P2 Locomotive Company and related matters

we need more buttons ! I have asked but admin did not reply .

 

With slip eccentric valve gear for the inside cylinder?

 

Stephenson .
GWR knew how to make it.

 

News of the appointment of an assistant to David Elliott has been posted on the P2 website here.



Foxy

 

Anybody who knows David, knows how busy he is, so this appointment to take some pressure off him is a good decision.

Sawdust.

 

... as well as being a damned good way to secure all the knowledge gained during construction of the A1 and P2 and ensure it cascades it down to upcoming projects.

 

Great news! Good to see that also ladies being involved in this fantastic project!

Knut

 

On the V4 2-6-2 No. 3403 thread, but more appropriately here

There's a philosophical conundrum here, somewhat analogous to the question whether Flying Scotsman as now running is the same locomotive that originally emerged from Doncaster when most of its parts have been replaced. How similar must two locomotives be to count as members of the same class? andrewshimmin is correct that the locomotive being built in Darlington has some differences from the originals. They include smaller cylinders for gauge friendliness, higher pressure to get about the same TE, slightly shorter boiler, improved poppet valve gear and a better design of pony truck. There are good reasons for all these differencies, but they are significant differencies for all that.

If things had been (very!) different – Gresley living a few more years and not retiring, WWII not happening – how might the P2s have been developed and what might a new member of the class have been like? Already with the second one the front end appearance had changed to be similar to the A4s, so it seems hardly likely that a new one would have been built looking like the first one.

 

The LNER P2 had outside cylinders with diameter 530mm,adhesive 80 and 107 tons total engine mass.
The French 141 -P 410mm 76 112
The french Mikado was measured to +2850 dhp and used very little coal
The LNER P2/ 5 could have had two outside 450mm hp cylinders and a single 900 mm low pressure between frames

https://fr.wikipedia.org/wiki/141_P_SNCF

 

As regards to the 'authenticity' issue, 2007 is undoubtedly a P2. Does anyone doubt the original spec of (Gresley) A1 1470 renders the 1st production example any more or less an A1? Like (Peppercorn) A1 60163, P2 2007 is the next in sequence. Clearly, the original locos had some development issues to be worked through (which was a rather major factor in A1SLT building the loco!), but it's worth noting that, as recorded by no less an authority than the LNER Encyclopedia, the original locos were sub-classified thus:

P2/1 No. 2001 (with poppet valves).
P2/2 Nos.2002-2005 (encompassing a fair few differences across the four)
P2/3 No. 2006 (longer combustion chamber & piston valves)

So, if we're arguing semantics, 2007 would, logically, be a P2/4 .... but most definitely a P2.

 

AU CONTRAIRE
- semantically .. the significant difference between an A1 (Gr) and an A3 is a higher pressure boiler and smaller (bore) cylinders, plus a bit of faff with Domes and tenders.
Not withstanding the casing the significant difference between an A3 and an A4 is, again Boiler Pressure and cylinders... So if you slapped the drawings for 2007 in front of Sir Nigel his mind would go ' So Bert, whats this ? ah a P3 hmmm what ' ?
I think in a contemporary context we should stick with 'P2 (4)'

 

Do not forget the long travel valve gear.

 

Whilst I'd agree re:A3/A4, they always were identified as different beasties. The point with 1470 vs.production A1's (travel of valves notwithstanding) is the same as for virtually any prototype loco which is/was a departure from all that went before. The subsequent production batch(es) would almost invariably incorporate lessons learned, whether retrofitted to the prototype or not. The A3 rebuild, as the direct result of exchange trials, was far more involved and surely has to be considered separately.

The P2's, being a substantial departure in many respects, from all which went before, were almost bound to be recipients of modifications as the class "bedded in". 2001 was markedly dissimilar to 2003-5, but so was 2002 - as well as from it's immediate predecessor.

In this instance, the LNER's habitual subclasses rather come to our rescue and while three (now four!) sub-divisions across a class numbering in single figures was/is going it some, even by LNER standards, t'aint a record!

The LNER wasn't the only offender in this regard. The GSR had a few decidedly odd classifications, with some encompassing wildly disparate flavours under one banner and in other instances, identical locos being given totally different class ID's, on the basis that pre-grouping locos "returned to the fold" from different companies to which examples were sold. In this instance, think ex-LSWR 0488 returning from the East Kent to the Southern and gaining a separate classification to 0125 & 0520 despite these two having differences from one another. Confused? Cue theme tune from "Soap"!

If this lot isn't bad enough, consider the umpteen issues which would be thrown up if A1SLT totally lose the plot (or gain sufficient confidence - your call) and follow up the 2-6-2's with a reconstructed W1 (in either incarnation). Odds on, I'll be wormfood long before that point could be reached, but if I leave a Ouija board to NP in my will, perhaps a couple of our (now) younger members would be kind enough to let us de-perched old codgers know how it all panned out down the line!

 

So with a 900 mm (35.4") diameter cylinder between the frames, where do you propose to fit the valves?

 

Sleeve valve.
Very British

 

Doomed to failure, then.

 

Considering that the pacifics rebuilt from the P2s, those based on V2s, the new Thompson version and the smaller-wheeled Peppercorn pacifics were all regarded as subclasses of a single class A2, calling the new mikado a P2/4 seems about right, capturing both the similarities to and differences from the originals.

 

Go to France and undoom

ChapP2 by Hermod posted Feb 6, 2018 at 10:13 AM

Keep the two low-pressure valves and put in a big low-pressure cylinder instead of the two that was there

 

Or start a new build group to recreate this legend in France.

 

Let them finish 231E41 first. In truth I don't believe that the French will ever seriously contemplate a "new build". But it only takes one person with the dream and the money.

You would like a 141P, well a few fragments remain of these so they have not totally vanished. I thought you had gone for the 152P (that will teach me to only give a drawing only a cursory glance). These were built on the foundations built by the 242A1 experiment and were designed to maitain 5,000 ihp and achieve maximum outputs of 6,000ihp.

Chapelon was always conservative in his projections, the actual machines always over delivered. With some of the later developments that came about as a result of some the work carried out by his pupils/disciples/followers - call them what you will - stirred into the mix the end result would be delightful to some and quite horrifying to others.