Parachute selection

[joshdboss]

• [x] Calculate and determine the required parachute size for the rocket.
• [x] Order the required parachutes
• [ ] Test the parachute

[joshdboss]

Finding an adequate drogue chute seems difficult. Our rocket is rather light so the smallest size parachutes available (18 or 24 inches) aren't really adequate for a drogue. The 9 inch parachute used last time (the small yellow one) seems very weak to say the least.

I'm starting to like Bastian's idea of having a single parachute and "reefing it" using the pyrocutters. This also has the advantage that it allows us to grab a slightly bigger parachute and ensure a safe descent speed, as there is more room in the recovery bay. However, this requires us to test the parachutes before flying, potentially with a drone (and actually doing it this time ;) ).

I therefore suggest buying a shitty 9 inch parachute as a backup drogue. All that is left is therefore to size the main parachute.

[joshdboss]

Flat sheet parachutes (parasheets i.e. the hexagonal ones we used before) have a Cd around 0.75, while actual parachutes have a Cd around 1.5

[joshdboss]

Want a descent rate ideally under 25ft/s (~7.6m/s) when touchdown occurs

[joshdboss]

Parachute options: https://docs.google.com/spreadsheets/d/1b8HmD5SkbVCFXc4XlXuqUajm8nIzMWzUXoLjnkoNgdY/edit?usp=sharing

Main findings:

• There seems to be two standard parachute sizes that could work for us: 24" or 30" (measured circumferencially) with their equivalent diameters around 15.3" or 19.1".
• Fruitychutes and Spherachutes seem around 50% less bulky (both in weight and size) than PML or Rocketma parachutes
• Rocketman have a different shape with only 4 shroud lines and a loop on the top

[joshdboss]

Ordered rocketman 2ft. Just need to do some drop tests now when we receive it.