I am working on modifying an LMB triplex and am getting close to turning it into a 2-8-2-8-8-8-2. What I would really like to do to make things more “prototypical” if you’d like to say. Would be to widen the firebox since a wider firebox could burn anthracite coal which could in theory help generate more steam. I know this would be a massive endeavor and am wondering if there is any way to just make my firebox BIGGER while keeping a nice looking model.
Hi there. There’s a guy that used to post a lot here that did this using styrene. Here’s one of his posts :
https://forum.trains.com/t/lehigh-valley-2-8-2-scratch-bash-quick-look/272611
and
https://forum.trains.com/t/reading-n-1-2-8-8-0-kitbash/273973
Simon
You will not generate ‘more steam’ with anthracite or culm in a Wootten firebox – the high carbon content burns hotter but much more slowly and requires a consistent thin firebed (or the grate acts as if it is in a forge and has to be actively water-cooled, which is NOT something reliable on a freight engine in that era). See the relevant chapter in Sinclair’s ‘Development of the Locomotive Engine’.
While you want a larger grate area, it is far more important to increase the actual radiant uptake area above that grate, with a proper arch, circulators, and ‘combustion chamber’ for longer luminous flame-plume travel. Better still is recirculation of downcoming water in the convection (tube boiler) section to manifolds feeding the water legs, which reduces DNB there; the Cunningham jet-pump system could accomplish this very well with no moving parts.
In addition you’re going to have to provide some kind of reheat on the LP steam to get anything practical out of ‘all those legs’, particularly those under your ‘motor tender’. Chapelon did this reasonably well on the 160A1 with superheater-like passes in flues replacing the tubes at the bottom of the convection section, although he did not see a ‘big enough savings’ from it in that particular design.
What I would try as a start is the firebox off the PRR HC1 2-8-8-0. That may be a complex thing to fashion out of sheet (see the fabrication of the new firebox and wrappers for K4 1361) but it has as long a vertical rise above grate and long plume travel as anything if that era with grate above driver height.