Proportions of Cab to Boiler and Firebox Ratios

[844fan]

Ok guys got a bit of a odd one for you today. A friend of mine and I are doing a project where we design our own prototype designs of locomotives to a extent. I have a few fictional ones and so does he with a few real designs in there to balence it out. But as I was designing one engine for the project (A Victorian/Edwardian style 4-2-2 tender engine with the name Bennett Bell.) when it came time to add a cab I suddenly had problems with the sesign the cab ending up far larger than it had any right to.

 

So I'm trying to make the cab realistically proportioned for said loco and I was wondering back in the days of Sterling, Ivatt, Fowler, Stroudly, and Stannier (Forgive me for spelling errors I cannot check them as I post this.) did the men have a process to determine cab allowance and footplate size for crew members? I've seen a early draft of the blueprints of a A1 that while the cab was of Ivatt atlantic style it looked in proportion to the final design.

 

Another reason I ask this is as you can read in my signature below I like doing things my own way and like to come up with plans for Freelance Locomotives alongside the real prototypes. Maybe I liked Henry the green engine's concept of being a fictional locomotive inspired by early designs (That A1 design I mention is quite close to the mark on that part) or my love of industrial Tank engines I don't know but the fact stands in real practice it seemed there was a method to the madness of crew enclosure. Now I need to know what it was.