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Propeller Balancer App User Manual

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1. S data values on If the display is tall enough the e rr dialog will also contain a polar ERR mm e chart that shows a single polar point that has been generated from the current parameter values 2200 0 18 109 Fig 9 3 Dummy Data Setup 50 www smartavionics com Chapter 10 PB 3 Options Submenu The PB 3 options submenu is accessed from the main options menu and it contains these items Select PB 3 Internal Tacho Options Polar Options Accelerometer Scaling View Messages If you have paired your Android device with more than one PB 3 this menu entry is available to let you select the PB 3 to use Opens the internal tacho options dialog that contains options that control the behaviour of the internal optical tachometer Opens the polar options dialog that lets you configure the polar data source Opens the accelerometer scaling dialog Displays any diagnostic messages that the PB 3 has sent to the app 10 1 Internal Tacho Options Dialog When the internal optical tachometer is working correctly it detects the passage of the reflective tape once per propeller revolution For that to occur a threshold value the tacho level must be set to an appropriate value for the given conditions ambient light strength distance from the PB 3 to the reflective tape angle of incidence of the infrared beam etc If the tacho level is too low spurious reflections are detected and the R
2. Configure Logger Pops up the logger configuration dialog described next Point logger configuration dialog The point logger configuration dialog contains these items Point Logger Min RPM the minimum RPM of interest all polar points that have an Min RPM 1000 RPM less than this will be ignored Max RPM 2000 Max RPM the maximum RPM of Width 50 interest all polar points that have an RPM greater or equal to this will be IM Log X Log Y ignored Fig 9 2 Point Loggin Width the width in RPM of a single 9 ggng logger bucket Log X amp Log Y a pair of checkboxes that determine which axes will be logged Use the Android device s back button to dismiss the dialog The values shown in the example dialog would produce 20 logger buckets and the RPM ranges of the buckets would be 1000 1049 1050 1099 1100 1149 1950 1999 Both the X and Y axes would be logged When the logged data is uploaded from the PB 3 each non empty bucket will provide a single polar point which is an average of the points that were accumulated into the bucket 9 4 Database Submenu The database holds all of the polar points and spectra that have been captured It is stored on the Android device as an sqlite database file that is 2000 1000 50 46 www smartavionics com Export Data Submenu not directly accessible by other apps The database submenu provides actions for sharing saving loading
3. If a spectrum is being displayed the context menu will also contain items from the spectrum view context menu 36 www smartavionics com Delete Spectra Submenu 7 2 Delete Spectra Submenu The delete spectra submenu lets you choose a group of spectra to be deleted You will be asked to confirm the action before any spectra are really deleted Important All of the spectra currently shown in the list are possible candidates for deletion if the Show All Jobs option is checked it is possible to delete all the captured spectra from all of the unlocked jobs All Spectra Selected Spectrum All Older Than Today All Captured Today All Without Notes All spectra in the list are deleted The currently selected spectrum is deleted All spectra in the list that were captured before the current day are deleted All spectra in the list that were captured today are deleted All spectra in the list that don t have notes are deleted The following items are only shown when the Show All Jobs option is checked All In Job All Not In Job A dialog opens to let you select a job and all spectra in the list from the selected job are deleted Adialog opens to let you select a job and all spectra in the list that are not from the selected job are deleted www smartavionics com 37 38 www smartavionics com Chapter 8 Big Capture Button View The big capture button view simply contains one b
4. 21 centripetal force 55 56 colours vibration level 4 confirm quit 49 correction planes 67 D data export 47 import 48 database submenu 47 data source 50 data view 19 datum 9 delete points 31 spectra 37 direction of rotor rotation 16 divide screen 49 dropbox 47 dummy data 50 E edit notes 33 ellipse standard deviation 7 engine type 44 export data 47 exported image format 50 exporting images 4 F FFT window 25 file chooser 47 48 frequency domain 23 G graph view 21 H help 41 hide status bar 49 tabs 49 title bar 49 l image export 4 import data 48 Inches Per Second 4 55 internal tacho options 51 www smartavionics com 13 J job mode 3 44 L Language user interface 49 locked 3 lock job 44 log book 60 logger 4 M marker 11 master blade 9 measurement planes 67 min cycles 53 min tacho pulses 52 move line 10 64 O options internal tacho 51 polar 52 options menu 41 P pan amp zoom modal 49 pan zoom mode 18 paused options menu item 41 PB 3 average points 53 battery level 4 options menu 51 peak velocity 55 phase 57 phase angle 7 20 21 point logger bucket 45 configuration 46 submenu 45 polar coordinates 21 polar chart pan zoom mode 18 polar chart view 7 polar options 52 polar point edit notes 33 polar point list 29 primary axis 9 44 propeller dynamic balancing 56 mass i
5. In particular gyroplanes often suffer strong vibration at twice the rotor frequency This x 2 times 2 vibration is often much larger than the vibration due to imbalance and so even when the rotor has been mass balanced satisfactorily vibration will still be noticeable to the occupants Spectrum BRITTANY5 13 Aug 2013 14 47 28 RPM 370 IPS 0 07 very good 293IPS 750 2R 0 261PS 1500 m aR 0 regen 0 171PS 4600 0 041PS 1850 12 43R ou VELT ENE SSES IPS RPM BRITTANY5 x 13 08 2013 14 47 28 Smart Avionics Ltd 0 06IPS 350 R Fig 12 1 Rotor Spectrum With Large x 2 Peak www smartavionics com 63 Rotor Mass Balancing The above spectrum is from a gyroplane rotor that shows the very large x 2 vibration still present after the rotor was balanced You can see that the vibration at the rotor RPM 350 was only 0 06 IPS but the x 2 vibration at 750 RPM was 2 93 IPS that s nearly 50 times larger Unlike rotor mass imbalance the x 2 vibration cannot be suppressed by simply adding weights It is fundamental to the geometry of a 2 bladed rotor system and the physical properties of its components blades hub mast etc The x 2 vibration can be caused by a variety of reasons Some possibilities are The rotor teeter height is wrong The rotor blades are exhibiting in plane resonance which is excited twice per revolution when the blades are perpendic
6. Options Menu Pressing the Android device s menu button pops up an options menu containing these items Show Tabs Pause Continue Export Image Help Job List Points List Spectra PB 3 Options Dummy Data Options Big Capture Button Two Plane Balancing Export Data Import Data Database Point Logger Preferences About If the Hide Tabs preference has been set this menu item is available to make the tabs visible again Toggles the current view s paused state when paused the view is not updated If your Android device has a hardware keyboard the space key also toggles the paused state Exports the current view as a JPEG or PNG image Pops up a submenu that let s you choose which manual to view PB 3 manual or the app manual If the chosen manual can be found locally on the Android device it will be displayed using your preferred PDF reader If the manual cannot be found locally an attempt will be made to download it from the Smart Avionics website Pops up the job submenu Displays the polar point list Displays the spectrum list Pops up the PB 3 options submenu This menu item is only shown if the Data Source preference is set to PB 3 Pops up a submenu that gives you access to the dummy data setup dialog This menu item is only shown if the Data Source preference is set to Dummy Invokes the big capture button view Invokes the two plane balancing view Pops up the export data submenu
7. Pops up the import data submenu Pops up the database submenu Pops up the point logger submenu Opens the app s preferences view Opens a dialog that displays hardware and software revision numbers copyright information and the PB 3 s Bluetooth address To make it easy to check you are using the latest version of the app a button is provided that opens the app release history page at www smartavionics com in a web browser www smartavionics com 41 Job Submenu Quit App Back To Top Quits the app and returns you to the Android home screen A dialog will pop up to confirm the action If you would rather not have the confirmation dialog there is a preference to suppress the quit dialog Returns you to the current top level view This menu item is only shown when the current view is not a top level view The following directories located on the Android device s external storage sdcard are searched for the manual PropellerBalancer download downloads and Downloads You need a PDF reader app to be installed on your Android device to be able to readthe manuals The stock Android browser will not download the PDF files unless a PDF reader app is already installed 9 1 Job Submenu This menu contain items related to creating and configuring jobs Switch Axes Last Job Switch Job New Job Setup Job This item toggles the job s primary axis between the X and Y axes Make the previous current job t
8. The status bar is displayed at the top of each tabbed view It contains a number of fields separated by Most of the fields consist of a field name and value separated with The fields are Job String The name of the current job All data captured polar points and spectra exported images etc will be associated with this job An obvious value for a job name would be the registration letters of the aircraft whose propeller rotor is being balanced Job names are case insensitive and are always displayed using upper case letters Locked This field doesn t have a value and it is only shown when the current job is locked Axis X or Y or The accelerometer axis currently selected If the Alias currently selected axis has been given an alias that will be displayed instead of X or Y PSRU Number The ratio of the PSRU Propeller Speed Reduction Unit fitted to the engine Mode Prop or The current job s mode Rotor Tacho IntorExt The tachometer currently selected internal or external www smartavionics com 3 Menus Log On or Off Indicates whether the Logger is enabled or not If the Logger has logged some data the field will be displayed in green Bat Percentage The remaining capacity of the PB 3 s battery If the value is less than 20 the field is displayed in red Previous versions of this app labelled data items with a job tag job names are now used instead When the app is connecting to the PB
9. added or rotor shifting and capture a few polar points If you now select one of those points in the polar point list the point s captured point dialog will show the suggested adjustments required to improve the balance Carry out the suggested adjustment and capture some more points Repeat as required Although multiple adjustments may be suggested it is recommended that you only make one adjustment at a time and then capture further polar points for comparison It is also recommended that you make use of the feature that allows you to add a note some text to a polar point so that you can track the adjustments you make 66 www smartavionics com Chapter 13 Two Plane Balancing This manual has so far described how propellers and rotors can be balanced by measuring the vibration in a single plane I m referring to the abstract geometric surface not the aircraft The accelerometer has been mounted as close as possible to the hub of the propeller rotor and orientated such that it is sensing the vibration in the propeller rotor s plane of rotation Single plane balancing generally works well when the diameter of the object being balanced is much greater than its depth and also when it is attached to the supporting shaft at exactly 90 Aircraft propellers and gyroplane helicopter rotors typically satisfy those conditions and so can be balanced satisfactorily using the single plane method When the depth of the object being balan
10. 1 Minimising Other Sources of Vibration 55 11 2 Propeller mass imbalance i 55 11 3 Static Propeller Balancing 55 11 4 Dynamic Propeller Balancing 56 11 5 Taking a Vibration Reading 57 11 6 Balancing Procedure nne 59 11 7 After Balancing usa 60 11 8 Troubleshooting osteria iii 60 11 8 1 The displayed RPM is erratic or wrong 60 11 8 2 The current polar point position varies widely 61 11 8 3 Adding weight does not reduce the vibration level 61 12 Rotor Balan CIN g ssc axe a ere 63 12 1 Causes Of Rotor Vibration sersnernrrnrrrnrrsrnrnrrrvernrernrrrvernnrrnernnenn 63 12 2 Rotor Mass Balancing 64 12 2 1 Defining move lines 65 12 2 2 Using the move lines to balance 66 13 Two Plane Balancing sssessssnssneseeseesereetettestertrrttettnrtnrtnnttnttnrennennee nenne 67 13 1 Two Plane Balancing Method s nssnessnsnsensernerrerrerrnrrrrrrerrsrrnreee 67 13 1 1 Measurement and correction planes s nssnneennsnnneeeeenn 67 13 2 Two Plane Balancing View 68 13 2 1 Single accelerometer procedure 69 13 2 2 Dual accelerometer procedure s sesssnssnesnnissnneeniserneerenen 70 A Exported CSV Data Format
11. 3 progress messages are appended to the status bar If the height of your Android device s display is limited you can set a preference to hide the status bar 1 3 6 Menus View specific options are accessed through context menus menu pops Up when view is long pressed Common options are accessible via the options menu that pops up when the Android device s menu button is pressed Devices that run the more recent versions of Android Honeycomb or later generally don t have a menu button Instead the options menu is accessed via the device s Action Bar If the width of the display allows some of the option menu items Job List Points List Spectra etc will be shown in the Action Bar rather than in the option menu 1 3 7 Exporting images At any time a snapshot of the current top level view can be exported as a JPEG or PNG image by selecting Export Image from the options menu The images are saved into a directory called Pictures PB on the Android device s external storage SD card The image format used is determined by the exported image format preference After an image has been saved an image viewing app is invoked to display the image Typically Android image viewers provide menu options to share the displayed image using Bluetooth email etc Pressing the back button in the image viewer should return you to the Propeller Balancer app There are many Android image viewer apps that provide a variety of features A free
12. PB 3 will continue to capture polar points as long as it is switched on Later the logged polar points can be fetched from the PB 3 to the Android device The point logger works like this the PB 3 continuously captures polar points each point is a triple of RPM IPS DEG and their associated standard deviations and accumulates each polar point into a bucket There can be a number of buckets configured and which bucket a particular point is accumulated into depends on the point s RPM The configuration dialog described below allows you to specify the minimum and maximum RPM values the buckets cover and how wide in terms of RPM each bucket is The point logger submenu contains these items Start Logger Activates the logger if the logger already has some logged data you will be asked if you want to clear that data first Once the logger has been activated you may www smartavionics com 45 Point logger configuration dialog 9 3 1 quit the app and the logger will continue to log data If you turn the PB 3 off the next time you turn it on again it will continue to log data Stop Logger Deactivates the logger Get Logged Data Fetches the logged data from the PB 3 and enters it into the polar point database The logged data is cleared from the PB 3 You do not need to stop the logger before fetching the data Clear Logged Data Deletes any logged data stored in the PB 3 does not delete any polar points from the database
13. Point s Pop up the captured point dialog for the currently selected Details point Change Point s Pops up alist of the currently known unlocked jobs so Job you can choose the job that the currently selected point will be moved to This menu item is not shown when the current job is locked Edit Point s Notes Pops up a dialog that displays the notes for the currently selected point which you can then edit Previously used notes history can be selected from a drop down list which makes it very easy to reuse common phrases e g added washer moved washer forward etc This menu item is not shown when the current Job is locked Delete Points Pops up the delete points submenu that lets you delete groups of points from the database This menu item is not shown when the current job is locked i Note An individual point can also be deleted using the captured point dialog context menu Show Only Items Only polar points that have notes will be displayed in the With Notes list 30 www smartavionics com Delete Points Submenu Show All Jobs A checkbox that controls whether captured points from all known jobs are shown or not Show All Axes A checkbox that controls whether captured points whose axis differs from the current job s primary axis are shown or not Ifthe polar chart is being displayed the context menu also contains the Colour Background and Show Solution items from the polar chart context menu and also
14. You now have all 6 points required Take care to select the correct points when entering the data into the view 70 www smartavionics com Appendix A Exported CSV Data Formats A 1 Polar Point Data Format The polar point CSV data contains one row per exported point and each row contains these columns Date The date the point was captured Time The time the point was captured Axis The point s axis X or Y Rpm The propeller RPM RpmSD The Standard Deviation of the propeller RPM Ips The vibration magnitude IpsSD The Standard Deviation of the vibration magnitude Deg The vibration phase angle DegSD The Standard Deviation of the vibration phase angle Attrs A bit mask of attributes The bits have these meanings Bit 0 Accelerometer channel used 0 X 1 Y Bit 1 Tachometer channel used 0 internal 1 external Bit 2 Logger status 0 point was manually captured 1 point was Captured by the logger Bit 8 Start point status 0 point is not a start point 1 point is a start point Tag The point s Job Tag an empty string if it doesn t have a Job Tag Notes A string containing any notes associated with the point A 2 Spectrum Data Format The spectrum CSV data contains one row per exported spectrum and each row contains these columns Date The date the spectrum was captured Time The time the spectrum was captured www smartavionics com 71 Spectrum Data Format Axis PropRpm Engine
15. all points in the list that are not from the selected job are deleted www smartavionics com 31 Captured Point Dialog 6 3 Captured Point Dialog This dialog is displayed when a captured point is selected a point can be selected by short pressing its polar point list entry Also when a point is first captured by pressing the Capture button it will be automatically selected if the show point details after capture option is enabled in the job setup dialog The dialog is titled with the point s IPS amp DEG values For propeller mode jobs if the point is a start point that will be indicated in the dialog s title The dialog displays the point s details and a short description of the vibration 0 410 297 Start Point IPS 0 410 7 DEG 297 3 RPM 1554 0 AXIS X MODE Propeller AT 2 Jun 2013 13 30 54 TAG GXXXX Vibration level is slightly rough Try a trial weight of 16 g level Use 4 x AN970 3 or similar Use the Android device s back button to dismiss the dialog S Fig 6 2 Point Details A short press on the dialog will display the point on a polar chart as a filled circle X axis point or diamond Y axis point Other points from the same job are shown unfilled Press the Android device s back button to dismiss the chart Long pressing the dialog will display the captured point context menu 6 3 1 Propeller mode If the point is a start point an estimate of the amo
16. and clearing the contents of the database f Note Two of the actions described below require the user to choose the name of a file located on the Android device s external storage SD card Unfortunately the Android system earlier than version 4 4 KITKAT does not provide a file chooser To obtain that functionality you need to install a compatible File Manager app Currently the only compatible app is the OI File Manager which may be installed from the Market or downloaded from www openintents org The database submenu contains these items Share Database This saves the current database into a temporary sqlite file and then prompts you to select an app to share export that file Most devices should already have an email client gmail that can share the database file as an attachment If you install a cloud storage app like dropbox you can use that to send the database file directly to other computers Save Database This invokes a file chooser so that you can specify the name and location of a file to save the database into sqlite format A default filename is supplied but you can alter that if you wish Load Database This menu item invokes a file chooser so that you can select the sqlite file whose contents will be loaded after confirmation into the database Loading a file into the database will delete all of the existing data in the database so if you want to access that data again save the database first Clear Dat
17. case the T marker should be positioned at 0 degrees as shown in the previous figure lt Direction Of Rotation Master Blade umeg gt Fig 2 4 Marker Positions When Tape Aligned With Master Blade www smartavionics com Defining move lines Alternatively if the retroreflective tape is attached to the master blade such that when that blade is at the datum the tape is also lined up with the datum then the T marker s position must coincide with the actual position of the tachometer on the aircraft In Fig 2 4 the tachometer is mounted in the 4 o clock position and so that s where the T marker is placed The markers can be moved by selecting the Move Markers item from the polar chart context menu Alternatively the markers can be positioned by entering the required angles into the job setup dialog 2 2 2 Defining move lines os T i or washers on mb _ 330 gr 4 30 S i 60 i 380 bo VE 240 I a Tan 270 je 150 d E i SE span B 10 00 28 iS ni el washers on mo o ta SE di Fig 2 5 Moving A Move Line The orientation of a move line is defined by positioning on the polar chart two nodes node A and node B that the line passes through A move line s www smartavionics com 13 Move line setup dialog orientation is adjusted by dragging its nodes to positions on the chart that correspond to known condition
18. one that works extremely well for our purposes is QuickPic which can be installed via Google Play 1 3 8 Vibration level colours The background of the polar chart can optionally be coloured to give an indication of the level of vibration The same colours are also used for the background of the text wherever the vibration level is displayed textually The vibration level is expressed in units of Inches Per Second IPS 4 www smartavionics com Bluetooth Setup Here is a summary of the vibration levels along with their descriptions and colours Colour IPS Description 21 0 Very rough lt 1 0 Rough lt 0 5 Slightly rough lt 0 25 Fair lt 0 15 Good lt 0 07 Very good lt 0 04 Extremely good 1 4 Bluetooth Setup The PB 3 and the Android device communicate using Bluetooth and they have to be paired before communication can take place To pair the devices do the following 1 Turn on the PB 3 and check that its status LED is flashing regularly 2 On the Android device go to Menu gt Settings gt Wireless amp networks gt Bluetooth settings if Bluetooth is not yet enabled enable it now using the checkbox on that page 3 Press Scan for devices after a few seconds the PB 3 should appear in the list of Bluetooth devices displayed lower down on the screen you may need to scroll down to find it if the list contains several items Now pair with the PB 3 by pressing its entry in the list a d
19. out the balancing process Please see the PB 3 Propeller Balancer Manual for a description of the PB 3 sensors and how they are attached to the aircraft For maximum accuracy the dynamic balancing process should only be carried out in light winds Ideally the wind should be less than 5 kts The aircraft should be positioned so that it is pointing into any wind A Important Before you start the engine check that the job parameters and PB 3 options are all set appropriately Make sure the engine is thoroughly warm before taking any readings Firstly you need to decide what propeller RPM you are going to use while balancing For a typical propeller an RPM in the range 1500 2000 is often a good choice Using the polar chart view observe the movement of the current polar point circle and its associated grey standard deviation ellipse If you think it is necessary adjust the throttle to find the RPM that minimises the variation in the current point s position and the size of the ellipse www smartavionics com 57 Taking a Vibration Reading f Note When you adjust the throttle it will take a few seconds for the readings to settle down and a Toast will pop up to tell you that the RPM is not steady enough to capture a reading A Important Once you have determined the best RPM to use it is important to use the same RPM for each balancing run so that you get consistent results With a steady RPM being reported by the
20. 6 MASS IN IPS 0 49 MASS IN IPS 0 92 PLANE 1 DEG 114 PLANE 1 DEG 347 MASS IN IPS 0 4 MASS IN IPS 1 2 PLANE 2 DEG 79 PLANE 2 DEG 292 Solution Solution 50 X 1 18 82 X 1 14 Fig 13 3 Two Plane Balancing View Use the Android back button when you want to leave the two plane balancing view The data values entered are persistent so you can leave the view and return to it and the values will still be there An option menu item is provided to zero all of the data values which is a good idea when starting a new calculation 13 2 1 Single accelerometer procedure The two plane balancing procedure when using a single accelerometer is as follows Mount the accelerometer so that it is sensing vibration in measurement plane 1 With no trial mass attached in either correction plane capture a couple of points Attach a trial mass so that it is in correction plane 1 and capture a couple of points mark the position of the mass and remove it Now attach the same mass so that it is in correction plane 2 and capture a couple more points Mark the position of the mass and remove it You now have data for the 3 points in the left hand column of the table Move the accelerometer so that it is now sensing vibration in measurement plane 2 www smartavionics com 69 Dual accelerometer procedure As above capture 3 further sets of readings for the no mass mass in correction plane 1 and mass in correction plane 2 configurations to pro
21. L statements Note The action described below requires the user to choose the name of a file located on the Android device s external storage SD card Unfortunately the Android system earlier than version 4 4 KITKAT does not provide a file chooser To obtain that functionality you need to install a compatible File Manager app Currently the only compatible app is the OI File Manager which may be installed from the Market or downloaded from www openintents org The submenu provides this item Import SQL Data This menu item invokes a file chooser so that you can select the file containing SQL statements to be imported 9 7 Preferences View This view is accessed through the options menu It contains these items 9 7 1 Display Preferences Screen Orientation A spinner that lets you select one of Unspecified Portrait or Landscape Selecting either Portrait or Landscape will force the app to use that screen orientation irrespective of the orientation of the Android device Otherwise the screen orientation will be determined by the Android device s global settings 48 www smartavionics com General Preferences Divide Screen Hide Status Bar Hide Title Bar Hide Tabs Show Zoom Controls Use Legacy Polar Pan amp Zoom Auto start Big Capture Button User Interface Language A spinner that determines whether the screen should be divided into two areas when displaying lists of points or spectra Th
22. OCH Awr ha IPS RPM GXXXX X 02 06 2013 13 42 24 CD CO CO Fig 5 1 Spectrum View www smartavionics com 23 Spectrum View Context Menu The spectrum view is extremely useful for helping to diagnose vibration problems as it allows you to determine how much vibration is occurring at each of the frequencies of interest prop frequency blade pass frequency engine crank and half crank frequencies etc By default the plot s vertical axis represents velocity in IPS Alternatively the vertical axis can represent acceleration in G The display can be scrolled left and right by simply dragging the white area in the required direction Optionally a graticule can be displayed and interesting spectral lines can be labelled The horizontal and vertical scaling and the width of each of the spectral lines may be altered using the context menu The width of the spectral lines is specified in RPM per line Note that the display update rate is influenced by the width the narrower the width the slower the update rate If labels are being displayed they are positioned at the top of their respective spectral lines At the top of the view the current RPM and IPS are displayed Long pressing the view pops up a context menu 5 1 Spectrum View Context Menu The spectrum view context menu contains these items Capture Spectrum Captures the current spectrum and stores it in a database on the Android device Th
23. PM will appear erratic If the tacho level is too high the RPM will be erratic or not detected at all The PB 3 has the ability to automatically adjust the tacho level and it is recommended that you normally select the Auto Tacho Level checkbox The Tacho Level field shows the current tacho level and you can expect it to change every few seconds owing to the automatic level Internal Tacho Options RPM Tacho Level Auto Tacho Level Sensor Backlight Tacho Power Save Min Tacho Pulses 1377 Fig 10 1 Internal Tacho Options adjustment The dialog also displays the current propeller RPM so you can see if it is being reliably detected www smartavionics com 51 Polar Options Dialog In the event that the RPM is not being reliably detected see the RPM troubleshooting section for possible reasons why that could be so and nothing appears to improve the situation you can disable the automatic tacho level adjustment and enter a value directly into the Tacho Level field Note The reported RPM will be 0 if the tachometer is not detecting the optical tape and 1 if it is detecting a constant reflection e g the taped propeller blade is stationary in front of the PB 3 The Sensor Backlight checkbox controls an infrared LED within the PB 3 that provides extra ambient illumination to the infrared sensor thus increasing its sensitivity when the ambient light level is low Not all PB 3 s are fitted with
24. POI LNG lee Ee 29 6 1 Polar Point List Context Men 30 6 2 Delete Points Submenu n ss sssnnesnsssnnnnssennsenesennssnnsrrnnsrnnerrssrnnrrennne 31 6 3 Captured Point Dialog rape 32 6 3 1 Propeller mode anehe iaia it 32 632 Rotor moden 33 6 3 3 Captured point dialog context MENU 33 EE aaret 35 7 1 Spectrum List Context Menu rrrrrrrnnvrnnnnrennvvrrnnnrrnrnrerrnnvnnnnrsennnne 36 7 2 Delete Spectra Submenu 37 8 Big Capture Button View i 39 9 Options Meny vassere oase DA 41 9 1 Job Submenu Laser ee eebe 42 92 JOD Setup Dialog Lose ete 44 9 2 1 Propeller mode job setup ssessnnsnnnonnsnnneenrsnnnnnnsennneeessea 44 92 2 Rotor mode job setup EE 45 www smartavionics com ill Propeller Balancer App 9 3 Point Logger Submenu i 45 9 3 1 Point logger configuration dialog 46 9 4 Database Submenu i 46 9 5 Export Data Submenu ii 47 9 6 Import Data Submenu 48 9 7 Preferences VIEW Arad 48 9 7 1 Display Preferences ne 48 9 7 2 General Preferences eee 49 9 8 Dummy Data Setup Dialog 50 10 PB 3 Options Submenu ii 51 10 1 Internal Tacho Options Dialog 51 10 2 Polar Options Dialog ccnl 52 10 3 Accelerometer Scaling Dialog i 53 11 Propeller Balancing 55 11
25. Revision 23 Propeller Balancer App User Manual Smart Avionics Ltd www smartavionics com 25 05 2015 Propeller Balancer App User Manual Copyright 2003 2015 Smart Avionics Ltd Android is a trademark of Google Inc Bluetooth is a registered trademark of Bluetooth SIG Inc Table of Contents T introduction EE 1 1 1 Obtaining and Installing the App 1 1 2 Balancing System Overview 2 ee 2 TS ETE base 2 1 22 TADDEO VIEWS sr ilaria 2 133 Quitting TNE PP e alia 3 bibbia DE rhe eee te 3 LES Slats Dal ea Geol aici aisles 3 US RT UE 4 1 3 7 Gallen De 4 1 3 8 Vibration levekesol ursa 42 dass Naken 4 1 4 Bluetooth Setup areas GSE SER 5 1 5 Bluetooth Remote Capture Button 6 2 Polar Chart VIP iaoea eraai e a de d 2 1 Propeller Mode Polar Chart 8 2 1 1 Propeller mode solution 9 2 2 Rotor Mode Polar Chart EE 9 2 2 1 Rotor Mode Markers 11 2 2 2 Defining move E 13 2 2 3 Move line setup dialog 14 2 2 4 Rotor mode solution 15 2 3 Polar Chart Context Menu 2c ia 15 2 4 Panning and Zooming the Polar Chart 18 OW ate MGW RR RE RITO 19 A Graphi EN EE EEE EN 21 4 1 Graph View Context Menu rrrrrrrrrernvvrnnnrrrnnvrrrrnnrrrsrrrrrnvrnssnvesrnnne 22 DOC RELI VIE Asle MN 23 5 1 Spectrum View Context Menu 24 5 2 Spectrum Analysis Dialog rain 27 6 POLAR
26. Rpm RpmPerLine Propips NumLines Attrs Tag Notes V Or The spectrum s axis X or Y The propeller RPM The engine RPM i e PropRpm x PSRU ratio The width of each of the spectral lines The vibration magnitude at the propeller RPM The number of spectral lines magnitudes A bit mask of attributes The bits have these meanings Bit 0 Accelerometer channel used 0 X 1 Y Bit 1 Tachometer channel used 0 internal 1 external Bits 8 9 FFT Window type used 0 None 1 Hann 2 Flat Top The spectrum s Job Tag an empty string if it doesn t have a Job Tag A string containing any notes associated with the spectrum NumLines number of vibration magnitudes expressed as either velocities in IPS column name begins with a V or accelerations in G column name begins with an A 12 www smartavionics com Index A accelerometer 56 accelerometer scaling 53 alias axis 44 analyse spectrum 24 36 app installation 1 auto pause IPS level 25 auto start big capture button 49 average points 53 axes switch 42 axis 3 alias 44 primary 44 B balance solution 16 balancing procedure 59 battery level PB 3 4 big capture button view 39 41 65 auto start preference 49 Bluetooth pairing with PB 3 5 remote capture button 6 C capture button 7 20 26 polar point 58 remote button 6 spectrum 24 captured point dialog 32 cartesian coordinates
27. T Or Job PROP Axis X PSRU 1 0 Mode Prop Tacho Int Log Off Bat 69 RPM 1545 0 IPS 0 40 0 DEG 290t 0 ENGINE RPM 1545 Capture CD DI CO Fig 3 1 Data View The data values displayed are www smartavionics com 19 RPM the propeller RPM and associated percentage standard deviation IPS the vibration level and associated percentage standard deviation DEG the phase angle of the vibration in degrees and associated standard deviation the standard deviation is limited to a maximum of 90 ENGINE RPM this is simply the propeller RPM multiplied by the PSRU ratio Below the data values is the Capture button Pressing this captures the current polar point s and optionally the current spectra too When a point is captured its details are stored in the app s database Optionally a captured point dialog will open to display the point s details 20 www smartavionics com Chapter 4 Graph View The graph view displays the time domain vibration waveforms acceleration velocity or displacement plotted against time for one revolution of the propeller rotor The waveform may be plotted using either Cartesian or Polar coordinates Alternatively if data is captured from both X and Y axes it may be plotted as a 2 dimensional graph Propeller Balancer JOB LISTPOINTS LIST SPECTRA Propeller Balancer JOB LISTPOINTS LIST SPECTRA RPM 378 IPS 0 11 good RPM 378 IPS 0 11 g
28. View 69 www smartavionics com V vi www smartavionics com Chapter 1 Introduction The Propeller Balancer app hereafter referred to as the app provides the user interface for the PB 3 propeller balancer system manufactured by Smart Avionics Ltd The app aims to be compatible with any Android smartphone or tablet that supports Bluetooth wireless connectivity and is running at least Android version 2 1 The PB 3 system can also be used to balance Gyroplane and Helicopter rotors 1 1 Obtaining and Installing the App Note Before you can install the app you need to tell your Android device that it s OK to install non Market applications Go to Menu gt Settings gt applications and make sure that the Unknown Sources checkbox is checked The latest revisions of the app and this documentation can be found at the Smart Avionics website www smartavionics com If you have a barcode scanning app you can download the files directly to your Android device using these QR codes PropellerBalancer apk PropellerBalancerManual pdf When the app has been downloaded select it and you will be prompted to accept these permissions Requested Permission Why Permission is Required Storage To export images and data to the Android device s external storage SD card Network communications To communicate with the PB 3 System tools To request enabling of Bluetooth and adjustment of screen tim
29. a All Spectra if the Show All Jobs context menu item is checked 2 X Axis 02 06 2013 13 42 31 Job name Spectra if the curent job has non empty name Anonymous Spectra when the job s name is empty Each line in the list shows the accelerometer axis Wise used and the date and time the spectrum was captured If the list is showing spectra for all jobs each dala spectra s job name ES is displayed after the j prae axis name If a d Vue IS 2P N 0 011PS 9100 spectrum has notes ul VIA Wy AN JI associated with it they are also I displayed after the job name 0 101PS 4600 D I AAA A H Fig 7 1 Spectrum List If a spectrum was captured today the list entry s background will be white otherwise grey Pressing the Android device s back button will return you to the previous screen Ifthe divide screen preference is enabled the screen will be divided into two halves one half will contain the spectrum list and the other half will be used www smartavionics com 35 Spectrum List Context Menu to display the selected spectrum Otherwise the screen will just show the spectrum list To select a spectrum to display short press its entry in the list The list entry will be highlighted If the screen is divided the selected spectrum will be displayed alongside the list Otherwise it will be displayed in a spectrum view The spec
30. a sensor backlight and so for those that are not this option does nothing It is recommended that you leave it enabled all the time Selecting the Tacho Power Save checkbox allows the PB 3 to save battery power when the reflection from the taped blade is sufficiently bright The Min Tacho Pulses spinner sets the minimum number of infrared pulses that must be received by the tachometer to detect the passing of the taped blade The default value is 4 but you may need to increase the value if the tachometer cannot reliably detect the taped blade due to the other blades causing spurious reflections 10 2 Polar Options Dialog This dialog contains options that select the origin of the polar point Polar Options data and how the PB 3 averages that data These options have no effect Polar Mode Propeller F on the spectrum display The Polar Mode spinner selects the Average Toms 5 A algorithm used by the PB 3 to Propeller Mode Options calculate the polar point values l IPS Deg from the measured Min Cycles 4 4 acceleration data You can choose from Propeller Rotor Rotor 2nd Fi ig 10 2 Polar Options Harmonic Rotor 3rd Harmonic g H For propeller balancing you can use either Propeller or Rotor polar mode For PSRU ratios that are not 1 Propeller can produce more consistent results than Rotor By default propeller mode jobs use Propeller For rotor balancing the default is Rotor which must be used to ensure tha
31. abase After confirmation all of the data in the database is deleted Save the database first if you want to access that data again 9 5 Export Data Submenu The export data submenu provides the means to export polar point or spectrum data from the app You can export the data in either CSV Comma Separated Values format which is suitable for importing into spreadsheet applications or as SQL statements that may be imported into the propeller balancer app on another Android device You can limit the data output to a specific job or you can output data for all jobs The submenu provides these items www smartavionics com 47 Import Data Submenu Export CSV Data This menu item pops up a dialog that let s you specify which items are to be shared You can select either polar points or spectra to be output as CSV data which is suitable for importing into a spreadsheet The spectral line values can be output as velocities V or accelerations A The CSV data format is described in Appendix A Export SQL Data This menu item pops up a dialog that let s you specify which items are to be shared You can select polar point and or spectrum data to be output as SQL statements which are suitable for importing into the propeller balancer app or another sqlite compatible application 9 6 Import Data Submenu The import data submenu provides the means to import data points and or spectra that has previously been exported from the app as SQ
32. ain to return the rotor to the original condition and finally define the move line The process can be repeated to define the chordwise move line This time the adjustments would involve shifting the rotor mass on the teeter pivot Once both move lines are defined you can balance the rotor A Important To ensure that the move lines are good follow this advice Only make one adjustment at a time Always fly the aircraft at the same speed and weight when capturing the data Fly smoothly and avoid turbulence Capture multiple points 3 say to avoid being fooled by a rogue point Make the adjustment large enough to produce a noticeable effect If you are unsure how big an adjustment to make start small and keep doubling the adjustment until it produces at least 0 5 IPS preferably 1 IPS of movement on the polar chart compared to the original condition www smartavionics com 65 Using the move lines to balance ha Note Move lines are only valid for a given flight condition airspeed AUW etc and sensor configuration If you move the sensors or say invert an accelerometer axis the move lines will no longer valid Aircraft of the same type and configuration should have very similar move lines so you may well be able to use move lines defined on one aircraft on another aircraft 12 2 2 Using the move lines to balance With the move lines defined fly again in the original configuration no weights
33. already in use This item generates a job report in the form of a page of HTML which you can subsequently export via email Dropbox etc The report shows a simplified polar chart and a table containing the polar point details You can select from the following options which determine the points to be included in the report All Points all of the job s points are included Interesting Points all interesting points are included Interesting points are those that have notes the start point the first and last points and any other point that differs markedly in terms of the IPS and Deg values from the previous included point First And Last Points only the first and last points are included The report is formatted for a minimum screen width of 800 pixels and it is best viewed using a recent Web Browser i e Chrome Firefox IE9 on a PC laptop Use the Export menu option to export the report from the Android device GrPropeller Balance Report Job GTSIM 2 Date 3 Jun 2015 5 37 38 pm Mode Propeller Axis PSRU Ratio 2 15 Point Date Time IPS Deg Notes 20 08 2013 14 37 33 0 144 176 20 08 2013 14 48 17 0 116 262 20 08 2013 14 51 16 0 055 264 20 08 2013 14 54 14 0 059 234 20 08 2013 14 54 28 0 068 187 20 08 2013 14 56 47 0 037 4 20 08 2013 14 56 52 0 053 258 20 08 2013 14 57 01 0 044 47 Generated by Propeller Balancer 2 6 www smartavionics com Fig 9 1 Propelle
34. ases clockwise 0 360 The background colour of the chart makes it easy to determine the quality vibration level of a plotted point When balancing the propeller rotor the aim is to get the polar point as close to the centre of the chart as possible The current polar pointis displayed as either a black filled circle X axis points or diamond Y axis points If the job has been set up to capture data from both axes and the Plot All Axes menu option is selected both points will be displayed Otherwise only one of them from the primary axis will be displayed A summary of the polar points most important attributes is shown in a bubble above the point The format is RPM IPS DEG If the show solution option is enabled a terse description of what should be done to improve the state of balance is displayed below the point A grey standard deviation ellipse is drawn around the current polar point The size of the ellipse grows and shrinks depending on the variation in values of the vibration level and phase angle This provides a useful visual indication of how steady the readings are At the bottom of the display is the Capture button Pressing this captures the current polar point s and optionally the current spectra too When a point is captured its details are stored in the app s database Optionally a captured point dialog will open to display the point s details Each captured point is plotted on the chart as an unf
35. at was captured before any weights were www smartavionics com Propeller mode solution added Start points are plotted as filled blue circles Any point can be specified to be the start point 2 1 1 Propeller mode solution The propeller mode solution bubble contains a terse description of how the weight needs to be adjusted to achieve the best balance If the RPM of the current point is within 5 ofthe start point s RPM a solution of the form ANGLE x SCALE will be shown ANGLE is signed a positive value means move the weight forward in the direction of propeller rotation that many degrees and a negative value means move the weight backward opposite to the direction of propeller rotation SCALE is a multiplier that specifies the required change in weight e g a value of 1 2 means increase the weight by 20 a value 0f 0 5 means halve the weight If the current point s RPM is not close enough to the start point s RPM to calculate a solution the bubble will indicate how much the RPM needs to be altered 2 2 Rotor Mode Polar Chart The polar chart provides a plan view of the aircraft s rotor with the front of the aircraft assumed to be in the 12 o clock position the datum position With the rotor blades aligned in the 12 o clock 6 o clock position fore aft the blade at the front at the datum is the master blade It should be marked in some way to distinguish it from the other blade The accelerometer measur
36. balancer press the Capture button to capture a polar point The point s details will be displayed in the captured point dialog press the back button twice to return to the polar chart view Capture a few points if the propeller is obviously out of balance the points will be clustered together some distance away from the centre of the chart Now stop the engine and double check that the ignition is switched off Ifthe vibration level is already 0 15 IPS or less the propeller can be considered reasonably well balanced in ideal conditions the balancer is capable of balancing a propeller down to about 0 03 IPS so you may wish to continue the process to achieve a better result If you want to improve the balance you must carry out the balancing procedure as described in the next section OG To reduce battery drain in the PB 3 and the Android device it is best to exit the app using the back button when you are not actually capturing points or viewing the live data When you are ready to capture a new point just restart the app www smartavionics com Balancing Procedure 11 6 Balancing Procedure Important It is the operator s responsibility to ensure that any procedures or guidelines that have been issued by the manufacturers of the propeller engine or aircraft or some other agency e g the FAA CAA LAA BMAA that specify how the propeller is to be balanced are adhered to The following instructions describe
37. bearing For items that are supported at both ends the measurement and correction planes may be close together as is shown in the next figure www smartavionics com 67 Two Plane Balancing View CORRECTION PLANES MEASURING PLANES Fig 13 1 Two Plane Balancing An Object Supported At Both Ends For overhung items the configuration is as shown in the next figure Note how the 1 measurement plane is close to the 41 correction plane but the 2 measurement plane is far from the 2 correction plane CORRECTION PLANES MEASURING PLANES Fig 13 2 Two Plane Balancing An Overhung Object 13 2 Two Plane Balancing View The two plane balancing view presents a table into which the 6 required IPS DEG values are entered Each of the values is entered by pressing the appropriate button and selecting a polar point from a list that contains the current job s polar points Once the data has been entered the resulting solutions are shown below the table in the same format ANGLE x SCALE as the propeller mode polar chart solutions There are two solutions one for each correction plane Here is the two plane balancing view that already has the IPS DEG data entered into it and is therefore displaying solutions 68 www smartavionics com Single accelerometer procedure Propeller Balancer Two Plane Balancing Plane 1 Points Plane 2 Points NO TRIAL IPS 0 72 NO TRIAL IPS 1 35 MASSES DEG 238 MASSES DEG 29
38. ce vibration This vibration can be measured by mounting a sensor on the engine as close to the propeller as possible Conventionally the magnitude of a propeller s vibration is reported as a peak velocity in units of Inches Per Second IPS 11 3 Static Propeller Balancing A propeller can be statically balanced in the workshop using a static balancing tool This often involves suspending the propeller from its central axis If the www smartavionics com 55 Dynamic Propeller Balancing propeller is statically balanced the blades should be level If one blade is heavier than the others or its centre of mass is further from the centre of the propeller it will dip towards the floor If this occurs weight can be added to the hub on the opposite side of the central axis to the dipping blade to bring the propeller level All propellers should be manufactured with blades that have equal mass and mass distribution and so a new propeller should not require static balancing Propellers that have suffered damage to the blades stone chips or tip abrasion may well benefit from being statically balanced While statically balancing a propeller is worthwhile the best results will be obtained if the propeller is dynamically balanced together with the spinner 11 4 Dynamic Propeller Balancing Dynamic propeller balancing involves measuring the actual rotational vibration generated at a realistic propeller RPM and then adding weights to
39. ced is increased relative to its diameter or if it wobbles on the supporting shaft two plane balancing is required This chapter describes how the app can be used to carry out two plane balancing using the two plane balancing view which is accessible through the options menu 13 1 Two Plane Balancing Method The two plane balancing method is really very similar to the single plane balancing method It involves measuring the vibration when no trial mass is attached measuring the vibration with trial mass attached and then calculating a solution from those measurements The difference is that the trial mass is attached twice once in each plane and for each position of the trial mass not present attached in plane 1 and attached in plane 2 vibration readings are captured from both planes So that means that 6 IPS DEG values are required to be able to calculate the two plane balance solutions that are needed 13 1 1 Measurement and correction planes The planes in which the accelerometer s are mounted are called measurement planes The planes in which the trial masses and the final correction masses are attached are called the correction planes Typically accelerometers are mounted as close as possible to the bearings that support the object being balanced Generally speaking the object being balanced is either supported by bearings at each end so that its mass is mostly between the bearings or it has significant mass that overhangs one
40. correspond to integer multiples and also 1 2 of the engine crankshaft RPM are labelled or not If enabled www smartavionics com 25 Spectrum View Context Menu Label Cursor Line Show Capture Button Share CSV Data Note those spectral lines will have a red label showing the IPS and RPM values along with the appropriate multiplier E 2 E 2E 3E 6E A checkbox that controls whether a user selectable peak the cursor line is labelled or not If enabled the line will have a blue label showing its IPS and RPM values along with the multiples of the propeller and engine RPMs xPyE or multiple of the rotor RPM xR The current cursor line is selected by tapping the desired peak in the lower half of the spectrum display Tapping the upper half of the spectrum display moves the cursor to the next peak to the left or right depending on which side of the display is tapped A checkbox that controls whether the Capture button is displayed in the top right corner or not Pressing that button captures the current spectrum and stores it in a database on the Android device The list of captured spectra is accessible through the options menu Shares this spectrum as CSV data It is possible to use the spectrum view without a tachometer but in that case no analysis is possible and no propeller or engine lines will be labelled 26 www smartavionics com Spectrum Analysis Dialog 5 2 Spectrum Analysis D
41. d sense is required for each of these axes You can determine that information using a polar chart that has been augmented with move Don t confuse these axes with the accelerometer axes they are different 64 www smartavionics com Defining move lines lines A move line is literally a line drawn on a polar chart that shows the direction a polar point would move when a particular adjustment is made to the system For a gyroplane rotor two move lines are required one for the spanwise balance and another for the chordwise balance Important Before you start capturing any data please ensure that the current job has been configured correctly using the job setup dialog It is strongly recommended that you use the big capture button to capture the data while flying as this greatly simplifies the user interface Also ifthe machine has an open cockpit take precautions to avoid the Android device disappearing aft through the propeller If possible attach it firmly to a knee pad or to the aircraft structure 12 2 1 Defining move lines It is straightforward to define a move line All you have to do is capture two or more polar points that correspond to known conditions and tell the app what those conditions were For example to define the spanwise move line you would add weight to one of the rotor blade tips capture a few polar points move the weight to the other rotor blade tip capture a few more points remove the weight ag
42. data associated with the current polar point Show Related Spectrum Searches for a related spectrum whose capture time most closely matches the point s capture time If a spectrum is found that differs in capture time by no more than 30 seconds it is displayed Press the Android device s back button to dismiss the spectrum view Show On Polar Chart Displays the point on a polar chart as a filled circle or diamond Press the Android device s back button to dismiss the chart Edit Point s Notes Opens a dialog so that you can edit the notes associated with this point This menu item is not shown when the current job is locked Change Point s Job Pops up a list of the currently known unlocked jobs so you can choose the job that the currently selected point will be moved to This menu item is not shown when the current job is locked Export Image Exports the current view as a JPEG or PNG image Delete After confirmation the point is deleted from the database This menu item is not shown when the current job is locked A spectrum is related if it has the same job and accelerometer axis as the point www smartavionics com 33 34 www smartavionics com Chapter 7 Spectrum List The spectrum list is a scrollable list of the current job s captured spectra It is invoked via the options menu The list s bold title grr EE will be one of the Propeller Balancer JOB LISTPOINTS PB 3 OPTIONS following GXXXX Spectr
43. de pointing forward the datum position i lt Direction Of Rotation U D S Master Blade X Axis hi Fig 2 3 Marker Positions When Tape Aligned With Tacho www smartavionics com 11 Rotor Mode Markers The positions of the markers that are labelled X and Y indicate the directions of the positive accelerometer axes when the accelerometer is mounted such that its axes are parallel with the rotor s plane of rotation For example consider a machine whose rotor rotates anti clockwise when viewed from above If the accelerometer is mounted so that the positive X axis is pointing away from the rotor s axis of rotation in the 3 o clock direction i e pointing to the right when viewed from above the X marker should be in the 3 o clock 90 position as shown in Fig 2 3 When an accelerometer axis is perpendicular to the plane of rotation i e the axis is pointing vertically upwards its marker should be set to 0 degrees The marker that is labelled T indicates the position of the master blade at the point where the tachometer triggers To determine the position for this marker move the rotor until the retroreflective tape is illuminated by the beam from the tacho sensor and then measure or estimate the angle from the master blade to the datum position in the direction of rotation Often the tape can be positioned in front of the tacho sensor with the master blade at the datum position in which
44. e choices are Yes Always divide the screen even when it is small No Never divide the screen even when it is large Auto Divide the screen if the largest dimension is at least 480 pixels A checkbox that when enabled hides the Android status bar If you change this parameter you will need to exit the app and restart it for the change to have an effect A checkbox that when enabled hides the app s title bar Ifyou change this parameter you will need to exit the app and restart it for the change to have an effect A checkbox that enables the hiding of the view select tabs immediately after a view has been selected When the tabs are hidden the first item in the options menu will redisplay the tabs so you can then select a different view If the height of the Android device s screen is limited enabling this option makes better use of the available screen area A checkbox that enables the display of zoom controls when zooming is possible i e when the polar chart view is in pan zoom mode If your Android device supports multi touch you can hide the zoom controls and use pinch zoom gestures to zoom the display A checkbox that enables the legacy modal polar pan zoom behaviour Enabling this checkbox will automatically open the big capture button view when the app starts The language to use for all User Interface text buttons menus etc Can be set to System Default English or French Please note that d
45. e list of captured spectra is accessible through the options menu This menu item is not shown when a previously captured spectrum is being viewed or when the Capture button see below is displayed Analyse Spectrum Opens an analysis dialog that describes the current spectrum Set RPM Per Line Opens a dialog that lets you choose between 10 20 50 amp 100 RPM per spectral line This menu item is not shown when displaying a previously captured spectrum Set RPM Axis Opens a dialog that lets you choose a scaling value of 1 Zoom 2 5 or 10 for the RPM horizontal axis You can also use the Android device s volume up down buttons to adjust the RPM axis zoom Blade pass frequency is the prop frequency x number of propeller blades 24 www smartavionics com Spectrum View Context Menu Set IPS Axis Zoom Opens a dialog that lets you choose a scaling value of Auto 1 2 5 10 20 or 50 for the IPS vertical axis When set to Auto the scaling is automatically adjusted so that the tallest line uses 80 of the available display height Set FFT Window Opens a dialog that lets you choose the type of FFT window to use This menu item is not shown when displaying a previously captured spectrum The available window types are None No window is used so the display will show artifacts due to the spectral leakage that occurs when a periodic waveform is processed by a discrete Fourier transform Hann The Hann window reduces the spect
46. eckbox that controls whether the chart s background will be coloured or not A checkbox that controls whether a solution bubble will be shown below the current point s summary or not The solution bubble content is different for propeller and rotor modes Enters the legacy pan zoom mode You can also use the Android device s volume up down buttons to adjust the zoom Only available if the legacy modal pan zoom behaviour is enabled In rotor mode the context menu also includes these items Rotor Rotates Clockwise Move Markers Move Move Lines A checkbox that when checked specifies that the rotor rotates in a clockwise direction when viewed from above The T marker shows the direction of rotor rotation Normally the positions of the X Y and T markers are fixed This menu item enables move markers mode which allows you to reposition the markers by simply dragging them with your finger to the required positions The markers become blue when move markers mode is active To fix the markers again use the now visible Fix Markers menu item or just wait a short while and the markers will become fixed again automatically As you move the T marker all of the polar points on the chart move with it Moving one of the accelerometer axis markers X or Y just moves the points associated with that axis Selecting this item enables move move lines mode which allows you to adjust the positions of the existing move l
47. eout Accept the permissions and the app will be installed www smartavionics com 1 Balancing System Overview 1 2 Balancing System Overview The propeller rotor balancing system has these main components Accelerometer This is mounted near the propeller rotor to detect the vibration caused by any imbalance Optical A strip of reflective tape is attached to one propeller rotor tachometer blade and an optical sensor detects the tape as it passes and generates the tachometer signal required by the balancer For propeller balancing the PB 3 s built in optical tachometer would normally be used For rotor balancing an external tachometer must be used Signal processor This digitises the vibration signal and sends the resulting data to an Android device using Bluetooth wireless communications Android device This provides the interface through which the user interacts with the PB 3 For details of how the sensors are attached and other hardware related information please refer to the PB 3 Propeller Balancer User Manual 1 3 App Overview 1 3 1 Title bar The app s title bar displays the application name Propeller Balancer If the height of your Android device s display is limited you can set a preference to hide the title bar 1 3 2 Tabbed views The app has a tabbed interface that provides 4 top level views The polar chart view shows a polar charton which the data points captured during balancing are plot
48. es acceleration in two axes To balance a rotor you only need to use a single axis which is typically orientated to the side to side roll axis of the aircraft The job has an option that lets you specify the primary axis Which is the accelerometer axis to use during the balancing process You may also be interested in measuring the acceleration in the vertical axis and so the app is capable of capturing data points and spectra for both X and Y axes simultaneously and there is a job option to enable that The rotor mode polar chart displays 3 markers Two of the markers are square and they indicate the orientation of the X and Y accelerometer axes The other marker is arrow shaped and it indicates the position of the master blade at the point when the tachometer is triggered The arrow points in the direction that the rotor rotates when viewed from above www smartavionics com 9 Rotor Mode Polar Chart Propeller Balancer JOB LISTPOINTS LIST SPECTRA z e B MO Job ROTOR Axis roll PSRU 1 0 Mode Rotor Tacho Ext Log 0ff Bat 76 364 0 01 104 span no change Fig 2 2 Rotor Mode Polar Chart When balancing a rotor adjustments are determined by the relationship between the current polar point and one or more move lines Move lines are shown on the chart as dashed black lines A move line shows on the polar chart the direction the current polar point would move in when a particular adjustment is carried ou
49. gine vibration The optimal number of propeller cycles to average per reading depends on the PSRU ratio Given the PSRU ratio the app can determine the engine RPM which is displayed on the data view and also used to label spectra displayed by the spectrum view You can specify the PSRU ratio by either selecting one of the known engine types from the Engine spinner or by entering the ratio directly into the Ratio text field The known ratios are 44 www smartavionics com Rotor mode job setup Ratio Engine type 1 0 No PSRU direct drive engine or gyroplane rotor 1 82 Subaru Eggenfellner 212 Subaru NSI 2 27 Rotax 912 2 43 Rotax 912S amp 914 9 2 2 Rotor mode job setup For rotor mode jobs 3 angles in degrees can be entered The directions of the positive X and Y accelerometer axes The direction of the master blade at the point at which the tachometer is triggered The angles are measured to the datum in the direction of rotation the datum is located at the 12 o clock position on the polar chart For example if the X accelerometer positive axis was orientated in the 3 o clock direction the angle from it to the datum would be 90 degrees Note that it is also possible to configure these angles graphically using the move markers polar chart context menu item 9 3 Point Logger Submenu The PB 3 has the capability to autonomously log polar points Once logging has been configured and enabled the
50. he positions of the move line s nodes For example one node Value B could correspond to the condition of 10 washers being attached to the tip of the master blade and the other node for the opposite condition of 10 washers being attached to the tip of the non master blade These two values must be different in either magnitude or sign i e they can t both be 10 but one can be 10 and the other 10 Increment When the adjustment is calculated the resulting value will be a multiple of this increment So if you only have washers of one size then an increment of 1 would be appropriate but if you also had some washers that weighed half as much then an increment of 0 5 would be appropriate because then the suggested amount of adjustment would be to the nearest 1 2 washer 14 www smartavionics com Rotor mode solution Move Line Colour The move line s colour Supported colours are black red green blue magenta and orange Move Line Style The move line s style Supported styles are dashes arrows solid and dots Move Line Setup Name span Applies To Axis rollv Units washers on mb Value Q A 10 Value Q B 10 Increment 0 50 Move Line Colour Magentav Move Line Style Dots gt DELETE CANCEL ACCEPT Fig 2 6 Move Line Setup 2 2 4 Rotor mode solution The rotor mode solution bubble contains one or two suggestions for adjustments to be made to achieve the best balance Each move line provides one suggestio
51. he current job again Each press of this item toggles between the two most recently used jobs This item presents a list of all the known job names so you can select the job that is to become the current job All new polar points and spectra that are captured will be associated tagged with this job The job names are initially listed in alphabetic order A dialog button toggles between alphabetic ordering and job age ordering A job s age is simply the age of the job s last captured point or spectrum Opens a dialog so that you can enter a name for the new Job When the name has been entered two buttons are enabled that let you choose between creating the new job with default parameters or creating the new job with parameters that are copied from an existing job When you press the latter button you will be presented with a list of all the existing jobs and you can select one to copy the parameters from The new job is created and the job setup dialog is opened so that you can configure the job If you enter a name that is already in use you are given the option to switch to that job and if you decline to do that the new job name dialog reappears and gives you the chance to enter a new job name This item opens the job setup dialog 42 www smartavionics com Job Submenu Rename Job View Report This item presents a dialog into which you can enter the new name for the current job It won t let you use a name that is
52. ialog The spectrum analysis dialog displays text that describes the current spectrum To be able to do this the propeller rotor RPM must be known so you need to have a working tachometer You can export an image of the analysis by long pressing the dialog and pressing the Export Image context menu item The figure on the right shows a typical analysis exported image The analysis compares the vibration levels of the spectra at integer multiples of the propeller RPM to try to determine the number of propeller blades and if a plausible number is determined it is shown along with level of the blade pass vibration Analysis GXXXX 2 Jun 2013 13 42 31 The vibration due to imbalance is 0 13 IPS It looks like you have a 3 bladed propeller The blade pass vibration 0 16 IPS is greater than the vibration due to imbalance The vibration at crankshaft RPM 0 34 IPS is greater than the vibration due to imbalance 0 13 IPS The RMS acceleration is 0 85 G Smart Avionics Ltd Likewise if the vibration level atthe Fig 5 2 Spectrum Analysis prop crankshaft and half crankshaft RPMs are significant compared to the vibration at propeller RPM they are shown The rotor mode spectrum analysis is Similar except that it doesn t report the crankshaft related vibrations Analysis BRITTANY5 13 Aug 2013 14 47 28 The vibration due to imbalance is 0 06 IPS It looks like you have a 2 bladed rotor The b
53. ialog should appear inviting Bluetooth pairing request you to enter the security code which is 0000 The PB 3 should now be paired and its entry in list should say Paired but not connected The Android device and the PB 3 will remain paired until you unpair them by long pressing the PB 3 list entry and then selecting the Unpair option Fig 1 1 PB 3 Pairing Try 0000 or 1234 Cancel www smartavionics com 5 Bluetooth Remote Capture Button If you turn off the Bluetooth on the Android device when you next start the Propeller Balancer app it will ask you if you want to turn the Bluetooth on 1 5 Bluetooth Remote Capture Button Remote camera shutter release devices that use the Bluetooth HID protocol can be used as a remote capture button This is particularly useful for capturing polar points and spectra when flying a gyroplane or helicopter as the pilot does not have to hold the Android device or use the on screen controls at all The app has been tested with a device called the iKey3 but any device that behaves like a HID keyboard and sends an Enter key when its button is pressed should be compatible 6 www smartavionics com Chapter 2 Polar Chart View The polar chart view displays vibration readings plotted in a polar format Each plotted polar point has a vibration level and a phase angle The vibration level is zero at centre of the chart The phase angle is zero at the top of the chart and incre
54. if applicable the rotor mode context menu items 6 2 Delete Points Submenu The delete points submenu lets you choose a group of points to be deleted You will be asked to confirm the action before any points are really deleted A Important All of the points currently shown in the list are possible candidates for deletion if the Show All Jobs option is checked it is possible to delete all the captured points from all of the unlocked jobs The delete points submenu items are All Points Selected Point All Older Than Today All Captured Today All Without Notes All points in the list are deleted The currently selected point is deleted All points in the list that were captured before the current day are deleted All points in the list that were captured today are deleted All points in the list that don t have notes are deleted The following items are only shown when the Show All Jobs option is not checked and when the current job is using propeller mode All Before Start Point All After Start Point All points in the list that were captured before the start point are deleted All points in the list that were captured after the start point are deleted The following items are only shown when the Show All Jobs option is checked AII In Job AII Not In Job A dialog opens to let you select a job and all points in the list from the selected job are deleted A dialog opens to let you select a job and
55. ig button It is invoked viathe options menu The button text shows the current RPM and the number of captures completed since starting the view Touching the button captures the current polar point s and optionally the spectrum data Propeller Balancer JOB LISTPOINTS LIST SPECTRA Propeller Balancer JOB LISTPOINTS LIST SPECTRA Job GXXXX Axis X PSRU 2 43 Mode Prop Tacho Int Log Off Bat 69 Job GXXXX Axis X PSRU 2 43 Mode Prop Tacho Int Log Off Bat 69 RPM 1562 CAPTURED Fig 8 1 Big Capture Button View Initially the button s background is white and the RPM is not shown As soon as the RPM is detected it will be shown and the button is enabled When the button is touched the background becomes orange and when the capture operation is complete the background becomes green If the current job has the Capture Both Axes option set then polar points and spectra from both the X and Y axes will be captured Otherwise only points and spectra from the current job s primary axis X or Y will be captured The current job s Also Capture Spectra option must be set to capture the spectra otherwise just the point s will be captured Pressing the Android device s back button will return you to the previous screen A display preference can be set to automatically open the big capture button view when the app is started www smartavionics com 39 40 www smartavionics com Chapter 9
56. illed circle diamond so you can see how the points are clustering When zoomed in sufficiently each captured point is numbered with its position in the polar point list Long pressing the capture button pops up a dialog that lets you choose the size of that button So if you find the standard button too small you can make it bigger The chart can be panned by dragging it with a finger The chart can be zoomed using the zoom control buttons that appear when the chart is panned or by using pinch zoom gestures if your Android device supports them The visibility of the zoom controls is determined by the show zoom controls preference You can also use the Android device s volume up down buttons to adjust the zoom Long pressing the polar chart pops up the polar chart context menu www smartavionics com 7 Propeller Mode Polar Chart 2 1 Propeller Mode Polar Chart Propeller Balancer JOB LISTPOINTS LIST SPECTRA 2 B 8 B EY DEG Job PROP Axis X PSRU 1 0 Mode Prop Tacho Int Log Off Bat 69 a Ge Si x a ia S S S 018 l o6 204 11507 0 41 297 02 os 48 x 1 73 7 SS e A LS i Re EE WT p Pa S G Capture R a K P 8 SS SS DI Se Fig 2 1 Propeller Mode Polar Chart When balancing a propeller all adjustments weight added and or moved are determined by comparing the current polar point with the start point A start point is simply a polar point th
57. in blue otherwise its summary will be displayed in black If a point was captured today its background will be white otherwise its background will be grey Pressing the Android device s back button will return you to the previous screen www smartavionics com 29 Polar Point List Context Menu If the divide screen preference is enabled the screen will be divided into two halves one half will contain the polar point list and the other half will contain a polar chart Otherwise the screen will just show the polar point list To select a point short press tap its entry in the list The list entry will be highlighted and ifthe polar chart is being displayed the point will be displayed as a filled circle Ifthe polar chart is not being displayed selecting a point will immediately pop up the point s captured point dialog which will display the point s details When the polar chart is being displayed next to the list you need to press the selected point s list entry a second time to pop up that dialog Long pressing the point list pops up a context menu When the screen is divided to show both the polar point list and the polar chart you may press a point on the chart to select it If more than one point is a possible candidate for selection you willbe shown a list ofthe candidates so you may choose the point to be selected 6 1 Polar Point List Context Menu The polar point list context menu contains these items Show
58. ines by dragging the lines nodes The positions of the lines nodes is shown by bubbles that are displayed while this mode is active Drag the nodes so that they lie on top of the polar point s that correspond 16 www smartavionics com Polar Chart Context Menu Setup Move Line Select Move Lines To Use Add Move Line Show Move Line Names to a particular state of imbalance weight on one tip or the other etc To fix the move lines again use the now visible Fix Move Lines menu item or just wait a short while and the move lines will become fixed again automatically This item lets you select one move line to be configured For a short while the move lines node information is displayed so that you can identify the move lines Touch the move line that is to be configured and the move line setup dialog will appear Pops up a dialog containing a list of check boxes one for each defined move line You can select which of the move lines will be used to calculate the rotor mode solutions No more than 2 move lines can be selected at any one time Adding the move line involves setting up its parameters and positioning the line on the chart Selecting this item firstly pops up the move line setup dialog and when that dialog is dismissed using the Accept button move move line mode is entered so that the new move line s nodes can be positioned A checkbox that enables the display of the move line names When enabled
59. l direction and the secondary axis data is used for the horizontal direction To give you an idea of how the waveform progresses through the cycle a label is displayed every 15 degrees Pops up a list of full scale magnitudes for you to select from The first item in the list is Auto which automatically scales the waveform so that it fits the display A checkbox that selects display of acceleration This is the raw data coming from the accelerometer A checkbox that selects display of velocity This waveform is obtained by integrating the acceleration data Plot Displacement A checkbox that selects display of displacement This Colour Waveform Draw Graticule waveform is obtained by integrating the velocity data A checkbox that enables the colouring of the displayed waveform The beginning of the waveform is coloured red and the end of the waveform is coloured blue A checkbox that enables the display of the graticule and axis values 22 www smartavionics com Chapter 5 Spectrum View The spectrum view shows the vibration data in the frequency domain each spectral line represents the vibration level at a given RPM Propeller Balancer JOB LST PONTS PB 3 OPTIONS RPM 1520 IPS 0 07 very good 0 39IPS 3750 2 47P 1 02E 0 141PS 7550 5P I 0 101IPS 4600 3P In 0 07IPS 1550 I T_T 0 031IPS 3050 0 03IPS 6100 jie D aouen
60. lade pass vibration 2 93 IPS is much greater than the vibration due to imbalance The RMS acceleration is 1 81 G Smart Avionics Ltd Fig 5 3 Spectrum Analysis rotor It s just an estimate so don t panic if it reports the wrong number of blades www smartavionics com 27 28 www smartavionics com Chapter 6 Polar Point List The polar point list is a scrollable list of the current job s captured points It is invoked via the options menu The list s bold title grr Er will be one of the following Propeller Balancer JOB LISTSPECTRA PB 3 OPTIONS All Points if the JESS He Show All Jobs 1 X Axis 02 06 2013 0 381 299 context menu item is 13 30 45 1547 RPM Job name Points if z the current job has a 3 X Axis 02 06 2013 0 780 296 non empty name 13 34 48 1558 RPM i 4 X Axis 02 06 2013 0 733 289 Anonymous Points 13 34 57 1556 RPM when the current 5 X Axis 02 06 2013 0 099 104 job s name is empty 13 38 39 1544 RPM Each point s IPS DEG and RPM values are shown along with the date and time of capture and the accelerometer axis used If the list is showing points for all jobs each point s Job name is displayed below the axis name If a point has notes associated with it they are also displayed below the _ e axis name Fig 6 1 Polar Point List If a point has been designated as a Start Point its summary will be displayed
61. mbalance 55 mode 44 pitch imbalance 55 62 static balancing 55 PSRU 3 incorrect ratio 61 PSRU ratio 44 Q quit confirm 49 R related spectrum 33 release history 41 rotor direction of rotation 16 mode 44 RPM choice 57 erratic 60 S screen divide 49 orientation 48 sensor backlight 52 Share CSV Data 26 show tabs 41 show zoom controls 49 simulated data 50 solution bubble 16 space key 41 spectrum analysis 24 36 capture 24 delete 36 list 35 related 33 14 www smartavionics com spectrum view 23 sqlite 46 standard deviation ellipse 7 start point 8 29 32 choose 59 define 33 status bar 3 hide 49 switch axes 42 T tabs hide 49 show 41 tachometer 3 57 channel 44 min pulses 52 power save 52 set level 51 time domain 21 title bar hide 49 trial weight 59 two plane balancing 67 two plane balancing view 41 68 U user interface language 49 V vibration level colours 4 volume buttons 16 24 W wind 61 Z zoom controls visibility 49 www smartavionics com 75 76 www smartavionics com
62. n The format of the suggestions is name amount units where name is the move line s name if it has one amount is the amount of adjustment required and units are the units of adjustment if they were defined for the move line If more than one suggestion is shown they are ordered with the largest adjustment E 3 shown above the smaller adjustment 659 0 06 176 span 1 0 washers on mb 2 3 Polar Chart Context Menu The polar chart context menu contains these items The ordering is done by comparing the distances along the respective move lines that the polar point would need to move to reach the centre of the chart so the move lines units do not have to be the same www smartavionics com 15 Polar Chart Context Menu Plot All Jobs Plot All Axes Track Current Point Keep Centre Visible Colour Background Show Solution Pan amp Zoom Chart A checkbox that controls whether captured points from other jobs are plotted along with the current job s points or not A checkbox that controls whether captured points whose axis differs from the current axis are plotted or not A checkbox that controls whether the chart is to be automatically panned so that the current polar point is always displayed near to the centre of the screen A checkbox that controls whether the chart is to be automatically zoomed so that the centre of the chart is always visible when tracking the current point A ch
63. next This implies that some perhaps most ofthe measured vibration is out of phase with the propeller Any of the following problems will cause the position of the polar point to vary The incorrect PSRU ratio is being used You are using the wrong accelerometer axis The RPM is not being reliably detected Unless the RPM is correct the IPS and DEG and their associated standard deviations are meaningless The wind is gusting At low vibration levels just a few knots of wind can make it appreciably harder to obtain reliable data The engine is not running smoothly or the engine mounts are in poor condition You are using an RPM that is triggering an airframe resonance The accelerometer is not securely mounted or the sensing axis is not pointing at the propeller s axis of rotation or the sensing axis is parallel with the direction of Movement of the engine s pistons The spinner is wobbling The engine cowling is not fitted to minimise the effects of turbulence 11 8 3 Adding weight does not reduce the vibration level If the balancer shows a significant level of vibration with a small standard deviation and adding weight doesn t appear to reduce the level or substantially change the angle any of the following could be true The incorrect PSRU ratio is being used You are using the wrong accelerometer axis www smartavionics com 61 Adding weight does not reduce the vibration level The pr
64. ome more points to see what difference that has made Note If you need to attach the weight at a position that falls between the available attachment points it should be possible to attach two smaller weights either side of that position such that their combined influence is equal to the influence required i e if you need to have 3 washers at a position that is 1 3 of the way Apart from any weights that were added during static balancing don t remove those www smartavionics com 59 After Balancing between two attachment points you could put 2 washers on the preceding attachment point and 1 washer on the next attachment point this assumes the attachment points are not more than say 60 apart Depending on the quality of the captured points and how closely you follow the instructions you may well have to repeat this step a few times to get the best result Note The app does not actually say that the propeller is balanced or not it s left up to the operator to decide when to stop the process based on the IPS achieved 11 7 After Balancing When the balancing has been completed double check that all balance weights are securely attached If you have been using temporary weights to carry out the balancing they should be replaced with permanent weights whose mass and position are such that they have the same effect as the temporary weights If in doubt recheck the balance once the permanent weight
65. ood 0050 fo VI VU 270 BRITTANYS 13 08 2013 14 48 17 x Disp Inches Deg BRITTANYS 13 08 2013 14 48 17 x Disp Inches Deg 5 EG I a ey Eal Fig 4 1 Graph View Cartesian and Polar Formats If the Colour Waveform context menu option is selected the waveform is coloured red at the start of the cycle and blue at the end When acceleration is being displayed using the polar format the display also shows with a small red cross the position of the average of the plotted polar coordinates This gives you a visual indication of the vibration waveform s phase angle The waveforms size may be scaled manually using either the context menu or the Android device s volume controls or automatic scaling can be enabled At the top of the view the current RPM and IPS are shown and at the bottom status information that shows when the waveform was captured and what is being displayed Long pressing the view pops up a context menu www smartavionics com 21 Graph View Context Menu 4 1 Graph View Context Menu The graph view context menu contains these items Cartesian Plot Polar Plot 2 Axis Plot Set Full Scale Plot Acceleration Plot Velocity A checkbox that selects a Cartesian plot of the data A checkbox that selects a Polar plot of the data A checkbox that selects a 2 dimensional plot using data from both axes The primary axis data is used for the vertica
66. opeller is suffering from pitch imbalance the blades don t have equal pitch Pitch imbalance has to be corrected before the propeller can be dynamically balanced The amount of weight being added is too small to have an effect The heavier the propeller spinner the more weight has to be added to reduce a given level of vibration The weight is not being added at the correct position 62 www smartavionics com Chapter 12 Rotor Balancing Acknowledgement Smart Avionics gratefully acknowledges the assistance freely given by Mike Goodrich during the development and testing of the app s rotor balancing capabilities Mike provided much useful knowledge that aided the development process and has tirelessly been the guinea pig testing numerous versions of the software Any errors or omissions in the hardware software or documentation are the responsibility of Smart Avionics Ltd and not Mike Goodrich This chapter aims to provide an overview of the rotor balancing process Although the emphasis is on gyroplane rotor balancing it is also largely applicable to helicopter rotors Please see the PB 3 Propeller Balancer Manual and the Red LED Tacho Sensor Manual for details of how the sensors are attached to the aircraft 12 1 Causes Of Rotor Vibration Mass imbalance is one of the causes of rotor vibration and the PB 3 system can help you balance the rotor to eliminate that vibration Other vibrations may also be present
67. ources of vibration must be minimised before dynamic balancing is carried out A Important Unless the engine is running smoothly there is little point in trying to balance the propeller Carburettor imbalance dirty plugs loose engine mounts and general wear and tear are just some of the reasons why the engine could be producing excess vibration Propellers with an adjustable blade pitch will produce a lot of vibration if all the blades are not set to the same pitch This is critical if a blade s pitch differs from its neighbours by even a fraction of a degree it will produce vibration that appears to be caused by mass imbalance but cannot actually be removed by mass balancing A Important Before attempting to dynamically balance a variable pitch propeller either ground adjustable or in flight adjustable confirm that the blades pitch are equal to within the tolerance specified by the propeller s manufacturer typically 0 25 11 2 Propeller mass imbalance A major source of propeller vibration is propeller mass imbalance When an object rotates around an axis if the mass of the object is not uniformly distributed around that axis a force the centripetal force will be generated and will cause vibration As the magnitude of the force is proportional to the square of the rotational velocity at high RPMs high rotational velocity even a small mass imbalance in a propeller will generate an appreciable amount of force and hen
68. r Balance Report www smartavionics com 43 Job Setup Dialog 9 2 Job Setup Dialog 9 2 1 This dialog provides the means to configure the current job Some of the configuration values are specific to the job s mode propeller or rotor The common values are Locked A checkbox that when checked locks the job and all of its points and spectra so that it cannot be configured deleted renamed etc Mode The job s mode Propeller or Rotor Tacho Channel The tachometer channel to use Internal or External Primary Axis The primary accelerometer axis X or Y Capture Both Axes A checkbox that when checked enables data capture for both accelerometer axes Also Capture When this checkbox is checked a spectrum will be Spectra captured immediately after a point is captured Show Point Details When this checkbox is checked the captured point dialog After Capture is displayed automatically after a point is captured X Axis Alias An alternative name for the X axis which will be used in all views Y Axis Alias An alternative name for the Y axis which will be used in all views Propeller mode job setup For propeller mode jobs this item can be configured PSRU Ratio Here you can specify the gearbox ratio of the engine s Propeller Speed Reduction Unit PSRU This ratio is used for two purposes In propeller mode the PB 3 averages multiple propeller cycles for each reading it takes to reduce the effect of en
69. ral leakage and produces a display with fewer artifacts and better frequency resolution This is the default window type Flat Top The Flat Top window reduces the spectral leakage and produces the most accurate magnitudes Set Auto Pause Opens a dialog that lets you choose one of Off 0 01 0 02 IPS Level 0 05 0 1 0 2 0 5 1 2 or 5 for the auto pause IPS level If the spectrum contains a line whose IPS value exceeds the selected level the display will be paused The display can be un paused using the options menu Selecting Off disables the auto pause feature This menu item is not shown when displaying a previously captured spectrum Plot Acceleration A checkbox that controls whether the spectrum is plotted as acceleration G rather than velocity IPS Plot As Curve A checkbox that controls whether the spectrum is plotted as a continuous curve or as individual vertical lines Draw Graticule A checkbox that controls whether a graticule is displayed or not Label Prop Lines A checkbox that controls whether the spectral lines that correspond to integer multiples of the propeller rotor RPM are labelled or not If enabled each spectral line whose RPM is an integer multiple of the propeller rotor RPM has a green label showing the IPS and RPM values along with the appropriate multiplier P 2P 3P 6P for propellers or R 2R 3R 6R for rotors Label Engine Lines A checkbox that controls whether the spectral lines that
70. ration waveform and uses the resulting numbers to calculate The propeller will be statically balanced when the mass of each blade multiplied by the distance from the blade s centre of mass to the centre of the propeller is the same for all the blades 56 www smartavionics com Taking a Vibration Reading the magnitude of the vibration signal This magnitude is reported as a peak velocity in units of Inches Per Second IPS The accelerometer senses the magnitude ofthe vibration but more information is required to carry out the balancing process This is because it is not sufficient to know just the magnitude of the vibration signal It is also necessary to know the phase of that signal The phase of the signal is the relationship of the signal waveform to the angular position of the propeller Given the phase information it is possible to determine where the weight is required to be added to reduce the vibration By detecting when one particular propeller blade passes an optical sensor the balancer can measure and report the phase of the vibration waveform The optical sensor also works as a tachometer to measure the propeller RPM 11 5 Taking a Vibration Reading GU Warning Propellers can kill Make sure that the engine 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
71. s For example to set up the spanwise move line weight is first added to one tip and one or more polar points are captured in that condition Then the weight is moved to the opposite tip and more polar points are captured The move line s nodes are then positioned on the polar chart above the two groups of points The amount of weight added to each tip grams number of washers etc is entered into the move line setup dialog along with an optional name span chord etc and units grams washers inches of tape etc Once the move line is set up the solution for the current polar point will contain a suggested adjustment derived from the position of that point along the move line In move move lines mode the move line nodes are shown as white bubbles containing text 2 2 3 Move line setup dialog The move line setup dialog is used to configure a single move line It contains these items Name The move line s name It is simply used as a label and it doesn t have to be unique or defined at all if you don t want to name the move line Applies To Axis The name X Y or axis alias of the accelerometer axis that this move line is associated with Each move line can only be associated with one axis Units The units of adjustment for this move line Typical move line units are grams washers inches of tape degrees clockwise etc Value A The number of units of adjustment that correspond to t
72. s are installed Remove the sensors and the tape from the propeller blade Make an entry in the appropriate log book to record the vibration level achieved and the RPM used 11 8 Troubleshooting This section provides answers to common problems that can arise when balancing 11 8 1 The displayed RPM is erratic or wrong The RPM could be unsteady for the following reasons most likely first The optical sensor is not pointing at the reflective tape or the tape is not parallel with the sensor s window It may help to add one or more further strips of reflective tape to increase the width of the reflective area The sun is shining directly into the optical sensor s window or being chopped by the propeller The optical sensor is either too close lt 15cm or too far away gt 30cm from the propeller 60 www smartavionics com The current polar point position varies widely The angle of incidence of the infrared beam on the propeller blade is outside the acceptable range 15 40 The sensor is being confused by extra reflections from shiny propeller blades Try increasing the value of Min Tacho Pulses You can also try adding non reflective tape to the other blades in the same position as the reflective tape The engine RPM really is changing 11 8 2 The current polar point position varies widely This indicates that the vibration waveform is not consistent from one propeller revolution to the
73. s i 71 AT Polar Point Data Format sseeseesenenaeeeeererrntrnrretrnrrntrnrrrerrnrrnrenee 71 A 2 Spectrum Data Format 11 BEE et RR I O I 73 www smartavionics com List of Figures TPB P ae 5 2 1 Propeller Mode Polar Chatti illlo rai 8 2 2 Rotor Mode PolarChart acre 10 2 3 Marker Positions When Tape Aligned With Tacho 11 2 4 Marker Positions When Tape Aligned With Master Blade 12 2 5 Moving A MOVE LINE snena teia ei iiaeiai 13 2 6 Move Line Setup Luka ii 15 2 PolarChart Pan amp Z00Mxeic lean 18 DEE RE EE EE a EN 19 4 1 Graph View Cartesian and Polar Formats mosnrsnrnnenvrnvenvrrvrrvennenn 21 FL SPE VIN irlanda 23 5 2 Spectrum Analysis prop sales sne 27 5 3 Spectrum Analysis rotor sura idoli 27 61 Polar Pont EE 29 6 27 Polit Details aS See 32 6 3 Balance Solutron s sacello ai deli 32 TE SPM LS ETNE 35 8 1 Big Capture Button Views balconi 39 9 1 Propeller Balance Report i 43 9 2 Point Logging sa rurale een 46 9 3 Dummy Data SetUp NEA ETT dea 50 T05 Internal Tacho Options saldi 51 T0 2 Polar0ptions asce GSE 52 10 3 Accelerometer Scaling DE 53 VESKE NEVE Lue 56 12 1 Rotor Spectrum With Large x 2 Peak 63 13 1 Two Plane Balancing An Object Supported At Both Ends 68 13 2 Two Plane Balancing An Overhung Object 68 13 3 Two Plane Balancing
74. s per G configuration value Y Axis Counts G 382 which may be edited to alter the scaling Fig 10 3 Accelerometer Scaling Note As the accelerometers are DC coupled you can use gravity to calibrate them With an accelerometer sensing axis pointing straight down the reported G value should be close to either or 1G If you then reorientate the accelerometer so that the sensing axis is straight up the reported G value should be close to 1G again but in the other direction i e if it was ve before now it should be ve and vice versa Some offset is to be expected and does not affect the operation of the balancer so the aim is to get the span to be equal to 2G For example 0 95 to 1 05 has a span of 2 To calibrate an accelerometer axis simply subtract the smaller of the ADC counts per G values from the larger and divide the result If the ADC counts per G value is not shown on the accelerometer label assume a default of 1123 www smartavionics com 53 Accelerometer Scaling Dialog by 2 Enter that number in the input field and then check that the span really is 2G 54 www smartavionics com Chapter 11 Propeller Balancing 11 1 Minimising Other Sources of Vibration Propeller mass imbalance can be a major source of vibration However there are other sources of vibration as well To minimise the overall vibration level and to make the dynamic balancing process more effective all other s
75. t For example there would normally be a move line Style configurable default is dashed Colour configurable default is black 10 www smartavionics com Rotor Mode Markers associated with adding weight to either tip of the rotor blades to adjust the spanwise balance Adding weight to one tip would move the current polar point parallel to that move line in one direction and adding weight to the other tip would move the polar point parallel to that move line in the opposite direction Another common move line is associated with shifting the mass of the rotor system in a chordwise direction The move lines are not required to be orthogonal at 90 to each other Each axis X and Y can have any number of move lines defined and they will all be shown on the chart At any one time a maximum of 2 move lines may be selected to be used in the solution calculation Each job has its own move lines 2 2 1 Rotor Mode Markers The rotor mode markers show you how the accelerometer axes are aligned with the aircraft structure and also where the master blade is positioned at the time the tachometer is triggered Once defined you should not need to alter the position of the markers again unless you change the orientation of the accelerometer or the positions of the tachometer sensor and or the retroreflective tape With the markers correctly set the angles reported by the app can be related to the rotor when it is positioned with the master bla
76. t the strong 2nd harmonic twice per rev vibration that is normally present does not mask the vibration due to imbalance 52 www smartavionics com Accelerometer Scaling Dialog If you are interested in determining the amplitude and phase of a particular harmonic use the appropriate Rotor Harmonic option The Average Points spinner sets the number of polar points to average when calculating the current RPM IPS and DEG values and their associated standard deviations The default value is 5 When the polar mode is set to Propeller the acceleration data is averaged over multiple propeller cycles to reduce the effect of spurious vibration If the PSRU ratio has been set to 1 0 the number of cycles averaged is an even number that is proportional to the sensed RPM The higher the RPM the more cycles are averaged The Min Cycles spinner sets the minimum number of cycles to be averaged when the PSRU ratio is 1 0 The default value is 4 10 3 Accelerometer Scaling Dialog The ADC counts per G values determine the scaling of the Accelerometer Scaling accelerometer inputs Unless the characteristics of the PB 3 or the X Axis Counts 1941 accelerometer are altered these X Axis G 0 277 values should not need changing i from the default For each of the soon 382 accelerometer axes X and Y the Y Axis Counts 1679 current ADC counts value is displayed Y Axis G 0 963 along with the calculated G value and the count
77. ted it is the primary view used when balancing a propeller rotor RPM The data view shows an easy to read numeric display of the IP z g DEG current vibration data The graph view shows a graphical display of the vibration av waveform very much like a simple oscilloscope The spectrum view shows the vibration spectrum it can be a A very useful aid when diagnosing vibration related problems The desired view is selected by pressing the associated tab 2 www smartavionics com Quitting the app If the height of your Android device s display is limited you can set a preference to automatically hide the tabs once you have pressed one When the tabs are hidden the first item in the option menu makes them visible again 1 3 3 Quitting the app To quit the app from a top level view press the Android device s back button Alternatively you can use the Quit App option menu item from any view A dialog will pop up to confirm the action If you would rather not have the confirmation dialog there is a preference to suppress the quit dialog 1 3 4 Jobs The app provides a means of keeping the data associated with each balancing session you carry out separate A job is just a named collection of captured data items polar points and spectra along with a few values that configure the PB 3 s behaviour The most important configuration value is the job s mode which can be either Propeller or Rotor 1 3 5 Status bar
78. the balancing process from the point of view of operating the balancer and determining where balance weights are to be attached The exact detail of how balance weights are attached to the hub or spinner backplate is beyond the scope of this document If you have any doubt please consult your inspector engineer The position and the mass of the required balance weight is determined as follows 1 With no balance weights attached to the propeller capture one or more points Using the captured point dialog choose one of those points to be the start point 2 Now attach a trial weight The angular position of the weight is not important at this stage For a typical composite propeller a few AN970 washers would be a reasonable initial trial weight So having checked the ignition is switched off securely attach the trial weight using an approved method 3 With the trial weight in place capture a few more points When each point is captured the resulting captured point dialog shows a solution that tells you how the amount of weight and its position should be altered to improve the balance If the propeller is well out of balance all of the displayed solutions should be quite similar If the propeller is only slightly out of balance or there is an appreciable amount of vibration from other sources the solutions will vary more and youwill have to interpolate between them Adjust the position and amount of weight accordingly and capture s
79. the name of each move line will be displayed in a bubble positioned on the appropriate line www smartavionics com 17 Panning and Zooming the Polar Chart 2 4 Panning and Zooming the Polar Chart Only available if the legacy modal pan zoom behaviour is enabled In pan zoom mode the Capture button is hidden and two new buttons appear at the top of the view and optionally zoom control RPM buttons appear at the bottom of the G LER DE ali view Propeller Balancer TEST Axis X Tacho Int PSRU 1 0 Log Off Bat 100 The chart can be panned by dragging it with a finger Reset Cancel The chart can be zoomed by using 1 the zoom control buttons or by using pinch zoom gestures if your Android device supports them The visibility of the zoom controls is determined by the show zoom 1675 0 03 4 controls preference The new buttons are Reset centres the chart in the view and zooms out so that the whole chart is visible Cancel exits pan zoom mode without saving any changes To save the changes you have made Fig 2 7 Polar Chart Pan amp Zoom and exit pan zoom mode press the Android device s back button While in pan zoom mode current point tracking is temporarily disabled 18 www smartavionics com Chapter 3 Data View The data view provides a numeric display of the current vibration data values Propeller Balancer JOB LISTPOINTS LIST SPECTRA RPM IPS ale DEG n lt T
80. the propeller hub or spinner backplate to minimise the measured vibration level Because the balancing operation is carried out with the propeller and spinner attached to the engine the best possible solution is obtained The vibration is measured using a sensor known as an accelerometer The accelerometer is securely attached to the engine as close to the propeller as possible and it measures the acceleration of the front of the engine in one direction normal to the propeller shaft If the propeller is out of balance as the centre of mass rotates around the axis of rotation the resulting centripetal force tries to pull the propeller along with the spinner and engine towards the centre of mass This rotating imbalance force acts on the mass of the engine propeller combination and accelerates it It is this acceleration that is measured by the accelerometer If the accelerometer was very selective and measured only the vibration caused by the rotating out of balance propeller the signal it produced for one rotation of the propeller would look like a sine wave as shown here In reality the measured acceleration waveform is much more complex than a simple sine wave This is mainly because of the vibration generated by the engine and also the turbulence generated by the rotating propeller blades The dynamics of the engine mountings also affect the waveform Fig 11 1 Sine Wave The balancer s processing unit digitises the measured accele
81. trum view s context menu now has a Delete Spectra entry available so you can delete that individual spectrum Long pressing the spectrum list pops up a context menu 7 1 Spectrum List Context Menu The spectrum list context menu contains these items Delete Spectra Pops up the delete spectra submenu that lets you delete groups of spectra from the database Note An individual spectra can also be deleted using the spectrum view context menu Change Pops up a list of the currently known unlocked jobs so Spectrum s Job you can choose the job that the currently selected spectrum will be moved to This menu item is not shown when the current job is locked Edit Spectrum s Pops up a dialog that displays the notes for the currently Notes selected spectrum which you can then edit Previously used notes history can be selected from a drop down list which makes it very easy to reuse common phrases e g added washer moved washer forward etc This menu item is not shown when the current job is locked Analyse Spectrum If a spectrum is currently selected this menu item opens an analysis dialog that describes the spectrum Show Only Items Only spectra that have notes will be displayed in the list With Notes Show All Jobs A checkbox that controls whether captured spectra from all jobs are shown or not Show All Axes A checkbox that controls whether captured spectra whose axis differs from the current axis are shown or not
82. ue to a limitation of the Android system changing the language here doesn t have an immediate effect Rotating the screen and selecting the options menu can be sufficient to cause the displayed language to change but you may actually have to completely kill the app and restart it to get the desired result 9 7 2 General Preferences Confirm Quit A checkbox that enables the confirm quit dialog www smartavionics com 49 Dummy Data Setup Dialog Data Source A spinner that chooses the source of the acceleration and tachometer data used by the app In normal operation this should be set to PB 3 so that you can carry out real propeller balancing but it may be set to Dummy in which case the app just uses simulated data Ifyou change this parameter you will need to exit the app and restart it for the change to have an effect When using simulated data the app no longer shows any PB 3 related menu items or dialogs Instead there is a dummy data setup dialog that is accessed through the options menu Exported Image A spinner that chooses the format for exported images Format The choices are JPG and PNG CSV File Suffix The file suffix used for exported CSV files default csv SQL File Suffix The file suffix used for exported SQL files default sql 9 8 Dummy Data Setup Dialog This dialog features a number of sliders that adjust the parameters Dummy Data Setup used to generate the simulated RPM 2200
83. ular to the machine s direction of flight When the blades are perpendicular to the direction of flight more drag is produced Furthermore the amount of x 2 vibration being produced is influenced by the flight conditions rotor speed airspeed etc At this time the PB 3 system can only report the magnitude of the x 2 vibration and it does not offer any suggestions as to how the level of vibration can be reduced Perhaps in the future when the causes of the x 2 vibration are better understood it will be able to make helpful suggestions 12 2 Rotor Mass Balancing When a propeller is balanced it is normally the case that the balance weight can be added almost anywhere on spinner backplate and so both the angular position and amount can be varied as required By contrast gyroplane rotors are mass balanced by making adjustments in one or two fixed axes Spanwise The spanwise balance of a gyroplane rotor can be adjusted by adding weight to one rotor blade tip or the other Chordwise The chordwise balance of a gyroplane rotor is most often adjusted by shifting the mass of the rotor blades along the teeter pivot Exactly how this is done depends on the mechanical design of the particular rotor system but it could involve changing shims or adjusting a threaded component nut barrel etc The amount of movement required is often small a fraction of a mm What you need to know to balance the rotor is how much adjustment magnitude an
84. unt of weight required to correct the imbalance is shown Otherwise for non start points if a start point has been defined for the job instructions on how to improve the balance a solution are displayed The instructions tell you how the position and mass of the trial weight should be altered to reduce the level of vibration Directions are in terms of propeller rotation forward means in the direction of rotation and backwards means opposite to the direction of rotation 0 733 289 IPS 0 733 4 DEG 289 4 RPM 1556 0 AXIS X MODE Propeller AT 2 Jun 2013 13 34 57 TAG GXXXX Vibration level is rough Move the weight forward 163 Increase the weight to 1 24 times what it is now Fig 6 3 Balance Solution The estimate assumes that the engine is less than 100HP larger engines and heavier propellers will require more weight 25 for engines 100 300HP 200 for engines 300 HP 32 www smartavionics com Rotor mode 6 3 2 Rotor mode If move lines have been defined for the current job s primary axis the dialog shows the suggested adjustment for each move line 6 3 3 Captured point dialog context menu Long pressing the the captured point dialog pops up a context menu containing these items Use As Start Point Use this point as a start point This item is only available for propeller mode jobs Show Waveform Opens a graph view to graphically display the acceleration
85. vide the data for the 3 points in the right hand column It is important that when you attach the trial mass you use the same positions as you did previously It is also important that all of the points have the same RPM Enter all 6 points into the two plane balancing view and you will get two solutions one for the mass in each correction plane In the example shown above the plane 1 solution is 50 x 1 18 which says attach a mass that is 1 18 times the trial mass in a position that is 50 backwards against the direction of rotation from the position of the trial mass The plane 2 solution is 82 x 1 14 which says attach a mass that is 1 14 times the trial mass in a position which is 82 forwards in the direction of rotation from the position of the trial mass 13 2 2 Dual accelerometer procedure The procedure when using dual accelerometers is as follows Mount the two accelerometers such that one is sensing the vibration in measurement plane 1 and the other is sensing the vibration in measurement plane 2 With no trial mass attached in either plane capture a couple of points from each accelerometer Attach atrial mass so that it is in correction plane 1 and capture a couple of points from each accelerometer Mark the position of the mass and remove it Now attach the same mass so that it is in correction plane 2 and capture a couple of points from each accelerometer Mark the position of the mass and remove it

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