They also make a type that looks virtually identical to the regular 'brass' swivels, except with a little "tail" on the end of the hook that sticks out below the "latching" (gold-colored) part of a regular snap swivel-- thus providing something to prevent the loop from "straightening out" in the event of a hard deployment.

A regular "brass" snap swivel can, in a hard deploy, cause the loop end to be tugged hard enough to pop the tip out of the latch. I've recovered a few that way, where the loop popped open, but thankfully didn't "straighten out" and release the rocket from the parachute.

I've also had a rocket or two dropped from altitude because the loop DID straighten out in a hard deploy and allow the parachute to separate with the swivel from the rocket. Never good outcome.

Both types of "coastlocks" should prevent 99% of occurrences due to the snap swivel being "jerked" open in a hard deploy. The kind that looks like a black version of the regular brass swivels (except with the "tail" sticking out 90 degrees from the loop end, which catches below the latch groove when closed) will simply pull the "tail" of the loop up against the latch and take the shock in virtually all cases, where a regular "tailless" brass swivel will allow the loop to be jerked out from under the latch, popping open. OF course the loop style coastlocks that Bernard posted have a loop with a latch bent into the wire loop end itself, which would tend to tighten into the loop under stress, preventing a "pop open" in most cases.

Note I said "most cases"... in probably 9,999 out of 10,000 flights, the coastlocks will work reliably. Then there's that rare occurrence when a particularly heavy rocket in particularly bad deployment conditions will straighten out a coastlock too... I've seen pictures of it posted before. NOTHING is 100% foolproof, or bulletproof. BUT, a good Coastlock will reduce the probabilities to as near-zero as possible without doing something drastic (at which point, something else will fail anyway-- parachute, shroud lines, screw eye, plastic eye on the nosecone, shock cord, glue joints, SOMETHING... there's ALWAYS some weakest link, just a matter of where it is in the chain...

Later! OL JR

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The X-87B Cruise Basselope-- THE Ultimate Weapon in the arsenal of Homeland Security and only $52 million per round!

I'm just getting back into rocketry and see a lot about these snap swivels. What is a good brand and size to get for typical low-power rocket applications? Does it make much difference or are they all pretty much the same?

Depends on the rocket... size matters (well, MASS matters actually) but personally I just get the packs of "coastlock" swivels from Wal Mart, in whatever size looks appropriate for the rocket I'm building.

For small rockets, the smaller size will do. For larger rockets, I get a larger size.

Since coastlocks have either the locking tab sticking out of the loop that locks into the latch to prevent it from springing open, or the "loop" in the wire that locks it closed on the all-wire type, they're much more forgiving of deployment loads than the plain-Jane brass-n-wire typical snap swivel... so if you get a pack of coastlocks about the same size as the regular plain brass-n-wire snap swivel that came in the kit (presuming one DID come in the kit, or for a similar mass rocket) then it should be completely adequate...

If in doubt, going a LITTLE BIGGER never hurts... (unless your design is particularly mass sensitive... like a contest rocket or something... )

Later and good luck! OL JR

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The X-87B Cruise Basselope-- THE Ultimate Weapon in the arsenal of Homeland Security and only $52 million per round!

One of, if not thee, handiest knot ever. Aside from it never getting tighter or looser, it can be untied easily after being under extreme loads.

If you're only going to learn to tie one proper knot—this is the one.

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Retro-grouch

In my Boy Scout days I once held the Camp Sabattis record for tying six bowlines in something like 29 seconds.

Partly I was the record holder because most of the other competition knot tiers did clove hitches. The reason for that is, clove hitches can be done fast; some boys could knock off six of them in under 10 seconds. I couldn't hope to catch up with the fastest clove hitchers. But hardly anyone was doing bowlines.

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Rich Holmes
Camillus, NY
Secretary / newsletter editor
Syracuse Rocket Club

http://richsrockets.wordpress.com

And the Coast lock swivels are readily available at your local tackle shop or Sportsman stores. I have a small parts compartment box for the different sizes to use with the parachutes and for fishing.

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David Manning
SAM # 0455

I have a hard time putting the lines through the swivel eye and tying them. My fingers don't work like they used to. Ive been hanging the chutes and putting change in them. By morning the lines are straightened out, i.e. not curled.

I ordered the coast-lock swivels a couple months ago. I had never used them. They are very nice! I bought the large ones for midpower-sized rockets. I’ll get smaller ones eventually when current inventory runs low.

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Lee Reep
NAR 55948

Projects: Semroc Saturn 1B, Ken Foss Designs Mini Satellite Interceptor
In the Paint Shop: Nothing! Too cold!
Launch-Ready: Farside-X, Maxi Honest John, Super Scamp

Chute tangles detract from the fun. They're really frustrating with old eyes and fingers that don't work like they used to.

I just made a chute for my project. Each line is a different color. Tied a loop to the free end of each line. Tied the ring end of the swivel to the shock cord. Can install or remove the lines one at a time at the snap part of the swivel.

In theory, any tangles should be easily remedied.

We'll see what happens...

Some good info from Apogee: https://youtu.be/4Nwhha73YH4

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“I would like to die on Mars. Just not on impact”. — Elon Musk

“Minds are like parachutes--they only function when open”. —Thomas Dewar