FUTABA 8UHPS Instruction Manual page 31

The Normal revolution function mixes pitch commands into rudder in order to suppress
the torque generated by changes in the main rotor's pitch angle. Three are three different
settings of revolution mixing available: normal (NORM), idle-up 1 (IDL1), and idle-up 2
(IDL2). Only normal revolution mixing is displayed on the Basic Menu.
The revolution mixing rate can be input on a 5-point curve. For a clockwise-turning
rotor, the rudder is mixed in the clockwise direction when pitch is increased; for a
counterclockwise-turning rotor, the opposite setting is made. The operating direction setting
is changed by changing the signs of the numbers in the curve from plus (+) to minus (–) and
vice versa:
Clockwise rotation: -50, -25, 0, +25, +50% from low throttle
Counterclockwise rotation: +50, +25, 0, -25, -50% from low throttle
These numbers are the default initial values. You should replace them with the actual
values that work best for your model.
Procedure for adjusting revolution mixing
This procedure assumes that your model is trimmed, and no tail rotor command is needed
in hover.
1. Throttle low-side adjustment (between idle and hovering)
Repeatedly takeoff and hover and return to land. Adjust revolution mixing so that
raising and lowering the throttle does not cause a sudden fuselage heading change. If the
nose points left when landing from hover or when taking off, the low-side mixing rate is too
high. If the nose points in the opposite direction, the mixing rate is too small. Note that the
nose direction may not become stable when taking off if the helicopter is not steady before
takeoff, or if the rotor speed does not rise.
2. Throttle high-side setting (between hovering to high-power climbing)
Apply throttle while hovering to climb and then descend back to hover. Adjust
revolution mixing so that the nose does change heading when the throttle is raised and
lowered as in the low-side adjustment given above.
Revolution Mixing Setting
Top arrow indicates the
current stick position (2
arrows means it's
between points)
Curve Name
Curve Point
Display
Value
(NORM)
(Range: 0 -
+100%)
The REVOLU Normal
function is on at startup.
The blinking item on the
setting screen is the
current setting item.
Curve points 1-5
The bottom arrow shows the point on
the five-point curve currently being set.
1. Turn the REVOLU function ON
by pressing the (+) key ("ON"
displayed). Turn off (INH) the
function with the (-) key.
2. Input 5-point curve values
Move the lower arrow to the
position you want to set with the
CURSOR keys (the curve point is
indicated by the arrow below the
numbers 1-5, and the current
throttle position is above the
numbers). Enter the desired curve
value with the (+)/(-) keys.
• If you're unhappy with what you've
set, you may return to the default
value by pressing the (+) and (-)
keys simultaneously.
Initial values:
POS1 = -50%
POS2 = -25%
POS3 = 0%
POS4 = +25%
POS5 = +50%
To ATV
function
To PI-CRV function
Example Revolution-Norm
-33%
1
LOW
28
These keys are used to move
between the five points in the
REVOLU function.
Data input keys
Five-point Curve
+100%
+50%
13%
0%
10%
0%
-20%
-50%
-100%
2 3 4 5
Curve Point
← throttle stick → HI