P2 Locomotive Company and related matters

This discussion should be moved (Mods please) but while it's here* let's not bother with numbers but just have a qualitative look at the differences. The P2 will have essentially the same boiler as Tornado, of a similar size to all the other Class 8 Pacific boilers, so it will produce a similar amount of steam. The Franklin valves should allow slightly more efficient use of the steam, but that's probably not a big difference. The significant differences will be more TE and more adhesion weight, allowing better acceleration and better hill climbing, especially when the rail conditions are poor.

* "here" when I posted being the The Cornishman Express with Clan Line: 17/06/18 thread.

 

Following on from @MellishR's observation.... a slight aside ...... The differences between top performing athletes frequently come down to the odd fractional improvements here and there, over and above an already high benchmark. Whether or not steam locos' performance these days means that small incremental increases, due to designers 'breathing on' individual component assemblies makes much of a real difference, or are worth the extra cost and effort, tends to be rather more open to debate.

If the 'other P2' gets built, we'll have something closer to a true indication of whether radial or poppett valve gear is the better bet .... for a P2, at least!

 

IMHO when it comes to Steam locos, the incremental improvements when taken in the round do make a significant improvement. A3 vs A4 anyone...

But in the modern era, I think its less quantifiable. Coal, firing, and even driving are not what they used to be, and interpret that any way you like, but the point is, performance in the modern era is bound to be much less correlated to loco design than it used to be.

When it comes to the P2, the only concern must be the boiler being so much shorter, but then I have heard Tornado makes plenty steam...so...

 

Length per se isn't too critical: what matters are the proportions of heating service and free gas area to grate area. I don't think any of the surviving or new-build Class 8 locos will be far wrong there.

 

I'll just this here then.....



Foxy

 

Really gives you a sense of how it's going to look. Particularly if they either leave it on or re-fit it once the wheels are under it.

 

'Oh Sam, what a beauty!' That is a rather impressive sight.

 

Wibble.

 

Speaking for us all there.

 

Right, so, set of wheels later this summer and shes done?!

 

[QUOTE="
When it comes to the P2, the only concern must be the boiler being so much shorter, but then I have heard Tornado makes plenty steam...so...[/QUOTE]

Iindeed I had qualms - not on the steaming front but the weight distribution , but apparently the new fabricated cylinder assemblies are likely to be heavier rather than lighter than the original monobloc. The other concern ( and this could be designed into the valve gear) is that the Kyllchap is afaik another straight copy off Tornado, put P2 has potentially a larger exhaust volume and a sharper exhaust release... anyone heavy handed on the regulator could potentially pull the fire to bits ?

 

But, on the other hand, shorter boiler means longer smokebox, which should have a dampening effect on the exhaust beats and contribute to a smoother draw.

 

More pictures here.

It'll be nice to see her on her wheels. If things had been different, we'd have seen that wheeled over a year ago but having now built and assembled the boiler cladding onto the frames, it will give a much greater appearance of progress to the casual visitor

So if anyone fancies hurrying it along financially, you know where the website is

 

Wow! Sex on wheels that will be come Autumn time!

Richard.

 

With luck it should be possible to wheel the locomotive at DLW with the 'boiler' on since with 6' 2" drivers it will require less headroom.

Foxy

 

Headroom looks to be a premium there...

Will there be an open day once the wheels are on? Be great to come and see it and make a donation...

 

But surely she is built to the 13ft loading Gauge so the size of the wheels is somewhat irrelevant ?

 

I think the point being made is about the headroom needed to put a loco on its wheels within the constraints of the building height (or height above ground of cranes if done that way). To do so, you have to lift the loco (frames and anything attached at the time you do it) by half the wheel diameter, plus an additional allowance to allow the bottoms of the frames to clear the top of the axle boxes. All else being equal, a loco with 6'2" wheels would need 3" less headroom than one with 6'8" wheels when being put upon its wheels.

Tom

 

Ah yes I see. Thanks Tom

 

I think you need to lift the loco higher than half 'and a bit more' of the wheel diameter. You actually have to get the wheels under the frames in some way, even rolling in from the ends needs the lowest point of the front or rear beam to go over the full wheel diameter. A wheel drop on the other hand makes life so much easier.