Components:
Main Parachute
The main parachute is a 36 inch diameter ripstop nylon parachute made by Fruity Chutes. This parachute is deployed from the same section as the drogue parachute. The main chute is stowed in a parachute bag and deployed at 400 feet using a Tender Descender. The parachute is attached to the launch vehicle with a 20 foot length of ½ inch thick Kevlar shock cord, which is more than strong enough to stand up to any loads during ejection. The shock cord is secured to the avionics bay with a quarter inch quick link and a quarter inch eye-bolt, and is protected from tangling by being woven through the parachute bag’s “loops”. The 36 inch diameter parachute was chosen to minimize lateral drift, and still enable us to recover the launch vehicle safely and successfully. With a 36 inch chute, we have a final descent rate of 13.1 ft/s.
Drogue Parachute
The Drogue parachute is a 12 inch ripstop nylon parachute from Fruity Chutes, and will be made by the same manufacturer as the main parachute. It will be protected from the heat of ejection by Nomex wadding. The drogue parachute will be secured to the top of the motor stage and the bottom of the avionics bay by a 20 foot length of ½ inch Kevlar shock cord. The drogue parachute is deployed at apogee and its purpose is to slow the descent to a safe velocity for the main parachute to deploy. When the tender descender is fired, the drogue parachute jerks upwards on a secondary shock cord, which has approximately 4 feet of slack, which is also secured to the avionics bay and is attached to the drogue chute in parallel with the primary. The purpose of this is to aid in the deployment of the main parachute at 400 feet. The 12 inch drogue canopy was chosen to ensure that the drogue parachute would slow the rocket down to a reasonable speed to deploy the main parachute at, but to minimize lateral drift. A 12 inch drogue parachute gives us a descent speed of 61 ft/s in the final configuration of our rocket.
Payload Parachute
The payload parachute is an 18 inch diameter made by Fruity Chutes. The payload parachute is protected from the heat of ejection via the Nomex wadding that lies between the Avionics bay and the payload parachute. The parachute is attached to the payload with 20 feet of ½ inch Kevlar shock cord that will be able to withstand the impact of the parachute opening when it is ejected at 1000 feet. The 18 inch payload parachute gives us a final descent rate of 26.5 ft/s. As with all the other the other parachutes, the 18 inch size was chosen to give a safe descent speed while minimizing lateral drift.
Tender Descender
The tender descender is a new feature in our recovery system. It allows us to have 2 parachutes deploy from the same section of body tube. This feature allows us to simplify our rocket design, and eject the main and the drogue parachute from the same section. The Tender Descender has two quick links attached to it, with a small piece of Kevlar shock cord running through one of the eyebolts. At 500 feet, the middle piece separates from the bottom piece, and the quick links are released, but the mechanism stays attached to the bottom eyebolt. The top link is attached to the avionics bay, as well as the main parachute shock cord, and the drogue parachute slack-line. The bottom link is connected to the parachute bag flap, the parachute bag slackline, and the drogue parachute shock cord. When the Tender Descender fires at 500 feet, the drogue parachute will jerk upwards, pulling the deployment bag open and deploy the main parachute.
Shock Cords
On all our parachutes, we either use ½ inch or ¼ inch lengths of shock cord to secure them to quicklinks, which in turn are secured to eyebolts that are screwed into the bulkhead.
Thermal Protection
We use sheets of Nomex reusable thermal wadding to protect our parachutes from the heat of the ejection charges. The sheets that we are using are 12”x12” so that it sufficiently covers the parachutes. We use Shock cord protectors made of the same material.
Quick Links
Our parachutes are secured to various steel forged quicklinks, which then are connected to an eyebolt. The quick links provide a strong and sturdy surface to attach our parachutes to and allow for convenience when setting up for launch. The quick links are one quarter of an inch thick, giving a breaking strength of 880 lb.
Eye-Bolts
Steel eye bolts connect the steel quick links to the launch vehicle. They are inserted into a through hole in the bulkheads and are secured with a nut and a lock washer on the opposite side.