DESCENT SYSTEMS
PARACHUTE, RIGGING
The descent system design was a straightforward rocket recovery parachute and associated rigging that attached the parachute to both ascent system and spacecraft. The entire design was loosely based on Paul Verhage's design and on other groups with similar designs.
An outer abrasion jacket on the spacecraft encapsulated the spacecraft, and served as the attach points for the parachute rigging. On the upper perimeter of the jacket were four loops of Dacron tape sewn at the four corners of the jacket, to which 1 inch split rings were fitted.
An intermediate stage connected below to these split rings, and above to the parachute, consisting primarily of a ring used to keep the parachute riser lines from entangling. The assembly was loosely based on the Verhage design, but with simplifications, as the former design was difficult to fully implement and seemed overkill for this size of spacecraft. Further, a 8 inch plastic embroidery hoop was found, which was both lighter and stronger than the wooden hoops discussed in the Verhage reference. The system worked, but is an area where further tinkering is always needed. The line used was Dacron line, rated at 150 lb strength. The line was cut with a razor, and the ends fused with an open flame, as the Dacron is prone to unraveling otherwise.
The parachute was a Rocketman 36in parachute. The parachute arrived with the risers normally sewn together at their apex: these were detached and were formed into separate riser lines by looping the ends, and sewing the loops shut. Agan, 1 inch split rings were used, attached to the sewn loops. Brass fishing swivels, rated to 30 lb strength or greater, were also attached to the split rings, and were in turn tied to the intermediate-stage rigging.
Finally, the balloon itself was attached via Dacron line to a loop sewn into the apex of the Rocketman chute. This loop was a handy feature that made the Rocketman chute a good choice in the design.
An outer abrasion jacket on the spacecraft encapsulated the spacecraft, and served as the attach points for the parachute rigging. On the upper perimeter of the jacket were four loops of Dacron tape sewn at the four corners of the jacket, to which 1 inch split rings were fitted.
An intermediate stage connected below to these split rings, and above to the parachute, consisting primarily of a ring used to keep the parachute riser lines from entangling. The assembly was loosely based on the Verhage design, but with simplifications, as the former design was difficult to fully implement and seemed overkill for this size of spacecraft. Further, a 8 inch plastic embroidery hoop was found, which was both lighter and stronger than the wooden hoops discussed in the Verhage reference. The system worked, but is an area where further tinkering is always needed. The line used was Dacron line, rated at 150 lb strength. The line was cut with a razor, and the ends fused with an open flame, as the Dacron is prone to unraveling otherwise.
The parachute was a Rocketman 36in parachute. The parachute arrived with the risers normally sewn together at their apex: these were detached and were formed into separate riser lines by looping the ends, and sewing the loops shut. Agan, 1 inch split rings were used, attached to the sewn loops. Brass fishing swivels, rated to 30 lb strength or greater, were also attached to the split rings, and were in turn tied to the intermediate-stage rigging.
Finally, the balloon itself was attached via Dacron line to a loop sewn into the apex of the Rocketman chute. This loop was a handy feature that made the Rocketman chute a good choice in the design.
FLIGHT TERMINATION UNIT (FTU)
There was no flight termination cut-down unit in this design, and is not mandated (by the FAR) though many groups experiment with such. Adding a FTU seems to be a complicated step: the designs that use a heated nichrome wire to burn through a Dacron line are prone to failure. Electromechanical FTUs based on an uplink radio-command system, while reliable, are quite complicated. However, this is an area where creative tinkering would be welcome: having an ability to terminate the flight if the balloon was, for example, straying way off-course (e.g., towards the ocean) would be handy.