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Discussion in 'Recovery' started by Greg Furtman, Aug 17, 2019.
Does anyone else besides Jolly Logic make a chute release system?
There are a few flavors of "cable cutters" and "tender descenders". I think most of them are pyro based, I don't know of another electronic chute release system.
Not that I'm aware of. But....It's not that difficult to fabricate one for use with an exsiting altimeter and an E match for less than a dollar. Just think in terms of melting through in lieu of releasing the rubber band/elastic thread. I've even made one that works with nichrome wire.
I am aware of any other source. I own two and have many flights on them. May I ask what is the nature of your question?
Archetype Rocketry Cable Cutter
Tinder Rocketry Tender Descender
Prairie Twister cable cutter
There may be more...
Nothing more than a nylon bushing drilled to accept an Ematch head. Thread the elastic cord through and tie it around your chute/blanket bundle. When match fires, it burns through thread and releases chute. Some have tried similar with fishing line but it lacks the springiness/release characteristics on burn through so won't always work. Works identical to Chute Release, just very slightly more difficult to set up. As you can see, I do own a Chute Release. What you can't see is that I did not pay $129.99 for it since I bought it used. It's a neat little piece that seems to function as advertised.
This one functions the same without the need for an Ematch. Just a short piece of 30 ish gauge Nichrome wire to burn through the elastic or rubber band. I use it with my Eggtimer Quantum that allows you to adjust the "on" time of the firing circuit to ensure proper heating...
This give me an idea for a semi-reusable setup. The rubber band/elastic cord would be the expendable part, but what about using one of those electric flame-less cigarette lighters as the heat source? That way, you wouldn't have to replace the nichrome wire each time, and a case of some kind can be made to enclose the elastic cord around the heating element so resetting the thing on the ground "is a snap". The control would be any other altimeter set to fire a pyro, except the signal closes a relay to the lighter power. Once the parachute is released, a pin is pulled out of a connector to break the circuit to the lighter battery in case it gets stuck in the on position so it doesn't stay hot the whole way down.
Believe it or not, the Nichrome holds up surprisingly well. I made up several at once since they're so inexpensive (you could probably make a lifetime supply for less than ten bucks) but ended up not using most of 'em. At least not yet..And if one gets lost or destroyed it doesn't hurt at all, just dig out the next one and resume flying...
You may be overthinking it a bit. Adding to much "stuff" increases potential failure points and adds weight/bulk. Think in terms of minimal wiring connections since each one can potentially fail. I used nuts and bolts on my set up for ease of Nichrome replacement. After realizing how durable it is I considered a more "permanent" design, possibly wire wrap? If it wasn't so damn difficult to solder I'd have done that instead. "Keep it simple" is almost always best practice. In those terms the original Chute Release really shines, just the price is really hard to justify for such a simple device that can potentially be easily lost or damaged. Seems to be plenty of horror stories about that very thing here on TRF, here's a recent link with a few. https://www.rocketryforum.com/threa...ltimeter-4-and-other-jolly-logic-news.139205/ . A $20 Eggtimer Quark (or equivalent) and 50 cents worth of parts works identically and doesn't sting so much if you lose it, plus you can cost effectively have multiples on hand so as to not ruin you day of flying if something does go wrong. Personally I find it takes a ton of pressure off my launches by not having expensive items on board to worry about. I've lost and or destroyed enough "stuff" already, no need to pile on more...
I haven't yet lost much for electronic hardware with my rockets, but losing expensive stuff is always on my mind. As for the setup I'm thinking, it shouldn't be all that pricey. Like you said, the $20 Eggtimer would work perfect, and the lighter with battery would add maybe $2 and five or so grams. The setup in my head is a single box like the JL Chute Release attached directly to the parachute, so no additional wire to tangle or break, and the disconnect pin I mentioned could be as simple as a 1/8" headphone jack with a shorted plug that gets yanked out by the parachute.
It might be a bit over complicated, but I feel like it has the potential to be just as robust as the JL version, and could tangle less since the elastic is discarded entirely whereas the Chute release keeps it because you need that little pin. Also, I love to tinker, so the idea of building my own cheaper Chute release is appealing just from the standpoint of the challenge.
eBruce, if you come with anything please post it. Thanks.
Will do! Between this and an electronic "insurance policy" for guaranteed cluster motor ignition I've been working on, looks like me and my soldering iron might be busy for the next few months!
Fall will be here soon & then Winter, a time to catch up on indoor projects.
And don't forget the pics...
Rough preliminary sketch teaser for ya!
Cool, now hurry up and build it!
I thought it would be cool to have a consistent, slow opening parachute. Like it starts out as a drogue chute and then works it's way to a fully opened parachute.
Sounds like you're referring to parachute reefing. It's done by having a string restrict how far the parachute can open at the bottom, and then cutting said string when the parachute is needed fully open. It's a classic technique that you see used frequently with landing rovers on Mars, and practically every parachute in Kerbal Space Program. If memory serves, Bama Chutes offer some reefing setups for model rocket chutes.
Somewhere I've heard of running the shroud lines through a washer. The washer is shoved up to the shroud attachment points. On deployment the chute is largely reefed. As it falls, air catches the open parts of the chute and the washer slides down the lines for a slow opening. Never tried it myself, though.
Depending on how the parachute is packed, I'd think the washer would fall to the bottom of the lines before the parachute had a chance to open enough to hold the washer. Maybe something that can offer a bit more friction on the shroud lines like a used motor casing or scrap body tube section?
I think some experiments are in order!
I've watched two rockets hit the ground under a streamered main chute because it was not falling fast enough to open . These sliders require velocity to open.
Maybe a controlled reefing system instead of counting on it to conform to your will on it's own? Interesting concept, just not sure how practical it would be to make something that'd perform consistently. Looks like someone's been working on similar;
Going forward with my experiment.
I got and built an Eggtimer Quark, and bought two electric cigarette lighters. Turns out they are a bit more expensive than I thought (about $9 each), but not bad. Last night, I dismantled the lighters and ran a basic power test with the Quark. Good thing I bought both because one battery alone is enough to run the lighter, but barely powers the Quark. With both, the Quark is running on 7.4v, but I still had to isolate one of the batteries with a diode because the lighter refused to work (It must have a voltage regulator that disables the heating element if too much voltage is present. A smart safety feature.) I still have yet to incorporate a relay for the Quark to power to actually start the lighter and none of the safety disconnects are in yet, but I'm liking how this is turning out so far. I don't need an additional 9v battery like I originally thought, I can recharge the whole setup via USB, and the package looks like I can shrink it to much smaller than an Altoids tin. If I'm lucky, I can fit it all in a plastic $1 LED flashlight casing.
Here's a link to my original attempt with a video of it in action. Ignoring my struggles with arming the Quantum, you can see how clean the release is using the elastic thread. You can also see how long the Nichrome wire stays hot after cutting the thread, believe I had the trigger set to 1 second? https://www.rocketryforum.com/threads/quantum-based-hotwire-chute-release.141642/#post-1713016
Wallace, the your YouTube link doesn't work for me. It says video is unavailable.
Lemme look into it...
Video "should" work now..
I really like this idea but am curious, what do you think is the maximum chute size for this setup? And would you happen to have a picture of said chute wrapped in this manner? This and the nichrome idea are wonderful.
I've thought that something like this would be an interesting option where instead of bundling the chute with the elastic, make a cylinder to contain the chute. The cylinder would be split lengthwise and spring loaded - think fly-away rail guide kind of thing. The elastic would hold the cylinder shut and once the elastic is cut the cylinder springs open and releases the chute. I think this cylinder idea would significantly reduce the chance of tangles and would make it possible to use this elastic idea on larger chutes.
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