Great Planes Sportster Bipe 40 Kit - GPMA0510 - Manual (Page 24)

18. EXTEND THE RADIO ANTENNA
Run the antenna out of the radio compartment
of the fuselage and attach it to the front of the fin. DO
NOT cut the antenna wire!
19. CONNECT ALL LINKAGES (PUSHRODS),
ERATION AND SET THE THROWS
Attach clevises to the ends of the elevator and
rudder pushrods so they are adjustable at the tail. The
other ends may be attached by "Z" bends or other method
and does not need to be adjustable. Attach a clevis to the
end of the throttle cable and attach it to the engine throttle
arm. Attach the other end of the cable to the throttle servo
with a connector of your choice. The servos and linkages
should not interfere with each other. Set the control surface
throws as shown on the plan.
CONTROL SURFACES, CHECK RADIO OP-
20. RANGE CHECK YOUR RADIO SYSTEM;
CHECK THE CENTER OF GRAVITY; RE-
CHECK ALL ALIGNMENTS
Your model should balance at the point shown
on the plan. If it doesn’t, move the battery and/or receiver
around until the model balances at the point shown. If
additional balance weight is needed, add lead weights to
the nose
or tail to get the proper balance. Range check
your radio at your flying site as per your manufacturer’s
recommendations. Recheck your wing and stab align-
ments. Make sure the rudder is 90 degrees to the fuselage.
Check to see that all hardware is secure and that all equip-
ment is in good condition.
21. TRIMTHEMODEL
Make your first flights, with the help of an experi-
enced modeler/flyer if this is your first model. The model
may need some trim changes or adjustments to the control
surfaces after the first flight. Adjust the control surfaces
at the clevises until the model flies correctly.
SPORTSTER BlPE FOUR-CYCLE CONVERSION INSTRUCTIONS
The Sportster Bipe is a natural for 4-cycle experimentation. The unique looks of the Bipe just screams
“4-Cycle” and the lightweight air-frame and symmetrical airfoil means the Sportster design will make the most of
the 4-cycle fun. Whether you want to just “putter” around the sky, or loop, roll and snap, the Sportster/4-Cycle
combination is unbeatable!
Four-cycle engines offer many benefits-their quiet, realistic sound is pleasing to modelers and non-mod-
elers alike. Hightorque allows the use of high pitch or large diameter propellersfor a new style of flight characteristics.
They are also very fuel efficient for economical operation.
On the other side of the coin, 4 cycles are larger and heavier than equivalent power 2-cycles. That
means some special care must be taken to avoid a nose-heavy airplane, such as moving the firewall and radio
farther back than normal. We’ll help you with that task with these instructions.
CHOOSING YOUR ENGINE
It’s difficult to say what the optimum engine size is for your Sportster Bipe. The old rule of thumb was
to choose a 4-cycle engine with 1-1/2 times the 2-cycle displacement for equivalent horsepower. But recent
advancements by engine manufacturers have brought the power of 4 cycles way up and the weight of the engines
down. One good example is the Enya .46 Four Cycle. This engine weighs just a fraction more than most 2-cycle
.40’s and it produces comparable power and thrust.
For the Sportster Bipe, you can choose between a .40 and .60 size four cycle. A .40 will give docile
flight performance. A .60 provides plenty of thrust, but with a significant increase in weight and size. The .60 will
fit, but it’s goingto be tight. See the full size drawings followingof the Enya .46 and the
0S FS-61 mountedin the Bipe.
CHOOSING A MOUNT
Low weight and rigidity are important in 4 cycle mounting. Hayes and Tatone both make good mounts
for 4-cycle use. The Hayes AL-40 will fit the Enya .46. The AL-60 will fit the OS FS-61. Tatone produces aluminum
mounts that are predrilled for individual engines.
Both brands are lightweight.To improve rigidity, we recommend installingafront bulkhead.This essentially
gives a beam mount system that is extremely rigid but makes removal of the mount a little more cumbersome.
BUILDING PROCEDURE
Following are new steps that refer to 4 cycle installation to replace the steps in the front part of this
book. Refer to these steps here as you build your model. Step numbers here refer to the step numbers in the front
part of this book.
BUILDING THE FUSELAGE
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