Sneak Peak: Jolly Logic's Easy Dual Deployment

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John Beans

Founder, Jolly Logic
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Today I posted a "behind the scenes" look at our upcoming Chute Release product, which is just entering the flight testing phase. If you've been flying F-K motors and wished there was a simple way to do dual deployment so that your rocket wouldn't drift so far, you may be interested in this.

Check out the report, pics, and videos on the Jolly Logic website here.

As always, I'd love to hear your comments, either here or at [email protected]!
 
Reefing the chute for a "dual" deployment. One of those simple AND effective solutions! I like the alternate name HALO, btw.

I have a AT Cheetah sitting on an AT H135W that is just waiting for something like this...
 
Looks like this could do away with cable-cutters and Tender Descenders. If it is reliable, I'm in for my G-Force, Leviathan and MDRM.
 
I've been messing with cable cutters recently and they're really a pain. My last one didn't cut the cable tie and now I have repairs... Not enough BP... This seems a heck of a lot simpler. Would love it for a couple of my projects, but especially for my 3x29mm cluster.
Are there any limits to the unit's operating parameters? Too many Gs/too high an altitude, etc?
 
Wow! I've got a LOC Expediter that is set up for single deploy, and I haven't been looking forward to setting it up for dual deploy because I didn't want to hassle with the E-Bay. I'm getting one of these as soon as they're ready to go, because I want that Expediter to really cut loose!
 
Very nice! I was brainstorming using a cable cutter for almost the same...even possibly using a rubber band, but this looks much better in that you don't need a separate altimeter as well as the wire connection.

Nicely fills the void between the simplicity of single deploy and the complexity (and investments) of full dd.
 
That looks great. It would also let one fly higher on a given field...

I gather from the dimensions that it would be snug in BT-55/ST-13.
 
I've been messing with cable cutters recently and they're really a pain. My last one didn't cut the cable tie and now I have repairs... Not enough BP... This seems a heck of a lot simpler. Would love it for a couple of my projects, but especially for my 3x29mm cluster.
Are there any limits to the unit's operating parameters? Too many Gs/too high an altitude, etc?

Thanks, I updated the information:
1. There is no altitude limit (it only cares about the lowest 1000 feet or so, above that is your business)
2. The acceleration limit is just structural (as long as you don't break it).

I don't know what the structural limits of the electronics will be. The device itself will be made of tough polycarbonate and aircraft aluminum (7075, if you care). The "weak link" will be its ability to resist chip and wire damage from acceleration. I suppose if you were hard core, you could open it and carefully epoxy the wires and connectors, staying clear of the pressure chip. You wouldn't be able to replace stuff later, like the battery, but it would toughen it up.

Interesting fact that I'll add to the post as well: you can make these redundant by using two across from each other in a circle around your chute. If either one opens, the chute opens.
 
love this, nicely done! it's an idea I pondered but never put any time into. care to show the release mechanism?
 
Hi John,

This looks like a great product. Does it need vent holes in the rocket to sense the atmosphere, or does it work in a different way?

Thanks!
 
You should use vent holes, or at least one tiny vent hole. Something. Unlike vent holes for altimeters, here you are just trying to make sure that you don't have an air-tight can with built-up pressure once you put your rocket together. As long as the pressure can equalize to normal ground pressure before you launch, you'd be fine. That would require just a pin hole, or any path through your rocket which lets the pressure stabilize for at least 2.5 seconds before flight.

Chute Release monitors the ground pressure, then looks for a flight over 100 feet, then waits until the rocket is approaching the set altitude and begins opening in a timely way so that it has released by the appointed altitude.

If you think through all of that, the only thing you'd want to be careful about is that Chute Release has a valid starting reference point for ground, and that you "get the laundry out" somewhere up there.

Hope that makes sense.
 
That looks great. It would also let one fly higher on a given field...

I gather from the dimensions that it would be snug in BT-55/ST-13.

Maybe. It's pretty beefy right now. It might trim down a few millimeters. The flight test unit cases are 3D printed. That's not nearly as strong as injection-molded polycarbonate (you know, Lexan, bullet-proof stuff). So it may be a little over-engineered right now...
 
Thank you for the heads up, Mr. Beans. I saw your presentation at NARCON last year and have been hoping to see progress. Looks great.
I understand this is a prototype and will have to remain a larger size for the time being, but I hope someday there will be a way to further miniaturize the device for use in LPR.
 
What keeps it from sliding up and possibly off the chute?

There's nothing "pulling" on the Chute Release (the parachute shroud lines and shock cord take all of the drag and shock from the chute), and you can pretty tightly cinch it on so that it won't be easily shaken off. The back side of Chute Release has gripping ridges, and the rubber band doesn't slide easily on parachute materials.

I hope that explanation makes sense. We'll see how well it grips in testing.
 
Is the pressure chip affected by ejection gas? Also, what price range are these expected to fall in?
 
Is the pressure chip affected by ejection gas? Also, what price range are these expected to fall in?

It will sense ejection pressure (like our current altimeters), but it's designed to ignore it. You'll want to protect it just like you protect your chute from direct gases and embers, but it will be fine.

As far as price, that's not firmed up yet.
 
Maybe. It's pretty beefy right now. It might trim down a few millimeters. The flight test unit cases are 3D printed. That's not nearly as strong as injection-molded polycarbonate (you know, Lexan, bullet-proof stuff). So it may be a little over-engineered right now...

The only reason I bring that up is that my test hack for the A3 (you know, that Eliminator with the payload section I threw together) is ST-13. The Chute Release would make flying it on E motors in our club field much less nervous to do. The added mass would affect that a little, but not all that much....
 
The only reason I bring that up is that my test hack for the A3 (you know, that Eliminator with the payload section I threw together) is ST-13. The Chute Release would make flying it on E motors in our club field much less nervous to do. The added mass would affect that a little, but not all that much....

Ultimately, there ought to be a model small enough for any rocket; I plan to work on that, but that will take some custom servo design, which I'm looking forward to.

For this version, even if the width got down to 29mm (which it used to be until this latest rev), I'd worry about it not sliding out cleanly from a BT-55, which is 33mm. I think folks could make it work, like put most of the chute BELOW it and make sure that at the top it is clearly free and not snug or jammed in the tube, and maybe powder the tube. But that means that you'd need to be super-careful, which doesn't leave much margin for error. I don't know. Maybe?
 
Seriously, how do I sign up for tests? I've got a testbed rocket that this would be awesome in. I've got a bunch of launches coming up in less than a month... And what is the cost looking to be?
 
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