Special Additions, Functions, And Added Equipment Commonly Used On Powered Aircraft
Gyros: Just as torque rotates an aircraft on the runway during take-off, helicopters struggle with torque twisting the model
every time throttle is applied. For many years gyroscopes have been used on model helicopters to control this. In
competition aerobatics and scale aircraft competition alike, the usefulness of gyros has recently come to light. For in-depth
information on gyro types, please see p. 89.
For aerobatics, gyros on rudder and elevator fix over-rotation of snaps and spins as well as tail wagging in stall turns. (Futaba
offers a twin-axis gyro, GYA-352, that controls two axes with a single gyro.) For 3D aerobatics (below stall speed, such as torque
rolls), heading-hold/AVCS gyros on rudder and elevator dramatically simplify these maneuvers. For scale models, gyros are
frequently used to simplify take-offs and landings by keeping the model straight during throttle application.
Always be careful if using a heading-hold/AVCS gyro, as it will correct any change in yaw that is not caused by
movement of the rudder (like making a turn with just aileron and elevator). Typically, modelers use heading-
hold/AVCS settings only for specific maneuvers, such as take-offs and torque rolls, then switch to normal mode or
OFF for the remainder of the flight to avoid this risk.
While the 9C’s ACRO/GLID programming does not offer gyro-specific programming, simply adjusting the END POINTs of
the channel that is used to control the gyro’s gain will adjust the gyro’s performance in flight. For details on gain and other
gyro functions, please see the HELI GYRO programming, p. 89.
Retracts: Retractable landing gear is often used on scale models for increased realism and on high performance models to
decrease drag. The gear servo is typically plugged into CH5, which defaults to a 2-position switch for simplicity.
Mechanical retracts require the use of a specialized non-proportional retract servo. Retract servos go from full
travel one direction to full travel the other direction, then mechanically hold the gear into the locked position. A
regular servo used for mechanical retracts will continue to draw full power the entire time, prematurely draining
the battery and risking crash of your model. End point will not adjust a retract servo.
Pneumatic (air driven) retracts use a standard servo to control an air valve which directs air into or out of the retract units,
moving the gear up or down. Pneumatics are easier to install but require added maintenance of the air system.
Gear Doors: Some scale models with retracts also have separate gear doors to cover the scale gear. For one example of
how to operate the gear doors separately from the retracts, please visit our website: www.futaba-rc.com\faq\faq-9c.html.
Smoke Systems: Many scale and aerobatic models use smoke systems to provide increased realism or a more impressive
demonstration. There are many smoke systems available, with varying types of control. Most use a servo to increase/decrease the
flow of smoke fluid into the specialized smoke muffler. The oil is heated in the muffler, creating smoke.
It is a good practice to set up a “safety” that shuts off the smoke oil if the throttle is lowered below half-stick. For a detailed
example of a smoke system setup, please visit our website: www.futaba-rc.com\faq\faq-9c.html.
Kill Switches: For safety reasons, it is strongly recommended that an electronic kill switch be installed in all gasoline-
powered aircraft. In case of any type of in-flight problem (such as prop failure, exhaust vibrating off, throttle servo failure,
radio interference), the modeler can shut the engine off quickly and safely in flight. Additionally, FailSafe (F/S) settings
are recommended to shut the engine off in case of sufficient interference to trigger the PCM FailSafe settings.
Lastly, an electronic kill switch set to “off” prior to the aircraft’s power being shut off adds an additional safety should
someone accidentally turn on the mechanical kill switch on the exterior of the model.
Bomb Drops, Paratroopers, and other Released Items: Many sport and scale models include one or more of these fun
add-ons. Typically, all are controlled by a simple micro-switch plugged into CH9. The switch is assigned in AUX-CH.
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