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Line 44: − + − + + + + + + + + + + + + + + + + + + + + + + + + + − '''August 5 2059 PDT:''' After almost an hour of steady ascent, balloon reaches a maximum altitude of 10.298 km over (37.1502, -121.4077). Ascent rate had fluctuated above and below the initial rate of 3.8 m/s. In theory, a slight acceleration in ascent was expected. By this time the balloon was in the jet stream layer travelling north at nearly 30 m/s. − '''August 5 2103 PDT:''' Balloon reported an altitude of 10.291 km, a highly unexpected measurement. In retrospect, it is believed that venting began at this altitude, but the vent hole was far too small to vent the necessary volume, leading to envelope rupture. The resulting leakage prevented the balloon from reaching the calculated equilibrium altitude of 14-15km and caused what more resembles a latex profile than a zero-pressure balloon profile. − '''August 5 2055 PDT:''' Balloon reported first definitive descent at an altitude of 9.905 km. − '''August 5 2213 PDT:''' After an hour of descent at 2.5 m/s - 3.0 m/s, balloon reported a ground elevation of 29 km. The landing site was less than 100 m from a road in an apple orchard. − '''August 9 0316 PDT:''' Last RockBlock transmission received, with no indication of movement since flight termination.
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'''SSI-92''' (project designation '''CY-6''') was the sixth launch of [[Cycloon|Project Cycloon]] on October 5, 2019. It was the first interstate Cycloon flight, the first launch of a poly tubing ZPB, and the first ZPB flight for which telemetry at equilibrium and descent was acquired since [[SSI-20]]. This enabled the acquisition of valuable thermal data and verification of equilibrium altitude predictions. Continuing a trend, the payload was lighter still than that of its predecessor, [[SSI-91]].
'''SSI-92''' (project designation '''CY-6''') was the sixth launch of [[Cycloon|Project Cycloon]] on October 5, 2019. It was the first interstate Cycloon flight (and to-date longest distance), the first launch of a poly tubing ZPB, and the first ZPB flight for which telemetry at equilibrium and descent was acquired since [[SSI-20]]. This enabled the acquisition of valuable thermal data and verification of equilibrium altitude predictions. Continuing a trend, the payload was lighter still than that of its predecessor, [[SSI-91]].
==Project context==
==Project context==
'''Balloon''': 0.8 mil polyethylene tubing, paper bag topology, width 2.5 m, length 10 m, volume approximately 17.5 cubic meters. Total mass 1 kg with fill tube (PVC of length approximately 12 inches and diameter 1/2 inch).
'''Balloon''': 0.8 mil polyethylene tubing, paper bag topology, width 2.5 m, length 10 m, volume approximately 17.5 cubic meters. Total mass 1 kg with fill tube (PVC of length approximately 12 inches and diameter 1/2 inch).
'''Avionics''': TinyGPS, Teensy 3.2, BMP 280 transmitting at adjustable intervals over Rockblock. A SPOT Trace was accidentally omitted. This set of avionics was recovered [[SSI-91|CY-5]]. Controlled novel cutdown mechanism.
'''Avionics''': TinyGPS, Teensy 3.2, BMP 280 transmitting at adjustable intervals over Rockblock. A SPOT Trace was accidentally omitted. This set of avionics was recovered from [[SSI-91|CY-5]]. Controlled novel cutdown mechanism.
'''Power''': 9 L91 lithium AA batteries. 3 L91 lithium AA batteries on cutdown.
'''Power''': 9 L91 lithium AA batteries. 3 L91 lithium AA batteries on cutdown.
[[File:Ssi91profile.png|400px|thumb|right|The altitude profile resembled a standard latex launch due to reasons discussed in the synopsis]]
[[File:Ssi91profile.png|400px|thumb|right|The altitude profile resembled a standard latex launch due to reasons discussed in the synopsis]]
Inflation was eventful thanks to strong ground winds from due west. The envelope ruptured midway through filling and was patched before refilling. Additionally, a hole approximately 5 mm in diameter was patched.
Conditions at the launch site were ideal. Inflation was remarkably uneventful.
'''August 5 2011 PDT:''' Balloon released from a running start. Initial motion to the east at an ascent rate of 3.8 m/s --- significantly faster than the target ascent rate of 2.5 m/s.
'''October 5 1100 PDT:''' Balloon released --- no running start needed. Free lift was measured at approximately 0.5 kg. Initial ascent at about 2.5 m/s. Nearly no horizontal initial motion, followed by a gradual drift to the southwest and then southeast.
'''October 5 1219 PDT:''' Balloon appeared to equilibrate at 17.43 km, having ascended at 4 - 5 m/s in the second half of its ascent. Within significant figures, this was essential equal to the predicted equilibration altitude of 17.37 km. At the point the balloon had been moving due east and had been crossing the Diablo range.
'''October 5 1225 PDT''' Balloon reached a maximum altitude of 17463 m, at 36.929, -120.947 over the eastern foothills of the Diablo range. In the ensuing hours, the trajectory fluctuated within the rates of +/- 0.3 m/s, which was considered a very successful equilibration.
'''October 5 1547 PDT''' At this time, the balloon was over the peaks of the Sierra Nevada (John Muir wilderness), yet still held an altitude of 16.4 km.
'''October 5 1602 PDT''' GPS lost lock over 37.198, -118.72 at an altitude of 16330 km. This sparked intense speculation, and the rapidly dropping temperature of -22 C was momentarily blamed. During the lock, the barometer and Iridium triangulation functioned as telemetry.
'''October 5 1729 PDT''' In the previous 15 minutes, Iridium had been reporting with increasing confidence from Nevada, so an interstate transition was declared. By this time, the balloon was just above 15 km in altitude, having stalled its descent over the past half hour. Now, however, descent began in earnest.
'''October 5 1839 PDT''' Altitude was around 13.8 km, and descent rate increased to around 1 m/s, marking an inflection point. Landing was predicted near St George, UT.
'''October 5 1903 PDT''' Altitude near 11.5 km. Descent rate stabilized near 2 m/s and fluctuated around this value for the next hour or so.
'''October 5 1917 PDT''' GPS signal returned at an altitude of 9745 m. The temperature was -37 C, disfavoring the cold hypothesis. Instead, the threshholds of 10 km and 1600 PDT were noted with suspicion.
'''October 5 1924 PDT''' At an altitude of 8914 m and a descent rate just above 2 m/s, an impact at 2030 PDT near US-93 was predicted.
'''October 5 1828 PDT''' Landing declared at a ground elevation of 1511 m. Descent just before impact had slowed somewhat, consistent with predictions.
'''October 9 1035 PDT''' Last RockBlock comm, having shown no movement since landing.
'''Otober
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[[Category: High Altitude Balloons]][[Category: Balloon Launches]]
[[Category: High Altitude Balloons]][[Category: Balloon Launches]]