Shroud line length

[Sooner Boomer]

Is there a rule of thumb for the ratio of shroud line length to chute diameter? What happens to the Cd when the lines are shorter/longer? Mostly interested in DIY chutes, but also interested in what would happen if commercial chutes are modified.

OK, truth be told, the lines on almost all of my parachutes get shorter over time. They get so tangled, the only way to fix them is to cut the end off, detangle, then re-secure the lines.

 

[Banzai88]

I make all of my parachutes, in a variety of pattern, from 12" to 72". I follow the Fruity pattern when it comes to the math, and I've never had any issues. I even use this math with flat parachutes, too. Works like a charm.

https://fruitychutes.com/help_for_parachutes/parachute-help/how_to_make_a_parachute.htm

 

[Hobie1dog]

I make all of my parachutes, in a variety of pattern, from 12" to 72". I follow the Fruity pattern when it comes to the math, and I've never had any issues. I even use this math with flat parachutes, too. Works like a charm.

https://fruitychutes.com/help_for_parachutes/parachute-help/how_to_make_a_parachute.htm

thanks for the link

 

[Handeman]

I make the lines on all the chutes I make 1.5 time the diameter. By the time they are sewn on and a loop in the bottom, they are somewhat shorter, but that seems to make for a more stable chute with less rocking

 

[shockie]

1x to 1.5x diameter for low and mid power rockets....

https://www.rocketryforum.com/threads/optimal-length-of-parachute-shroud-lines.43704/

fruitychutes use 1.15x diameter for their mid to high power chutes

 

[boatgeek]

Based on experimental evidence from our TARC team, you don't start materially reducing the chute CD/increasing descent speed until the shroud line (from chute corner to center securing point) is around 0.5 to 0.75 * chute diameter.

 

[tfish]

All of my DIY chutes are flat chutes..up to 72". I base my shroud line lengths on the chutes flat measurement x .89
I cut them twice as along and loop that shroud line to two attachment points.

and yes..you really need to choke up on those lines to see and speed up of decent.

Tony

 

[shockie]

Based on experimental evidence from our TARC team, you don't start materially reducing the chute CD/increasing descent speed until the shroud line (from chute corner to center securing point) is around 0.5 to 0.75 * chute diameter.

What chute material and chute size are you talking about?

 

[Tech 68]

When talking to Buddy Michaelson about my 18 foot chute I bought from them, I found out the shroud lines are 18 feet long.

 

[Dane Ronnow]

I make the lines on all the chutes I make 1.5 time the diameter. By the time they are sewn on and a loop in the bottom, they are somewhat shorter, but that seems to make for a more stable chute with less rocking

+1

 

[boatgeek]

What chute material and chute size are you talking about?

Flat sheet thin mil ripstop nylon 18"-24" diameter. Reefing is typically done with a few wraps of electrical tape so it's relatively easily removable.