Here are a cople of code times that provide a realtime update of balloon position on google earth etc.

<?xml version="1.0" encoding="UTF-8"?>
<kml xmlns="http://earth.google.com/kml/2.1">
<Document>
  <NetworkLink>
    <Link>
      <href>test2.kml</href>
      <refreshMode>onInterval</refreshMode>
	<refreshInterval>10</refreshInterval>
    </Link>
  </NetworkLink>
</Document>
</kml>

<?xml version="1.0" encoding="UTF-8"?>
<kml xmlns="http://earth.google.com/kml/2.1">
<Document>
    <Style id="track">
      <LineStyle>
        <color>fff010c0</color>
      </LineStyle>
      <PolyStyle>
        <color>3fc00880</color>
      </PolyStyle>
    </Style>

    <Style id="place">
      <IconStyle>
        <scale>1</scale>
        <Icon>
          <href>http://weather.uwyo.edu/icons/purple.gif</href>
        </Icon>
      </IconStyle>
    </Style>

      <Placemark>
        <name>Launch</name>
        <styleUrl>#place</styleUrl>
        <description>Launch location was ... at ...</description>
        <Point>
          <altitudeMode>absolute</altitudeMode>
          <coordinates>-0.092096,52.250872,55</coordinates>
       </Point>
      </Placemark>

    <Placemark>
      <name>Flight Path</name>
      <styleUrl>#track</styleUrl>
      <LineString>
        <extrude>1</extrude>
        <altitudeMode>absolute</altitudeMode>
        <coordinates>
  -0.092096, 52.250872,   55
  -0.089721, 52.252995,  166
  -0.082192, 52.258184,  379
  -0.072153, 52.263721,  597
  -0.059924, 52.269104,  819
  -0.030587, 52.277540, 1279
   0.002241, 52.283403, 1761
   0.035656, 52.288259, 2269
   0.069353, 52.292391, 2803
   0.102276, 52.297056, 3368
   0.132938, 52.303864, 3970
        </coordinates> 
     </LineString>
    </Placemark>

      <Placemark>
        <name>Position Now</name>
        <styleUrl>#place</styleUrl>
        <description>Current Position is ... at ...</description>
        <Point>
          <altitudeMode>absolute</altitudeMode>
          <coordinates>   0.132938, 52.303864, 3970
          </coordinates>
        </Point>
      </Placemark>

  </Document>
</kml>