FUTABA GY601 User manual

AVCS GYRO
GY601
INSTRUCTION MANUAL
YAW-AXIS STABILIZER FOR MODEL HELICOPTER
(RATE GYRO)

2Thank you for buying a GY601 AVCS gyro.
Before using your new gyro, please read this manual thoroughly and use the
gyro properly and safely. After reading this manual, store it in a safe place.
•No part of this manual may be reproduced in any form without prior permission.
•The contents of this manual are subject to change without prior notice.
•This manual has been carefully written. Please write to Futaba if you feel that any
corrections or clarifications should be made.
Warning: This product contains a chemical known to cause cancer and
birth defects (or other reproductive harm).
FOREWORD
The GY601 gyro is an AVCS (Angular Vector Control System) rate gyro
developed for model helicopter competition.
[GY601 Features]
•Super narrow pulse (760µs) drive system substantially improves servo
reresponse. An S9251 digital servo is used.
•Microcomputer high-speed arithmetic processing substantially improves
gyro response.
•High resolution 12-bit A/D accurately converts the sensor output to a
digital signal.
•Newest SMM (Silicon Micro Machine) and low-back aeroform case
improve vivibration resistance and neutral characteristic.
•Amp mounts an LCD that allows accurate data setting.
[S9251]
•Special servo for the GY601. Compatible with super narrow pulse (760µs)
drive.
•Operation speed 0.07sec/60º. High response realized.
•Alumite case w/heat sink effectively cools the motor heat.
Always use the special S9251 servo with the GY601.
The GY601 cannot operate with servos other than the S9251.
The servo may be destroyed.

3
FOR SAFETY
•Meaning of Special Markings ---------------------------- 4
•Mounting/Operating Precautions ------------------------ 4
•Fuselage Maintenance Precautions ---------------------- 6
•S9251 Usage Precautions --------------------------------- 7
TABLE OF CONTENTS
BEFORE USE
•Set Contents------------------------------------------------- 8
•AVCS Gyro ------------------------------------------------- 9
INSTALLATION AND ADJUSTMENT
•Installing to Fuselage -------------------------------------32
•Flight Adjustments ----------------------------------------37
DATA SETTING
•Name and Function of Each Part------------------------12
•LCD Display and Edit Keys -----------------------------13
•Function Map ----------------------------------------------14
•GY601 Functions Setting --------------------------------15
•Remote Gain Function------------------------------------21
•Initialization------------------------------------------------30
REFERENCE
•Specifications ----------------------------------------------40
•Definition of Abbreviations------------------------------41
•GY601 Parameters Sheet---------------------------------42

4FOR SAFETY
Insert the connectors fully and firmly.
If a connector works loose due to vibration during flight, control may be lost
and result in a dangerous situation.
FOR SAFETY
To ensure safe use, observe the following precautions.
Meaning of Special Markings
Pay special attention to the safety at the parts of this manual that are
indicated by the following marks.
Mark Meaning
Procedures which may lead to a dangerous condition and
cause death or serious injury to the user if not carried out
properly.
Procedures which may lead to a dangerous condition or
cause death or serious injury to the user if not carried out
properly, or procedures where the probability of
superficial injury or physical damage is high.
Procedures where the possibility of serious injury to the
user is small, but there is a danger of injury, or physical
damage, if not carried out properly.
Symbol: ; Prohibited ; Mandatory
Mounting/Operating Precautions
Always use the GY601 with a PCM proportional system.
Using the GY601 with an FM proportional system, when noise enters, the
wrong neutral position may be memorized.

5
FOR SAFETY
Always use the accessory sensor tape to install the sensor to the fuselage.
This is necessary to securely fasten the sensor to the fuselage so that
operation of the gyro does not transmit unwanted fuselage vibrations directly
to the sensor.
When mounting the sensor, provide a little surplus so that the sensor
connection cables are not too taut.
If the sensor cables are too taut, the gyro will not display its full perfor-
mance. If the sensor peels, control will be lost and result in a dangerous
situation.
Mount the sensor and control amp so that metals or other conductive
objects do not touch these cases.
The GY601 uses a conductive resin case to reduce electromagnetic interfer-
ence. Because the surface of the case is conductive, metal objects may cause
a short circuit.
Mount the sensor and servo at least 2cm apart.
When using a GV-1 governor, mount the sensor and GV-1 amp at least
5cm apart.
When using the GY601 with a motor-driven helicopter, mount the
sensor and drive motor at least 10cm apart.
Noise from the servo motor, GV-1 amp and drive motor may cause the
performance of an erroneously operated gyro to drop.
During initialization, the message “-Hello-” appears on the GY601 LCD
screen.
Do not move the helicopter until this message disappears (in about 3
seconds).
Also, do not move the transmitter rudder stick from the neutral position
during this period.
Precautions When Turning on the Power Switch
Always check the direction of operation of the servos.
If you attempt to fly the model when a servo operates in the wrong direction,
the fuselage will spin in a fixed direction and enter an extremely dangerous
state.

6FOR SAFETY
Check the remaining receiver/gyro/servo nicd battery operating time
during the adjustment stage and decide how many flights are remaining.
When the rudder neutral position was changed by the linkage, the
rudder neutral position in the AVCS mode must always be re-read
before use.
Re-reading method:
Turn on the transmitter in the AVCS mode, then turn on the
gyro . Or quickly switch (interval of within 1 second) the
remote gain channel switch between the AVCS mode and
Normal mode at least three times and switch the AVCS side
with the transmitter in the ON state. This memorizes the new
rudder position inside the GY601.
Never use the transmitter rudder trim in the AVCS mode.
When the rudder is trimmed during flight, the neutral position will change.
When using the GY601 in the AVCS mode, set revolution mixing to
OFF.
Avoid sudden temperature changes.
Sudden temperature changes will cause the neutral position to change. For
example, in the winter, do not fly immediately after removing the model
from inside a heated car and in the summer, do not fly immediately after
removing the model from inside an air conditioned car. Allow the model to
stand for about 10 minutes and turn on the power after the temperature
inside the gyro has stabilized. Also, if the gyro is exposed to direct sunlight
or is mounted near the engine, the temperature may change suddenly. Take
suitable measures so that the gyro is not exposed to direct sunlight, etc.
Fuselage Maintenance Precautions
Use a tale rotor drive tube or other part with a high torsion perfor-
mance for the tail drive.
Take the strength of the tail into account during inspection and adjust-
ment.
The amount of improvement of gyro performance has a considerable effect
on the fuselage vibration level or the size, type, linkage method, looseness,
etc. of the tail rotor.

7
FOR SAFETY
Always perform proper maintenance for ultimate performance.
The rigidity of the fuselage tail has a large effect on gyro performance.
Make the fuselage vibration as small as possible.
Fuselage vibration has an adverse affect on gyro operation.
Since a higher gain than usual can be used then the tail rotor is more
effective, the load on the tail is also greater.
S9251 Usage Precautions
Current Drain:
The S9251 is designed to be used with the GY601 gyro only, especially to
operate at high speed. Therefore, the servo starts, a correspondingly large
current flows and the current drain is, therefore, large. Constantly pay
attention to the remaining capacity of the Nicd battery and decide the
number of safe flights. Always pay attention to the following points:
•Always use an Nicd battery. A dry cell battery will not display the
spspecified performance.
•When using the S9251 in a system with a battery fail safe function,
the cut-off voltage is set to a high value. Shortening of the flight time
due to this must be included in calculation.
•Install the servo so that it does not get caught on the push rod or
does not loosen even when operated over its full travel. If unreason-
able force is applied, the current drain will increase tremendously and
shorten the life of the servo and accelerate battery consumption.
Do not use the S9251 with applications other than the GY601 gyro.
The S9251 is designed to be used with the GY601 only, and will not operate
in other applications. Trouble may also occur.
Immediately after flight, do not touch the S9251 case.
The heat sink section of the case is extremely hot, and may cause burns.
When mounting in the fuselage, install the S9251 so that it does not
touch the servo case and metal parts of the helicopter frame.
The middle case has an aluminum heat sink construction, and will generate a
large amount of noise if touched. In this case, it will become impossible to
receive and is extremely dangerous.

8BEFORE USE
Set Contents
After unpacking the GY601 set, first check if the following parts are
provided:
BEFORE USE
Sensor tape (x3)
Mini screwdriver (x1)
GY601 sensor (x1)
GY601 control amp
(x1)
S9251 servo (x1)
(Only a set w/servo)

9
BEFORE USE
Differences Between AVCS Gyro and Conventional Gyro
Compared to a convention gyro, the AVCS gyro has a substantially im-
proved tail control capacity. Gyro operation also differs from that of
conventional systems in a number of ways.
The following sequentially describes the conventional gyro and the AVCS
gyro.
Conventional gyro
The conventional gyro detects movement of the helicopter's tail and controls
the rudder servo so that movement of the tail stops.
Now, consider hovering when the helicopter is exposed to a side wind, the
tail drifts. When the tail drifts, the gyro detects the tail rotation angular
velocity and operates the servo in the direction that stops the tail from
moving. Drifting of the tail is stopped by control from the gyro. When the
tail stops drifting, the control amount from the gyro becomes zero. Since the
helicopter is always exposed to side wind, even in this state, the tail starts to
drift again. When the tail drifts, the gyro tries to stop it again. The "drifting
stop" operation is repeated and the tail continues to drift in the wind
direction in this manner. The higher the gyro sensitivity, the smaller the
amount of this drift. However, if the sensitivity is high, hunting will occur
and, therefore, the sensitivity amp has a limit.
• Drifting stop
Forward
Side wind
AVCS Gyro
AVCS gyro
This following describes how the AVCS system works when the helicopter
is exposed to a side wind while hovering, the same as the preceding item.
When the helicopter is exposed to a side wind, the tail begins to drift. The

10 BEFORE USE
Differences in rudder control method
The following describes the differences between conventional gyro and
AVCS gyro rudder control.
The conventional gyro sends the rudder control signals from the transmitter
to the rudder servo and starts to move the tail. When the tail moves, the gyro
detects this movement and generates a signal to stop it. If the tail continues
to move even in this state, a rudder control signal larger than the signal from
the gyro must be applied from the transmitter. That is, the difference
between the rudder control signal from the transmitter and the control signal
that attempts to stop this from the gyro becomes the actual amount of
movement of the tail. Ordinarily, the rudder control signal is amplified
• The tail remains extremely stable.
Forward
Side wind
gyro controls the servo so that the movement of the tail stops, the same as a
conventional gyro. At the same time, a sensor is controlled so that the tail is
rotated in the opposite direction (returns to the original position). In short,
the conventional gyro performs an operation known as "drifting stop", but
the AVCS system performs an operation that "stops drifting and returns to
original position". The "return to original position" operation added to the
AVCS system improves rudder trim operation. In other words, the gyro can
automatically trim the rudder against side winds. This also applies to reverse
flight. When a helicopter is flying in the forward and reverse directions, the
rudder trim is changed to advance, but with the AVCS system, this trim
change is performed automatically and instantaneously so that the tail
remains extremely stable even during high-speed reverse flight.
The AVCS system requires a high-precision angular velocity sensor. The
GY601 realizes a high-precision angular velocity detection function and
extremely small output drift by using a new type of gyro sensor. This
minimizes rudder neutral position drift during flight and eliminates the need
to trim the rudder during flight.

11
BEFORE USE
several times over by the gyro amp and is balanced with the gyro control
signal so that the transmitter can be used at the normal steering angle.
The AVCS system uses a different rudder control method. As described in
the preceding section, it has additional functions that "attempt to return
movement by external force to the original position" and that generate an
angular velocity proportional to the rudder control signal. That is, it func-
tionally controls the speed of rotation of the tail. The original AVCS
(Angular Vector Control System) came from this.
•In the AVCS mode, when the transmitter rudder stick is moved when
the helicopter was stopped, the rudder servo controls operation until
the tail reaches the specified rotational speed.
•Trim deviation of the rudder control signal also becomes a signal that
causes the tail to turn so that even a little trim deviation causes the
tail to move. Therefore, the rudder trim is made the same in all flight
states and must match the neutral reference signal at the gyro. The
method of reading the rudder neutral signal at the gyro will be
described separately.
•Since the rudder mixing signals from the transmitter also become a
tail rotation signal, all the rudder mixing functions must be disabled.
•In the AVCS mode, the gyro automatically trims the rudder so that
linkage changes cannot be verified. Initially, the GY601 trims the
rudder by flying in the Normal mode to take the rudder linkage neutral
position. This centers the linkage. At this time, this rudder neutral
reference point is read to the GY601.
Giving the gyro the rudder neutral reference signal and performing
tail operation by referring to this signal in the AVCS mode in this
way is how the AVCS system differs from the conventional system.

12 DATA SETTING
DATA SETTING
GY601 control amp
Name and Function of Each Part
LCD contrast trimmer
Allows adjustment of the contrast so that the LCD display is easiest to see.
It is adjusted with the accessory mini screwdriver.
(Receiver connectors)
Remote gain input
Rudder input
Edit keys
Used when setting data.
Operated by pushing with the
accessory mini screwdriver.
(Input/output terminals)
Gyro sensor input
Rudder servo output
GY601 gyro sensor
LCD display
Displays the set data. (8 characters X 1 line)
Stick to the body using the accessory
sensor tape.
To control amp

13
DATA SETTING
LCD display
Set data display and operation
status monitoring are possible.
LCD Display and Edit Keys
Edit keys
Setup screen call
The setup screens can be sequen-
tially called with the FUNC+ or
FUNC- key. For the order in which
the setup screens are called, see the
function map.
Data setting
Perform data setting with the DATA+
or DATA- key. When setting a value,
the data is increased when the
DATA+ key is pressed and is
decreased when the DATA- key is
pressed. The mode can also be
selected using either the DATA+ or
the DATA- key.

14 DATA SETTING
Function Map
Normal screen display
(P15)
Gyro Gain Adjustment
(P16)
Gyro Reverse
(P16)
Rudder Control Gain
(P17)
Control Delay I
(P17)
Gain Tracking
(P18)
Flight Mode
(P19)
Operation Mode Setting
(P18)
Linkage Limit Setting
(P20)
FUNC ”-” key
FUNC ”+” key
Power ON
Power on screen display
(P15)
Control Delay D
(P17)
AVCS sense
(P20)

15
DATA SETTING
GY601 Functions Setting
Power on screen display
When the gyro power is turned on after the transmitter power was
turned on, -Hello- blinks for about three seconds to initialize the data
inside the gyro. During this period, do not move the transmitter
rudder stick or the helicopter. If the transmitter rudder stick or the
helicopter is moved by mistake, the rudder neutral data will not be
correctly read.
Normal screen display
•Operation mode display
N : NOR mode
A : AVCS mode
: Neutral offset
•Actual gain (sensitivity)
display •Power supply voltage display
•During rudder neutral reset operation,
**** is displayed.
•During rudder servo reset operation by
rudder stick, ---- is displayed.
Low battery alarm
When the power supply voltage drops to 3.8V or less,
LOW Batt is displayed. When this message is displayed,
immediately stop use and recharge the Nicd battery.

16 DATA SETTING
Gyro Reverse Initial value: NOR
Sets the gyro operation direction. NOR or REV can be selected.
Set so that when the helicopter is banked right, left correction rudder
is applied and when the helicopter is banked left, right correction
rudder is applied.
Gyro Gain Adjustment Initial value: 100%
Adjusts the gyro gain. Setting range is 0 to 120%.
Two-point (G:1, G:2) gain adjustment is possible. When A is
displayed, the gyro is in the AVC mode and when N is displayed, the
gyro is in the NOR mode in accordance with the operation mode
setting.

17
DATA SETTING
Rudder Control Gain Initial value : ACG: 120%, NCG: 130%
Adjusts the rudder stick operation gain. Setting range is 10% to
250%.
AVCS and NOR mode gain can be set independently. In the AVCS
mode, ACG is displayed and in the NOR mode, NCG is displayed.
The display automatically changes to A or B according to the
direction of the rudder stick and the gain of each direction can be set.
This function is used when tracking rudder operation gain between
the AVCS and NOR modes.
Control Delay I Initial value : 0%
Sets the delay when the rudder stick was pushed operated. Setting
range is 0 to 100%. Rudder stick left and right can be set separately.
Control Delay D Initial value : 0%
Sets the delay when the rudder stick was returned. Setting range is 0
to 100%. Rudder stick left and right can be set separately.

18 DATA SETTING
Gain Tracking Initial value : +0%
Adjusts left and right tail braking tracking. Setting range is -20% to
+20%.
For example, when there is a sense of hunting when stopping left
pirouette or the helicopter drifts when stopping right pirouette, shift
Trk in the + direction. In the opposite case, shift Trk in the - direc-
tion.
Operation Mode Setting Initial : CMT
Sets the gyro operation mode. Settings are NOR, AVC, and CMT. In
the NOR mode, both G1 and G2 operate in the AVCS mode. In the
CMT mode, G1 operates in the AVCS mode and G2 operates in the
NOR mode. In the NOR mode, the GY601 operates the same as an
ordinary gyro. In the AVC mode, the GY601 always operates in the
AVCS mode. In the CM mode, the GY601 can be used in both the
AVCS and NOR modes.

19
DATA SETTING
Flight mode Initial value : F3C
Switches the flight mode. Settings are F3C or 3D.
The F3C mode emphasizes tail suppression and stop. The 3D mode
slightly sacrifices tail suppression and stop, but lets you control
pirouette speed completely proportional with the rudder stick
operation amount and is suitable for 3D flight.
<3D mode steering angle setting>
During 3D mode setting, the transmitter rudder steering angle
is set to 100% and approximately 500º/second high pirouette
speed. Therefore, initially set the transmitter rudder steering
angle to a low value so that the tail can be safely controlled.
(About 70%)
The pirouette speed is proportional to the rudder steering
amount without regard to the gyro sensitivity.

20 DATA SETTING
AVCS Sense Initial value : 100%
Adjusts the rudder control characteristic in the AVCS mode. Setting
range is 50 to 150%.
Check the rudder operation feeling and stopping characteristic and
adjust. When the flight mode (page 19) is the 3D mode, this value
becomes the pirouette standard value.
Linkage Limit Setting Initial value : 100%
Sets the rudder servo travel limit.
Operate the rudder stick and adjust the rudder servo travel limit by
pressing the +/- key so that the servo moves to the maximum linkage
position. Use the same procedure to set both the left and right limits .
When setting, move the servo substantially so that the rudder angle
automatically becomes 200% and limit setting is easy. A or B is
displayed for the right and left directions.
Note: When this screen is displayed, the GY601 does not operate as
a gyro. To check operation, return to the initial screen, etc.