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The engine is fairly
large. On the back of the firewall is the small, 1,200
mAH sealed lead acid battery, the throttle and spark
levers, and the transistorized ignition. On the engine
side of the firewall is the fuel/oil tank, and the coil
mounted towards the bottom. The battery is perhaps oversized.
If you make a similar engine and ignition, you could
probably mount an 800 mAH 6 or 12 volt battery and be
assured of lengthy runs.
The fuel capacity I
estimate at around 6 to 8 oz, which provides for a medium
to full throttled run of perhaps 12 minutes.
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Difficult to see are the
linkages which carry the throttle and spark commands
forward to the carburetor and distributor base
respectively. The engine is turning 5,200 RPM with the
big 22" propellor. When the electronic ignition
(hall effect) was properly functioning, I did measure
over 6,000 RPM on occasion. I think the top end right now
is limited by the dwell, with some floating of the
mechanical points taking place at the high RPM. |
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A nice 3/4 view. The
legs of the firewall are welded from square section
tubing, while the feet were turned from bar, drilled, and
welded to the ends of the tube. The red paint is a
regular alkyd spray enamel. About the only thing i am unhappy
with is the balance of the engine. It vibrates a bit more
than I would like, probably due to the use of steel
connecting rods rather than the aluminum called for in
the plans. I don't think the extra strength is necessary,
and in fact 7075 alloy aluminum is generally just as
strong as the mild steel I used.
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Easier to see now are
the control levers and the black plastic housing which
contains the ignition circuit. On the fuel/oil tank are 2
standard brass plumbing fittings, with the 2 screw caps
modified slightly for appearance. The oil control needle
valve is the smaller knurled thumb screw on the far left
at the top of the tank. The spark plug wires are #18 test
probe wires which are especially pliable and well-suited
for this duty. I have noticed a little softening of the
rubber insulation around the heads where they get a bit
oil soaked, but in general they perform well.
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