Chute Cord Length

[cdma77]

I bought a surplus chute and it has a pretty long cord. I am wondering what is the ideal length for the chute cord to the nosecone ?

Thanks,
Jeff

 

[rabidsheeep]

do you mean the shockcord or the shroud lines on the chute?

for shockcords, the longer the better really as long as you can easily pack it the tube, for shroud lines ive never really noticed a difference... i guess longer lines= a longer time for the chute to fully open?

 

[cdma77]

Originally posted by rabidsheeep
do you mean the shockcord or the shroud lines on the chute?

for shockcords, the longer the better really as long as you can easily pack it the tube, for shroud lines ive never really noticed a difference... i guess longer lines= a longer time for the chute to fully open?

I meant shroud lines !

 

[flying_silverad]

Originally posted by cdma77
I meant shroud lines !

Shroud length can equal the diameter of the chute. You can adjust from there but it's a good place to start.

 

[powderburner]

I think the optimum shroud length is something like 1.5 or 2 times chute diameter

 

[Micromeister]

I've found 1 to 1.25 times the chute diameter is fine for sport models. 1.5 to 2 times the diameter for competition 8 to 12 shroud line mylar chutes.

 

[edwardw]

I always go 2x the diameter of the chute. Make for some really long lines when the chutes get big!

Edward

 

[polaris]

Here is some technical talk from a reference that is seems to be widely accepted – Parachute Recovery Systems Design Manual, T. W. Knacke, 1992.

PP 5-20

“ Figure 5-20 shows the possible increase in drag coefficient from line ratios, Le/Do, up to 2.0. Parachutes with no skirt restrictions, such as flat and conical circular parachutes, increase the drag coefficient up to the line ratios of 2.0.”

Where
Le is the suspension line length
Do is the nominal diameter of the parachute (SQRT(4So/Pi))
So is the surface area of the parachute canopy including vents and slots

PP 5-21

“Calculations indicate that line-length ratios above 1.5 may be detrimental because of the associated weight increase of the longer lines. Systems that employ parachutes in clusters or use first-stage drogue chutes require longer risers. Parts of these risers may be replaced by longer suspension lines on the individual parachutes to increase parachute drag and decrease the required parachute diameter and parachutes assembly weight.”

I hope this helps.