"Shrimping" Parachute Failure Mode?

[redfax 0]

Hi, I saw a Nat Geo documentary on the mars rover program, and apparently they had this problem with the chutes called "Shrimping". The lines wouldn't get tangled, and the chute wasn't streaming, but the circular canopy would kind of fold on itseld, with several points on the circular canopy bunching around the centre, without touching.
Of course this reduced the available drag.
The engineers acted like they had no clue why this was happening, but that might conceivably have been staged for the camera's benefit (you know, a bit of a cliffhanger).
Anyway they ended up restricting the vent hole and the problem went away.

The chute was of a design called "Disc-Gap-Band), I don't know if the problem occurs with any other kind of canopy.

All google searches turn up either references to Forrest Gump, or to the sexual practice...

If anybody has any information on this, it would be greatly appreciated.

[riggerrob 643]

I have never heard of "shrimping" before, however, "squiding" refers to a stage in the opening sequence of a conventional round parachute.

The first step - to inflating a round parachute - involves dragging it to line-stretch, then air starts rushing in until it reaches the apex/top. Then air starts backing up, bulging the top of the canopy, making it look like a "squid."
Some ejection seat parachutes have "anti-squidding liines" to pull the apex down - near level with the skirt - to reduce filling time. Also known as "center lines" on Para-Commander/LeMoigne class canopies.

Try thinking of a "Disc-Gap-Band" as a round parachute with a lot of holes = high geometric porosity. This is similar to the ring-slot parachutes used as landing drag chutes by old (Century series) jet fighter planes. All the holes reduce opening shock at high airspeeds, but if you reduce opening shock too much, it might never open.

[jonjonson 0]

did you see this on an imax movie???

[redfax 0]

Sorry guys! I saw this on a hotel tv while travelling. I didn't have internet connection, and by the time I got home and looked it up, a week had gone by and I'd completely changed seafood species!

Sorry to bother...

[freeryde13 0]

I'm no prude , but what is sexual shrimping , I can't even imagine ....never mind , I don't want to know .

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people see me as a challenge to their balance

[Genego 2]

"Shrimping" is the act of licking or sucking your partners toes for sexual pleasure.

Not quite as bad as you thought?

I live with fear and terror, but sometimes I leave her and go skydiving.

[mjosparky 4]

Round parachute actually open by Bernoulli’s Principle. High speed air rushing past the outside of the canopy creates low pressure and the higher pressure inside the canopy forces the canopy to inflate.

I have seen a situation during testing where the pressure inside and outside equalize before the canopy inflates. This condition leaves the canopy in a “streamer” until if/when something disrupts this balance. That is the closest I can think of to the situation you described.

My idea of a fair fight is clubbing baby seals