Futaba 8UHFS, 8UHPS - Manual (Page 78)

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The Invert function is used to make inverted flight easier. Instead of having to
learn to reverse controls mentally, when switch H is moved forward (and the INVERT
function is activated), the direction of operation of the elevator, rudder, and pitch
servos is reversed. In addition, the pitch servo throw is reduced to about two-thirds
of the normal throw.
Before using the INVERT function, be sure that you helicopter is trimmed for
good normal flight. You’ll need to set up your linkages carefully to use the INVERT
function.
You can adjust the pitch curve and cross position setting when this function is ON
with the inverted pitch curve (PI-CRV, INVR) and inverted cross position (INVERT,
CROSS) menus in the Advance Menu. You can plug your gyro into CH7, and its
sensitivity may be controlled by switch C.
INVERT Function Programming
Turn off the INVERT function (move switch H to the rear position) and select a
servo arm that provides the proper negative and positive pitch angles to allow
autorotation. Hook up the linkage to the servo.
Since the normal flight pitch curve uses NORM, IDL1, IDL2, and HOLD, set up
your helicopter for trimmed flight in hover, forward flight, and autorotation. To
program the inverted flight pitch, turn on the INVERT function (switch F set to
forward position) and activate the pitch curve inverted (PI-CRV, INVR) menu within
the Advance Menu to program the pitch. Whenever INVERT is activated, the
elevator, flap, and pitch servos respond in the opposite direction to how they respond
for forward flight. In addition, elevator and rudder trim is also reversed. The
hovering pitch function is active only at the forward flight side.
You can set the inverted cross position at the "INVERT, CRSS" screen within the
Advance Menu (see p. 77).
Setting up inverted flight mode
To TRIM function
To SWASH or PARA
Turn the INVERT function ON by
pressing the (+) key ("ACT"
displayed). Turn the function off with
the (-) key ("INH" displayed).
Both the inverted pitch curve (PI-CRV
INVR) and inverted cross position
(INVERT CRSS) functions in the
Special Mix Menu can be activated
simultaneously.
Data input keys
ACT/INH display
(initially set to INH)
function