HOBBYEAGLE A3 Mini User manual

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User Manual
V1.0 Nov, 2021 Revision

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Thank you for purchasing our products. A3 Mini is a high-performance and functional 6-axis mini gyro
system designed for R/C airplanes. The smaller size and more compact design make it more suitable for
the small electric airplanes. With the new feature of multi-protocol serial receiver support, it could be
compatible with most single line mini receivers on the market. In order for you to make the best use of
your gyro and to fly safely, please read this manual carefully and set up the device as described below.
IMPORTANT NOTES
Radio controlled (R/C) models are not toys! The propellers rotate at high speed and pose
potential risk. They may cause severe injury due to improper usage. It is necessary to observe
common safety rules for R/C models and the local law. Read the following instructions thoroughly
before the first use of your gyros and setup the gyro carefully according to this manual. We also
recommend that you seek the assistance of an experienced pilot before attempting to fly with our
gyros for the first time.
After power on, A3 Mini needs to perform an accurate gyroscope calibration, keep the
airplane stationary after power on and wait while the LED flashes blue. The LED will stay solid
blue if a slight movement is detected and the calibration will not start until you stop moving the
airplane, however, making the airplane level is NOT required during the initialization.
A stick centering is also required following the gyroscope calibration. Always put all the sticks
center (the throttle stick in the lowest position) before power on the airplane, and do not move
the sticks until the initialization is done.
Make sure to check the gyro direction of Aileron, Elevator and Rudder channels after
installation and always perform a test of them before each flight. An opposite reaction of the
gyro could lead to losing control or even crash!

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INSTALLATION
NOTES
Never use the hot-melt glue or nylon ties to fix the gyro onto the airplane!
You need only one piece of the tapes each time, a soft or thick mounting may probably impact
the performance of the gyro.
The gyro is a sensing device, please make enough space around it and keep as far away from
other electronic devices or wires as possible.
Mounting Orientation
Use one of the supplied double-sided tape to attach the gyro to your airplane firmly. For best performance,
the gyro should be mounted as close to the C.G. as possible, and the housing edges must be aligned
exactly parallel to all three rotation axes of the plane. The gyro can be attached flat or upright, and even
upside down, however, you have to ensure the arrow on the sticker always point to the heading direction,
otherwise the gyro will not work normally in ANGLE, LEVEL and HOVER modes.
① Flat, face up ② Flat, face down
③ Upright, button down ④ Upright Inverted, button up

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CONNECTION
Single-line Receiver Connection
A3 Mini supports PPM and multi-protocol digital serial receivers which allows you to connect the receiver
to [Serial RX] with only one single wire. Depending upon the protocol selected, A3 Mini will use the preset
channel assignment to recognize the channels from the receiver. Refer to the table below and check if
your radio transmits the channels in the correct order. Choose “None” for those channels you do not use.
Table 1: Serial Receiver Protocols and Default Channel Assignment
Serial Receiver Protocol
AIL
ELE
THR
RUD
MODE
GAIN
PPM Receiver
CH1
CH2
CH3
CH4
CH5
None
Futaba S.Bus (FrSky SBUS or WFLY WBUS)
CH1
CH2
CH3
CH4
CH5
None
Spektrum DSM/DSMX 1024 Satellite
CH2
CH3
CH1
CH4
CH5
None
Spektrum DSM/DSMX 2048 Satellite
CH2
CH3
CH1
CH4
CH5
None
Spektrum SRXL
CH2
CH3
CH1
CH4
CH5
None
Multiplex SRXL/JR XBUS Mode B
CH2
CH3
CH1
CH4
CH5
None
Graupner SUMD
CH2
CH3
CH1
CH4
CH5
None
FlySky iBUS
CH1
CH2
CH3
CH4
CH5
None

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NOTES
Please note that the remote master gain channel is disabled as default. Assign a channel
number for channel GAIN to activate this feature if you need.
Pay attention to the polarity of the plugs. The Orange or White signal line must always be on
the inner side of the gyro.
You will need to purchase an optional adapter if you are using a Spektrum satellite receiver.
Servo Connection
A3 Mini supports standard fixed-wing, flying-wing (Delta-wing) and V-tail. Connect the servos to the
corresponding connectors by following the illustration below.
NOTES
Make sure that there are no mixing functions active on your transmitter. Have a look at the
radio’s servo monitor and verify that each stick controls only one output channel.
Most flying-wings have no rudder, in this case, [RUD] is unnecessary to connect.
FLIGHT MODES
A3 Mini provides 6 flight modes which can be switched by a 3-position switch of the transmitter during
flight. The factory default mode allocation of the switch is NORMAL - LEVEL - ANGLE. The color of the
LED shows the current flight mode of the gyro while in use.
Table 2: Colors of the LED for flight modes
Solid Red
GYRO OFF Mode
Solid Blue
NORMAL Mode
Blue, Flashing
LOCK Mode
Solid Violet
ANGLE Mode
Violet, Flashing
LEVEL Mode
Violet, Fast Flashing
HOVER Mode
.
.

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1. GYRO OFF Mode
When operating in GYRO OFF mode the gyro will be deactivated completely, and the airplane will be
completely under the control of your transmitter as it was before installing the gyro. This mode is usually
used for testing purpose only.
2. NORMAL Mode
The NORMAL mode, also known as the ‘Rate mode’, is the most basic function of the gyro. It works
based on the rotation rate control of each axis of the airplane. When operating in this mode, the gyro will
only correct currently occurring rotational movements, a momentary reaction will be applied to the servos
when the airplane rotating on corresponding axis, after rotation the servos will move back to their neutral
position as soon as the airplane standing still immediately. The NORMAL mode can be used with nearly
any size and type of airplanes. It can effectively improve the stability and precision of the airplane and
reduce the stall point specially.
3. LOCK Mode
The LOCK mode is also known as the ‘Attitude Lock mode’, ‘3D mode’ or ‘AVCS mode’. Different from
NORMAL mode, the gyro will perform a permanent correction for rotational movements on each axis
constantly. That is when you release the sticks the airplane will stop and lock its current position
immediately. This mode is well suited for practicing basic 3D maneuvers such as hovering or knife edge.
Since it can help you to lock the attitude of the airplane, it is also helpful for landing.
4. ANGLE Mode (Former Trainer Mo de)
The ANGLE mode, also known as the ‘Trainer mode’ or ‘Attitude mode’, will limit the maximum angle of
the airplane on both roll and pitch axes. Roll and loop are not allowed in this mode, the airplane will be
stabilized all the time, independent of any stick input. This prevents the airplane from being tilted into a
larger angle that may cause a danger. As soon as the sticks are released, the airplane will be brought
back to horizontal position automatically. You can use this mode as emergency rescue, or in other
applications, e.g., to have a training for new beginners or to use for FPV. The maximum allowed angle
can be set in the configurator. In addition, changing the stick rate can also affect the max tilt angle.
5. LEVEL Mode
The LEVEL mode is also known as the ‘Auto-Level mode’, ‘Auto-Balance mode’ or ‘Horizon mode’. When
operating in this mode, the airplane will be brought to horizontal position automatically when releasing
the sticks. Different from the ANGLE mode, there is no maximum angle limitation in this mode and the
airplane will be stabilized only when there is no specific control input from aileron and elevator sticks.
This mode can be used if the pilot becomes disoriented and would like to save the airplane from crashing.
6. HOVER Mode
The HOVER mode, also known as the ‘Auto-Hover mode’, provides the same functionality as the LEVEL
mode. The only difference is that when you release the sticks, the airplane will be brought to vertical
position (nose up) and keeps hovering. This mode is designed to help you to learn hovering maneuver

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and reduce the probability of crashing.
GAIN ADJUSTMENT
Basic Gain
Both the configurator and the program card provide basic gain settings for Aileron, Elevator and Rudder
separately. Basic gain determines the momentary reaction strength of the gyro. In general, the higher the
gain the harder the airplane will stop after rotation and the more stable and precise the airplane will fly.
But if the gain is too high the airplane will tend to oscillate at high frequency on the corresponding axis. If
too small, the operation and stability will not be so good and the airplane does not stop precisely and
overshoots. The gyro will be deactivated completely if you set the basic gain to 0%.
For the first flight test it is recommended to start with a lower basic gain setting (e.g. 30%) and switch the
gyro to NORMAL mode. In case the airplane starts to oscillate in flight then reduce the gain of the
corresponding axis. If the control feels weak and imprecise and does not hold position when stopping
then increase the gain, according to this approach, fine tune the basic gain until you get the best
performance.
Mode Gains
Furthermore, the gains corresponding to each flight mode can also be setup separately, including the
Lock Gain, Angle Gain, Level Gain and Hover Gain, these gains should be adjusted based on the basic
gain and only work with the corresponding flight mode.
Remote Master Gain
A3 Mini also supports the remote master gain control. You can make a linear adjustment by using a
volume or slide lever on your transmitter or make a 3-level gain selection using a 3-position switch. This
function is optional, the master gain will always default to 100% if you do not connect it. Master gain will
not affect the basic gain and flight mode gain settings on the gyro.
GYRO DIRECTION
After installation, lift the airplane up and make it quickly rotate around the roll, pitch and yaw axes
respectively. Make sure all the control surfaces react in the correct directions referring to the figures below.
VERY IMPORTANT!
It is extremely important to make sure that the gyro reacts in the correct direction for each channel
before flight. An opposite reaction of the gyro could lead to losing control or even crash!

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Check the gyro direction for Aileron
Quickly move the right wing downward around the roll axis, the right aileron surface should flap down and
the left flap up as shown below.
Check the gyro direction for Elevator
Quickly move the nose of the airplane downward around the pitch axis, the elevator surface should flap
up as shown below.
Check the gyro direction for Rudder
Quickly move the nose of the airplane to the left around the yaw axis, the rudder surface should flap right
as shown below.

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Quick Gyro Reversing
A3 Mini also provides you a quick approach to reverse the gyro direction without connecting it to a PC or
a programming card. For example, to reverse the gyro direction of Aileron, press and hold the button
while moving and holding the Aileron stick right or left for about 2 seconds, release both the button and
the stick when the LED flashes White once, indicating that the gyro direction of Aileron has been reversed
and saved. Similarly, move the Elevator stick up or down for Elevator channel and move the Rudder stick
right or left for Rudder channel while long pressing the button until the LED starts to flash White once.
LEVEL AND HOVER CALIBRATION
When flying in ANGLE mode or LEVEL mode, A3 Mini needs to know the angle of the airplane in both
roll and pitch directions, this is achieved by calculating the attitude of its own. A small angle deviation
caused by installation can lead to an unexpected behavior when flying in ANGLE mode or LEVEL mode.
For this reason, a level calibration is recommended to offset the error caused by installation and to
establish a proper level reference of your airplane after installing the gyro.
Before calibrating, the airplane should be placed on the horizontal ground and make the wing
parallel to the ground. Make the airplane slightly nose-up because a certain elevation angle
is usually required to maintain level flight for most airplanes.
Click the “Level Calibration” button on the Sensor tab of the configurator to start the
calibration. The whole calibration process will take you several seconds and the LED will
blink Blue rapidly during calibrating. Do not move the airplane until the calibration is done.
After a successful calibration, the result will be saved and displayed on the screen, you can
adjust them manually in the future. If you get a rapid Red blinking during calibration, this
means the result exceeds the maximum permissible value (i.e. ±25deg), in this case, you
have to re-install the gyro to reduce the deviation caused by installation.
As a same reason, a hover calibration is recommended to perform after installation if you want to fly with
HOVER mode. The procedure is quite similar to that of level calibration. The only difference is that the
airplane should be lifted vertically to the ground instead of putting it on the ground in Step 1.
TIP: In Step 2, press and hold the button for about 2 seconds, release the button once the LED turns
solid White can quickly perform a level calibration, similarly, press and hold the button more than 4
seconds until the LED starts to flash White continuously can quickly start a hover calibration.
PROGRAMMING
Please download the HobbyEagle A3 Configurator and the USB driver installer from our
website: https://www.hobbyeagle.com/a3-configurator/.
The software supports Windows XP, Windows 7, Windows 8 and Windows 10 (32 or 64 bit).
If the installation fails, please download and install Microsoft .NET Framework 4 first.
Install the USB driver before connecting the gyro to the PC.
Step 1
Step 2
Step 3

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NOTES
Always use the included USB adapter and the black data cable to connect the gyro to the PC
or the programming card. NEVER use the common USB cables those for mobile phones or
other products on the market with our gyro, this will cause the connection to fail.
It is recommended to use the new Program Card X for A3 Mini, please upgrade the card to the
latest version using the A3 Configurator.
If you are using an old program card, please limit the working voltage of the gyro to 5.5V,
otherwise, the program card may get damaged!
SPECIFICATIONS
Main Controller:
32-bit MCU
Sensors:
High-precision 3-axis gyroscope and 3-axis accelerometer
Gyroscope Scale Range:
±2000dps
Accelerometer Scale Range:
±4g
PWM:
800uS - 2220uS, Neutral 1500/1520uS, 50Hz - 333Hz
Input Voltage:
DC 3.6V - 8.4V
Operating Temperature:
-10℃ - 50℃
Size:
30×19.5×7.5mm
Weight:
4.8g (excluding wires)