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This is how
I started the crankcase. I first drew a nine-sided polygon on
the computer, then sawed it out with my scroll saw. Normally
you would use the nice template that comes with each 1:12 scale
Williams Brothers cylinder kit, but my engine needed to be undersized
to fit the 1:14 scale model I was building. |
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According to
the drawings and photos I had of LeRhone engines, the next "layer"
of the crankcase needed to be a round disk. I couldn't find a
steel washer the right size, so I found some wood the right thickness
and used my scroll saw to cut out a disk the right diameter to
fit the cylinder intake pipes. I then used my drill press as
a makeshift lathe to smooth it closer to a perfect circle. |
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I searched through
all my bolts and nuts and washers until I found a washer the
right thickness and diameter to simulate the bolt flange. I made
a template and center punched the bolt locations. At first I
tried using small drops of epoxy for bolt heads, but it flowed
out into oversized pools, so I later switched to tiny plastic
nuts from my spares box. |
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The next "layer"
needed to be dome shaped. Because I have installed many radio
controlled garage door openers, I was familiar with carriage
bolts. The domed head of a carriage bolt was the first thing
that popped into my head. I chucked the bolt into my drill press
and let it do the work while I held the hack saw in position. |
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In this photo
I am trying to determine whether the nine 1:12 scale Williams
Brothers cylinders are going to fit around the undersized crankcase,
and still fit inside the 1:14 scale engine cowl. |
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In this photo
the dome has been installed on the crankcase. It's epoxied to
the steel washer behind it (which was previously epoxied to the
wood disk behind it, which was previously glued to the 9-sided
wood part). Also, one of the 1:12 scale Williams Brothers cylinders
is sitting in place just to try to visualize how the engine is
going to look. The "drive shaft" is a 3/16" drill
bit, most of which is out of sight in a chunk of 2 X 4 behind
the white paper. |
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This is a staged
photo of the last of the nine engine cylinders being installed.
The next steps (no photos) were to install the pushrods and intake
pipes. I used little pieces of tubing to simulate the fittings
where the pushrod enters the crankcase. I used little pieces
of plastic rod stock to simulate the bolts that attach the intake
pipes to the crankcase and to the cylinder heads. The finished
engine appears elsewhere on this page. |
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This photo shows
the wood piece I made to hold the rear end of the engine drive
shaft in place inside the fuselage. It also shows the drive shaft
-- an ordinary drill bit. If you look closely you can see a white
nylon bearing that I found at the hardware store and installed
in the wood piece. There's another nylon bearing just like it
in the firewall, which is the front support for the drive shaft.
Also notice the spark plug wires on the rear of the engine. The
rear of the engine won't be visible after the model plane is
finished, so I didn't worry about it's appearance, but the spark
plug wires will be visible to anyone who examines the engine
through the openings in the engine cowl. |
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This is the
completed model engine. |
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This photo shows
how I determined how much space was required between the firewall
and the engine, in relation to the position of the engine cowl
to the fuselage. This was critical because the engine just barely
clears the inside of the engine cowl, when properly positioned.
Various combinations of spacers and washers were tested and measurements
were taken for the amount of drive shaft that needed to extend
forward of the firewall to provide the right amount to extend
through the propeller. |
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This is a "staged"
photo of how the front end of the model airplane would look.
For this photo, everything was held in place on a 3/16 drill
bit that goes into a 2 X 4 behind the scene. I ended up keeping
the drill bit as the crank shaft because I liked the way it looked
and, well, why not? |
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