Plastic reefing rings for HPR?

Any further adventures to relate using these for HPR recovery?

https://www.rocketryforumarchive.com/showthread.php?t=7379

The plastic "cabone rings" are used in knitting, so they are easily found locally in any store with a crafts section:

https://www.amazon.com/s/ref=nb_sb_...e,arts-crafts&rh=i:arts-crafts,k:cabone rings

Something to remember about rings versus true sliders -- when testing horizontally, you don't have gravity pulling on the ring. When a parachute inflates, it's vertical, and the ring can fall without any tension from the lines.

A slider, on the other hand, has grommets and fabric to provide more resistance.

-Kevin

troj said:

Something to remember about rings versus true sliders -- when testing horizontally, you don't have gravity pulling on the ring. When a parachute inflates, it's vertical, and the ring can fall without any tension from the lines.

A slider, on the other hand, has grommets and fabric to provide more resistance.

-Kevin

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Thanks. Prior to deployment, the ring would be at the base of the chute canopy and I think it would be a toss-up as to whether the chute trying to inflate would be resisted/slowed by the ring before the chute had straightened out enough for the ring to just fall down the lines. That's the practical experience info I'm after - what does it do? A ring that is just large enough to fit over the shroud lines without falling on its own with the lines straightened might be the answer. A rubber o-ring that is slightly stretched when placed over the shroud lines might prevent gravity sliding and roll down the lines upon inflation of the chute. I know sliders will work, but I'm after cheap, easy to find and install methods to prevent the sudden opening shock, probably not as well as a slider would, but better than nothing.

I need to find a tall building or structure with an owner who will let me drop 4 lb weights with a chute attached. Anyone else with something like that readily available is welcome to beat me to it. The drops would be recorded on HD video for analysis. Sounds like an easy NARTS project for someone.:wink:

Today with the Bare Necessities mockup we used a ring in an attempt to slow deployment.

We're not sure if it worked because our keychain camera fell off during boost and is lost...

PML tried the rings 20 years ago. It must have not worked out to well or we all would be using them.
Gary

crossfire said:

PML tried the rings 20 years ago. It must have not worked out to well or we all would be using them.
Gary

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Anyone here from PML who can elaborate on that? Unless it somehow results in non-deployments or shroud line failures, I don't see how it can't be better than nothing. I know someone who I saw use a short length of 3/8" diameter launch lug on the shroud lines of a 24" chute that most definitely had a beautiful chute deployment slowing effect, not an extremely gradual opening, but definitely avoiding the explosive "pop" opening, thereby avoiding very hi-G stresses on recovery components and possibly even preventing zippers. That's what I'm after.

Just give PML a call and ask for Frank he's a great guy who will help you out.
Gary

crossfire said:

Just give PML a call and ask for Frank he's a great guy who will help you out.
Gary

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I talked with Frank and he said it was impossible to recall specifics because it was 20 years ago, but the rings were deemed to be inconsistent in preventing recovery system failures and zippering over the wide range of flight profiles they desired to cover, so they went on to develop with much additional experimentation and testing the current PML methods to more consistently prevent recovery system failures and zippers - wider, tubular shock cords which were unusual at that time, piston ejection, and spill holes in parachutes. He said he'd be very interested to see the documented results of any modern experimentation with reefing rings, something that would be easier to document these days because of on-board recording accelerometers and HD video cameras with optically stabilized zoom lenses for ground-based tracking.