JL Chute Release questions

[boatgeek]

Great tip! I got a roll of 3/4" elastic band material for $5 on Amazon. Works perfectly bench testing. I have flown four times with my JLCR using a rubber band without issue but was concerned about the band catching on the chute or being too tight or too loose. One new rubber band broke while installing it. This promises to be a much better set up.
View attachment 456762

I might give this a try in 1/4" elastic. I have a vast stash of that hanging around from mask making.

 

[crossfire]

Great tip! I got a roll of 3/4" elastic band material for $5 on Amazon. Works perfectly bench testing. I have flown four times with my JLCR using a rubber band without issue but was concerned about the band catching on the chute or being too tight or too loose. One new rubber band broke while installing it. This promises to be a much better set up.
View attachment 456762

Have you tried in flight with the elastic?

 

[SkyFire]

Have you tried in flight with the elastic?

Not yet but rcktnut who posted the tip has. If the weather is favorable on Saturday I will be doing an empirical test (flight) and will post the results.

 

[rcktnut]

I might give this a try in 1/4" elastic. I have a vast stash of that hanging around from mask making.

I tried 1/4" elastic not enough energy stored in it to be reliable when fully stretched. That is why I used 3/4 in. I have 7 flights using it now with various dia. chutes no problems at all. You guys have to read the other thread I explained it there. Again post #50 on up Jolly Logic Chute Release | The Rocketry Forum When adjusting the length for the chute bundle make sure that the elastic is fully stretched. Can also make the bundle as tight as you want. I make them pretty tight make sure the don't open at apogee.

 

[SkyFire]

One of the problems I have seen while bench testing with a rubber band is that the pin won't release if the band is too tight. Friction between the chute and the rubber band is the culprit. The elastic band is nylon and doesn't have this issue. Also, being able to easily adjust the elastic band based on the chute size is a big plus.

 

[RobertH3]

They should be shipped with elastic or a set of variously sized "scrunchies" for hair - lost my first HPR last weekend due to rubber band issue and laundry quantity. The rubber bands, pardon me, "suck" and are the biggest fail. Thinking about launching an HPR with a JLCR makes me cringe. My HPR's are going to 100% dual deploy, and my JLCR works great in low and mid-power rockets BT70 and up. That's where it'll stay.

Cheers / Robert

 

[RalPh8]

I just flew my JLCR this past weekend at a DARS launch. Once set at 800ft and the 2nd set at 600ft and both times it released and worked perfectly. Still debating if I’ll use it for my level 2 attempt.

 

[Orien]

Regarding the rubber band digging into the chute and getting stuck, could you just put a strip of paper underneath the rubber band?

 

[user 30299]

I regularly use the JLCR on these two HPR rockets; Super Batray (4", 54mm motor, Madcow kit) and Phoenix (4", 38mm motor, Madcow kit). Both rockets weigh in at 5.5 lbs, no motor. But I stopped using the rubber bands and strictly use the hair bands. I have not had a hair band break or fail to release the chute. I do have to be careful packing the chute and attaching the JLCR to the harness.

 

[neil_w]

I got my JLCR last winter, then the pandemic hit, so here 15 months later I'm just doing my first bench-testing with it. I tried with some 3/8" elastic and it worked perfectly every time I tried.

Downside: I'm not quite sure how to attach it in a way that makes it easy to swap between different lengths, as compared a rubber band or hair band which is naturally a loop, and easy to hitch and unhitch. I'm hoping I can get by with the same length for all my parachutes (which range from 15"-24") but still it'd be nice to be able to change more easily when necessary. Any suggestions?

View attachment 456762

How do you have the elastic attached to the pin in that picture?

 

[SkyFire]

Flew three different rockets today using the JLCR with a 3/4" elastic band.
Rockets; 2.6", 3" and 4".
It worked perfectly!
Still test the release before each launch.

 

[mo2872]

My son flew our JLCR for the first time today and it worked perfectly with the supplied bands. Could be different next time, I suppose.

 

[Wally Ferrer]

I started using the rubber shock cords left over since I started replacing them with Kevlar, can be any length practically that I need...

 

[mo2872]

I started using the rubber shock cords left over since I started replacing them with Kevlar, can be any length practically that I need...

Now that’s a good idea!

 

[Powderman]

I am 1 for 4 on the chute release. The first two flights with it, the rubber band got stuck to the parachute. I switched to a hair band on the third flight and it worked as intended. On my fourth flight with the chute release, the parachute came out of the device at ejection. The rocket was okay but it was a long walk.

Despite these problems, in my experience, the device itself has always functioned as intended, releasing the pin at the right altitude. The issues come from the way your parachute is packed. I highly recommend the hair band in place of the stock rubber bands as it produces almost no friction with the nylon parachutes at all. If that's not an option for some reason, then your best bet is to leave the chute release packed for as little time as possible so the rubber band doesn't settle into the parachute too much.

I've been using the CR for about 6 months now. I successfully completed my L2 at Argonia back in February with one and flew a J435SW to 4000' this last weekend with one. I have around 18 flights on this one with zero failures. I read through all the comments and reviews before I started using it and have been very deliberate on how the parachute is packed and folded. In regards to having the chute pull out - you have to make sure the CR tether is shorter than the chute and shroud lines or it will pull out. It is a great tool, but like everything, you must use it with some care.

Powderman

 

[RalPh8]

I used my JLCR four times in the last two weeks and all times it opened perfectly. Including on my level 2 cert flight. Literally no difference between now and when I used it back and January other than the colder weather back then and this time the altitude was set 600-800ft. Hmmmm

 

[Budro0]

I'm a little late to the party, but I had concerns about the rubber band releasing the chute and getting hung up in the tube at ejection. I cut a small piece of nylon about 5" square. I use that kinda like a nomex blanket, except I wrap the folded chute in it, then wrap the JLCR over that. Finally I flip down one corner over the rubber band. The rubber band then does not have direct contact with the chute or the body tube. I have about 10 flights like that on the JLCR and have had no issues whatsoever. I can post up pics if anyone is still curious.

 

[Astronaut Cheeseball]

I'm a little late to the party, but I had concerns about the rubber band releasing the chute and getting hung up in the tube at ejection. I cut a small piece of nylon about 5" square. I use that kinda like a nomex blanket, except I wrap the folded chute in it, then wrap the JLCR over that. Finally I flip down one corner over the rubber band. The rubber band then does not have direct contact with the chute or the body tube. I have about 10 flights like that on the JLCR and have had no issues whatsoever. I can post up pics if anyone is still curious.

Please do!

 

[Nathan]

I have had three JLCRs and in my experience they are much less reliable than conventional dual deploy, for the reasons others have stated. I don't use them anymore.

 

[bobbyg23]

I have had three JLCRs and in my experience they are much less reliable than conventional dual deploy, for the reasons others have stated. I don't use them anymore.

Interested in getting rid of them?

 

[Nathan]

Interested in getting rid of them?

One was lost when the tether broke, one was lost when the rocket came down in a pond, and one was broken when a rocket came in ballistic.

 

[cerving]

One was lost when the tether broke, one was lost when the rocket came down in a pond, and one was broken when a rocket came in ballistic.

What caused the ballistic recovery? That's not something a JLCR can prevent... which is one reason why we came up with the Eggtimer Apogee altimeter.

 

[Budro0]

Please do!

Here ya go.

This is the swatch of nylon. You can see how great my sewing skills are. This nylon is basically parachute material, but it seems stiffer although about the same weight. Anyway, it's slick.


Roll your chute as you do (this chute is smaller than I usually use, which causes issues below)


Place parachute on blanket


Wrap like a nylon taquito. This is where the chute/blanket size can catch you up. I don't like the edges to overlap like I show here.


You can see here where the rubber band contacts the far side of the blanket. I've not actually had issues with it releasing, but I worry the band binding on that overlap. So make sure the blanket really only goes under the band.


Then it's just a matter of flipping the leading corner (as it exits the tube) back over the band.


And the final product.

 

[Nathan]

What caused the ballistic recovery? That's not something a JLCR can prevent... which is one reason why we came up with the Eggtimer Apogee altimeter.

It was back when there was a problem with ejection charges on 38mm CTI VMax motors. There was no ejection and it came in ballistic.

 

[cerving]

It was back when there was a problem with ejection charges on 38mm CTI VMax motors. There was no ejection and it came in ballistic.

Yeah, those "whomp motors" burn so fast that they don't always light the delay grain. NAR/TRA put out a joint advisory on them... they require electronic deployments on them now. CTI doesn't actively make them anymore, probably because they'd have to either figure out a way to get the delay grain to light reliably or plug the motor; either way, they'd probably have to them them recertified.

 

[boatgeek]

Yeah, those "whomp motors" burn so fast that they don't always light the delay grain. NAR/TRA put out a joint advisory on them... they require electronic deployments on them now. CTI doesn't actively make them anymore, probably because they'd have to either figure out a way to get the delay grain to light reliably or plug the motor; either way, they'd probably have to them them recertified.

My understanding was that one of the chemicals unique to VMax was implicated in the fire, and that was why they stopped making those motors. The fire was in a different part of the plant from the hobby motors, though.

/thread drift