Baker 23-90 Uniflow

This is a typical scene at a modern US steam engine and tractor show.
These shows draw thousands of people, although the crowd politely got
out of the way for this shot.

A video camera captures the scene for posterity.

This is a model of a steam traction engine owned by a friend of ours,
a 23-90 Baker Uniflow built around 1925, about 75 years ago.
Despite its age, it is a good runner, producing massive power.
This is largely due to the skill and effort of the owner.

The owner provided a large number of measurements, while I had taken
many photos of his and other similar engines.
Thus, the model is quite accurate, although not yet complete.


This is an exercise in textures. A variety of directional textures,
primarily 2 and 3 color maps using Bumps, were used, to show
the normal weathering patterns of a steam engine.

Every object in the scene has a directional texture, except the
black parts of the video camera.

It is all hand coded CSG.
Lettering uses POV TTF, rather than using image maps.
This allows the wood texture of the roof to show in the lettering.

The grass is a heightfield, scaled very narrow and tiled.
I created the heightfield file in POV, using a bozo texture.
This resulted in individual blades of grass, with a natural height variation.
A small amout of matrix skew was applied so that the grass would
not be perfectly vertical. I made a subtraction plug in the shape
of the engines' wheels, so the grass would not show inside the wheels.
The neatly cut grass is not unusual at these steam shows, since they
are frequently held at fairgrounds or parks.

The dirt field is an HfLab heightfield, scaled very low, just to break up
the uniformity of the field.

The smoke is Interior/Media. I worked on it quite a while, but
am still not very satisfied with it.

Most of the gears have teeth made with a Radial transparency map,
but the upper pinion was modeled, since it is more visible.

The engine with red wheels was cloned from the Baker at an early
stage of development, but I ran out of time to give it much detail.
It is intended to be an Advance-Rumeley, one of the many US builders.
It is posed in the background, with its shortcomings hidden
by the foreground engine and the edge of the picture.

A second Baker is in the right background.

Although the majority of US engines had roofs, these were an extra cost
option, thus many, such as this Advance, were open to the elements.

The video camera is made of 3 superellipsoids, sliced and diced via CSG,
plus a few other CSG bits.

The image on the video camera screen is an image map, rendered
with the POV camera placed at the video camera's location.

Note that the glass oiler on top of the crosshead guide is half full.
Also note the hex nuts on the cylinder heads.

There should be some people in the scene, but I ran out of time.

I rendered at 1024x768, with a really tight AA of 0.04, since this
showed the detail better, and seems to give the scene more snap.
...Apologies to those with small monitors!

Due to work on another project, I only had 3 weeks to work on the scene.
The new AMD box really sped up development, allowing many quick
test renders, and ran the final version in just over an hour.


An earlier version of the image, with less smoke,
was benchmarked on 3 PC's, with these times, at 1024x768 AA 0.04 :

P-200, 64 mb RAM, W98a very long time
P-850, 128 mb RAM, NT4.02 hour 0 min 53 secs
AMD-1100, 1.1 GHz, 128 mb RAM, W-ME1 hour 9 min 17 secs

On simpler images, without Media, I have observed the speed ratios of:


...however, the large amount of Media and textures in this scene
was apparently handled much better by the AMD than the P-850.

BTW, Windows ME is the most unstable OS I have used since Windows 3.1.
The best part about it is that it reboots really fast after a crash!

I suspect that 128MB is not enough memory to run W-ME, as it often
locks up solid when several large apps are running.
It appears that the swapper has bugs...?

Extra credit question:

The 23-90 designation denotes horsepower on the drawbar and the
belt pulley respectively. These numbers are quite conservative
by modern standards. This engine has been measured well above
100 actual hp, probably equivalent to several hundred automotive

The Uniflow design was unique to Baker traction engines,
but also used in large industrial power systems.
In this design, the exhaust steam is released at the bottom
of the power stroke, via ports in the cylinder wall.
The more common design requires the used steam to be pushed
back out through the valves, wasting a great deal of power
due to the back pressure. The Uniflow design also gives the
Baker a unique sound, a deep bark rather than a whoosh.

Additionally, the Baker patented valve gear is used,
the same as was used on high performance steam locomotives.

This was a very "technical" engine for its time, with many
efficiency features.

Baker-Pilliod is still in business, in the original building
in Swanton, Ohio. Additionally, the Baker descendants own
the serial number 1 engine, which is operated at various
steam shows.

Some Dimensions:

Front wheels:40" OD x 12" face
Rear wheels:64" OD x 24" face
Flywheel:38" OD
Crank disk:24.25" OD x 3.25" thick
Cylinder:15" OD x 23" long
Gear face widths:4" and 4.75"
Boiler:32" OD x 105" long
Firebox:50" long
Total boiler + firebox:155" long
Total width:95.5"

Early Development Image

Copyright 2002, 2003 North East Systems