Smokebox length, A2/3 vs A1, diagram 118 boiler

[Atlantic 3279]

Does anybody know please, how the smokebox lengths compared on these two types of loco, when each were fitted with the diagram 118 boiler. They look in photos as if they may have been the same, but amongst the many dimensions stated in RCTS 2A I have so far failed to find the answer(s). This may turn out to be highly relevant to a possible modelling exercise.
I offer my thanks in advance for any assistance.

[mick b]

Nothing obvious in the few books I have . I will however look forward to developments !!

[Tom F]

I've always thought they look similar, but as you say Graeme, RCTS does give different sizes.

Anyhow, as Mick says, I too look forward to these developments

Tom

[Atlantic 3279]

Hmmm, it is by no means yet certain that there will be any developments - I'm merely revisiting an idea that evolved a while ago, in view of a recent mention of something similar and the availability now of a possibly better starting point than was previously the case, for what I have in mind.
I reckon the two smokeboxes are, for modelling purposes, near enough the same length but the A2/3 double chimney sits further back than that of the A1. One person who could, I am sure, confirm the details, is unfortunately "out of the communication loop" for the time being. I may be able to ask him at a later date, which is okay as I'm in no hurry. Failing that I'll have to either assume, or send Mr Edgson some money.

[2512silverfox]

I would agree that the most sensible route in the first instance would be to get the relevant Isinglass drawings. John was a stickler for correct information so I am sure that whatever he says for the particular type of boiler would be spot on.

[locoian]

For what its worth, the length of the smokebox for the A1 is 9ft 3 1/64 in. Taken from the arrangement drawing of the smokebox used to build TORNADO.

Don't know about A2, have not yet built one

Ian

[Atlantic 3279]

Thanks Ian, that figure may at least be of use in verifying the accuracy of any A1 drawings or parts that I consider using in a model.

[Atlantic 3279]

Isinglass drawing now acquired, so I should have a useable dimension for the A2/3.

[Pebbles]

I think you will find that in 4mm the smokebox lengths are within approximately 1mm of each other, the A1 being the longer.

[Atlantic 3279]

Not quite as little as 1mm if these figures are correct: My newly acquired Isinglass drawing gives the externally visible length of the rolled plate forming the A2/3 smokebox, with diag 118 boiler fitted, as 8’ 10 5/8”. Ian above quotes 9’ 3 1/16” for the A1. Unless Ian’s figure (for instance?) includes some material that is hidden under the first cladding band, that would make the difference 4 7/16” if my maths is correct, or approximately 1.5mm in 4mm scale.
No matter what the case, I’m grateful for all of your contributions.