P2 Locomotive Company and related matters

Point taken.

 

I can be fairly safe in saying that not many people around here consider him to have much to do with Wales itself.

 

Though how many of the previous "Princes'" of Wales have had much to do with Wales........... Considering that the title is more of an "Honourary" one given to the eldest son of the sitting Monarch.

 

Given that the original members of the class were built for working heavy trains north of Edinburgh, and all had Scottish "connection" names, surely "Duke of Rothesay" would have been an appropriate name for the new locomotive, if they wanted to name it after the current Prince of Wales.

Or, if you want an even bigger nameplate, HRH's correct Scottish title is actually "HRH The Prince Charles, Duke of Rothesay".

 

But as explained several times, the name hasn't been picked necessarily for the LNER/Scottish connection, in much the same vein Tornado was picked for the A1, it's about publicity and maximising the earning potential of the project through the name.


That being the case, "Prince of Wales" is about as appropriate as any name. Prince of Wales itself has an LNER connection (more so than Tornado) so it does at the very least "fit" the locomotive better in terms of historical connections.

A rose by any other name would smell as sweet, or something akin to that with locomotive names. As long as the P2 runs, the name is immaterial to me.

Speaking of which, I am reading a copy of Steam Railway I have borrowed, and it states that "unofficially, Lentz gear is gaining favour". Given no.2001 was originally converted to be standard with the five other P2s in terms of their valve gear, is not perhaps prudent to investigate a full walschaerts alternative to both Lentz and Caprotti too? I understand the argument for Lentz in that it was used successfully towards the end of steam traction elsewhere, but I have been told that the walschaerts valve gear on the P2s was similar to (and shared components with) Gresley's V2 class - would this not give the trust something of a head start, surely, for measuring up existing and suitable components?

I do not decry the work of the DoG supporters. Theirs is a superb locomotive, and the first real "mission impossible" made possible in terms of mainline steam overhauls. It simply seems logical to me for the A1 Trust to continue with the use of walschaerts as a known quantity, if the aim is to get the P2 up and running as quickly as possible. Changing the design slightly to original style Earl Marischal (minus the extra deflectors) would not change the whole look of the new P2 completely.

I won't harp on about this though - I'm not an engineer and my understanding of locomotive valve gear is limited.

 

Not quite Lentz gear. What was essentially a point contact following the cams on the original gear caused the wear on the design. This precipitated the revision to the later stepped cams offering a limited range of fixed admission or cut-off points. The A1 Trust are looking at Franklin Patents, Franklin was later part of Alco. They are probably looking at Franklin B type valves and associated gear. The Lentz gear never proved satisfactory on this locomotive design. The Trust has committed itself to the original design, 2001, "Cock o' the North" call,it what you will. This was a prototype and these frequently prove themselves to be less than satisfactory. The second prototype, 2002, was not satisfactory either though it was an improvement on 2001. In fact the class was never fully developed.
So what has been taken on is the re-engineering of an unsatisfactory design in order to make it fit for acceptance in today's conditions. Great challenge. The chassis design has been looked at and analysed and largely confirmed what was suspected, going further supplying solid data. So far, so good. However the commitment to poppet valves acknowledged pretty well from the beginning that the original fitment was not satisfactory hence the BC alternative. At least the 71000 people have a wealth of experience with this. But now the project is looking elsewhere. They may end up wishing that they had gone for 2002. It would be a great deal easier and less costly.

 

Franklin? Big Limitation at speed despite the usual big speed claims.
What about Caprotti just on the centre cylinder?
Right noise as per the original, make modern technology work with a full remote system control of the cams/scrolls? It's all in a handy box with a spare set for the regular routine maintenance that any poppets require.
OVS Bulleid would be proud of you! I mean Gresley.

 

Nah....it's being named after the pub near Carr House loco in Doncaster. Gresley Road is just round the corner from it!

http://www.yelp.co.uk/map/prince-of-wales-doncaster

*Hides behind sofa*

 

High speed? The P2 has 6' 2" wheels so will be limited to 75mph. 90mph may be the dream for enthusiasts reinforced by the ease of 4464's performance. The P2 is not an A4. Are we talking about line speed or rotational speed?
How much complication can you afford? This project relies on donations and to turn it into a means of solving a locomotive valve gear design problem of significant complexity is something of a step beyond creating a faithful working replica. To take on what could be a major technical challenge with limited funds would have a significant impact on the funding of the project. Fortunately the cylinder design has not been decided on.
I will admit the obvious. The more primeval aspects of steam locomotives hold little appeal for me. So noise to me equates to high back pressure, inadequate blast pipe tip area, and more. And there is no one who remembers what the original 2001 sounded like so what the new version sounds like is not particularly important except to the decibel enthusiasts. I would like to think that those in charge of this project would be talking very seriously with those who have had experience with poppet valve gears on any locomotive if they are still resolved to pursue their initially stated route.

 

If I do not appear to be particularly enthusiastic about this project I have good reason. I hope that those who support it understand honest concerns.

 

Based on what?

 

6' 2" drivers didn't inhibit the Bulleid Pacifics, especially the MNs. I accept the original P2 was a different beast but 6' 2" drivers on their own do not disqualify a modern loco from high speed.

 

I know you are referring to the current permitted speeds based on the wheel diameter, but without checking my facts (it's getting late), didn't the 5AT project propose a design speed of 113 mph with 6' 2" wheels? Why would 2007 not be capable of high speeds?

Dave

 

The locomotive might well be capable of higher speeds than 75mph, but unless NR has a change of heart, 75mph will be 2007's maximum speed.

 

We all know that but I'm interested in the reasons behind 242A1's misgivings and other than NR's say-so, why he thinks 2007's driving wheel diameter would be a disadvantage in the over 75 speed stakes.

 

Apart from the obvious restriction, i dont see a problem with the capabilty for high speed with a P2, If a 9F can push 90mph a P2 Certainly could....
The strength of this locomotive is that it will have more adhesion weight than any other locomotive in its class, combined with its high tractive effort we should have some pretty quick starts and some extraordinary climbing - regardless of the valve gear /name

 

The locomotive could achieve higher speeds. From the records that I have to hand it appears that the class never reached 90mph, 87.5mph was recorded down Stoke Bank wth 2001 while on a test run. The class were not built for speed though like all Gresley locomotives they could have moved along quite smartly if required to do so. However the class did give concern when it came to steaming. It proved to be quite a task to get the design to maintain a high output. All too frequently any attempt was met with a falling pressure gauge - see Part 6B for some numbers. Going down Stoke was one thing in terms of evaporation a high powered ascent was quite another. Eventually the design was sent to Scotland, good enough maybe but far from fully tuned up.

Doubt has been expressed over the suitability of Franklin valves for high speed work. That is why I was wondering quite what was meant. Line speed or rotational speed? The PRR K4S performed well enough on these valves but there is a view that they were difficult to maintain. So some clarification would be useful with respect to that doubt. And no one likes a locomotive that is difficult to maintain for long unless it has some peculiar redeeming features.

So 75mph is the NR limit. Even though this project might be considered a 2-8-2 version of an A2 (not a P2 in the truest sense) would the design ever be countenanced for 90mph? Is there any need for it to be? Providing a satisfactory conclusion is reached with regard to the poppet valve issue then 75 is a fair figure. Get it wrong and it may well be lower.

 

Thanks 242a1, The Franklin gear is a bit of a mystery to me, but one figures that the similarity in Layout to the lentz set up from which it evolved is what is interesting the P2 Group
The amount of space available atop the middle cylinder is a problem for the Br Cap. Cam box, and a Cam box in a smoke box is perhaps....unwise.
I havent thought about it hard enough to figure out whether the middle cylinder could be pushed up with the cam box underneath, but perhaps the change of Pony truck control system prevents this also, Interesting that the British experience of Poppet valve engines - Less gutsy on start up but fast, efficient and free running at speed is the opposite of the comments on the Franklin...

 

I can't see steaming being a problem, as the boiler will be based on that of Tornado (with any mods necessary from lessons learned) and Tornado is certainly not noted for being short of steam.