Parachutes and Bags

Parachutes

Sizing

Our guiding equation for sizing parachutes:

We used our calculator (linked here) to help us determine how we would size our rocket based on the original values we were given for terminal velocity and the coefficient of drag. We made this calculator so that we would be able to change the sizes of the parachute as both the terminal velocity and the coefficient of drag were things that could change over the course of the semester.

Design

For our two main parachutes we decided to buy them from Rocketman Chutes, (linked here). For our drogue parachutes we decided that we wanted to design and manufacture them ourselves. To do this we chose a simple octogonal design with a small eye hole (based off of previous drogue parachutes on Phoenix). We finalized these designs before the end of the design cycle in December.

Manufacturing

Manufacturing of the drogue parachutes took place during IAP 2024. Overall, this was one of the more time consuming and careful manufacturing jobs that recovery completed for Project Prometheus and included some failures in addition to successes.

Materials

• Ripstop Nylon (in white  for the lower ring and purple/red for the main section)
• Nylon Webbing*
• Durable Sewing Thread
• Tough String

*Note on Nylon Webbing in Successes and Failures section

Process

1. Sizing a pattern out of paper
2. Pinning Fabric to pattern then cutting out fabric
3. Pinning ½ inch seams on the edges of the main section and the lower ring)
4. Lower Ring:
1. Sewing seams along the top and bottom
2. Sewing sides together (double stitching, folding over so there are no raw edges showing)
5. Main Section:
1. Sewing the bottom rim seams (no raw edges showing)
2. Sew Webbing folded over along the eye hole on the top side (to cover raw edges)
6. Connection 
1. Pin webbing (8 pieces, all in line with the corners of the octagon) so it has two extra inches near the eye, two inches left as space between the ring and the main section, and three inches after the lower ring
2. Start by sewing the webbing onto the lower ring **sew two lines on either side of the webbing**
3. Then sew up to about an inch and a half away from the eye of the parachute
4. Fold over the extra two inches and leave a small loop over the eye
5. Sew the final part from the eye to where you stopped before
7. Final Steps:
1. Thread through a small piece of tough string through the top loops you made
1. Use a needle to get it through the top loops
2. Insert it into itself
3. Sew over insertion
2. Check for any loose threads
3. Check for holes in the parachute (see *section yet to be written* for how to fix holes in a parachute

Successes and Failures