[SEL] re: Castings/now hot bulb engines

[Rob Skinner]

Hi again Curt,
One more thing I forgot to mention about the Blackstone
design.  See the big round hole on the right side of
Patrick's picture?  That's where the fuel and air come in.
Remember in the Akroyd-Stuart design, fuel was injected.
The Blackstone inducted fuel AND air into the vaporizer,
through what looks like a conventional carburetor.  The
mixture is still to rich to burn until clean air is forced
into the vaporizer.

Rob


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Hi Curt, 
Really, it's dirt simple.  To start, let's put the picture
of Patrick's Blackstone out of our heads.  We'll first talk
about the Hornsby-Akroyd style vaporizer.  

Visualize a stubby little propane bottle like you'd put on a
plumber's torch.  That's pretty close to what the inside of
the vaporizer looks like, except on the inside of the
vaporizer there are ribs running lengthwise.  The neck of
the bottle is the throat that goes to the cylinder. 

In the side of the vaporizer is a hole into which fits the
injector nozzle.  The lamp is placed under the domed end of
the vaporizer until it is sufficiently hot -- but not too
hot.  If you heat it up too much, all the goodness goes out
of the fuel.  We can discuss "goodness" at another time.

When the engine is running, oil is squirted into the
vaporizer on the intake stroke.  It hits the walls and
instantly vaporizes, but there is insufficient oxygen for it
to burn.  On the compression stroke, clean air is forced
into the vaporizer.  When the oxygen rich air mixes with the
hot oil vapor, ignition occurs.  

Understand now?  Dirt simple.  However, every design
engineer with a slide rule and a sheet of paper has is own
idea of what will bring him fame and riches.  Blackstone
built an "improved" vaporizer which you see in Patrick's
pictures.  Interestingly, the exact same design was used by
Ronaldson Bros. & Tippett on their Australs.  

Take a look at Patrick's picture again.  You see TWO
chambers connected by a narrow passageway.  The end with the
threads is what sticks out the back of the engine.  The area
at the top of the picture is what attaches to the cylinder.
The smaller chamber is on the bottom, and it is here where
the flame from the lamp is applied.  

The first major difference in this design is the cylindrical
area near the top of the picture.  Into this bore fits a
"timing valve"  It's a cylinder with a notch cut out of it.
It rotates such that the vaporizer and the cylinder are
isolated from one another.  On the compression stroke, the
timing valve opens, allowing air into the vaporizer.  

The second major difference I've only seen on the Austral.
I've never had a Blackstone apart or seen detailed drawings
of the guts.  So I'll explain it from the down-under
perspective.  

Note the threaded areas.  Into the smaller chamber is
screwed a plug;  the hole is just there for manufacturing.
Into the larger chamber is screwed an "ignitor case."  Don't
get hung up on the nomenclature, it's not like a low tension
ignitor.  It's a hollow cylinder that barely sticks into the
vaporizer.  There are some small holes in the ignitor case.
On the inside of the ignitor case is the "ignitor coil."
All it is a wound up strip of metal.  The idea is that the
coil will retain heat, aiding in ignition.  

It's much simpler than ignition systems with invisible
magnetism and magic electrons, huh?

Rob