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Hospital_Rocket

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I bought a Viper from Commonwealth and tossed in the box was one of thos parachutes Steve is often selling on eBay.

They were made for aerial flares, and are ripstop with 1'4" wide cloth shrouds.

Ok

Now the weird part. one of the shrouds is anchored in the center of the canopy.

Does anyone have any idea why this would be done?

A
 

Mike

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A complete stab in the dark here...could it be there to help unfurling? No idea if it would have any effect (postive or negative)
 

jflis

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It's a trim line for, effectively, dual deploy with only one deployment... :)

To get the full effect, you attach the chute with the center shroud pulled short, causing the center of the chute to be pulled down allowing the edges of the canopy to flair up and out (sort of an inverted cone).

This allows the device to drop quickly and smoothly. At some predetermined time (either time or altitude) the center shroud is cut allowing the chute to fully deploy and inflate.

it's neat to see in operation :)

jim
 

AndyC

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Or it could be a PDA (pulled-down-apex) chute. I believe some flare chutes are made like this. Essentially, by pulling down the apex a little (not enough to invert the chute as jflis describes - just enough to create a 'dimple' in the top of the chute), it actually increases the chute's drag. ie. a slower descent for the same-size chute. The trade-off is in stability - a PDA chute will tend to oscillate more. Do a search on the web for paraglider emergency parachutes - as these are often pulled-down-apex designs. Anyhow - they look cool!!:D
 

Hospital_Rocket

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Now that would be interesting. If one were to find a way to link that middle shroud with something like heavy fishing line and then attach an e-match to it to cause the shroud to sever.


Hmmm....
 

Justin Horne

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This could be a really interesting use for an ARRD...
Could be great to see!!

Justin H.
 

daveyfire

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Defy Gravity documents the trim line method in the manual for the Tether:

http://www.macson.com/_pass5/dg/tether.html

near the bottom, the "Technical Manual". I have one and it's a neat little unit, cheaper than the ARRD and works really well :)

As for the PDA chutes, I think by pulling down and creating a dimple in the center, you increase the drag, as andyc said. As a matter of fact, the Quantum Chutes that RocketRage sells (http://www.rocketrage.com) have the PDA feature to increase their drag coefficient. Works very well!
 

DynaSoar

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Originally posted by Hospital_Rocket
I bought a Viper from Commonwealth and tossed in the box was one of thos parachutes Steve is often selling on eBay.

They were made for aerial flares, and are ripstop with 1'4" wide cloth shrouds.

Ok

Now the weird part. one of the shrouds is anchored in the center of the canopy.

Does anyone have any idea why this would be done?

A
Either:

1. It's from a flare, like an M275, and the center line is a trigger that sets off the flare only after the chute is opened, or, more likely,

2. it's an anti-cupping line. It pulls the center down so any air the goes in is more likely to push the chute wide, so it doesn't catch just enough air to open with the gores parallel and not opening farther (cupping).

Or maybe both.
 

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