Changes

| header = SSI-83

| header = SSI-83

| img link = File:Ssi83small.png

| img link = File:Ssi83small.png

| launch date =April 17, 2019, 22:30 PDT

| launch date =April 17, 2019, 22:30 PDT

| launch site = Pigeon Point Light Station, Pescadero, CA

| launch site = Pigeon Point Light Station, Pescadero, CA

| flight length = 267 km

| flight length = 267 km

| flight profile = Marine tether

| flight profile = Marine tether

| last coordinates = 35.2168, -121.0458

| last coordinates = 35.2168, -121.0458

| landing date =  

| landing date =  

| landing coordinates =

| landing coordinates =

}}

}}

'''SSI-83''' (project designation '''CY-1''') was the maiden launch of Project Cycloon on April 17, 2019. A proof-of-concept of Cycloon's aero-marine platform architecture, it was the first marine-tether profile launch in SSI's history. It was also a rare nighttime launch, a rare weekday launch, and the first-ever launch from Pigeon Point Light Station.

'''SSI-83''' (project designation '''CY-1''') was the maiden launch of [[Cycloon|Project Cycloon]] on April 17, 2019. A proof-of-concept of Cycloon's aero-marine platform architecture, it was the first marine-tether profile launch in SSI's history. It was also a rare nighttime launch, a rare weekday launch, and the first-ever launch from Pigeon Point Light Station.

==Pre-Launch==

==Project context==

Discussions of Cycloon's maiden launch had been underway since shortly after the project's inception in January 2019. Demonstration of technologies and concepts not previously utilized in SSI balloon launches was considered the highest priority objective for the first launch: in particular, demonstration of the onboard HF transceiver and marine tether system. It was initially envisioned that the HF transceiver system would be first tested via a ground-tethered balloon in February 2019, followed by a demonstration of the marine tether in March. However, as progress on the HF transceiver stalled, partly due to supply-chain delays, it was decided to move forward with the marine tether launch.

Discussions of Cycloon's maiden launch had been underway since shortly after the project's inception in January 2019. It was initially envisioned that the HF transceiver system would be first tested via a ground-tethered balloon in February 2019, followed by a demonstration of the marine tether in March. However, as progress on the HF transceiver stalled, partly due to supply-chain delays, it was decided to move forward with the marine tether launch.

The flight profile for the marine tether launch was initially envisioned to involve a slow daytime ascent and nighttime descent into the Pacific ocean under passive altitude control. This would have offered significant technical challenges in terms of precision filling and weighing in order to ensure a slow enough ascent to survive until sunset. Nevertheless, this flight profile offered appealing advantages in terms of flight endurance; several simulated profiles in February traveled due west into the Pacific, offering a nearly indefinite potential mission duration. In order to demonstrate the long-term viability offered by the marine tether concept, such endurance was considered a high priority.

The flight profile for the marine tether launch was initially envisioned to involve a slow daytime ascent and nighttime descent into the Pacific ocean under passive altitude control. This would have offered significant technical challenges in terms of precision filling and weighing. Nevertheless, this flight profile offered appealing advantages in terms of flight endurance; several simulated profiles in February traveled due west into the Pacific, offering a nearly indefinite potential mission duration. In order to demonstrate the long-term viability offered by the marine tether concept, such endurance was considered a high priority.

By March, it became increasingly clear that such a rise-fall-float profile would be increasingly unlikely due to seasonal wind patterns. While the development of Apex Vent, another Cycloon project, would have opened up numerous more windows, it was decided that it would be infeasible to delay the maiden launch until after its development. Thanks to the technical simplicity of a float-only profile, such a profile became the target of launch window searches.

By March, it became increasingly clear that such a rise-fall-float profile would be increasingly unlikely due to seasonal wind patterns. While the development of Apex Vent, another Cycloon project, would have opened up numerous more windows, it was decided that it would be infeasible to delay the maiden launch until after its development. Thanks to the technical simplicity of a float-only profile, such a profile became the target of launch window searches.

'''Payload:''' Solid plastic permeable enclosure and two inner waterproofing layers. The aim of this configuration was to increase system density as much as possible, such that balloon envelope failure would lead to immediate loss of communications, while protecting the system against occasional waves. Mass: 1.73kg.

'''Payload:''' Solid plastic permeable enclosure and two inner waterproofing layers. The aim of this configuration was to increase system density as much as possible, such that balloon envelope failure would lead to immediate loss of communications, while protecting the system against occasional waves. Mass: 1.73kg.

'''Avionics:''' Teensy 3.2, BMP280, BNO055, TinyGPS, and RockBlock modem on a protoboard, transmitting all data at lengthening intervals. A SPOT Trace was added at the launch site due to avionics difficulties. No RockBlock communications were received; in post-analysis, a bug was found in the code.

'''Avionics:''' Teensy 3.2, BMP280, BNO055, TinyGPS, and RockBlock modem on a protoboard, transmitting all data except orientation at lengthening intervals. A SPOT Trace was added at the launch site due to avionics difficulties. No RockBlock communications were received; in post-analysis, a bug was found in the code.

'''Power:''' 42 standard alkaline AA batteries.

'''Power:''' 42 standard alkaline AA batteries. This was calculated to be sufficient for three weeks, the most optimistic conditions possible.

'''Tether and floater:''' 30m paracord tether from balloon to payload and 30m paracord tether from balloon to floater. Total tether mass: 0.42kg. Floater mass 2.0kg and volume slightly over 2.0L. Optimizations for floater mass and volume, tether length, and balloon fill were considered for the sake of greater endurance and tether angle during strong winds.

'''Tether and floater:''' 30m paracord tether from balloon to payload and 30m paracord tether from balloon to floater. Total tether mass: 0.42kg. Floater mass 2.0kg and volume slightly over 2.0L. Optimizations for floater mass and volume, tether length, and balloon fill were considered for the sake of greater endurance and tether angle during strong winds.

==Flight synopsis==

==Flight synopsis==

 

'''April 17 2230 PDT:''' Balloon released. SPOT transmissions regular.

'''April 17 2230 PDT:''' Balloon released. SPOT transmissions regular.

'''April 19 0814 PDT:''' SPOT transmissions resumed from (35.48765,-121.26381). Trajectory had been staying southward despite increasing west winds, making landfall time and location increasingly uncertain.

'''April 19 0814 PDT:''' SPOT transmissions resumed from (35.48765,-121.26381). Trajectory had been staying southward despite increasing west winds, making landfall time and location increasingly uncertain.

'''April 19 1118 PDT:''' Erratic, slow southward motion begins from (35.45337,-121.21738), in contrast to the relatively rapid, southeastward motion thus far and particularly contradicting local wind conditions. In post analysis, it was determined that the floater and tether likely became snagged on a large piece of floating debris at this time. At the time, it was uncertain if the balloon had failed and the payload were floating.

'''April 19 1118 PDT:''' Erratic, slow southward motion began from (35.45337,-121.21738), in contrast to the relatively rapid, southeastward motion thus far and particularly contradicting local wind conditions. In post analysis, it was determined that the floater and tether likely became snagged on a large piece of floating debris at this time. At the time, it was uncertain if the balloon had failed and the payload were floating.

'''April 19 2326 PDT:''' After a full day of erratic motion with frequent extended STOPs, the trajectory accelerates to the southeast from (35.35143,-121.12985), consistent with surface winds.

'''April 19 2326 PDT:''' After a full day of erratic motion with frequent extended STOPs, the trajectory accelerated to the southeast from (35.35143,-121.12985), consistent with surface winds.

'''April 20 1013 PDT:''' Transmissions resume after a STOP from (35.23742,-121.06796), still consistent with winds.

'''April 20 1013 PDT:''' Southeastward motion continued after a STOP from (35.23742,-121.06796), partially but not fully consistent with winds, which still predicted imminent landfall.

'''April 20 1103 PDT:''' Last contact, the second of two consecutive STOP signals, from 13.7 km WSW of Point Buchon in San Luis Obispo county. A follow-up call to Point San Luis lighthouse in the afternoon yielded no observations, and the flight was deemed terminated.

'''April 20 1103 PDT:''' Last contact, the second of two consecutive STOP signals, from 13.7 km WSW of Point Buchon in San Luis Obispo county. A follow-up call to Point San Luis lighthouse in the afternoon yielded no observations, and the flight was deemed terminated.