So, recently I've been gripped by a serious curiosity of "what if Nationalisation hadn't happened?" Combined with rediscovering my love for the Canadian Pacific Royal Hudsons' aesthetics and a curiosity regarding Gresley's W1, I began wondering what might have been.
Firstly, we clearly have to make a number of assumptions for any post-war adoption of a 4-6-4 locomotive by the LNER. 1) That the railways were able to financially sustain themselves post-war, thus avoiding nationalisation, and 2) That the LNER were not in a financial position to carry out the dieselification plan that was actually put forward post-war, and 3) That traffic on the ECML or GCR was sufficient to justify a more powerful locomotive than could be provided on a 4-6-2 wheelbase. Clearly, these assumptions are somewhat contradictory, but for the sake of argument:
Why a 4-6-4? During and immediately post-war the average passenger service was much heavier than pre-war due to the reduced wartime service, compounded by the poor state of the track and consequent speed restrictions. In this environment I seem to recall the Gresley W1 being praised for its higher tractive effort than the Pacifics. If we assume that the need for extra-long passenger trains persisted even as the infrastructure improved, it's possible a series of Hudson/Baltic express locomotives would be desirable. So, based on the premise that such a 'W2' locomotive would be designed by Arthur Peppercorn to meet such a requirement, I drew up these rough specifications based on Gresley's W1, using the statistics provided by this very site:
Cylinders: Three 20"x26"
Motion: Gresley/Walschearts
Piston Valves: 10.5" diameter
Boiler: 6'5" max diameter, Max Working Pressure of 250psi.
Heating Surface: Similar to Gresley's dia.111 boiler for the W1
Grate area: 50 sq.ft
Wheelbase: 40' (Engine); 16' (Tender)
Again, this is utterly conjecture and truth be told I don't have an extraordinary understanding of the workings of a steam locomotive. From what I do understand however, is that the large 20" cylinders and relatively high heated surface area of the boiler allowed the W1 to produce a lot of power and thus put down a lot of tractive effort, but that the standard 10" piston valves limited the motion and prevented it achieving any particularly high speeds. Based on the ratio of cylinder size to piston size on Peppercorn's A1 locomotives (19" with 10" valves), I made the possibly (probably) wrong assumption that increasing the piston valves by half an inch would improve the locomotive's top speed. I have no doubt Peppercorn would have made more modifications than simply taking Gresley's design and sticking larger valves on it, and in my head I picture an elongated Peppercorn A1 with an additional trailing axle. But, I'd appreciate the input of those more knowledgeable on the subject than I as to how Peppercorn might have gone about designing such a locomotive?
Oh, and obviously I'm happy for people to inform me how utterly idiotic my changes to the design are and how increasing the piston diameter by half an inch either achieves nothing or results in a catastrophic boiler explosion.
