The superheater contributes most to efficiency when the loco can be run at a near constant steam rate which allows the maximum steam temperature to be achieved. On the long well graded stretches of the ECML with a loco using a short cut off, and even at highest service speed only using about half the normal maximum evaporation rate of the boiler, the superheater gets good and hot, and the efficiency contribution is large. The fireman can maintain the classic 'thin fire', blazing hot but of no great depth, firing little and often. That means the flue gases and thus the superheater is hot, and the steam rate is low enough not to cool the superheater.

But on a route with many gradient changes and speed restrictions on curves this is not the case. A bigger fire has to be built up to tackle heavy gradients at slow speed, steam rates are high enough to cool the superheater, if the crew are concerned that they may be checked by a train ahead then a big fire necessary to cover the need for any restart and/or low speed slogging uphill goes to waste after cresting the bank. It's simply not a good route for a loco design biased toward developing power at speed. Really the route needed re-engineering to remove as many speed restrictions as possible so that a loco of this type could 'blaze away' with little restraint.

[Coronach]

In engineering, there's always a price to pay for enhanced performance, and unless it is possible to use a (near inevitably) more expensive 'unobtanium' to overcome the effect of higher forces using a given weight of structural material, then accelerated flexing and wear of that structure will be the result. That's how they won the 'Concrete Mixer' tag! Read D.W. Harvey's assessments of this attempt to get a quart of performance out of a pint pot of structural strength, for confirmation. This problem might have been avoided had Thompson had more time in which to test the design in a year or more of ordinary service, before placing the build order. Quite how he would have revised it, now that is quite a question...
The boiler was a shy steamer too, never a characteristic to win a design friends among footplate crew. On the main line suburban services out of Kings Cross they were heartily disliked by KX loco men used to the GN and GE tank locos which 'steamed all day long'. Moving much of the allocation to Hitchin apparently helped, they got a more sympathetic reception there. Anecdotally, I had this explained to me as "The Hitchin men had regular exposure to Derby loco designs; by comparison the L1 was a decent machine".
There's not a lot of doubt that the P2s were mismanaged in service, often driven with regulator part open on long cut offs, rather than by the full regulator short cut off method. That will degrade the thermal efficiency.

I hope a P2 does get built, and in further developed form too, for example with the Caprotti gear used on DoG to such effect.

Thanks Hatfield. Sometimes you have to look beyond the 'tabloid rhetoric' to find the practical truth and it's nice to see it couched in bald engineering terms as in your post, so thanks.
Interesting to hear the comments about the L1s and it's pretty clear that posting a new type to the wrong shed could have a significant effect on a type's reputation.
As good evidence of this, consider the difference in attitude to the 'Clan' pacifics between the Kingmoor men and the guys at Polmadie and Haymarket.
Admittedly, the Kingmoor boys used to stick a fishplate down the blastpipe when the gaffers weren't looking!

Dave.

[Leviathan63]

In my honest opinion, I think Thompson had some good point of views when it came to locomotives. True, most of his engines weren't successful, but some of them had strong points. As mentioned, A1/1 Great Northern had more power rebuilt as compared to being originally an A3. I think its best to respect the man not for his mistakes, but to his contributions that would later assist in the evoloution of LNER steam locomotives.

[60800]

When it comes to his carriages, I can't put him wrong.

[Steve05]

Yips,

I just noticed I’m a L1…no wonder I’m shaking! How many posts do I need to do in order to evolve?

Many have said this before and I’ll be another, but one cannot help but feel that P2’s reallocated to the ECML would have excelled with the heavy wartime loads, so no need to rebuild. It’s seems such an obvious solution but not undertaken by Thompson. Is there a cogent reason for this?

Regards
Steve

[Hatfield Shed]

1. Of all the big engines, the P2s were the one class that were not performing to the expected standard, and were few in number.
2. Here's a new engineer, wanting to try out his ideas for an 'ideal' big engine layout.
3. New engineer to locomotive committee: I have a plan for bettering the big engine fleet to meet current conditions. I can prototype this plan by an economical rebuild of this small class of existing locos, which are proving troublesome in service. The deal is: six troublesome locos to be rebuilt for little more than the cost of a heavy works overhaul each, and on re-entering service will be the six best big engines in service.
4. With the new design thus proven, all new big engine construction will move to the new design.

[Steve05]

Hi,

Interesting and I thank you. This certainly seems like his plan of attack and summaries his cogent reasons for his actions.

Regards
Steve

[Blink Bonny]

Ay up!

Thanks to Hatfield Shed and S A C Martin for those most illuminating descriptions of just why the L1s failed to meet expectations.

You are both Officers and Gentlemen, sirs.