JLCR question for low to mid power flying

[sgirard]

I have gotten back into rocketry since my retirement and have a question about the JLCR. The closest club to me is about 100 miles so I fly by myself at a friend’s pasture. I scratch build everything and build the largest and lightest rockets I can (I like big). I fly mostly D and E motors mainly to keep the altitude 400 feet or below due to field size and being in my seventies with some health issues, I don’t want to walk forever for recovery. I use only motor deployment and do not hold any level 1,2, or 3 classifications. I was thinking, if I still have my ejection at apogee and used a chute release I could get some higher flights and still control the recovery somewhat. I sew my on chutes out of nylon 18” and larger. So, with some background out of the way here are my questions.

• Will the Jolly Logic chute release hold an 18” nylon chute or is it too small? I have never seen one in person.
• If you have some type of problem with the flight and you never reach the set altitude for chute release, can I assume the chute won’t release? I didn’t know if there was some sort of failsafe built into the release, I’m guessing not but had to ask.

Thanks for any response.

Steve

 

[jmasterj]

I've had trouble with small chutes like that but I'm sure others have figured it out.

It's supposed to release as soon as it's descending below the set altitude, so it should be fine. I've never tested that, though.

 

[Sparkyflyer14]

You can always use different size rubber bands for your different chutes.

In the instruction booklet it says that if the flight does not go over the designated deployment height, the chute release will automatically open at apogee.

 

[kuririn]

You can always use different size rubber bands for your different chutes.

In the instruction booklet it says that if the flight does not go over the designated deployment height, the chute release will automatically open at apogee.

Small correction:
There are two sizes of bands provided. Per instructions, the smaller band is for chutes smaller than about 36".
The larger band is for chutes larger than 36". The instructions do not mention what the upper limit is.
Also from the instructions: " If the flight never reaches the selected release altitude and is falling, Chute Release will open right away".
Hopefully the ejection charge will fire before it hits the ground.

 

[sgirard]

Thanks for the replies
Sounds like one of them would work for me as long as the smaller rubber band will hold a 18" chute. Are these special rubber bands? I wonder if you could get one that will hold (if the smaller one won't) from an office supply store.

 

[Antares JS]

I recommend using a hair band if you can get a pack of them. Rubber bands have an annoying tendency to stick to the parachutes.

 

[sgirard]

Ok thanks, I found a place to download the user manual. So I will do that and read it, I guess I should have done that first and maybe got my questions answered.

 

[rcktnut]

I would consider also what kind of shock cord you are using, the robustness of your recovery system. You don't want to lose a $140.00 JLCR do to a failure in your recovery system. I own 2 JCLR's and personally will not use them in light weight "Estes" type constructed rockets. They do work great on my HPR rockets that are not dual deploy, in the manner like you wish to do, using a bigger motor in them for higher flights.
Here's a good thread to read on the JCLR: https://www.rocketryforum.com/threads/jolly-logic-chute-release.159948/

 

[jahall4]

Reliability of the JLCR can be greatly increased for all chutes, and particularly so for large ones, by using a Recovery Sled and EPDM Rubber bands.

 

[sgirard]

Good point rcktnut, I am using 350 lb kevlar on my shock cords. Usually 4 times the body tube length. Like I said, I scratch build everything. Most all my rockets are between 3" and 4 1/2" body tubes and none weigh over 2 lbs. So if I tether the chute release to the shock cord or eyelet on my nose cone (like my altimeter two) I may gut the body tube but save my hardware on chute (I think). I will spend some time checking out other peoples setup, and learn about recovery sleds while i'm at it.

 

[T-Rex]

Reliability of the JLCR can be greatly increased for all chutes, and particularly so for large ones, by using a Recovery Sled and EPDM Rubber bands.


View attachment 562304

But now you are exposing the chute release to corrosive ejection gasses. I is my understanding that it should be inside the burrito (could be wrong, wrong a lot)

 

[jahall4]

But now you are exposing the chute release to corrosive ejection gasses. I is my understanding that it should be inside the burrito (could be wrong, wrong a lot)

Ideally, but it is exposed to gasses any way. Blankets protect from burning particles of BP. In this case A) not room to wrap the whole thing (BT-60 size tube very tight) and B) rigging aft (not shown) of the pictured bundle provides additional protection from the ejection charge, think of as a baffle. Here is a more typical implementation...

 

[DaHabes]

I recommend using a hair band if you can get a pack of them. Rubber bands have an annoying tendency to stick to the parachutes.

To add to this, you can use one band for the smaller chutes, and if too loose, tie an extra knot in it to tighten it further. You can combine two hair bands for larger chutes, again adding an additional knot if some tightening is needed. ALWAYS, test your recovery package before you fly it to make sure the chute release band is stretched tight enough to pull free when released.

The chute release recovery package can start to get VERY tight in any body tube smaller than BT-70. In BT-60 or 38mm airframes, you'll likely need a small chute (smaller than you might fly otherwise, so be mindful of fin geometry and attachment) that is tightly packable (thin mill or Spherachute Ultralight). I have a 38mm which was designed to go high (a mile+) but I neglected to factor in the chute release when I built it. If I eliminate the nomex protector and only use dog barf, wadding, it should work, but I still haven't had the gumption to fly it yet. I need another round of ground testing to validate. Without a nomex protector and with inadequate dog barf, I melted two Spherachutes in my initial ground tests.

 

[schneijt]

But now you are exposing the chute release to corrosive ejection gasses. I is my understanding that it should be inside the burrito (could be wrong, wrong a lot)

I once had a failure where the band never released from a nomex burrito correctly, so the rocket came down with no chute. The pin had released, but the band was caught on the nomex almost like velcro, so the burrito couldn’t open. Ever since, I keep the JCLR/chute bundle inside the nomex bundle.

 

[DaHabes]

I once had a failure where the band never released from a nomex burrito correctly, so the rocket came down with no chute. The pin had released, but the band was caught on the nomex almost like velcro, so the burrito couldn’t open. Ever since, I keep the JCLR/chute bundle inside the nomex bundle.

For me a lot depends on how well I can pack the chute in the nomex blanket. Ideally you would place the JLCR inside the blanket. However, having the JLCR on the outside of the blanket will hold the wrapped nomex such that no hot material can get to the parachute. That can be needed if 1) the blanket barely covers the parachute or 2), the wrapped burrito is small compared to the airframe diameter such that the burrito can fall apart upon acceleration, which defeats its purpose. Since nomex blankets tend to be sized to the airframe, you can't go bigger or smaller on the nomex without running into either a burrito that is too loose or one that is too tight for the airframe. The other value of placing the JLCR on the outside of a burrito is that it is not possible for the band to grab onto the folds of the parachute and not release. It will slide off much more easily from the nomex.

Dino Chutes made a nice cover for the JLCR (I have one), so placing the JLCR on the outside of the burrito isn't a worry. However, since they went out of business, that option ist kaput. It would be nice is some other vendor would pick up the idea and provide an equivalent.

 

[John Beans]

Everyone has pretty much answered your questions (yes, Chute Release can handle the chutes you're using; yes, it will open even if you don't reach your planned release altitude as long as it travels over 100 feet for a couple of seconds).

I should mention that Pat Butler shut down Dinochutes, so while you may find the protectors still in stock some places (we ran out), they are no longer being made.

 

[jahall4]

To add to this, you can use one band for the smaller chutes, and if too loose, tie an extra knot in it to tighten it further. You can combine two hair bands for larger chutes, again adding an additional knot if some tightening is needed. ALWAYS, test your recovery package before you fly it to make sure the chute release band is stretched tight enough to pull free when released.

The chute release recovery package can start to get VERY tight in any body tube smaller than BT-70. In BT-60 or 38mm airframes, you'll likely need a small chute (smaller than you might fly otherwise, so be mindful of fin geometry and attachment) that is tightly packable (thin mill or Spherachute Ultralight). I have a 38mm which was designed to go high (a mile+) but I neglected to factor in the chute release when I built it. If I eliminate the nomex protector and only use dog barf, wadding, it should work, but I still haven't had the gumption to fly it yet. I need another round of ground testing to validate. Without a nomex protector and with inadequate dog barf, I melted two Spherachutes in my initial ground tests.

Yep, design, built, flew rocket similar to what you describe. 38mm really to small, BT-60 works okay. The one pictured here on its way to 2K. Love Julie's ultralight chutes have several incl. two 12'.

 

[jahall4]

Everyone has pretty much answered your questions (yes, Chute Release can handle the chutes you're using; yes, it will open even if you don't reach your planned release altitude as long as it travels over 100 feet for a couple of seconds).

I should mention that Pat Butler shut down Dinochutes, so while you may find the protectors still in stock some places (we ran out), they are no longer being made.

John, I've thanked you before, but I'm going to do it again and again... Thank you, for your contribution to the sport!

 

[sgirard]

Thanks John for your answers, and yes everyone has gave me the information I needed. I read the users manual (that I should have read to begin with) and the information was there also. I feel the chute release will allow me to fly larger motors a still control the recovery some what.

 

[sgirard]

ordered my JLCR and should be here in a couple of days. so now I enter something new for me. I plan on having my motor ejection at apogee and free fall (or tumble) to a lower altitude for the chute release open the main. Is this considered a type of dual deployment? Now I'm going to play with openrocket to learn how to set up for dual deploy. I just updated my beta 5 to the 22.02 release. I want to know if the program will calculate the speed at main chute deploy. I assume I will have to play with a streamer or small drogue chute that deploys at apogee. I know a lot of people know how to do this so if you got anything that will help me along, please let me know. I'm starting from scratch on this dual deployment.
thanks

 

[jahall4]

ordered my JLCR and should be here in a couple of days. so now I enter something new for me. I plan on having my motor ejection at apogee and free fall (or tumble) to a lower altitude for the chute release open the main. Is this considered a type of dual deployment? Now I'm going to play with openrocket to learn how to set up for dual deploy. I just updated my beta 5 to the 22.02 release. I want to know if the program will calculate the speed at main chute deploy. I assume I will have to play with a streamer or small drogue chute that deploys at apogee. I know a lot of people know how to do this so if you got anything that will help me along, please let me know. I'm starting from scratch on this dual deployment.
thanks

Yes, it is considered dual deployment because deployment is happing as 2 separates events. Without lots of effort Triunal deployment is possible using the JLCR to deploy a backup main. Here in an example of just that...

 

[Buckeye]

Yes, this is dual deployment. Yes, you need a fake chute at apogee to simulate the tumbling until the main chute deploys at the set altitude. Play around with the fake chute until you get a 50 ft/s or so descent rate. That's probably a good starting point for your MPR. You won't know the true rate unless you measure it with an altimeter onboard. OR will calculate the speed over the entire flight time. Plot it. Everbody gets worked up about speed at main deploy on DD flights thinking that the main chute will shred. With typical good construction techniques and components, this will not happen even over a wide range of speeds. Fly it.

 

[Handeman]

I usually look for 75 - 100 ft/s between apogee deploy and main, even higher if I can get it. You are more likely to get a zipper than shread a chute if something goes wrong, but you have to be moving pretty fast for that to happen. I've never seen a main shread if the apogee deployment worked correctly. Even 100 ft/sec is a pretty slow chute deployment relatively. Skydivers are around 300 ft/s when they deploy, which is why they use sliders to slow down deployment and protect the fragile human.

The only chute I've ever had shread was an old umbrella converted to a chute that deployed because of a bad delay at motor burnout and at about 350 MPH (513 ft/s). A couple years ago I had a rocket that didn't open at apogee, came down ballistic, but did deploy the main at 400 ft. We're near sea level so terminal velocity is about 300 MPH (440 ft/s) with a 0.6 Cd. It didn't zipper the payload and the chute I got in 2003 with my PML Callisto with +100 flights on it already, didn't shread either. I did have long shock cords which may have helped prevent the shreads, they also allowed the fincan to slap the ground before it reached the end of the cord. The fin can didn't fair too well.

Any commercial chute should be able to handle 150 ft/s or faster deployments without damage. If you are deploying faster than that, a shreaded chute will probably be the least of your worries.

 

[sgirard]

Thanks Guys
I played with a fake chute in OR and see how that works and you gave me some numbers to work with so I will play with that for a while. I understand flying will be the real test, but I'm not too concerned. My real goal is to be able to fly higher and still keep a safe recovery within my limited flying field.
Thanks everyone for the help.
Steve

 

[danisman]

What about just having a 12" drogue deploy at apogee to slow primary descent a bit, making main chute deployment potentially less traumatic? This would be pretty close to true DD without the electronics.
Great discussion, thanks to everyone for sharing their wisdom and experience!
David

 

[bjphoenix]

What about just having a 12" drogue deploy at apogee to slow primary descent a bit, making main chute deployment potentially less traumatic? This would be pretty close to true DD without the electronics.
Great discussion, thanks to everyone for sharing their wisdom and experience!
David

I think this would depend on the "density" of the rocket. This happened with motor deploy of my Estes Executioner- anybody familiar with that kit will understand that it is fairly large and very light for its size, hence I would call it low "density". A D12 blew the nose cone but the parachute ended up flush with the front end of the body tube. It all came down sideways, not too fast because of the low density, and was not damaged when it landed on our grassy field. So a relatively low density model could get by without a drogue, a high density model would benefit from a drogue.
I gather from some discussions that a long high density rocket might still fall nose first even with the nose cone dragging along behind, something like that would need a drogue.