Functional Requirements:

Parachutes

• Descent Velocities

• Drogue descent velocity: 65 - 165 ft/s
• Main descent velocity: <36 ft/s
• Redundancy in parachute deployment triggers
• Design: 
• Required drag coefficient and high stability
• Easy to manufacture

Safety Factors

• Lines and attachments: 1.5 safety factor for shock force of parachute deployment calculated with rocket dry mass
• Parachute joints and seams: 3 safety factor

Recovery Trajectories:

• Single Separation, Dual-Deployment (Tender Descender)
• First deployment (Drogue Parachute): Apogee (108,000 ft)
• Second deployment (Main Parachute): 1,500 ft

Parachute Sizing:

Design Constraints:

• Descent velocity (terminal velocity)

Want to Find:

• Diameter of parachute

Other Variables:

• Coefficient of Drag (CD):
• Estimation for Drogue: 0.55
• Estimation for Main: 1.6
• Will require testing to confirm
• Air density at deployment altitude
• Drogue: ~108,000 ft AGL
• Main: 1,500 ft AGL
• Launch: 2000 ft ASL
• Vehicle mass: 80.32lbs dry mass

Parachute Design Overview:

• Designing and sewing Zephyrus drogue and main parachutes in-house

Parachute Components:

• Canopy
• Gores
• Vent/Spill Hole
• Shroud/Suspension Lines
• Shock Cord