Parachutes

Parachutes are used by the Rocketry Research organization as a means of slowing rockets during descent.  The parachutes have been made from rip-stop nylon acquired from a local sail maker. 

Drag tests of a 6 foot diameter rocket parachute.

Drag test of a 9 foot diameter parachute

Patterns for making the above parachute

Parachute Deployment

The parachute deployment system used by the rocketry research organization was made with the goals of light weight and reliable operation in mind. Light weight is achieved by using an almost all fiberglass construction method. The system has undergone many tests consisting of deploying the parachute from the ground with no failures. This system is flexible in that it will work with a heavier nose cone or a lighter nose cone with no modifications needed. It has been tested successfully with a 2.2 kg payload in the nose cone.

Description of Operation:
The deployment system has an electrical connector for the rocket computer to ignite a charge of black powder. When this charge goes off a floating bulkhead pushes up against a fixed ring on the inside of the nosecone. This force pushes the nosecone off a sleeve attaching it to the rocket. As the nosecone is traveling away from the rocket a cord between the floating bulkhead and the main rocket body unwinds. Once this cord unwinds fully, the floating bulkhead is pulled away from the ring in the nosecone. The floating bulkhead is attached to the parachute which is in the nose cone and as the nosecone continues to travel away from the rocket the parachute is pulled out. The floating bulkhead is also attached to the nosecone.  The kevlar cord that is in the combustion chamber is wrapped with electricians tape to protect it.

Concerns with the current design:

1. at high altitude deployment, the low air pressure may decrease the efficiency of the black powder.

Fixes:
use more black powder to correct this or use a pressurized rocket casing, or fill the explosion chamber up with something to displace the air as an insulator.


2. the round kevlar cord can be frayed or cut easier than a tubular or flat cord on the rocket body if a high speed deployment occurs.

Fixes:

Use a tubular cord for bigger rockets.


Pictures and drawings of the parachute deployment system



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