PB-4 Propeller & Rotor Balancer
Hardware Manual
Smart Avionics Ltd.
16/04/2019www.smartavionics.comRevision: 1.6
PB-4 Propeller & Rotor Balancer: Hardware Manual
Revision: 1.6
Publication date 16/04/2019
Copyright © 2003-2019 Smart Avionics Ltd.
Android is a trademark of Google Inc.
iOS is a trademark of Apple Inc.
Dropbox is a trademark of Dropbox inc.
Gyroplane photographs courtesy of Mike Goodrich and Jerôme Prompsy.
Table of Contents
1. Introduction ................................................................................................... 1
1.1. Balancing system overview ............................................................... 1
1.1.1. Wi-Fi network components ..................................................... 1
1.2. Accessing the PB-4 user interface .................................................... 3
1.2.1. Accessing the PB-4 user interface (AP mode) ...................... 3
1.2.2. Accessing the PB-4 user interface (STA mode) .................... 3
1.3. Batteries ............................................................................................. 4
1.4. PB-4 panel .......................................................................................... 5
1.5. Environmental limits .......................................................................... 7
1.6. Operator warning ............................................................................... 7
2. Preparing for Propeller Balancing ................................................................ 9
2.1. Additional items required .................................................................. 9
2.2. Positioning the aircraft ...................................................................... 9
2.3. Mounting the accelerometer ........................................................... 10
2.4. Mounting the tacho sensor ............................................................. 12
2.5. Attaching the reflective tape ........................................................... 14
2.6. Attaching the cables ........................................................................ 15
2.7. Positioning the PB-4 ........................................................................ 16
3. Preparing for Rotor Balancing ................................................................... 17
3.1. Mounting the sensors ...................................................................... 17
3.2. Positioning the PB-4 ........................................................................ 21
3.3. Offline capture button ..................................................................... 22
4. The PB-4 User Interface ............................................................................. 23
4.1. Getting started with the browser based user interface ................. 23
5. Upgrading the PB-4's Firmware ................................................................. 25
5.1. Upgrading the UI firmware .............................................................. 25
5.2. Upgrading the CPU firmware .......................................................... 25
5.3. Upgrading the Wi-Fi firmware ......................................................... 26
A. Battery Charging & Replacement .............................................................. 27
A.1. Replacing the RTC battery .............................................................. 27
B. Specifications ............................................................................................. 29
B.1. Main unit .......................................................................................... 29
B.2. Accelerometer ................................................................................. 29
B.3. Tachometer ...................................................................................... 29
C. EMC Compliance & Safety Information .................................................... 31
D. CE Declaration of Conformity .................................................................... 33
Index ................................................................................................................ 35
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List of Figures
1.1. Wi-Fi roles when PB-4 is in AP mode ....................................................... 2
1.2. Wi-Fi roles when PB-4 is in STA mode ..................................................... 2
1.3. PB-4 panel .................................................................................................. 5
2.1. Accelerometer axes and orientation ...................................................... 10
2.2. Accelerometer mounted on a Rotax 912 gearbox ................................ 11
2.3. Tacho sensor with flexible mounting plate ............................................ 12
2.4. Tacho sensor mounted on cowling ........................................................ 13
2.5. Tacho sensor angle of incidence ........................................................... 14
2.6. Cable taping ............................................................................................. 15
3.1. Standard sensor orientation (top view) ................................................. 18
3.2. Sensors mounted on an ELA rotor head (top view) .............................. 19
3.3. Sensors mounted on an ELA rotor head (side view) ............................. 20
3.4. Sensors mounted on an ELA rotor head (bottom view) ........................ 20
3.5. Sensors mounted on a Magni prerotator drive ...................................... 21
4.1. Initial screen ............................................................................................ 23
A.1. Locating the PB-4 board securing screws ............................................. 28
A.2. Correct orientation of RTC battery ......................................................... 28
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Chapter 1. Introduction
This manual describes the hardware of the Smart Avionics PB-4 product and
how to prepare for balancing a propeller or rotor using the PB-4. The balancing
procedures and the features of the PB-4 software are covered in the user
interface manual (pb4_ui_manual.pdf).
1.1. Balancing system overview
The PB-4 balancing system has these main components:
Accelerometer
Optical
tachometer
Digital processor
(CPU)
User interface
device
The PB-4 uses Wi-Fi to communicate with the user interface device which can
be any computer that supports a modern browser and Wi-Fi. Obviously, the
most suitable devices for use in aircraft are lightweight tablets. A 7" format
tablet is a good choice for use while balancing as it is not too bulky but still
has reasonable screen resolution. Later, you can look at the resultson a device
with a bigger screen, e.g. a laptop computer. The following text simply calls
the user interface device a tablet.
This is mounted near the hub of the propeller/rotor to
detect the vibration due to imbalance.
A strip of reflective tape is attached to one propeller/rotor
blade and an optical sensor detects the tape as it passes
and generates the tachometer signal required by the
balancer.
This processes the vibrationsignalandsendsthe resulting
data over a Wi-Fi network to be displayed on the user
interface (UI) device.
This provides the means whereby the user can view the
results and interact with the PB-4 using a standard web
browser. The PB-4 may also be used with the Propeller
Balancer Android app.
1.1.1. Wi-Fi network components
The PB-4 uses a Wi-Fi network to communicate. Most commonly, a Wi-Fi
network consists of an
traffic to and from the stations is routed through the access point. The PB-4
can operate as either a Wi-Fi station or as a Wi-Fi access point depending on
where you are located at the time.
1.1.1.1. PB-4 is the Access Point
When you are at the airfield doing the balancing, you would not normally have
an access point available. Fortunately, the PB-4 can be the access point (as
well as being a balancer). By starting the PB-4 in AP mode, it will be an access
access point
and one or more
stations
. The network
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point and the tablet will be able to communicate with it directly as shown
SSID: PB4-
XX
PB-4
AP MODE
TABLET
WEB BROWSER
HOST ADDRESS
ALWAYS 172.21.21.1
PB-4 & UI device
communicate via
PB-4's built in AP
ACCESS
POINT
SSID: YOUR WIFI NAME
PB-4
STA MODE
TABLET
WEB BROWSER
HOST ADDRESS ASSIGNED
BY ACCESS POINT
PB-4 & UI device
communicate
via separate AP
below. Note that unless the tablet has some other means of accessing the
internet, it will only be able to talk to the PB-4 in this configuration.
Fig 1.1. Wi-Fi roles when PB-4 is in AP mode
1.1.1.2. PB-4 is a station
Wi-Fi network components
When you are back indoors, your tablet will most likely be already configured
to use an existing access point at that location. The PB-4 can be started as a
station (STA mode) and it will then use the same access point as the tablet
so they will be able to communicate. In this configuration, your tablet will be
able to access the network (internet, printers, etc.) as normal.
Fig 1.2. Wi-Fi roles when PB-4 is in STA mode
For the PB-4 to be able to talk to the access point, it needs to know the access
point's SSID (Wi-Fi network name) and password. The PB-4 supports Wi-Fi
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Accessing the PB-4 user interface
Protected Setup (WPS) which makes setting up the access point credentials
easy. The SSID and password may also be entered into the PB-4 manually if
required.
Note
One way of remembering which mode you need to use is that when
you are "at the AirPort" useAP mode and when you "STAy at home",
use STA mode!
1.2. Accessing the PB-4 user interface
Safari users please note that the PB-4 is not compatible with Safari's “Private
Mode”.
Accessing the PB-4 user interface from your tablet's browser requires the
PB-4 and the tablet to be using the same Wi-Fi network.
1.2.1. Accessing the PB-4 user interface (AP mode)
When the PB-4 is in AP mode, the Wi-Fi network name (SSID) will be PB4-XX
where XX are two letters/digits. You will need to tell your tablet to use that
Wi-Fi network (via its Wi-Fi configuration). At the airfield, the tablet will probably
use the PB-4 Wi-Fi automatically because your normal Wi-Fi is not available.
If not, you will have to tell the tablet to use the PB-4 Wi-Fi manually.
Once the tablet is using the PB-4 network, you can load the user interface
page into the browser. If your tablet supports MDNS, you can simply use
pb4.local as the host name in the browser. Apple devices (mac/ipad/iphone)
and most Linux systems have MDNS, most Windows systems do not. If not,
use the IP address 172.21.21.1. Having accessed the PB-4 user interface
page, just add a bookmark for that page in your browser called something like
"PB-4 AP Mode (at the airfield)".
1.2.2. Accessing the PB-4 user interface (STA mode)
When the PB-4 is in STA mode, the Wi-Fi network name(SSID) will be whatever
you normally use at the current location. The PB-4 will need to be taught that
SSID and the associated password. The PB-4 supports WPS for automatically
obtaining the SSID and password from the access point which is quick and
easy if the access point also supports this feature. Alternatively, you can
manually enter the credentials by starting the PB-4 in AP mode, loading the
user interface into your browser (as described above), connecting to the PB-4
(click on red button) and then going to Menu / Options / PB-4 Configuration
/ Set Access Point Details.
Once the PB-4 is able to connect to the local network, you can load the user
interface page into the tablet's browser. Again, if MDNS is supported by the
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Batteries
tablet, the host name pb4.local can be used. Otherwise, you need to find out
the IP address that has been assigned to the PB-4 by the access point. Follow
these steps:
1. Turn on the PB-4 in STA mode (press the on/off switch until LED 2 goes
green). When you release the switch, LED 2 will go off and then after a few
seconds will flash green slowly if the PB-4 has successfully managed to
log into the access point.
2. Turn the PB-4 off (press switch until the LEDs go out).
3. Turn the PB-4 on again but this time start it in AP mode (press on/off only
until LED 1 comes on).
4. Access the PB-4 user interface page with your browser as described in the
previous section, connect to the PB-4 (click on red button) and then go to
Menu / About. The about box will contain a line that says STA Mode IP
Address: XX.XX.XX.XX. The address that is shown is the IP address that
has been assigned to the PB-4 by the access point, note it down.
Having found out the PB-4's IP address when in STA mode, you can use that
address to access the user interface page and then add a bookmark for that
page in your browser called something like "PB-4 STA Mode (at home)".
1.3. Batteries
The PB-4 is poweredby 4 x 1.2V AA NiMH rechargeable batteries. The batteries
are easily accessible via a hatch in the bottom of the PB-4 case. The PB-4
itself cannot charge the batteries, they have to be removed and charged in an
external charger. It is also possible to use non-rechargeable 1.5V AA batteries
in the PB-4.
The PB-4 also contains a CR2032 3V coin cell which provides backup power.
This battery will require replacing every now and then.
See Appendix A for more information on battery charging and replacement.
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1.4. PB-4 panel
LED1 &
ON-OFF
SWITCH
LED2 &
JACK
SOCKET
TACHO ACCEL 1 ACCEL 2
Fig 1.3. PB-4 panel
The panel contains:
PB-4 panel
On-off
switch
The on-off switch is a push button. When turning the PB-4 on,
how long you hold the button pressed affects the Wi-Fi mode
used. Outdoors, when balancing, a short press is required to
start the PB-4 in AP mode.
Turn on PB-4
(AP mode)
Turn on PB-4
(STA mode)
Turn on PB-4
(WPS mode)
Press the on-off switch until the LEDs light
(about ½ second), then release switch. After a
few seconds, LED 2 should slowly flash green
to show that it is in AP mode waiting for the
tablet to connect.
Press and hold the on-off switch until LED 2
changes from green to red (about1 ½ seconds).
On release, LED 2 will go off until the PB-4 has
finished initialising. If the PB-4 has the right
credentials for the access point, LED 2 should
now be slowly flashing red to show that it is in
STA mode waiting for the tablet to connect.
Press and hold the on-off switch until LED 1
flashes quickly (about 5 seconds). The PB-4
has entered WPS mode. Press the WPS (QPS)
button on the access pointand the PB-4 should
receive the credentials from the access point.
If successful, the PB-4 will restart in STA mode
(LED 2 slowly flashing red). Otherwise, the PB-4
will restart in AP mode and LED 2 will be slowly
flashing green.
Turn off PB-4
Factory reset
Press and hold the on-off switch until LEDs go
off (about ½ second).
With the PB-4 turned on, press and hold the
on-off switch. LED 1 will go out after ½ second
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PB-4 panel
but keep pressing until LED 1 becomes red
again (about 10 seconds). It will then reset all
configuration values to their defaults. This will
not lose any job data stored on the PB-4.
LED 1
LED 2
The main purpose of LED 1 is to indicate whether the PB-4 is
receiving a tacho signal.
PB-4 is switched off.Off
RPM is detected.Green
(continuous)
RPM is not detected.Red
(continuous)
WPS mode entered.Red (flashing)
The main purpose of LED 2 is to indicate the current Wi-Fi mode
and whether the user interface is connected to the PB-4.
Off
flash)
Green
(continuous)
PB-4 is switched off or Wi-Fi is still being
initialised.
AP mode - user interface not connected.Green (slow
AP mode - user interface is connected and
receiving data.
Accel 1 &
accel 2
connectors
Tacho
connector
Jack socket
STA mode - user interface not connected.Red (slow
flash)
Red
(continuous)
One or two Smart Avionics 2-axis accelerometers may be
connected using 4-wire cables. If you are only using 1
accelerometer, always connect it to Accel 1.
Connects (using a 3-wire cable) to the Smart Avionics Red LED
Tacho Sensor that is measuring the propeller/rotor RPM. This
is tacho channel A.
A 3.5mm jack socket that is used to connect a pilot operated
push switch that triggers data capture. This allows data to be
captured in flight without the tablet needing to be present.
The socket connections are:
• Barrel - ground.
• Ring - tachochannel B input (contact Smart Avionicsfor details
if you wish to use this).
STA mode - user interface is connected and
receiving data.
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Environmental limits
• Tip - capture switch input (connect to ground to capture).
1.5. Environmental limits
Please operate the PB-4 within the following environmental limits:
1.6. Operator warning
Warning
The PB-4 contains a microwave transmitter (the Wi-Fi module). To
be compliant with the FCC RF radiation exposure limits, the PB-4
should not be located closer than 20cm from a human body while
operating.
-20° to +45° C (-4° to 113° F)Temperature
5% to 95% non-condensingRelative humidity
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Chapter 2. Preparing for Propeller Balancing
Caution
Propellers can kill.
Make sure that the ignition is switched off before touching the
propeller.
Always assume that the engine could fire when the propeller is
being moved.
Make sure that the aircraft is securely chocked or tied down while
carrying out the balancing process.
2.1. Additional items required
To carryout the balancing process,you will need the following items in addition
to the balancer kit:
• Balance weights (typically AN970 washers) and a means of securely
attaching them to the spinner backplate.
• If necessary, a bracket for mounting the accelerometer onto the front of
the engine (optional, depending on engine type and installation details). An
M6 screw and washer are supplied which can be used to attach the
accelerometer to the back of a Rotax 4-stroke gearbox if the vacuum pump
option is not fitted.
2.2. Positioning the aircraft
The following points should be observed regarding positioning the aircraft for
a propeller balancing session:
1. The position must be safe for ground running of the engine. Typically, the
engine will need to be run at cruise RPM and the aircraft should be braked
and chocked and, if necessary, tied down.
2. If the sun is low on the horizon it is best if the sun does not lie within the
arc of the propeller when viewed from the location of the tacho sensor.
3. If there is any wind, point the aircraft as close into wind as possible while
observing point 2 above. If the wind is greater than 10kts or gusty it will be
difficult to obtain a really good balance.
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X Axis
Y Axis
Mounting the accelerometer
2.3. Mounting the accelerometer
Remove sufficient cowlings to gain access to the front of the engine. Mount
the accelerometer (40mm square with a 6mm hole through the middle) as
near to the front of the engine as possible with the accelerometer's sensing
axis pointing directly at the propeller's centre line.
The accelerometer's X axis coincides with the direction of the sensor's cable
socket and its Y axis is at 90° to the direction of the cable socket.
Fig 2.1. Accelerometer axes and orientation
Note that the accelerometer does not have to be directly above the propeller's
axis of rotation. However, to get the best results you should not mount the
accelerometer such that the sensing axis is parallel with the engine's cylinders.
On a Rotax 4-stroke engine that doesn't have a vacuum pump attached, the
best place to mount the accelerometer is on the rear of the gearbox using one
of the available tapped holes and the supplied M6 screw and washer.
Important
The sensing axis used must intersect the axis of rotation of the
propeller.
Remember to configure the job to use the correct axis.
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Mounting the accelerometer
Fig 2.2. Accelerometer mounted on a Rotax 912 gearbox
If the accelerometer cannot be bolted directly to the engine, some form of
bracket will be required. Obviously, the details of this are engine specific but
it could be as simple as a strip of metal with a hole drilled at each end. If a
bracket is used, it must be sufficiently stiff to ensure that the accelerometer
does not move with respect to the engine.
However the accelerometer is mounted, it must notbe subjected to excessive
temperatures. The temperature of the sensor should not exceed 85° C. If
necessary, thermally insulating material can be sandwiched between the
accelerometer and the engine (or bracket) to reduce the amount of heat
conducted to the accelerometer. If the surrounding area will be very hot, the
accelerometer could be wrapped in thermally insulating material (once the
cable has been attached).
Important
The accelerometer is robust but may be damaged if dropped on a
hard surface.
It is preferable to refit the engine cowling to minimise the turbulence generated
by the airflow from the propeller. For some aircraft, the cowling will have to
be refitted to provide a suitable mounting position for the optical sensor.
However, if the balance weights are to be added to the rear of the spinner
backplate, it may pay to leave the cowling off (if possible) during the balancing
process so that it is easier to gain access to the weights. Once the balancing
has been completed, the cowling could be replaced and a final reading taken
to determine the level of vibration achieved.
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Mounting the tacho sensor
2.4. Mounting the tacho sensor
Owing to the variation in aircraft cowling shapes and sizes, only generic
instructions can be provided here. You may find that a little experimentation
is required to obtain the best results.
The tacho sensor is drilled for a 6mm fastener and so it may be securely bolted
to the airframe using a suitable bracket. With an adequately strong bracket,
it would be safe for the aircraft to be flown with the sensor attached in this
way (assuming no other safety issues arise).
For ground use only, a flexible plastic mounting plate is provided. The sensor
is bolted to the plate and then the plate may be taped to the aircraft cowling.
The supplied soft washer should be placed between the tacho sensor and the
mounting plate to increase the friction as this will reduce the fastener torque
required.
Fig 2.3. Tacho sensor with flexible mounting plate
Caution
This method of mounting the tacho sensor on the cowling is
perfectly adequate when the aircraft is stationary on the ground.
Under no circumstances should the aircraft be flown with the tacho
sensor attached using the flexible mounting plate.
Caution
If the propeller is a pusher, i.e. the cowling is in front of the propeller
rather than behind, extra care should be taken to ensure that the
tacho sensor cannot become detached from the cowling and hit
the propeller blades. As a minimum, tape the accelerometer cable
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Mounting the tacho sensor
to the cowling so that it will restrain the tacho sensor in the event
of it becoming detached from the cowling. If you have any doubt
as to the security of the tacho sensor, don't risk destroying it and
the propeller.
Position the tacho sensor such that the sensor block is pointing towards the
propeller. If the sensor's orientation is correct, the blades will sweep across
the sensor block as the propeller rotates. The distance from the front of the
sensor to the propeller should be in the range 5-75cm.
Fig 2.4. Tacho sensor mounted on cowling
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Normal
TACHO
SENSOR
Approx 30 degrees
angle of incidence
(from normal)
Attaching the reflective tape
Fig 2.4 shows the tacho sensor mounted an aircraft cowling.
Important
To detect the propeller RPM reliably when the propeller blades are
reflective, the tacho sensor should be positionedsuch that the angle
of the LED beam is not normal to the faces of the propeller blade.
Rotate the tacho sensor so that it is approximately 30° from the
normal (either in front of or behind the normal). Fig 2.5 illustrates
this.
2.5. Attaching the reflective tape
Fig 2.5. Tacho sensor angle of incidence
If the angle is too small, the tacho sensor will tend to detect the
other blades (especially if they are highly reflective) and the RPM
will appear erratically too high. If the angle is too large, the blade
with the reflective tape will not be reliably detected and the RPM
will appear zero or erratically too low.
With the engine ignition switched off, rotate the propeller so that one blade
lies directly on the sensing axis of the tacho sensor. Make sure that the area
on the back of the blade where the tape is going to be attached is clean. Apply
a strip of 25mm wide masking tape to the back of the propeller at the point
that the red beam will hit the blade. Wrap the tape a short distance around
the leading edge of the blade but don't wrap it around the trailing edge.
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Cowling
Cable
Tape
Attaching the cables
Important
The tape must be oriented such that it is parallel to the tacho
sensor's body. This ensures that as the blade sweeps across the
tacho sensor, the maximum length of reflective tape will be seen
by the sensor. This may mean that the tape is not at 90° to the
leading edge of the blade but that doesn't matter.
Now put a strip of the reflective tape on top of the masking tape, it should
extend to close to the leading edge but not actually wrap around the leading
edge.
If you subsequently find that the tacho sensor cannot reliably detect the RPM,
verify that the tape really is in the correct position. You may find that adding
another strip of reflective tape next to the first strip will improve the situation.
Tip
When the tacho sensor is connected and the PB-4 is powered up
and connected to the tablet, the red LED will flash regularly. If the
tacho sensor is receiving a large amount of reflected light, the LED
will stop flashing. To check that the sensor is correctly orientated,
move the propeller so that the tacho sensor's beam is pointing at
the most reflective portion of the background (but not the tape). If
the LED is continuously on, rotate the sensor until the LED starts
flashing. Check that the tape still passes through the LED beam.
2.6. Attaching the cables
Connect the accelerometer and tacho sensor to the PB-4 using the supplied
cables (4 pin connectors for the accelerometer and 3 pin connectors for the
tacho sensor). Make sure the connectors' retaining collars are screwed down
(take care to only rotate the metal retaining collar and not the plastic body of
the connector).
Any slack in the cables should be taken up by coiling the cable and then
applying a few strategically placed pieces of masking tape to stop the cable
flapping around in the propeller breeze.
Fig 2.6. Cable taping
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Positioning the PB-4
If you tape the cables as shown in the above figure, they are unlikely to come
adrift.
Important
To obtain the best results, the cables should be kept away from
sources of electrical interference such as ignition leads,
magnetos/ignition units, generators/alternators/regulators and
their associated wiring.
Be especially careful to ensure that the cable cannot get close to
rotating components or very hot surfaces.
2.7. Positioning the PB-4
The PB-4 enclosure can be positioned in the cockpit if the cables are long
enough or even just on the ground. Remember that Wi-Fi signals cannot pass
through metal and so if the aircraft has a metal fuselage the person operating
the tablet will have to be able to see the PB-4 enclosure.
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Chapter 3. Preparing for Rotor Balancing
3.1. Mounting the sensors
For gyroplane rotor balancing, the accelerometer and the tacho sensor must
be mounted on the rotor head using one or more brackets. Exactly how this
is achieved is dependent on the design of the rotor head. A common
configuration (e.g. for AutoGyro & ELA gyros) is to position the reflective tape
on the underside of the prerotator disk with the tacho sensor mounted below
the disk. Another common configuration (e.g. for Magni gyros) is to mount
the sensors aft of the mast with the reflective tape attached to one of the rotor
blades. However the sensors are mounted, you must ensure that the reflective
tape is always aligned with the beam from the tacho sensor whatever the
position of the rotor head. i.e. moving the aircraft's control stick should not
affect the alignment.
The following general points should be observed:
• The figures below show both sensors mounted together, they can also be
mounted separately, if desired.
• The bracket(s) need to be sufficiently sturdy to take the weight of the
sensors and to not resonate at any frequency less than 2 times the max
rotor RPM.
• The accelerometer must be securely mounted such that at least one of its
sensing axes passes through (or close to) the rotor's axis of rotation and
that sensing axis is also parallel to the rotor disk (this is the horizontal axis).
• If you want to measure the vibration in the vertical direction, the other
accelerometer sensing axis should be normal (90°) to the rotor disk.
• The tacho sensor must besecurely mounted such that the distance between
the LED and the reflective tape is between 2cm and 75cm. A distance of
10cm to 30cm (4" to 12") works best. The supplied soft washer should be
placed between the tacho sensor and the mount to increase the friction as
this will reduce the fastener torque required.
• If the background itself is reflective (light coloured paint or metal, especially
if the surface is rough), the tacho sensor should be rotated so that the light
beam strikes the reflective tape at an angle from the normal. The closer the
LED is to the reflective tape, the more the sensor will need to be rotated.
For short distances and highly reflective backgrounds, the sensor may need
to be rotated at least 45° to minimise the spurious reflections from the
background.
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Datum
Accel
X Axis +
Tacho
Tape
Master
Blade
Direction Of Rotation
Y Axis +
Mounting the sensors
Tip
When the tacho sensor is connected and the PB-4 is powered up
and connected to the tablet, the red LED will flash regularly. If the
tacho sensor is receiving a large amount of reflected light, the
LED will stop flashing. To check that the sensor is correctly
orientated, move the rotor so that the tacho sensor's beam is
pointing at the most reflective portion of the background (but not
the tape). If the LED is continuously on, rotate the sensor until
the LED starts flashing. Check that the tape still passes through
the LED beam.
• The cables from the accelerometer and the tacho sensor must be securely
attached to the rotor mast (e.g with cable ties) such that they cannot
interfere with any part of the cyclic control or prerotator mechanisms.
The standard accelerometer orientation advocated by Smart Avionics is to
point the X axis to the right (when viewed from above) and point the Y axis
forward.
Fig 3.1. Standard sensor orientation (top view)
A simple procedure for positioning the reflective tape is:
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Mounting the sensors
1. Place the master blade at the 12 o'clock position (pointing forward when
looking from above).
2. Turn on the PB-4 so that the tacho light is shining on the part to be tracked
during rotation (adjust the angle of the tacho as required).
3. Attach the reflective tape to the centre of the area the tacho light is
illuminating (having degreased that area first).
Here we see the sensors mounted on the rotor head of an ELA gyroplane.
Note that the tacho sensor has been rotated to approximately 45° from the
normal to avoid spurious reflections from the prerotator disk.
Fig 3.2. Sensors mounted on an ELA rotor head (top view)
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Mounting the sensors
Fig 3.3. Sensors mounted on an ELA rotor head (side view)
Fig 3.4. Sensors mounted on an ELA rotor head (bottom view)
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Positioning the PB-4
Here the sensors are mounted on a Magni gyro using a different style bracket
that is strapped to the prerotator drive. The reflective tape is attached to the
bottom of one of the rotor blades.
Fig 3.5. Sensors mounted on a Magni prerotator drive
3.2. Positioning the PB-4
The PB-4 enclosure must be constrained so that it cannot become loose in
flight. Preferably, it will be located inside the aircraft's cockpit where it could
be held (but not by the pilot!) or tucked into a pocket, etc. If it is to be mounted
outside of the cockpit, it must be securely attached to a properly designed
and constructed mount.
Important
It is the operator's responsibility to ensure that the PB-4 enclosure
is safely constrained and that it cannot become a flight hazard.
Important
When the sensors, cabling and PB-4 have been installed, verify
that the normal range of movement of the rotor head is still
available and that the cables cannot become tangled in the controls,
engine or propeller.
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Offline capture button
3.3. Offline capture button
The PB-4 kit includes a push button with cable that can be plugged in the
PB-4's jack socket. Pressing the push button will capture a polar point and/or
a spectrum even if the tablet is not connected to the PB-4. This means that
you can capture data simply with the push button without even taking the
tablet flying. The capture button is equipped with a velcro strap which can be
used to attach it to the control stick or some other convenient location.
Please see the user interface manual for details of how the offline capture
button is configured and enabled.
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Chapter 4. The PB-4 User Interface
The PB-4 actually supports two completely separate user interfaces:
Web Browser The PB-4's primary user interface is browser based and it
should be usableon any system that provides a webbrowser
that supports recent web standards.All browsers have quirks
so you may find that the PB-4 user interface performs better
(or worse!) when you use a different browser.
Android App Recent versions (version 3.1 onwards) of the Propeller
Balancer App that Smart Avionics provides for use with the
PB-3 can also be used with the PB-4. To use the PB-4, in the
Propeller Balance App go to Preferences / Data Source and
select PB-4. The next time the App is started, it will look for
a PB-4 rather than a PB-3. See the Propeller Balancer App
manual for further information.
4.1. Getting started with the browser based user interface
Just a few words here to getyou started. When you loadthe PB-4 user interface
into your browser, it will display a splash screen for a few seconds and then
show an initial screen similar to Fig 4.1.
Fig 4.1. Initial screen
This shows a polar chart and a list of captured points (both empty as no points
have been capturedyet). At the top of the screen, a couple of important buttons
are displayed along with the name of the current job. The buttons are:
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Button
Getting started with the browser based user
interface
This pops up a menu that lets you choose various actions.Menu
Connect /
Disconnect
Button PB-4 battery level. When you are actually collecting data
For the full description of how to use the PB-4 browser based user interface,
please go to Menu / Help.
The PB-4 user interface is "responsive" - the layout changes depending on the
resolution and orientation of the user interface's screen. It should be usable
on many different user interface devices. For lower resolution devices, you
may find that changing the orientation to landscape is beneficial.
This button toggles theconnection to the PB-4. When connected,
the button becomes green and the text changes to display the
(points/spectra) or when you are configuring the PB-4, you will
need to be connected. If you are just looking at the data for the
current job, you do not need to be connected.
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Chapter 5. Upgrading the PB-4's Firmware
The PB-4 software is partitioned into 3 parts (UI, CPU and Wi-Fi), each of which
may be upgraded separately by uploading the appropriate file to the PB-4.
Important
Before upgrading any of the firmware, ensure that the PB-4's battery
level is adequate (20% or more). The upgrade procedures do not
take more than a couple of minutes.
Note
Unfortunately for ipad/iphone owners, iOS (the system used by
ipads/iphones) does not support uploading files via the browser so
you will need to use a laptop or PC to carry out the upgrades1.
5.1. Upgrading the UI firmware
The UI firmware consists of the web files (HTML, CSS, Javascript) that are
loaded into the tablet's browser. New UI firmware will be packaged as a file
named pb4ui-
version
.zip.
To install new UI firmware, load the PB-4 UI into a browser and then go to
Menu / Options / Upload UI Files where you can select the zip file to upload.
The contents of the zip file will be uploaded to the PB-4 and the next time you
load the UI into your browser, you will be using the new files.
In the unlikely event of this procedure failing and rendering the unit unusable,
please contact Smart Avionics for instructions on how to recover.
5.2. Upgrading the CPU firmware
The PB-4 CPU firmware is responsible for digitising the vibration signals,
calculating the IPS/DEG values, doing the spectral analysis, storing the results,
etc. New CPU firmware will be packaged as a file named pb4-
To install new CPU firmware, load the PB-4 UI into a browser, connect to the
PB-4 and then go to Menu / Options / PB-4 Configuration / Upload PB-4 CPU
Firmware where you can select the .fw file to upload. The contents of the .fw
file will be uploaded to the PB-4 and the unit will restart and then program the
CPU with the new firmware. Do not turn the PB-4 off while this is being done!
When the programming has finished, LED 1 should flash green quickly. Press
the on/off switch and the PB-4 will turn off. Next time you turn it on, the new
firmware will be used.
version
.fw.
1
It may be possible if 3rd party software (e.g. Dropbox) is installed on the UI device
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Upgrading the Wi-Fi firmware
In the unlikely event of this procedure failing, LED 1 will flash red quickly. Press
the on/off switch and the PB-4 will turn off. Because the update failed, the
PB-4 will revert to using the firmware that was installed when it was made.
You can retry the procedure and if it fails again, please contact Smart Avionics
for advice.
5.3. Upgrading the Wi-Fi firmware
The Wi-Fi Firmware is installed into the PB-4's Wi-Fi module. New Wi-Fi
firmware will be packaged as a file named wifi-
To install new Wi-Fi firmware, load the PB-4 UI into a browser, connect to the
PB-4 and then go to Menu / Options / PB-4 Configuration / Upload PB-4 Wi-Fi
Firmware where you can select the .dfu file to upload. The contents of the
.dfu file will be uploaded to the PB-4 and the Wi-Fimodule will be programmed
with the new firmware. Do not turn the PB-4 off while this is being done! When
the programming has finished, LED 1 should flash green quickly. Press the
on/off switch and the PB-4 will continue.
date
.dfu.
In the unlikely event of this procedure failing, LED 1 will flash red quickly. Press
the on/off switch and the PB-4 will continue. Because the update failed, the
PB-4 may now not be accessible via the Wi-Fi. If that happens, it is likely that
the unit will need to be returned to Smart Avionics to be made usable again.
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Appendix A. Battery Charging & Replacement
The PB-4 is powered by 4 x 1.2V AA size batteries. It is supplied with high
quality NiMH batteries that can be recharged over 2000 times. Furthermore,
these batteries self discharge very slowly and so the batteries will remain
charged for a long time when the PB-4 is not in use. It is recommended that
the batteries are charged using an intelligent battery charger at a 500mA rate.
Please follow the instructions supplied with the battery charger.
It is also possible to use other brands of battery and even non-rechargable
AA batteries if that's all that is available. If you are using different batteries,
the battery level indicator will probably not be correct as it is calibrated for
the supplied batteries but the unit will keep running until the batteries are
exhausted even if the battery level indicator reaches zero.
A.1. Replacing the RTC battery
The PB-4 also contains a CR2032 3V coin cell which powers the unit's Real
Time Clock (RTC) when the PB-4 is powered down. Very occasionally, this will
need replacing and a message will appear on the UI when the battery needs
to be changed. To do that, carry out the steps below.
Caution
When handling the PB-4's circuit board, avoid generating static
electricity (don't walk about, brush your hair, stroke the cat, etc!)
Hold the board by the metal sensor connectors and the edges.
1. Remove the AA batteries from the battery compartment.
2. Remove the 4 screws that hold the case halves together and separate the
top from the bottom.
3. Remove the battery connector from the circuit board (flat connector with
red/black wires).
4. Undo the two screws that hold the circuit board in the case (see Fig A.1).
5. Remove the circuit board along with the front panel from the case.
6. The battery is contained in a holder on the underside of the board, push the
old battery out of the holder using a non-metalic item.
7. Insert the new battery fully into the holder ensuring that the + sign on the
battery is towards you and away from the board (see Fig A.2).
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Replacing the RTC battery
8. Replace the board in the case and fasten it in place with the two screws.
9. Reconnect the battery connector (it is not polarised so can go either way
round).
10. Reassemble the case halves and replace the 4 screws.
11. Replace the AA batteries.
12. Safely dispose of the old CR2032 battery in accordance with your local
regulations.
Fig A.1. Locating the PB-4 board securing screws
Fig A.2. Correct orientation of RTC battery
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Appendix B. Specifications
B.1. Main unit
2.4GHz IEEE 802.11 b/g/nWi-Fi standard
Required user interface
range
B.2. Accelerometer
Web standards compliant browser supporting
HTML5, CSS, Javascript and WebSockets.
100-13,000 RPMBalancing RPM range
2Tachometer channels
2 x dual-axisAccelerometer channels
100-25,500 RPM (100 RPM per spectral line)Spectrum display RPM
None, Hann, Flat TopSpectrum (FFT) Windows
approx 8 hoursBattery life (1900 mAh)
163mm × 95mm × 33mmDimensions
330 gramsWeight
0 to 25,000 RPMRPM Range
Nominal ± 5.36 GAcceleration Range
3.5V to 5V at 5 mASupply Voltage
B.3. Tachometer
Output Signal
AnalogueOutput Signal
46mm (plus cable and connector) × 40mm × 20mmDimensions
60 gramsWeight
M6Mounting Hole
1cm to 100cm (under ideal conditions)Sensor To Tape Distance
60 to >100000 RPMRPM Range
3.5V to 5V at 60 mASupply Voltage
One pulse per revolution with the rising edge
synchronised to the centre of the tape
63mm (plus cable and connector) × 55mm × 24mmDimensions
85 gramsWeight
M6Mounting Hole
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Appendix C. EMC Compliance & Safety Information
To ensure EMC compliance, please observe the following conditions when
using the PB-4:
• Do not use the PB-4 in close proximity to other electrical equipment capable
of generating large amounts of electrical interference.
• All electrical equipment in the aircraft that is not required for either safety
reasons or to facilitate the running of the engine should be switched off
while the PB-4 is being used.
• As described in this manual, avoid routing the PB-4's cables near to sources
of electricalinterference (such as engine ignition components and cabling).
• Only use cables approved by Smart Avionics for connecting the sensors to
the PB-4.
• To satisfy FCC RF exposure limit compliance, the PB-4's Wi-Fi transmitter
must not be co-located or operated in conjunction with any other antenna
or transmitter.
The following safety statements should be observed:
• The protection provided by the unit will be impaired if it is used in a manner
not specified by the manufacturer.
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Appendix D. CE Declaration of Conformity
We, Smart Avionics Ltd. Chorlton Lane Farm, Chorlton, Malpas,
Cheshire. SY14 7ES. United Kingdom, declare, on our own
responsibility, that the PB-4 conforms with the essential
requirements of the Radio Equipment Directive 2014/53/EU.
Conformity is declared to the following harmonised standards:
EMC EN61326-1:2013 “Electrical equipment for
measurement, control and laboratory use - EMC
Requirements”.
RF EN 300328 V1.8.1 “Electromagneticcompatibility and
Radio spectrum Matters (ERM); wideband
transmission systems; Data transmissionequipment
operating in the 2.4 GHz ISM band and using
wideband modulation techniques”.
Safety IEC 61010-1:2010 (3rd edition) and EN 61010-1:2010
“Safety requirements for electrical equipment for
measurement, control and laboratory use”.
Equipment type: Battery powered portable test/measurement.
Environment: External/Workshop.
I, the undersigned, hereby declare that the PB-4 conforms to the
above Directive.
Mark Burton
Director
Smart Avionics Ltd.
11 July 2016
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Index
U
User Interface, 23
A
accelerometer
mounting, 10, 17
mounting bracket, 11
sensing axes, 10
temperature, 11
aircraft
positioning, 9
B
balance
weights, 9
batteries, 4, 27
C
cables, 15
capture
offline button, 22
connect
button, 24
W
Wi-Fi
access point, 1
station, 1
wind, 9
WPS
invoking, 5
F
factory reset, 5
firmware
upgrading, 25
G
gyroplane rotor, 17
O
on-off switch, 5
P
PB-4
positioning, 16, 21
R
reflective tape, 14, 17
T
tacho sensor
angle, 14, 17
mounting, 12, 17
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