15 / 19
15
AUGUST
WING
SPAN
MAAALogo.
still be able to be returned to glow
operation if the testing proved
unreliable. Needless to say the
engine has still not seen a drop of
methanol.
The conversion
The most involved part of the
conversion was the installation of
a small magnet in the prop driver.
If you can drill a straight hole
this should not be a problem. My
engine was sourced second hand
so voiding the warranty was not
an issue for me. The hall sensor is
then glued with a high heat epoxy
to a suitable sized hose clamp.
The hose clamp provides the spark
timing adjustment. The remainder
really is plug and play.
The testing provided positive
results. After adjusting the hall
sensor timing I was pleasantly
surprised. With a 16x6 Master
Airscrew prop I was achieving a top
RPM of 7800 and an idle of 1350.
Yes, I even had die hard electric
enthusiasts stopping to admire
the idle. I have only run about two
litres of fuel through the engine to
date, so I imagine the top RPM may
improve slightly.
I chose not to fit a pumped Walbro
style carburettor because I am not
bothered by the poor transition. It
does not affect engine reliability.
My engine has only stopped when
the tank has run dry or when the
ignition is turned off. To avoid
overheating I have mounted the
engine so the cylinder head is
as exposed to as much airflow
as possible. In fact, I have not
encountered any overheating,
noticeable discolouration or fuel
vaporisation to date.
The verdict
The 55-inch wingspan Ultimate
10-300 (120-140 size) flies very
well with this newly converted
engine. Initial reservations about
the reduction of power from the
unleaded fuel were unjustified,
even with the slightly reduced
top RPM compared to glow fuel
operation. The Ultimate is very
suitably powered and is capable of
smooth aerobatics including knife
edge and large loops if a pattern
style use of inertia is maintained.
It’s no 3D machine, but that was
never the aim.
Would I recommend the
conversion? Yes I would. The minor
challenges were easily resolved
and a 1350 RPM reliable idle makes
it so worthwhile.”
By Andrew Barrett