Flying Scotsman

So this has always been a question of mine and AIUI, exact stats for the cut off and the DBHP could be shown by a dynamometer car roll for these runs, but where there isn't one, you'd have to be interrogating the crew after the run, or on the footplate, and the calcs shown would be estimates (because in fairness, I don't think you can claim 100% accuracy from timing on the footplate - which is fine, the logs give a good indicator of performance, dependent on the time keeper concerned).

 

If you are on the footplate, cut-offs can be read fairly easily (subject to the caveat that the number on the indicator is just that - an indication, not necessaruily a measurement). Regulator settings are more difficult, not least because regulator linkages can have a lot of play in them. (Some are better than others). If you have a steam chest pressure gauge you have more indication as to what is going on, but many locos, especially older ones, didn't have them.

For many locos, I suspect the available regulator settings are "cracked", "full first valve", "2nd valve cracked", "a bit more" and "full beans".

Tom

 

You do get too serious at times.

 

This is such a typical gaslighting set of comments. You say something contentious, I respond with examples, you then say lighten up, or words to that effect, because you want to make the other person (me in this instance) look unreasonable.

Bad faith discussions on Nat Pres really need to be ended: either we are serious railway enthusiasts talking enthusiastically about our pet projects and interests or we're not. I'm the former, and proud of it, and I am not going to apologise for that.

 

There is, separately, a question about how much we should do certain projects and whether they add value to what's preserved or not. That's not about whether a project is or isn't worth doing in the abstract, but whether it will add to the sum of what we have or actually distract from what we have.

Going back to Flying Scotsman, that's why I ultimately fall on the side of leaving the draughting as is - because the gain is limited.

 

FS is obviously in a category of its own and must be a centrepiece of whatever is put on in 2030 for the 200th anniversary of Rainhill. But more generally, you do have to wonder (a) what the future total market size is for steam on the main line, (b) what the market position is for 'independents'. Would LSL or WCR want to 'sign' a loco like Green Arrow on similar terms to Bahamas or SNG? Sorry for thread drift, treat these as rhetorical questions.

 

Tom, three of the examples I quoted were from Messrs Nock, Nelson and Weight who
were on the footplate. In the case of Nock and Nelson their original notes are held
within the RPS archive,

R.I.Nelson was a very experienced ‘footplate observer’ and his records are very
detailed i.e he endeavoured to note every change in controls. Norman MacKillop
once wrote effusively, praising Mr.Nelson’s abilities.

O.S.Nock’s notebooks, beautiful writing, have far less detail.

I have no doubt that R.A.H.Weight’s notes would have been very detailed, in fact
when on the footplate he concentrated on the ‘controls’ and less on successive Mile
posts ( I met him when he was active still within the SLS in the late fiftiesearly sixties )
but the details I quoted are ex CJAllen in a 1930 RM P&P article.

The RFO and 55% was ex Hugh Ellison who was a very experienced and careful observer.
He knew the Waverley route and the crews well. The figure also equates, for what it’s
worth with my EDHP calculation. ( Hugh would have spoke to the crew after the
event I assume, as I invariably did, and still do ! Although the apparent serious
attack on the gradient may perhaps have been discussed ahead of the event

I agree entirely that all logs etc have to be carefully assessed. No names but there are
some often quoted sources whose logs do not withstand close scrutiny too well.

Michael Rowe

ps apologies, this was a response to your previous post. .

 

I thought I had been involved in a discussion wrt the Jubilee double chimney. Please see attached.

Michael Rowe

 

The question is not simply about 'single chimney versus double chimney' - the real question concerns 'non-optimised draughting versus optimised draughting'. This is well covered in Jos Koopmans' book: in general double and multi-jet blastpipes perform better, particularly in large locomotives, but getting the geometry and sizing of blastpipe and chimney right is even more important and best performance of all comes from considering the draughting in combination with tube and superheater sizing and optimising the steam circuit as a whole. That is what the 'Chapelon revolution' was really all about.

Thus there is no serious doubt that the LNER Kylchap double chimney engines were better than their single-chimney sisters but other locomotives were rather hit-and-miss: double chimneys greatly improved the GWR Kings and Castles in other designs a well-designed single blastpipe out-performed a poorly-designed double; Jubilees never really fulfilled their true potential because the relationship between draughting and boiler tube sizing wasn't right.

Bottom line? On locos like the LNER pacifics, the Kylchap double chimney is probably worth at least an extra coach in haulage capacity but (perhaps just as important in today's conditions) it gives better acceleration and also better steaming with poor quality coal. However, as in the case of Waverley route records, with a heavy train on a difficult route performance may depend as much on adhesion as on steaming capacity. On other locomotives double chimneys are generally superior but they need to be considered individually on the basis of their records - for example, my guess is that the Jos Koopman single chimney on 'King' 6023 was probably even better than the standard double chimney but both considerably out-performed the original single chimney.

 

This, for me, is what it's really about. And many need to take their "enthusiast blinkers" off and realise that steam is no longer amongst its brethren of similar speed any more, but mixing it with an ever-accelerating Big Railway. Wasn't the raison d'etre for the P2 to be able to get a heavy load up to 60/75 quicker than its counterparts?

 

I suspect, but do not know, that the Double chimney on the Jubilee was merely fitted as a
direct replacement. I would be happy to be proven wrong ?

I agree entirely that it is about the overall optimisation of the exhaust system design.

I have previously referred to various draughting changes on the A3s eg -Longer SH tubes in the
1920s with adverse results due to being closer to the smokebox i.e lower S/H temperatures, -
Incorporation of modified Swindon type cowls etc in the mid 1950s resulting in higher
evaporation figures but lower water and coal efficiencies, presumably a lower final
steam enthalpy. - Subsequently the Kylchap fitting - A thirty year evolution. The essence
of Chapelon was to optimise all at one time ?

Michael Rowe

 

Drawings for 45596's new draughting arrangement were drawn up at Derby Works in early 1960, so it appears to be a new design. It must be noted that 5684 was fitted with a double kylchap exhaust in 1937, but reverted back to a single chimney after a year. 5553 and 5742 were fitted with double chimneys for a time, with 5742 not reverting back to a single chimney until 1955, long after 5553. Perhaps a member of the Bahamas team could clarify the situation.

 

You could have a look on our website 45596 LMS Jubilee Class 'Bahamas' - The Bahamas Locomotive Society (bahamas45596.co.uk)
Or buy the book Locomotives & Recollections - The Bahamas Locomotive Society (bahamas45596.co.uk) It's only £8 and any funds raised go to a really good cause!! Not long since there was a similar thread on NatPres

 

Apart from Bahamas four Jubilees have been fitted with double chimneys at various times. 5684 Jutland acquired a Kylchap in 1937 that apparently give impressive results but in was removed a year later. 5553 Canada and 5742 Connaught were given plain twin exhausts in 1940, 5553 lost it fairly quickly but 5742 retained it until 1955. In 1956 45722 Defence was tested with a double exhaust on the Rugby Testing Plant (? The one taken off 45742). Apparently it gave good results in extra power output but the chimney was removed.
I will endorse what Pete has said above, the £8 book is a good read with a lot of detail about the engine’s history. It’s an even bigger bargain as it’s got one of my pictures in it!!!

 

Just altered my post as you were doing yours, John.

 

The model in the photo of Bahamas smokebox, blastpipe and chimney arrangement is on display in our museum at Ingrow, made by one of our highly skilled long term members Pete Skellon.. it's a bit more accesible than the actual locomotive!

 

Gratifying to see NR verifying my suspicion that a Jube isnt a patch on an A3, and is in fact the lowest performer in its class, being the only express loco with timing speed below running speed.

V2? Only a full disposition can inform the direction of overhaul.
Anything is repairable in theory, cracks can be welded, bores can be re-machined, but it wont have escaped the attention of the custodiands of the V2 that a number of new blocks have been made in recent years, and a fabricated monoblock was made for the P2.

The question i have is does a budget exist for both an A3 and a V2 to run at the same time...?

Its easy to imagine the beancounters questioning the need to run more than 1 mainline loco out of the NRM budget at any one time.

 

On a bit of a tangent, but I am surprised at the Jubilee's standing.

From my research and reading, the LNER board and some of their engineers seemed to appreciate them, the Jubilees being mentioned in the notes for ES Cox's report on the conjugated valve gear as one of the LMS three cylinder types with a very low failure for the middle big end.

 

Isn’t comparing a Jubilee to an A3 a bit like comparing apples and oranges anyway?

I get the impression from what I have read that the jubilees were not initially a great success but over time gained a good reputation for the work that they were envisaged for, which at the time was a different role to the A3.

Similarly now, I was under the impression that 45690/45699/45596 all have a good reputation for turning out good performances and having quite good availability/reliability.

With regard to Scotsman- as I have mentioned elsewhere, I’d really like to see it back in Apple Green and I’m in agreement with @s.a.c Martin regarding it being it’s most “iconic” form that most people probably identify with- there has got to be something to be said for that.

With regard to the chimney conundrum, I’d be curious to see whether given modern modelling and techniques, how much performance loss would be expected to be lost when compared to the current double chimney arrangement.

The “historic condition” argument is a bit of misnomer, the locos history did not end in the 60s, if you wish to perpetuate this argument then the air braking needs to be turfed off along with all the main line gubbins- in which case the argument about performance is null and void because it would be restricted to heritage line service anyway- there are always going to be compromises.

Chris

 

Yes. Given that there was nothing bigger than a Jubilee out of St Pancras before 1959(?), they must have been capable machines on the Palatine, Thames-Clyde etc. But if they were the standby at Crewe in not tip top condition and got put on a heavy train to Euston in place of a Scot, then they were out of their class. Wouldn't their nearest comparators at 5XP be more like V2, N15, Modified Hall, BR Clan?