FUTABA GY502 User manual

AVCS GYRO

GY502

INSTRUCTION MANUAL

YAW-AXIS STABILIZER FOR MODEL HELICOPTER

(RATE GYRO)

Thank you for buying a GY502 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.

FOREWORD

The GY502 is an AVCS (Angular Vector Control System) rate gyro

developed for use with .60 type and other model helicopters.

[Features]

•High-speed arithmetic processing by microcomputer allows high-speed

pulse drive of servos. (Compatible with high-speed digital servos)

•Sensor vibration resistance and neutral characteristics have been improved

by the use of a low back aerofoam case.

•Amplifier mounts an LCD for accurate data setting.

[Applicable servos]

Gyro performance largely depends on the servo used. The higher the speed

and response of the servo, the higher the gyro gain and the better the gyro

performance. From this standpoint, a digital servo is perfectly suited for use

with a gyro. We recommend the use of a high-speed digital servo especially

developed for gyro use.

•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.

FOR SAFETY

•Meaning of Special Markings ---------------------------- 4

•Mounting/Operating Precautions ------------------------ 5

•Fuselage Maintenance Precautions ---------------------- 7

TABLE OF CONTENTS

BEFORE USE

•Set Contents------------------------------------------------- 8

•AVCS Gyro ------------------------------------------------- 9

•Digital Servo Compatibility -----------------------------11

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

•GY502 Functions Setting --------------------------------15

•Remote Gain Function------------------------------------21

•Initialization------------------------------------------------30

REFERENCE

•Specifications ----------------------------------------------40

•Definition of Abbreviations------------------------------41

•GY502 Parameters Sheet---------------------------------42

4FOR SAFETY

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 proce-

dures 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

FOR 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.

Mounting/Operating Precautions

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

performance. 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 GY502 uses a conductive resin case to reduce electromagnetic

interference. 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 GY502 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.

6FOR SAFETY

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 GY502.

During initialization, the message “-Hello-” appears on the GY502

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.

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 mea-

sures so that the gyro is not exposed to direct sunlight, etc.

FOR SAFETY

Check the remaining receiver/gyro/servo nicd battery operating

time during the adjustment stage and decide how many flights

are remaining.

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 GY502 in the AVCS mode, set revolution mixing

to OFF.

Fuselage Maintenance Precautions

Use a tale rotor drive tube or other part with a high torsion

performance for the tail drive.

Take the strength of the tail into account during inspection and

adjustment.

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.

Since a higher gain than usual can be used then the tail rotor is more

effective, the load on the tail is also greater.

Always perform proper maintenance for ultimate performance.

The rigidity of the fuselage tail has a large effect on gyro perfor-

mance.

Make the fuselage vibration as small as possible.

Fuselage vibration has an adverse affect on gyro operation.

8BEFORE USE

Set Contents

After unpacking the GY502 set, first check if the following parts are

provided:

BEFORE USE

Sensor tape (x3)

Mini screwdriver (x1)

GY502 sensor (x1)

GY502 control amp

(x1)

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

GY501 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.

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