FUTABA GY240 Instruction Manual

Thank you for buying a GY240 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 correc-
tions or clarifications should be made.
1 F
OREWORD
The GY240 is a high performance, small, and light weight
AVCS (Angular Vector Control System) gyro developed
for model helicopters.
Because the sensor section and control circuit are inte-
grated, mounting is easy.
AVCS Gyro
Conventional gyros send control signals to the rudder servo
only when the tail of the helicopter moves. When the tail
stops moving, the control signal from the gyro becomes
zero. Conversely, the AVCS gyro continues to send control
signals to the servo even when the tail of the helicopter
stops moving.
The following sequentially describes the conventional gyro
and the AVCS gyro.
Operation of Conventional Gyro
Basic operation is described by considering the case when
the helicopter is hovering under cross-wind conditions.
With a conventional gyro, when the helicopter encounters a
cross-wind, the force of the cross-wind causes the tail of the
Special Markings
Pay special attention to the safety at the parts of this manual that are indicated by the following marks.
Mark
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:
helicopter to drift. When the tail drifts, the gyro generates a
control signal that stops the drift. When the tail stops
drifting, the control signal from the gyro becomes zero. If
the cross-wind continues to cause the tail to drift in this
state, the "stop" operation is repeated until the tail faces
downwind. This is called the "weathervane" effect.
Operation of AVCS Gyro
Conversely, with an AVCS gyro, when the helicopter
encounters a cross-wind and the tail drifts, a control signal
from the gyro stops the drift. At the same time, the gyro
computes the drift angle and constantly outputs a control
signal that resists the cross-wind. Therefore, drifting of the
tail can be stopped even if the cross-wind continues to
effect the helicopter. In other words, the gyro itself auto-
matically corrects (auto trim) changes in helicopter tail trim
by cross-wind.
Considering operation of an AVCS gyro, when the tail of
the helicopter rotates, the servo also rotates in accordance
with the angle of rotation of the tail. When the tail stops
rotating, the servo judges that it has stopped in that posi-
tion. This is the auto trim function.
Meaning
; Prohibited ; Mandatory
2 F
EATURES
Adoption of AVCS
Since rudder trim changes caused by changes in tail
reaction torque changes due to wind and other meteorologi-
cal changes and main rotor rotation variations are automati-
cally cancelled, tail (rudder) operation is easy, making it
perfect for beginners.
SMM gyro sensor
Use of a new extremely small drift SMM (Silicon Micro
Machine) gyro sensor virtually eliminates rudder trim
changes during flight.
3 S C
ET ONTENTS
The GY240 comes with the following accessories:
GY240
Ratings
(Integrated sensor type AVCS rate gyro)
• Control system: Digital advanced PI (Proportional Integration) control
• Gyro sensor: SMM (Silicon Micro Machine) system vibration gyro
• Operating voltage: +4 to +6VDC
• Operating temperature range: -10˚C to +45˚C
• Dimensions: 27 x 27 x 20mm
• Weight: 25g (including connector)
• Functions: Sensitivity trimmer, gyro operating direction adjustment switch,
AVCS on/off switch
4 F A C
UNCTIONS ND
AVCS on/off switch (AVCS)
Turns the AVCS function on and off. In the "off" position, the GY240
operates as a conventional gyro.
Gyro direction switch (DIR)
Switches the gyro control direction. Must be switched according to the main
rotor rotating direction and rudder linkage direction.
(If you try to fly a helicopter with a clockwise rotation rotor with the gyro in
the reverse direction, the nose will swing to the left.)
Gyro sensitivity trimmer (GAIN)
Gyro sensitivity setting trimmer. Set to the maximum value at which the tail
does not hunt (minute vibration).
High-speed, high-precision control
High-speed, high-precision control realized by digital
advanced control by microcomputer.
Small, light weight, integrated type
Small size (27 x 27 x 20mm) and light weight (25g) are
realized through high precision mounting technology.
Conductive resin case
Conductive resin case improves anti-EMI (static electricity,
radiowave interference) characteristic.
Mini screwdriver (for adjustments)
Double-sided tape (3 sheets)
ONNECTIONS
Rudder input connector
Connects to the receiver rudder channel (ch4) output connector.
Rudder servo
Rudder servo connector
Connects the rudder servo.