Separated Payload Finder

On occasion, a payload will fearlessly attempt a return to the earth without the benefit of a sheltered existence under a parachute. You can use this calculator to attempt to find it.

Step one. You need to load the Flight Data file created by the Packet Terminal screen. If you did not use Balloon Track to capture this file during the flight, then run an APRS capture through the Packet Terminal in Simulation mode and the file will be created.

IMPORTANT: Your APRS file MUST have timestamps either in the form of timestamps transmitted within the APRS string or timestamps as added by's system. This is critically important as the winds aloft data is generated by knowing the passage of time between packets to determine wind speed (actually balloon speed but it's the same thing).

Step two. Enter the estimated descent rate of your separated payload in feet per minute at sea level. Watch out for this one as the program "helpfully" fills this in with the descent rate you currently have entered on the program configuration (Setup) screen.

Step three. If you want a range and bearing from a location you can enter it in the select bearing site box. You can manually enter any location you wish however, if you click on the drop down button a list of all locations in your Launch Sites, Landing Sites, Alternate Sites and VOR Sites files will be available. Bearing and range results will be in Statute Miles and degrees true for standard locations and for VORs only, nautical miles and degrees magnetic. However, for the VOR degrees to be magnetic you must take the manual step of checking the VOR box. This parameter is also automatically filled out with the launch location indicated on the setup screen for the program.

Step four. In the Export Options box, select a format to export to, comma delimited, APRS or Street Atlas.

Step five. In the middle of the screen kind of hidden away are some additional Export options. You can limit the export to records with a minimum of 10,000 feet of altitude separation. You can limit the export to the ascent phase of the flight only. Or you can select both or neither. I added this ability so that much smaller files could be created which might be sent via the APRS network to tracking teams in the field.

Ok, you're halfway there. Click RUN. The program then does several things.

1.) It reads the data from the Flight Data file and generates a new Winds Aloft data file based on that data encountered by the balloon as it ascended (most accurate).

2.) The program then runs a drop prediction based on that wind data for each altitude of every record in your Flight Data file. The program uses the latitude and longitude of the balloon at that altitude position to initialize the drop calculation. The results of this global calculation are displayed in the table at the bottom of the screen. If you have selected to limit the export to every 10K feet or ascent only that will NOT be reflected here. This is the entire run with every record showing. The limitations on export will be applied as the export file is created.

NOTE: The altitude generated for all these records is the Separation Altitude, NOT the altitude of the balloon. These positions are all touchdown predictions located on the ground.

Now, click on Export. Depending on which type of export you indicated one of these dialog boxes will display.



Make the appropriate selections and click the export button and you're done. The export file will be created in the location you indicated when selecting a name for the file. If you typed the file name in then the file will be located either in the folder designated on the setup screen for holding Log Files or, if you haven't designated one, in the application's home folder.

After you have imported your file into a mapping  or APRS program you might think you are actually looking at a flight track.

NO!! Well, not really. This series of positions are the many landing locations predicted from all those altitudes, latitude and longitudes in the Flight Data file.

If you have selected to include labels for the Street Atlas (SA) export then the map will be pretty cluttered with text. However, if you zoom down with SA you will be able to make out the individual labels.

In its first incarnation this routine helped find a "lost" payload from a recent flight (with the aid of a helicopter following the "track" of the various landing positions).