Jolly Logic Chute Release - Apogee Deployment

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lhall3b

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Good evening. I am new here so please excuse me if this is inappropriate for this forum. I have scoured prior posts and haven't found quite what I'm looking for. Please point me in the right direction if this has been addressed elsewhere.

We recently launched to 4,000 feet and it was our first go at a dual deployment with JLCR for our main. We set it to release at 300 feet, but our JLCR deployed at or near apogee along with our drogue. We know this from our GPS data and on-board camera. It resulted in a drift of just under 1 mile (very high winds that day). Thankfully all systems were recovered successfully but we are baffled as to why our main didn't deploy at the prescribed altitude. I have seen other threads were release pins or elastic bands broke, but all of our components were completely intact. We performed shake, release and "puff" tests prior to launch, without issue. We believe the band was tied with sufficient tension and the tether had enough slack as to not carry any shock cord load. I'm wondering if anyone has experienced anything similar or might offer some insight as to where we could have gone wrong. I imagine there was some user-error involved but we don't really know where to begin our troubleshooting.

We are also trying to put together a white paper of sorts for future team members as to potential failure scenarios or misconfigurations, so maybe this could serve as a foundation for that. For instance, is there a "sleep" mode? Will the device default to apogee release if it detects any user errors (as apogee release is obviously more desirable that no release!), etc. I can provide pictures of how it was wrapped if that helps.

I'd also like to add that this product is fantastic and we are very excited to use it for future launches!

For reference, I am with the Rutgers Rocket Propulsion Lab, recovery team.

Thank you for any help!
 
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The chute release uses barometric readings to determine altitude and release point. There is a chance that during installation of the rocket components after turning on the chute release, you created enough of a pressure delta that it tricked it into activating.

Other potential failures are the band slipping off the chute or an unforeseen action catching it during boost or ejection (deployment is a very non-linear event and can be quite unpredictable)

Did you fold your chute according to Jolly Logic's method, or substitute your own packing method?
 
What is the rocket's diameter, and what chute size? And you said dual deployment, but was it a single payload area and you used the motor's deployment charge? Have you had good recoveries with the JLCR on other launches?

Nytrunner's failure points can & do happen.
 
@QFactor @Nytrunner Thank you both! Already gaining some some insight from your response queries.

There's a photo of our folded configuration attached.

This was our first ever launch with the JLCR. Inner diameter of the recovery bay is 3.9 inches. The main chute w/ JLCR control is 50 inches in diameter. Both drogue and main occupy the recovery bay and we use a single deployment charge. However, we use e-match + black powder (2 grams) rather than motor deployment charge. Deployment was controlled by an RRC3 in the avionics bay. I attached an Open Rocket screen capture below for reference.

The more we investigate (and thanks to your suggestions) we are thinking either the ejection forces were too great or we may have tricked the barometric altimeter. Maybe we should use less black powder and assure there is enough space for the pressure sensors to detect atmosphere. We've never been too fine about how much black powder we use - only that it's enough to separate and not so much that we burn holes in our chutes. Now, with the JLCR, we may need to consider excess force more carefully. The 2 chutes and the JLCR required fairly tight packing, though they did evacuate the body tube easily enough.
 

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Based on the photograph above, I’d say your chute bundle is way too loose.

Really? Interesting, before launch we actually thought it might be too tight. It's over 4 foot diameter chute. There's a lot of material, can't even really see the elastic band in the shot. Maybe a better shot here below? It withstood a pretty significant tug but I suppose we can look into that, too. Thanks!
 

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o1ldude is right about the chute bundle. The pictures show a 50" Top Flight chute. Practice folding your chute so that you get a "clean" chute bundle. The drag resistance on the chute during initial descent from apogee could easily pull/push the chute out from under the band. You also mentioned it was a tight pack for getting the chute in the payload bay. Did you have to use a bit of force to make everything fit ?
 
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Do you need the drogue if the main+JLCR deploy at apogee? The bundled main can act as a drogue. That will help will the fit in the recovery bay.
 
@QFactor @Nytrunner Thank you both! Already gaining some some insight from your response queries.

There's a photo of our folded configuration attached.

This was our first ever launch with the JLCR. Inner diameter of the recovery bay is 3.9 inches. The main chute w/ JLCR control is 50 inches in diameter. Both drogue and main occupy the recovery bay and we use a single deployment charge. However, we use e-match + black powder (2 grams) rather than motor deployment charge. Deployment was controlled by an RRC3 in the avionics bay. I attached an Open Rocket screen capture below for reference.

The more we investigate (and thanks to your suggestions) we are thinking either the ejection forces were too great or we may have tricked the barometric altimeter. Maybe we should use less black powder and assure there is enough space for the pressure sensors to detect atmosphere. We've never been too fine about how much black powder we use - only that it's enough to separate and not so much that we burn holes in our chutes. Now, with the JLCR, we may need to consider excess force more carefully. The 2 chutes and the JLCR required fairly tight packing, though they did evacuate the body tube easily enough.
It looks to me like the JLCR is tethered to a chute shroud line. That’s a no-no.

EDIT: hmmm, I’m gonna take this one back. I could have sworn you weren’t supposed to attach to a shroud line, but i don’t recall where I saw it and it looks like the user manual says you can.
 
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It looks to me like the JLCR is tethered to a chute shroud line. That’s a no-no.

EDIT: hmmm, I’m gonna take this one back. I could have sworn you weren’t supposed to attach to a shroud line, but i don’t recall where I saw it and it looks like the user manual says you can.
You probably heard right - don't attach to the shroud line. I have seen the chute release get tangled in the lines. But I will admit this could be attributed to way people pack the chute. It all comes down to how you pack the chute. So I always attach it to the harness, and have never experienced any tangle issues.
 
Everyone - thank you so much for all the input! This is exactly what I was hoping for. I will take ALL of this feedback to our team. We've got a lot to think about and discuss at our next meeting in prep for our next launch (in 2 weeks!). Seems like the folding, packing and tethering really needs more attention.

I did have one other general question that might be better addressed elsewhere, but maybe someone knows a quick answer..

How long after we initialize the device will it hold our set point? For instance, are there any implications to setting our deployment altitude, and then our rocket sitting on the launch pad for 3 hours? Will the device wait indefinitely to detect launch?

Thank you all again. I will add updates here if anyone is interested in our results!
 
Everyone - thank you so much for all the input! This is exactly what I was hoping for. I will take ALL of this feedback to our team. We've got a lot to think about and discuss at our next meeting in prep for our next launch (in 2 weeks!). Seems like the folding, packing and tethering really needs more attention.

I did have one other general question that might be better addressed elsewhere, but maybe someone knows a quick answer..

How long after we initialize the device will it hold our set point? For instance, are there any implications to setting our deployment altitude, and then our rocket sitting on the launch pad for 3 hours? Will the device wait indefinitely to detect launch?

Thank you all again. I will add updates here if anyone is interested in our results!

Are you competing in the NASA Student Launch competition? Or one of the other competitions?

I think the JLCR stays on the whole time. So you want to be sure you have it fully charged before putting the rocket on the rail.
I suggest you send Jolly Logic an email to confirm the power-on condition.
 
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Are you competing in the NASA Student Launch competition? Or one of the other competitions?

We are competing at Spaceport America Cup next Summer, but we intend to surpass their flight ceiling well before then. November 7, we are launching at METRA to test out our full stack. We have at least one more scheduled launch in January as well at FAR.

I think the JLCR stays on the whole time. So you want to be sure you have it fully charged before putting the rocket on the rail.
I suggest you send Jolly Logic an email to confirm the power-on condition.

Awesome, will do! Thanks!
 
We are competing at Spaceport America Cup next Summer, but we intend to surpass their flight ceiling well before then. November 7, we are launching at METRA to test out our full stack. We have at least one more scheduled launch in January as well at FAR.



Awesome, will do! Thanks!

So are you going for the 10,000 ft. or the 30,000 ft. ? I have reviewed the team designs in this competition and the NASA one too.
 
We are going for 30,000 ft. at SA Cup!

Awesome!

Make sure you have that motor dialed in and all the necessary tracking electronics.

Wish you the best of luck.

(I promise not to say anything to the Ohio State team about you guys . . . )
 
Having had a few failures with JLCR followed by a string of successes, I'd recommend the following:
1. I agree with posts above - don't tie it to a shroud line.
2. Qfactor's post above shows three pictures. It should look like the middle picture. The one on the right is asking for trouble because the shroud lines can get wrapped around the shock cord and then the chute wont inflate (don't ask me how I know).
3. There was a discussion a while back about this and I summarized and wrote up the best of it (posts from Cameron Anderson) in the attachment. I had several failures prior, but since I have followed it have had a string of only successes.
 

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(I promise not to say anything to the Ohio State team about you guys . . . )

😂 take it to the fields.... 😂

Thank you! We've got some (proprietary) electronics in the nose, a Raven, 2x RRC3, Missleworks GPS, maybe a Telemega, too. Intent on leaving nothing to chance!
 
Having had a few failures with JLCR followed by a string of successes, I'd recommend the following:
1. I agree with posts above - don't tie it to a shroud line.
2. Qfactor's post above shows three pictures. It should look like the middle picture. The one on the right is asking for trouble because the shroud lines can get wrapped around the shock cord and then the chute wont inflate (don't ask me how I know).
3. There was a discussion a while back about this and I summarized and wrote up the best of it (posts from Cameron Anderson) in the attachment. I had several failures prior, but since I have followed it have had a string of only successes.

Great insights! Thanks for the doc!!!

Is this the thread you're referring to? Found this one today..

https://www.rocketryforum.com/threads/jolly-logic-chute-release-tips-and-technique.143005/
 
Having had a few failures with JLCR followed by a string of successes, I'd recommend the following:
1. I agree with posts above - don't tie it to a shroud line.
2. Qfactor's post above shows three pictures. It should look like the middle picture. The one on the right is asking for trouble because the shroud lines can get wrapped around the shock cord and then the chute wont inflate (don't ask me how I know).
3. There was a discussion a while back about this and I summarized and wrote up the best of it (posts from Cameron Anderson) in the attachment. I had several failures prior, but since I have followed it have had a string of only successes.
The chute release is set up that way on purpose for that rocket. It has a nose weight that brings the rocket down fast, in a straight vertical line - nose first. This also keeps the bottom end of the chute pointing up so that the descent doesn't try to inflate the chute and push it out from under the band. Been using this arrangement for a couple of years. Like yourself, we learn from experience and close calls.
 
It can be complicated, but one thing I noticed:

1. Realize that while the bands grip with friction, parachute material slides easily over itself
2. In the photo attached, CR is gripping the outside layer of fabric, but that fabric doesn't grip the fabric below it well
3. If you snap this bundle away rapidly and stop it with the shock cord, it can "turn inside out," with the chute tugged out from inside the band

The goal is a bundle that can't be shaken apart, yet still falls apart completely after release.

That usually means:
1. Even if you z-fold, at least roll the bundle at the end so that you can "lock together" the bundle
2. Shrouds are probably best inside the bundle, not wrapped around the outside (they aren't needed to hold the bundle closed
3. Feel free to lengthen the tether, as long as nothing is likely to catch it and yank the CR off; tether is better too long and loose than short and tight

Hope that helps?

P.S. Chute Release stays on until the battery charge runs too low, that's about 4-5 days on a full charge. But don't use it that way, because the weather can shift 10 feet (3m) per hour, adding inaccuracy to the release point.
 

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It can be complicated, but one thing I noticed:

1. Realize that while the bands grip with friction, parachute material slides easily over itself
2. In the photo attached, CR is gripping the outside layer of fabric, but that fabric doesn't grip the fabric below it well
3. If you snap this bundle away rapidly and stop it with the shock cord, it can "turn inside out," with the chute tugged out from inside the band

The goal is a bundle that can't be shaken apart, yet still falls apart completely after release.

That usually means:
1. Even if you z-fold, at least roll the bundle at the end so that you can "lock together" the bundle
2. Shrouds are probably best inside the bundle, not wrapped around the outside (they aren't needed to hold the bundle closed
3. Feel free to lengthen the tether, as long as nothing is likely to catch it and yank the CR off; tether is better too long and loose than short and tight

Hope that helps?

P.S. Chute Release stays on until the battery charge runs too low, that's about 4-5 days on a full charge. But don't use it that way, because the weather can shift 10 feet (3m) per hour, adding inaccuracy to the release point.

Thank you, John! Living up to the legend that is Jolly Logic support!

Seriously, thank you all - this is all great stuff.
 
We are competing at Spaceport America Cup next Summer, but we intend to surpass their flight ceiling well before then. November 7, we are launching at METRA to test out our full stack. We have at least one more scheduled launch in January as well at FAR.



Awesome, will do! Thanks!


Per the Spaceport America Cup application..
Recovery
Describe your recovery system; dual-deploy, size and style of chute, number of chutes, length of shock cord,
"Chute Release" commercial products no longer approved.

Clarified on the HeroX forums..
https://www.herox.com/SpaceportAmericaCup2021/forum/thread/6632
Tony Alcocer
Spaceport America Cup
RSO
 
Per the Spaceport America Cup application..
Recovery
Describe your recovery system; dual-deploy, size and style of chute, number of chutes, length of shock cord,
"Chute Release" commercial products no longer approved.

Clarified on the HeroX forums..
https://www.herox.com/SpaceportAmericaCup2021/forum/thread/6632
Tony Alcocer
Spaceport America Cup
RSO

Thanks tfish! We are not using JLCR for SA Cup. We have our own deployment system. Just recently purchased the JLCR for other projects. Thank you!
 
It can be complicated, but one thing I noticed:

1. Realize that while the bands grip with friction, parachute material slides easily over itself
2. In the photo attached, CR is gripping the outside layer of fabric, but that fabric doesn't grip the fabric below it well
3. If you snap this bundle away rapidly and stop it with the shock cord, it can "turn inside out," with the chute tugged out from inside the band

The goal is a bundle that can't be shaken apart, yet still falls apart completely after release.

That usually means:
1. Even if you z-fold, at least roll the bundle at the end so that you can "lock together" the bundle
2. Shrouds are probably best inside the bundle, not wrapped around the outside (they aren't needed to hold the bundle closed
3. Feel free to lengthen the tether, as long as nothing is likely to catch it and yank the CR off; tether is better too long and loose than short and tight

Hope that helps?

P.S. Chute Release stays on until the battery charge runs too low, that's about 4-5 days on a full charge. But don't use it that way, because the weather can shift 10 feet (3m) per hour, adding inaccuracy to the release point.
Thanks John.
Could you also offer the OP, and all other contributors to this thread, some clarification of where the JLCR should be tethered to so as not to wrench the JLCR off the chute bundle.
Thanks.
 
Thanks John.
Could you also offer the OP, and all other contributors to this thread, some clarification of where the JLCR should be tethered to so as not to wrench the JLCR off the chute bundle.
Thanks.

However you choose to tether Chute Release, the guiding principles should include:
  • Never tether it in such a way that the tether gets yanked, ever
  • Pull the shock cord tight, and ensure that the tether still has no tension
  • Shake it vigorously, make sure it's still not yanked
  • Realize that if your bundle slides apart, it may move Chute Release and tug the tether
  • However long you make the tether, be sure it won't snag on something
I always use a loose cow hitch to tether Chute Release. Remember to tether it before you wrap the band if you do this, because once the band is on you can't do that.

The tether should never have to hold more tension than the weight of Chute Release plus some acceleration of it flying around after release. We ship it with 300 pound braided line, which is overkill.

Hope that all helps?
 
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