Great Planes Reactor Biplane .61 GP/EP ARF - GPMA1023 - Manual (Page 19)

19
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1. Take an estimated measurement of where the engine
head will protrude from the cowl. In this case the front of the
cutout will be approximately 4-1/2" [115mm] from the back
of the cowl.
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2. According to the measurement, mark the location on
the cowl.
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3. Using a powered rotary tool with a small cutting bit,
make the fi rst cut in the cowl much smaller and slightly
farther aft than you know will be required, but good enough
for a starting point. Try fi tting the cowl over the engine and
mark where the cut needs to be enlarged. In the photo, the
cowl isn’t very close to fi tting, but it’s a start.
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4. Continue to fi t, mark and cut the cowl as necessary until
you can get it at least partially into position. As you proceed,
try to keep the cutout as small as possible. Later, once the
cowl has been mounted to the fuselage, the cutout will be
trimmed to perfection.
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5. Once you can get the cowl to fi t onto the fuselage over
the engine, set the cowl aside. Use a fi ne-point felt-tip pen
to draw a line on both sides of the fuselage aligned with the
front of the fi rewall. Mark two points on both sides of the
fuselage 1/8" [3.2mm] aft of the lines for the cowl mounting
screw holes.