FAQ

updating the Flight Coach software, using it offline
After the first online use, the FlightCoach will work offline automatically; just point your browser to the same https://www.flightcoach.org/ribbon/plotter.html link.
Fc is using your browser caching Service Worker technology to automatically ‘install’ and update itself with the new software version. It including storing it on your device for offline use.
FC displays your current and available versions in the top left corner. If they differ then your SW will update itself (must be online for updates). The browser cashing is a bit complex as it needs to cater for several scenarios, including supporting older versions if a user is still using them.
If you wish to test it, access FC online and then disconnect your device from the Internet and access the FC link again, it should work.
In case when the software does not update automatically, the steps below apply gentle persuasion to the browser to refresh its cache. If it does not work, a full cache reset needs to be performed. Follow your OS/browser instructions. Some operating systems and browsers are more stubborn then others.
To make sure that you use the latest SW please apply the following:
- close all the browser tabs that are running FC. Best is to close all the tabs and restart the browser
- make sure that you are online
- open the plotter from flightcoach.org/ribbon/plotter.html and wait for the load to finish (model should appear). Perform hard refresh:
  - Win, Linux, Android – in Chrome on a device with keyboard
    - Ctrl-Shift-R
  - Android – in Chrome on a device with no keyboard
    - go to Settings > Site Settings > Data Stored
    - find fligthcoach.org, click on it
    - hit Clear & Reset button, it will clear all data for FC only
    - exit Settings and refresh FC using the Reload icon (rounded arrow) from Options (three vertical dots)
    - optionally, instead of doing the above, check and uncheck the Desktop Site in Options (3 vertical dots). It makes the browser to hard refresh the data for this site and updates the cache with the latest SW
  - iOS with keyboard – open FC in Safari. Keypress and hold the Command button on the keyboard. Within the URL bar, click on the refresh icon reload arrow icon in the browser
  - iOS with no keyboard – open FC in Safari. Within the URL bar, click on the refresh icon reload arrow icon in the browser. If it does not work, the entire cache in the browser must be cleared.
log BIN files are not created
- incorrect firmware – install fixed wing from ardupilot.org
- incorrect parameters – install latest from this site
- HW not powered or not functioning – confirm that GPS is working
- missing SD Card
what is the size of log files
- typical file will have 12-15M size (6-7 min F3A flight). This is assuming that the Ardupilot is initialised just before the flight and switched off upon landing
how can I see what is in the log file
- use Ground Station software (like Mission Planner) to access the logs. You can also open the log file directly (using a hex editor), this is advanced users option only.
plotter does not open BIN file. The Site Selection dialog does not appear or does not progress further
- plotter has been designed to work on latest browsers (Chrome or Safari) using relatively modern technologies. Please check that your Operating System (OS) has been upgraded including the browser. Using older OS or browser versions as well other browsers may not work.
- plotter application needs access to local file system, javascript and caching apps must be allowed. Please check your OS settings
- Some of the devices used may have work company OS versions or polices installed that may restrict plotter functionality. Please check the BIN file on other devices. If it works (and usually it does) the issue is with the local device.
- Please refer to the ‘debugging plotter and BIN file issues’ below for further steps especially monitoring the browser javascript console
Plotter does not show any data from BIN file (BIN Converter did not find useful XKF1 data in the BIN file message)
- Hardware issues
  - incorrect parameters in Ardupilot for the Kalman Filter to work properly. Please load the parameters from this website (Setup/Configuring Ardupilot). Confirm that they have been correctly loaded using Compare functionality in the Mission Planner
  - GPS is not working or not sending data to Ardupilot. Check cables, LED blinking, review GPS log data in Mission Planner
  - The system did not arm or armed late. For the system to arm properly it needs to be stationary and with no vibrations sensed by the accelerometers. It means that it should be started when the vehicle is on the ground, not moving and with stopped engine. You need to hear the arming sounds and the LED needs to go to solid green before you can proceed
- Plotter software does additional checks in the log, discarding data where
  - some position values are 0. A number of initial log points may be recorded with missing values (set to 0), that is how the filter works. Record sufficient amount of data for filter to stabilise. Review the log file XKF1 data in Mission Planner
  - there is no points available that are above the -10m altitude. Highly unlikely, indicates seriously compromised altitude from GPS. For ground tests, please use the GroundTest/Test style at the bottom of the list
- Plotter will discard the entire log (valid or not) if the provided Site coordinates are too far from the Origin (Provided site GPS coordinates are more than 120m from the origin message). Re read the BIN file again and use manual option with Copy Origin button
File contains no valid data points message
- Plotter filters out the data below the selected schedule minimum threshold relative to the GPS Origin. If the GPS Origin has been incorrectly captured high, the entire log may be rejected. The only solution is to fly again and hope that the GPS record the Origin with correct altitude
how to initialise system so it has the correct Origin
- Origin is captured when GPS has locked in and several other conditions are met, like model velocities are very small, etc. This is needed to have the Origin as accurate as possible. To facilitate it, the model shall be stationary and less than 120m from your pilot position, and (roughly) leveled and then controller shall be powered. It will go through initialisation sequence including arming itself and will wait for the GPS to lock in. First time on the day it may take longer, otherwise it should be 2-5 s. On some HWs, the blue LED goes green and another blue LED in GPS starts blinking. It means that the Origin has been defined, time to go flying. Confirm indications on your HW. Otherwise, when you carry the model or you are already flying, the Origin may not be set at all or set in some remote position.
- BTW, all displayed GPS position (Origin, Pilot, Center) are links that will take you to Google Maps, just click them.
- Origin can be manually adjusted in Settings. The three additional controls on the right allow moving the Origin sideways and up and down. Setting values are stored so please remember to reset it to 0,0,0 for your next flight.
my flying site is not in the database
- enter the site data manually, both the pilot and center line point (the center line stretches from the pilot position away towards the horizon and divides the flying space into the left and right. The center point is a point anywhere on the center line, the further out the better accuracy of the angle). If unknown or the Origin is more than 120m away, select Copy Origin button after selecting the manual site.
- send as the details (country, district, locality, site, pilot’s GPS, center point GPS). Find accurate pilot’s GPS and center point GPS (no more than 100-120m away from the pilot) and send us the details. Use this FORM
the origin is more than 120m
- in the next flight initialise the system with 120m from pilots position. The limit is there so the system can differentiate more than 1 site in the same location
- If you want to ‘recover’ a log captured with Origin set ‘on the move’ or Origin further than 120m, you may try selecting manual site and pressing Copy Origin button. It should show the ribbon although the center line direction will be skewed. If Origin in the dialog shows 0,0,0 – bad luck.
there are steps and jumps in the flight path
- please redo your gyro, accelerometers and compass calibration. Refer to https://www.flightcoach.org/log_file/
- GPS is catching up with satellites and calculations, just keep using it, next flight will be better. If it persists, maybe your GPS receiver is covered with something metallic, review HW installation. Try installing the latest parameters from this website
- mount the hardware containing sensors in a way that is isolated from the frame vibrations (use soft foam)
- make sure that the HW is sufficiently powered. Some SBEC/power boards powered directly from flight batteries need at least 4 cells to power them to smooth out voltage variations
why this color selection
- experimentally selected for the best visibility in outdoor application on a laptop
can I load my own model airplane to the plotter
- at this stage, no
debugging plotter and BIN file issues
- open to plotter, please use Ctrl-Shift-r to fully reload the plotter from the website
- open Inspect window Ctrl-Shift-i (Chrome only) and see what messages (if any) do you see in Console tab. You can ignore the font errors. Then try to load a BIN file and check console again.
- download and Open the demo JSON flight from the website.
- if you can see the flight and there is no errors it points to a sus BIN file.
- load your BIN file into Mission Planner and see if you can extract any kind of data
- confirm that you have used correct FM in controller with our copy (from website) of parameters written to the controller. Plotter looks for specific parameters and some may not be enabled in default setup. They are XKF1, XKF2, ORGN. Please see if you can see them in the log in Mission Planner.
- BIN may slightly vary between vendors. Please sends us your BIN file.
keeping record of my flights
- it is safer to keep the BIN version of the files for long term storage. JSON file format is still evolving and may change, making the older version obsolete. JSON is handy to share the files with other pilots that use the same version of the plotter.
how accurate is Flight Coach
- our tests show that the flight (absolute) positioning matches the best GPS positioning accuracy (2-3 meters). Because GPS positioning is augmented with inertial navigation using Extended Kalman filters the recorded flight path averages GPS positions (and errors) and smooth the path delivering appearance of much higher accuracy. Attitude of the model is presented with a single degree precision.
  - untrained human – 50-150m
  - trained human – 20-50m
  - this system – 2-3m
  - differential 2000$ GPS systems – 10cm
how secure is the app
- application uses cookies to store last use app settings locally and it only includes ribbon width, model wingspan, schedule, pilot and center GPS positions, site name
- application caches all its source code in javascript, site and schedule dB and model shape in the browser app cache for offline use
- the app does NOT send to network ANY data related to the user, device, flight, etc.
graphs and ribbon coloring
- the graphs have been normalised:
  - roll – 0 deg, level flight (upright or inverted), -90/90 deg, knife edge the the left/right
  - pitch – -90/0/90, down/level/up
  - yaw – 0 deg, flying to the right, -180/180, flying to the left, 90/-90, out/in, in order to save real estate the yaw is displayed as a half value to match the -90/90 deg scale of the other graphs, numerical value needs to be doubled
- while the pitch and yaw are calculated from the model attitude translated to the extrinsic (pegged to this planet, does not move) ThreeJS XYZ coordinate system, the roll is calculated in the model’s intrinsic (pegged to the model, moves with the model) coordinate system. It helps to present the crossbox maneuvers better. At some selected points the roll needs to change the sign (rotation maths) and it shows as a narrow stripe on the ribbon that is safe to ignore. The roll numerical value is matched to 15 deg color shades. Unlike in the graphs, the upright and inverted level flight are presented as different colors.
Missing Messages and SD Card management
- FlightCoach has ability to use several types of Ardupilot messages (sources XFK1, ATT, POS) to derive the flight path. Some of the messages are more sensitivities to the SD Card issues than others. Each source messages are tested for missing messages in order to deliver a quality flight path. If a source has too many missing messages (current threshold is 30), the source is rejected and the source selection defaults to XFK1 source (much more robust to missing messages)
- Ardupilot SD Card logging outs a high demand on the SD Card writing speed performance. It is highly recommended to use SD Cards with high writing speed performance. The performance can be tested using a variety of widely available tools
- Our experience shows that it is beneficial to create a 16GB partition only on the SD Card (even is the SD Card provides larger size) and to reformat the partition at the first sign of missing messages. Re formatting is the easiest way to resolve any SD Card or file system issues that impacts writing performance (store any previous log files elsewhere before reformatting)
- Ardupilot logging performance (less missing messages) is affected by the LOG_FILE_BUFSIZE Ardupilot parameter (Maximum AP_Logger File and Block Backend buffer size (in kilobytes). The File and Block backends use a buffer to store data before writing to the SD Card. Raising this value may reduce missing messages in your SD card logging. This buffer size may be reduced depending on available memory. User may experiment with values ranging from 4-64.
Adding a new schedule
- We can add new schedules to the FC and release them to everyone. No “private” schedules can be added with limited visibility
- To add a new schedule, please let us know where does it fit into the schedules hierarchy (F3A FAI, F3A UK, US AMA, IMAC, F3C, F3S, F2B, Generic, Ground Test).
- We also need
  - name of the schedule (e.g. P25, Unlimited)
  - minimum altitude (usually it is set to 10m)
  - model to display (current options are biplane, monoplane, jet, heli). There is an option to add other models but it needs to be managed separately
  - maneuvers
    - short name (3-6 chars)
    - K factor
    - % split (width wd)
- The splits % can be read from a (well flown) JSON file that will serve as a split template. When the JSON file is opened in a text editor a “mans” section contains split information. Each maneuver has a “wd” parameter from the splitter. We always allocate 5% for the Takeoff and subsequent values can be read from the JSON. Total % for all maneuvers should add to 100% so usually Landing picks up the slack. Please round to 1-2 decimal places.
  
  In the example below, tkoff would be 5%, sLoop 6.44%, etc.
  
  “mans”: [
  {
  “name”: “tkoff”,
  “k”: 0,
  …
  “wd”: 8.384094754653127,
  …
  },
  {
  “name”: “sLoop”,
  “k”: 5,
  …
  “wd”: 6.435984207557812,
  …
  },

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