SSI-92 - Revision history

Bjing at 22:34, 7 December 2019

2019-12-07T22:34:16Z

← Older revision		Revision as of 22:34, 7 December 2019
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	[[SSI-91]] was a milestone in realizing flights with in-house manufactured ZPBs, yet due to unexpected termination no data on the equilibrium altitude and descent characteristics were obtained, thus failing to fulfill one of the major objectives of that flight. Meanwhile, a candid assessment of the ZPB manufacturing process proved discouraging. In mid to late August, a new manufacturing technique was devised based on commercially available polyethylene tubing, which promised to be far more durable and scalable. (The altitude limitations were deemed acceptable for the time being). Orders for commercial tubing were placed, set to arrive in September. In light of these developments, a third summer ZPB launch which had been planned for the weekend of September 1 was cancelled.		[[SSI-91]] was a milestone in realizing flights with in-house manufactured ZPBs, yet due to unexpected termination no data on the equilibrium altitude and descent characteristics were obtained, thus failing to fulfill one of the major objectives of that flight. Meanwhile, a candid assessment of the ZPB manufacturing process proved discouraging. In mid to late August, a new manufacturing technique was devised based on commercially available polyethylene tubing, which promised to be far more durable and scalable. (The altitude limitations were deemed acceptable for the time being). Orders for commercial tubing were placed, set to arrive in September. In light of these developments, a third summer ZPB launch which had been planned for the weekend of September 1 was cancelled.

	With the end of the summer, onboarding approached, and it was hoped to do a Cycloon demonstration launch very near the beginning of the year, on '''October 5, 2019'''. Ideally this would be ballast-controlled, collecting data and paving the way for a fully controlled launch in the middle of the quarter. It was also hoped to do this launch from Pigeon Point, but by September 23, wind forecasts proved unfavorable. Additionally, momentarily it was planned to launch two ballast controlled balloons (as a means of forcing Cycloon to self-manufacture a ballast mechanism), but as 3D printing attempts in the last week of September failed, it was decided to fly only one standard (non-controlled) ZPB. Nevertheless, a significant worksession on September 29 produced two balloons and two sets of avionics (one new, one recovered from [[SSI-91]].		With the end of the summer, onboarding approached, and it was hoped to do a Cycloon demonstration launch very near the beginning of the year, on '''October 5, 2019'''. Ideally this would be ballast-controlled, collecting data and paving the way for a fully controlled launch in the middle of the quarter. It was also hoped to do this launch from Pigeon Point, but by September 23, wind forecasts proved unfavorable. Additionally, momentarily it was planned to launch two ballast controlled balloons (as a means of forcing Cycloon to self-manufacture a ballast mechanism), but as 3D printing attempts in the last week of September failed, it was decided to fly only one standard (non-controlled) ZPB. Nevertheless, a significant worksession on September 29 produced two balloons and two sets of avionics (one new, one recovered from [[SSI-91]]).

	Relatively close to the day of the launch, demands for an improved cutdown mechanism intensified. Amidst an absence of nichrome, a novel cutdown mechanism involving two ematches and a socket was devised, implemented, and tested the night of October 4.		Relatively close to the day of the launch, demands for an improved cutdown mechanism intensified. Amidst an absence of nichrome, a novel cutdown mechanism involving two ematches and a socket was devised, implemented, and tested the night of October 4.

Bjing at 09:58, 6 December 2019

2019-12-06T09:58:22Z

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	\| launch coordinates = 36.849, -121.433		\| launch coordinates = 36.849, -121.433
	\| flight duration = 9h:28m		\| flight duration = 9h:28m
	\| flight length =		\| flight length = 564 km
	\| flight profile = Standard zero pressure		\| flight profile = Standard zero pressure
	\| landing time = October 5, 2019, 20:38 PDT		\| landing time = October 5, 2019, 20:38 PDT

Bjing at 08:47, 6 December 2019

2019-12-06T08:47:41Z

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	[[File:ssi92rates.png\|400px\|thumb\|right\|Ascent rates against altitude]]		[[File:ssi92rates.png\|400px\|thumb\|right\|Ascent rates against altitude]]

			[[File:Ssi92profile.png\|600px\|thumb\|right\|Flight profile]]
	Conditions at the launch site were ideal. Inflation was remarkably uneventful.		Conditions at the launch site were ideal. Inflation was remarkably uneventful.

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	'''October 9 1035 PDT''' Last RockBlock comm, having shown no movement since landing.		'''October 9 1035 PDT''' Last RockBlock comm, having shown no movement since landing.

	[[File:~~Ssi92profile~~.png\|800px\|thumb\|center\|Flight ~~profile~~]]		[[File:Ssi92traj.png\|800px\|thumb\|center\|Flight trajectory up until loss of GPS]]
	{{balloon-footer}}		{{balloon-footer}}

	[[Category: High Altitude Balloons]][[Category: Balloon Launches]]		[[Category: High Altitude Balloons]][[Category: Balloon Launches]]

Bjing at 08:46, 6 December 2019

2019-12-06T08:46:00Z

← Older revision		Revision as of 08:46, 6 December 2019
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	==Flight synopsis==		==Flight synopsis==

	[[File:~~ssi91traj.png\|400px\|thumb\|Mission trajectory]]~~		[[File:ssi92rates.png\|400px\|thumb\|right\|Ascent rates against altitude]]
	~~[[File:ssi91launch.png\|400px\|thumb\|left\|Balloon ascending after release]]~~
	~~[[File:Ssi91profile~~.png\|400px\|thumb\|right\|~~The~~ altitude ~~profile resembled a standard latex launch due to reasons discussed in the synopsis~~]]

	Conditions at the launch site were ideal. Inflation was remarkably uneventful.		Conditions at the launch site were ideal. Inflation was remarkably uneventful.
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	'''October 9 1035 PDT''' Last RockBlock comm, having shown no movement since landing.		'''October 9 1035 PDT''' Last RockBlock comm, having shown no movement since landing.

			[[File:Ssi92profile.png\|800px\|thumb\|center\|Flight profile]]
	{{balloon-footer}}		{{balloon-footer}}

	[[Category: High Altitude Balloons]][[Category: Balloon Launches]]		[[Category: High Altitude Balloons]][[Category: Balloon Launches]]

Bjing at 08:39, 6 December 2019

2019-12-06T08:39:36Z

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	{{balloon-launch		{{balloon-launch
	\| header = SSI-82		\| header = SSI-92
	\| img link =		\| img link =
	\| designations = '''CY-6'''		\| designations = '''CY-6'''
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	'''October 9 1035 PDT''' Last RockBlock comm, having shown no movement since landing.		'''October 9 1035 PDT''' Last RockBlock comm, having shown no movement since landing.

	~~'''Otober~~

Bjing at 08:39, 6 December 2019

2019-12-06T08:39:14Z

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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==
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	'''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.
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	[[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

	'''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.~~

	{{balloon-footer}}		{{balloon-footer}}

	[[Category: High Altitude Balloons]][[Category: Balloon Launches]]		[[Category: High Altitude Balloons]][[Category: Balloon Launches]]

Bjing at 07:47, 6 December 2019

2019-12-06T07:47:57Z

← Older revision		Revision as of 07:47, 6 December 2019
Line 16:		Line 16:
	}}		}}

	'''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.		'''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]].

	==Project context==		==Project context==
Line 22:		Line 22:
	[[SSI-91]] was a milestone in realizing flights with in-house manufactured ZPBs, yet due to unexpected termination no data on the equilibrium altitude and descent characteristics were obtained, thus failing to fulfill one of the major objectives of that flight. Meanwhile, a candid assessment of the ZPB manufacturing process proved discouraging. In mid to late August, a new manufacturing technique was devised based on commercially available polyethylene tubing, which promised to be far more durable and scalable. (The altitude limitations were deemed acceptable for the time being). Orders for commercial tubing were placed, set to arrive in September. In light of these developments, a third summer ZPB launch which had been planned for the weekend of September 1 was cancelled.		[[SSI-91]] was a milestone in realizing flights with in-house manufactured ZPBs, yet due to unexpected termination no data on the equilibrium altitude and descent characteristics were obtained, thus failing to fulfill one of the major objectives of that flight. Meanwhile, a candid assessment of the ZPB manufacturing process proved discouraging. In mid to late August, a new manufacturing technique was devised based on commercially available polyethylene tubing, which promised to be far more durable and scalable. (The altitude limitations were deemed acceptable for the time being). Orders for commercial tubing were placed, set to arrive in September. In light of these developments, a third summer ZPB launch which had been planned for the weekend of September 1 was cancelled.

	With the end of the summer, onboarding approached, and it was hoped to do a Cycloon demonstration launch very near the beginning of the year, on '''October 5, 2019'''. Ideally this would be ballast-controlled, collecting data and paving the way for a fully controlled launch in the middle of the quarter. It was also hoped to do this launch from Pigeon Point, but by September 23, wind forecasts proved unfavorable. Additionally, momentarily it was planned to launch two ballast controlled balloons (as a means of forcing Cycloon to self-manufacture a ballast mechanism), but as 3D printing attempts in the last week of September failed, ~~this too~~ was ~~discarded~~. Nevertheless, a significant worksession on September 29 produced two balloons and two sets of avionics (one new, one recovered from [[SSI-91]].		With the end of the summer, onboarding approached, and it was hoped to do a Cycloon demonstration launch very near the beginning of the year, on '''October 5, 2019'''. Ideally this would be ballast-controlled, collecting data and paving the way for a fully controlled launch in the middle of the quarter. It was also hoped to do this launch from Pigeon Point, but by September 23, wind forecasts proved unfavorable. Additionally, momentarily it was planned to launch two ballast controlled balloons (as a means of forcing Cycloon to self-manufacture a ballast mechanism), but as 3D printing attempts in the last week of September failed, it was decided to fly only one standard (non-controlled) ZPB. Nevertheless, a significant worksession on September 29 produced two balloons and two sets of avionics (one new, one recovered from [[SSI-91]].

	Relatively ~~near~~ the ~~flight~~, demands for an improved cutdown mechanism intensified. Amidst an absence of nichrome, a novel cutdown mechanism involving two ematches and a socket was devised, implemented, and tested the night of October 4.		Relatively close to the day of the launch, demands for an improved cutdown mechanism intensified. Amidst an absence of nichrome, a novel cutdown mechanism involving two ematches and a socket was devised, implemented, and tested the night of October 4.

	==Configuration==		==Configuration==

	'''Balloon''': 0.3 mil polyethylene, paper bag topology, width 1.8 m, length 7 m, volume approximately 6 cubic meters. Total mass ~~0.26~~ 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 transmitting at adjustable intervals over Rockblock. SPOT Trace~~. Attempts to interface this Teensy with a BMP 280 were universally unsuccessful~~. This set of avionics was ~~finished from the incomplete second set made for~~ [[SSI-87\|CY-3]].		'''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.

	'''Power''': 9 L91 lithium AA batteries. ~~Resistive heater running~~ on ~~single L91 battery~~.		'''Power''': 9 L91 lithium AA batteries. 3 L91 lithium AA batteries on cutdown.

	'''Payload''': Styrofoam enclosure. Mass 0.62 kg.		'''Payload''': Styrofoam enclosure. Mass 0.55 kg

	'''Mass budget''': 0.88 kg total.		'''Mass budget''': 1.57 kg total.

	==Flight synopsis==		==Flight synopsis==

Bjing at 07:28, 6 December 2019

2019-12-06T07:28:30Z

← Older revision		Revision as of 07:28, 6 December 2019
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	==Project context==		==Project context==

	~~In August,~~ [[SSI-91]] was a milestone in realizing flights with in-house manufactured ZPBs, yet due to unexpected termination no data on the equilibrium altitude and descent characteristics were obtained, thus failing to fulfill one of the major objectives of that flight. Meanwhile, a candid assessment of the ZPB manufacturing process proved discouraging. In mid to late August, a new manufacturing technique was devised based on commercially available polyethylene tubing, which promised to be far more durable and scalable. (The altitude limitations were deemed acceptable for the time being). Orders for commercial tubing were placed, set to arrive in September. In light of these developments, a third summer ZPB launch which had been planned for the weekend of September 1 was cancelled.		[[SSI-91]] was a milestone in realizing flights with in-house manufactured ZPBs, yet due to unexpected termination no data on the equilibrium altitude and descent characteristics were obtained, thus failing to fulfill one of the major objectives of that flight. Meanwhile, a candid assessment of the ZPB manufacturing process proved discouraging. In mid to late August, a new manufacturing technique was devised based on commercially available polyethylene tubing, which promised to be far more durable and scalable. (The altitude limitations were deemed acceptable for the time being). Orders for commercial tubing were placed, set to arrive in September. In light of these developments, a third summer ZPB launch which had been planned for the weekend of September 1 was cancelled.

			With the end of the summer, onboarding approached, and it was hoped to do a Cycloon demonstration launch very near the beginning of the year, on '''October 5, 2019'''. Ideally this would be ballast-controlled, collecting data and paving the way for a fully controlled launch in the middle of the quarter. It was also hoped to do this launch from Pigeon Point, but by September 23, wind forecasts proved unfavorable. Additionally, momentarily it was planned to launch two ballast controlled balloons (as a means of forcing Cycloon to self-manufacture a ballast mechanism), but as 3D printing attempts in the last week of September failed, this too was discarded. Nevertheless, a significant worksession on September 29 produced two balloons and two sets of avionics (one new, one recovered from [[SSI-91]].

	~~Thus, it was immediately decided that a repeat launch would be attempted, with nearly~~ the ~~exact same configurations~~, ~~except~~ for ~~the addition~~ of a ~~SPOT Trace~~ and ~~strengthening of RockBlock connections. Since~~ a ~~repeat build would require little additional design work, it~~ was ~~decided that the repeat launch would be attempted on the evening of '''August 6, 2019''' from Pigeon Point.~~		Relatively near the flight, demands for an improved cutdown mechanism intensified. Amidst an absence of nichrome, a novel cutdown mechanism involving two ematches and a socket was devised, implemented, and tested the night of October 4.

	~~As simulations from Pigeon Point showed the trajectory heading northeast over the Bay Area, it was decided on July 30 to request permission to launch from Garin Regional Park in Hayward~~, ~~CA instead. That same day~~, ~~avionics work began~~ and ~~was concluded on August 1. Due to~~ the ~~anticipated short duration~~ of ~~the flight, it was decided to reduce the power bank from 18 to 9 batteries. On July 31, the launch was moved to '''August 5, 2019''', and on August 2 the new launch site was rejected.~~

	~~The construction of the ZPB and final payload assembly occurred on August~~ 4~~. It was generally agreed that the quality of the balloon was inferior to that of the first attempt due to several reasons~~.

	==Configuration==		==Configuration==

Bjing at 07:13, 6 December 2019

2019-12-06T07:13:29Z

← Older revision		Revision as of 07:13, 6 December 2019
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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.

			==Project context==

			In August, [[SSI-91]] was a milestone in realizing flights with in-house manufactured ZPBs, yet due to unexpected termination no data on the equilibrium altitude and descent characteristics were obtained, thus failing to fulfill one of the major objectives of that flight. Meanwhile, a candid assessment of the ZPB manufacturing process proved discouraging. In mid to late August, a new manufacturing technique was devised based on commercially available polyethylene tubing, which promised to be far more durable and scalable. (The altitude limitations were deemed acceptable for the time being). Orders for commercial tubing were placed, set to arrive in September. In light of these developments, a third summer ZPB launch which had been planned for the weekend of September 1 was cancelled.


	~~==Project context==~~		Thus, it was immediately decided that a repeat launch would be attempted, with nearly the exact same configurations, except for the addition of a SPOT Trace and strengthening of RockBlock connections. Since a repeat build would require little additional design work, it was decided that the repeat launch would be attempted on the evening of '''August 6, 2019''' from Pigeon Point.

			As simulations from Pigeon Point showed the trajectory heading northeast over the Bay Area, it was decided on July 30 to request permission to launch from Garin Regional Park in Hayward, CA instead. That same day, avionics work began and was concluded on August 1. Due to the anticipated short duration of the flight, it was decided to reduce the power bank from 18 to 9 batteries. On July 31, the launch was moved to '''August 5, 2019''', and on August 2 the new launch site was rejected.

			The construction of the ZPB and final payload assembly occurred on August 4. It was generally agreed that the quality of the balloon was inferior to that of the first attempt due to several reasons.

	==Configuration==		==Configuration==

			'''Balloon''': 0.3 mil polyethylene, paper bag topology, width 1.8 m, length 7 m, volume approximately 6 cubic meters. Total mass 0.26 kg with fill tube (PVC of length approximately 12 inches and diameter 1/2 inch).

			'''Avionics''': TinyGPS, Teensy 3.2 transmitting at adjustable intervals over Rockblock. SPOT Trace. Attempts to interface this Teensy with a BMP 280 were universally unsuccessful. This set of avionics was finished from the incomplete second set made for [[SSI-87\|CY-3]].

			'''Power''': 9 L91 lithium AA batteries. Resistive heater running on single L91 battery.

			'''Payload''': Styrofoam enclosure. Mass 0.62 kg.

			'''Mass budget''': 0.88 kg total.

	==Flight synopsis==		==Flight synopsis==

			[[File:ssi91traj.png\|400px\|thumb\|Mission trajectory]]
			[[File:ssi91launch.png\|400px\|thumb\|left\|Balloon ascending after release]]
			[[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.

			'''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.

			'''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.

	{{balloon-footer}}		{{balloon-footer}}

	[[Category: High Altitude Balloons]][[Category: Balloon Launches]]		[[Category: High Altitude Balloons]][[Category: Balloon Launches]]

Bjing at 06:52, 6 December 2019

2019-12-06T06:52:23Z

← Older revision		Revision as of 06:52, 6 December 2019
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	\| landing coordinates = 37.144, -115.262		\| landing coordinates = 37.144, -115.262
	\| last = 91		\| last = 91
	\| next =		\| next = 93
	}}		}}