Changes

| 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

[[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.

==Flight synopsis==

==Flight synopsis==

[[File:ssi91traj.png|400px|thumb|Mission trajectory]]

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

[[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.

'''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.

 

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

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