V2 4771 Green Arrow to return?

A fabricated block could be a way forward, like the P2. It would depend on whether the highest priority for Green Arrow was retaining its originality or becoming operational. It seems that both are not possible.

 

Indeed. My point, given the persistence of the view (myth?) that the monobloc is irreparable, is that the means of repair or replacement can't assume that a fabricated replacement would be acceptable.

 

Isn’t there a question of reversibility? That is, hypothetically you could remove the existing cylinder block and preserve it; and replace with a new set of cylinders (of any construction method, it wouldn’t matter visually); but doing so wouldn’t preclude a later reconstruction of the loco with its original cylinders, albeit for static display only. So a restoration with new cylinders doesn’t seem to me to preclude a future return to “original” condition if that was deemed important. (*)

(*) As an aside on that, if the monobloc cylinders are considered a significant engineering artefact in their own right, then they are probably better appreciated in any case as a standalone item, and possibly - speak it quietly! - sensitively sectioned.

Tom

 

It's a fair question, but that then also leads into questions of preservation ethics - questions that cannot be answered definitively, and are in reality matters of judgment rather than right/wrong

 

I agree however, at least until the 2019 policy is revised, it may be assumed NRM’d be open to considering the idea if there was a source of funding. Otherwise, logically, the policy would either not have mentioned GA as a candidate or could easily have said it’d be considered only if the existing cylinders were repairable.

 

I think casting techniques have moved on since the 1930's...

 

My understanding was that initially, the plan was that 4771 would go to Doncaster temporarily whilst 990 was undergoing conservation work, and the two engines would be swapped in due course. Whether that is still the plan, I don't know. All I can say is that 990 remains on display in the Great Hall at present.

 

Capabilities especially around moulds certainly have, but so have other production methods, especially for complex one offs.

 

Interesing.

With modern tecniques and tech, its all repairable, weld can be added, machined back, heat treated, etc etc, but there is a legitimate question on preserving the original block as part of the original rationale for preservation.

If we want to preserve that, and run the machine, its reasonable to have a go at casting a new monoblock and put the old one on display.

I suspect the bigger question here is that this cannot in any way be done in isolation.
Tear out the monoblock and more will be found.
And there is the boiler.

So its almost certainly £1m before we even get out the gate... and... is it appropriate use of funds that the NRM have 2 mainline locos in ticket with all the associated costs at the same time... ???

 

One hoped the Streamlined Duchess would be top of the list or is damaging the casing too much of a risk...