#camelback

Reality Check:

The Gwamalgarac is a Camelback Garratt, in earth terms.

The "Wootten Firebox" is used on Camelbacks for burning low-grade coal (or anthracite waste), and so the cab is placed in the middle of the boiler. The disadvantage is that one failure mode of a steam locomotive is that the running gear of the locomotive could break, and rods could come crashing through the frames. In a Camelback, the engineer is usually directly above the moving rods.

a Garratt locomotive is one where the boiler is slung between two engine sets. These were mostly used in Australia and various African colonial railways, seeing limited use in Europe and never making it to America. On Gymnome, they make up a large fraction of large steam engines. They can take curves fairly easily, and are more stable at speed than other articulateds, and the boiler can get huge while still fitting everything in the loading gauge.

Technical Overview:

The Gwamalgarac has quite a few design peculiarities. The frames run directly through the firebox, which is too wide to fit between frames, posing new thermal and structural engineering concerns and making the boiler somewhat harder to maintain.

The locomotive uses outside stephenson valve gear (usually stephenson valve gear is found on inside-motion locos, and walschearts is used on outside-motion locos). The cutoff is controlled by a screw reverser, which interfaces with a steam servo on each engine set to lift and lower the expansion link (the moving part that determines the valve timing).

The Breadloaf cab is a typical design style for this time period, but provides plenty of space for the crew. The steam dome and throttle are inside the cab, with the safety valve and whistle atop the cab. The other dome is a sand dome, although it's quite inefficiently placed, requiring the sand to travel through two pivot points to reach the wheels. The firing cab, which on real Camelbacks is usually just a tiny shelter with little more than a roof, is larger and more spacious, since extra room is needed behind the firebox for the pivot point anyway.

The smokebox is fitted with a "coffin" style feedwater heater, resulting in the baffling water path of front tender -> front pivot -> engineer's injector valve or -> feedwater heater -> fireman's injector valve -> boiler.

The wootten firebox is intended for burning anthracite waste or 'culm,' which burns smokelessly. However, the Gymnomi locomotive here is burning very low grade coal with lots of impurities, generating lots of cinders and ashes. As a result, a Rushton cabbage smokestack is used to generate a vortex to centrifugally separate the cinders from the smoke to reduce fires. The big stack would probably be retained even if it were converted to burn culm, since it is considered stylish.

The Gwamalgarac is a compound expansion steam engine, which uses exhaust from the high pressure cylinders to drive larger low pressure cylinders.

As a result, the steam takes another dizzying path: being generated in the boiler and collected by the throttle in the steam dome, before being routed out behind the driving cab, along the ceiling and walls of the firing cab, then into the rear pivot, and into the rear high pressure steam chest. It then gets used by the rear engine, and then exhausted back through the rear pivot, through the bottom of the firebox between the grates and the ash pan, below the boiler frames, through the front pivot, into the front low pressure steam chest. Then it is used by the front engine, and then it exhausts through the front pivot and finally into the smokebox and out the smokestack.

The couplers are dual-mode chopper and screw-link coupler, for interfacing with multiple types of cars from different railroads.

The Process:

Here's the first sketch I made, more or less as a shitpost at first:

Then I decided to do a more serious drawing, resulting in this original design.

The boiler was the expanded and the cab shrunk to result in the final proportions. The sketch was cleaned up and detailed.

I drew the environment before coloring and rendering the locomotive, since I wanted to know how the loco colors would look in advance. Note the shading reference orbs in the sky, which thankfully i remembered to remove from the final version.

This is how I left the drawing at about 2AM last night.

After returning from a doctor's appointment I got back to work around 11:30 am.

I decided to start shading with the specular reflections first, and then add drop shadows and shading. The bright sky reflections are typical of British steam locomotives kept in good condition and really elevate the piece i think.

After spending a few hours rendering, I added the finishing touches like some shading changes and weathering:

The crew are: the Stoker, in the firing cab, the Engineer, in the driving cab, the Conductor(s) adjusting the inline compound air compressor, and the Brake Officer climbing the front tender ladder.

Their uniforms are typical of rail workers in this region and time period and are an icon of the working class. The headwear is a flat-topped cap with a pleated white visor.

In the background are trees, which I originally designed for Train Misconductor, the video game me and my friend are making set on this planet (albeit like 60 years later than this drawing).

The creek crossing started out as a narrow stone bridge when the branchline was originally built to a narrower gauge. When the line was regauged to broad gauge, the bridge was reinforced with steel struts. The axle loading of the Gwamalgarac looks awfully heavy for a branchline, but Gymnome's gravity is 80% that of Earth after all.

The animals in the foreground are currently just called "cows," and come from a set of domesticated gymnomi animal drawings i did a while ago. I haven't thought nearly enough about the ecology and biology of Gymnome--and most of what I have thought about is concerning the motile slime clade that the Gymnomi belong to rather than the animal clade. These are probably a wild variant of the "cows."

The slime creature on the right side of the foreground is a semi-aquatic creature that feeds along shores like this, keeping part of itself in the water so it does not dry out.

Variants: