Purpose:
The demonstrator recovery system utilized a black powder piston to actuate the nose cone and deploy a reefed parachute. Reefing is used in order to descend from deployment at apogee at 2000 ft at 65 ft/s and disreef at 1500 ft for a 25 ft/s descent. The nose cone and parachute must be attached to the mission package tube (MPT).
Requirements:
The parachute begins reefed and descends at 65ft/s and disreefs at 1500 ft to descent at 25ft/s
The piston deployment must separate the nose cone and the MPT
The line cutters must cut the control line at 1500 ft
- The whole system must stay attached to the MPT at all times
Details/Design:
The Demonstrator Recovery system is composed of two main systems: the piston and piston parts, which are responsible for the actuation of the piston, which pushes the nose cone out of the MPT and deploys the parachute, and the parachute and reefing system, described below.
The piston system is composed of a piston, a piston mount, a piston diaphragm, a u-bolt, and a control line reefing part (not shown, is screwed onto the piston above the diaphragm and situated under the u-bolt). The piston is actuated by a firebolt containing black powder. Two are included in the parachute for failure mode mitigation. The piston then pushes forward. The piston mount is attached to the MPT to hold the piston in place. The piston diaphragm attaches the u-bolt and is situated to press against the lip of the nose cone. When the piston actuates, the piston diaphragm moves upwards, breaking the shear pins holding the nose cone to the MPT and disconnecting the nose cone from the rocket. The nose cone and parachute are attached to the MPT through lines attached to a quicklink attached to the u-bolt. When the piston actuates, these lines go under tension, which yanks parachute out of the parachute bag and nose cone, deploying the parachute. The parachute bag is attached to the nose cone so that it falls with the rocket.
Reefing Method:
Reefind is a parachute technique that allows the initial diameter of the parachute to be restricted by adding a control line to the bottom of the parachute, which is pulled to a certain circumference and forces the parachute to follow, thus restricting the diameter. In order to disreef and expand to the parachute's full size, the control line is cut. Demonstrator utilized a semicircle method of reefing. Two lines are wrapped in semicircles around half of the parachute. They both run through the middle, where a third line, the control line, pulls them down and towards the center. The control line is responsible for tensioning the two semicricle loops and keeping the radius constrained. This control line is then threaded down into the line cutters. When the electronics system senses the altitude of 1500 ft, it ignites the black powder within the line cutters, which cut the control line and release the full parachute.
Manufacturing:
Parts were made out of Aluminum 6061 or 3D printed. If they were made out of aluminum, they were manufactured through mill, lathe, and waterjetting. Additonally, parts were tapped to correctly size screw holes.
Testing:
- Wind Tunnel Testing:
- Confirmed the CD of the parachute as 1.6.
- Tested the disreefing method and confirmed that the ignited line cutters could cut the control line
- Ground Testing:
- Tested the separation of the nose cone and the MPT
- Confirmed parachute deployment
- Test 1 concluded that the paracute bag was stuck in the nose cone. The issues was fixed and retested, where the parachute deployed properly.