This flight was launched the evening of 10/27/2014. This evening flight to test out a few ideas and attempt to capture images of a rocket flight out of Wallops Island just up the coast. Sadly the rocket launch was scrubbed at the last minute due to a stray boat in the launch area.
The payload consisted of the old blue plastic box (11th flight) with three wide angle video cameras; each set to different exposure values (one with its IR filter removed -- giving everything a pink hue). A strobe light was attached to the bottom of the payload. APRS and Spot provided tracking. And a radio controlled nichrome cut-down system was included to ease removal from a tree (including this seems to prevent our payloads from landing in trees). This totaled 1kg including parachute. The balloon was 600g and was filled to 2100g of neck lift with H2.
The balloon launch was timed, not only to cover most of the NASA launch window; but also to see if the balloon would be visible at altitude from observers on the ground (the sun sets about 18 minutes later up there). Also the International Space Station was scheduled to pass overhead. The balloon was NOT visible from the ground, nor was its strobe. The use of the wide angle lenses really shrunk images (notice how small the moon is in the above image), and the ISS was not seen. One can assume that the NASA flight would not have been visible either, if it had launched. The strobe charge circuit produced an EMP which was visible on the videos (stronger the closer the camera was to the strobe).
Ascent was rather turbulent. Although the jet stream was calm, there were times when the payload was tossed out horizontally from the balloon (see middle of ascent rate graph below). This turbulence also unfurled the parachute earlier than expected, but by that time the payload was above 10km, so the ascent rate didn't drop too low.
The flight followed its predicted path very closely. It burst early, but that was expected. Previous night flights ended early as well, presumably due to lack of solar heating on the latex balloon (making it cold and brittle). On this flight, almost all of the balloon returned with the payload -- only the very top of the balloon had failed. The balloon was completely intact within a meter of its neck [A quick use of a wire tie to close up the hole and we now have a 300g balloon for ground demonstrations]. The burst itself was barely discernible on video, only the increasing rush of air as it fell gave away that burst had happened.
Knowing that most of the balloon might survive, the payload was equipped with a under-hung parachute that would keep it 7m away from the payload. The parachute though, tangled during descent and the payload fell at ~10m/s. The large piece of balloon remaining 2m below the parachute created air turbulence that caused the chute to twist-up and fail [Note for the future: The chute should be >10m away from the payload instead of 7m]. All equipment survived the 'landing' in grass and all three cameras recorded a satisfying THUD upon impact.
Prediction prior to launch per HABHUB.
Running several of these predictions ahead of time and then saving the resulting KML files, allows the flight team to pick the correct prediction based upon actual launch conditions. In the case of this flight, we were just positively buoyant with a neck weight of 2kg before launch. By choosing the saved prediction with 2.1kg of neck lift we were able to closely match the actual flight.