P2 Locomotive Company and related matters

Forgot about that one. Not exactly a success.

 

Yes, the rather hopeless RR Vulture. The airframe was pretty much the same as the Typhoon.

 

Getting back to the P2, according to Heritage Railway they've already got 50K more than they needed for the planned work on the frames - what comes next?

 

My bets are on casting the wheels, as like most new builds I've noticed at there, getting to the rolling chassis stage is considered a major milestone and real show of progress to the public, thus proving their true capability of completing the project.

Though, on seconds thought, if they are only building the two main frame plates (the two sides of the frames), perhaps they should focus on the rest of the frame components in order to get the frame completely assembled. Certainly I've noticed quite a few groups that have pressed ahead with wheeling the chassis, even though the frames aren't completely assembled (with such components as the cylinder missing), just so that they can show they mean business. I can understand why they do that, so as to make a statement, though I do not personally believe that the P2 group should feel that they need to do this in a hurry. They've already proven themselves with the construction and operation of Tornado (albeit it with slight bumps along the way), so with this project I think they should focus on getting one part of the locomotive completely constructed, in this case being the frames, then move on to the next item. Yes I do want to see continuous and steady progress being made, but I don't want them to feel like they need to prove themselves, that part is already well covered and running around the country in blue...

 

Agreed Jonathon most enthusiasts would know that Sir Visto and Spion Kop were winners of "classic" races How many actually know that SpionKop is the Dutch name for a hill in South Africa where in 1900 a battle in the Boer war was fought. Locomotive names played a huge part in my general knowledge.

 

There are good reasons for wheeling the chassis sooner rather than later. It gives you something to nail a lot of small, affordable (sponsored?) components to and it can be moved around as a unit. In the case of No. 2007 reaching this stage will be more costly than many other builds because of the choice of roller bearings - at least the Trust has patterns for horn guides, cannon boxes, etc. available (in fact they have a 'spare' cannon box in stock) so casting the wheels as early as possible might make sense.

Foxy

 

Any idea how the monobloc interfaces with the frames Foxy? Will it slot in after the frames are erected, or do we need it beforehand?

 

Far as i Know Sheff a Monobloc isnt going to be attempted. Cylinder casting will be done Club Sandwich style ( as 3 parts)
The basic design principle has a yardstick ( the V2 also done mostlyas monobloc, some as three parts).
Heads are still being scratched as to how to realise the caprotti gear alongside the middle cylinder rather than above it. Until this is solved the middle cylinder casting will be on hold. That still leaves plenty of other things to be geting on with.

 

The P2 website says 'fabricated cylinders monobloc'..

 

Indeed - hence my question.

 

Perhaps 'fabricated monobloc' is an oxymoron.. LOL

 

Surely Fabricate and monobloc are slightly contradictory - monobloc - single piece - by means of fabrication ie assembling and joining of parts ?

 

I think they mean a one piece fabrication of all 3 cylinders and valves - looking to get rigid platform for the BR Caprotti I believe.

 

The flip side of that argument is being pursued by the Bluebell Atlantic team - they are deliberately not putting the chassis on the driving wheels, because it leaves more space for working between the frames. Currently the frames are propped up about a foot high than their natural level, and it is easy to move from outside to inside and vice versa to attach all the various pipework associated with the brakes, steam heating, lubrication etc, while putting the frames at a convenient height. By contrast, if the loco was sat on its wheels, access between the frames, especially without a pit, would be much more problematic, at the very least slowing down assembly.

Eventually the loco will have to go onto its wheels, not least so the last part of the motion can be assembled. But delaying that point as late as possible has a lot of advantages.

Tom

 

Given the kit available at Darlington - pit, jacks etc I don't think the P2 team will have the constraints that the Beachy Head team have Tom.

 

How was the fitting of caprotti gear done on the Duke of Gloucester? Just curious as I seem to recall the centre cylinder was forward of the outside two, which is something I am not 100% certain is possible to do on no.2007, given the space available at the front end?

 

If they could design it to be as stiff as possible where all the piston and valve TDC's were milimetrically exactly in alignment when in steam it would certainly be easier to keep the loco in tune as it would be one less variable to worry about. Redesigning the front stretchers using a modern CAD tool to reduce the amount of lateral flexing of the frames during the outer piston strokes would also improve precision. I have no doubt the biggest challenge though is to get the Caprotti right for the middle cylinder as said above. If only they had the money to get access to a top engine consultancy such as Ricardo all that sort of thing would be so much easier.

 

Correct me if I'm wrong but the middle cylinder drives the second axle, as do the outside cylinders. For the middle con rod to clear the front axle, the middle cylinder will be at a higher level and at a greater angle than the others. This means uneven distribution of piston thrusts which can only complicate the derived Caprotti operation.
I do hope the P2 trust sort this out and don't revert to Walschaerts gear..

 

And what, exactly, is wrong with reverting to Walschaerts gear? The original 2001 was fitted with Lentz gear which did not give the required level of performance. So the A1 group want to produce a 2-8-2 loosely based on the LNE P2 design and fitted with BC gear. 71000 has the most complicated installation of this gear to date and people are still trouble shooting it. The cost implication of producing a one off new design of this gear needs to be borne in mind. The Trust has at its disposal a document, a proposal, that if it were to be applied to this project would produce a locomotive that would offer a level of performance far higher than that currently being considered. It would deliver a superior mechanical performance in addition to the more obvious areas.