Jolly logic chute release - unusual failure

[KevinT]

I was at the ROC launch today and used my Jolly logic chute release and experienced an unusual failure that caused the chute to not deploy.

Upon inspection I noticed that the pin did in fact release form the Jolly logic as expected, but the ring that holds the release pin to the rubberband has needle sharp ends (at least mine does) and it traveled a couple of inches and embedded itself into the chute protector material and got stuck, thus preventing the chute from releasing.

I'm either going to file the end of the ring smooth or replace the ring with something different.

This is just a heads-up.

 

[OverTheTop]

Thanks for the heads-up

 

[BrendanH69]

Upon inspection I noticed that the pin did in fact release form the Jolly logic as expected, but the ring that holds the release pin to the rubberband has needle sharp ends (at least mine does) and it traveled a couple of inches and embedded itself into the chute protector material and got stuck, thus preventing the chute from releasing.

I was hesitant about those "key ring" edges yesterday when I was replacing the rubber band on my JLCR. I avoided putting the rubber band over the top of the ends as I was worried the edges might "prick" the rubber and cause it to snap under load. Didn't think about the risk of them snagging on the nomex blanket, so thanks for the heads up.

 

[wonderboy]

...but the ring that holds the release pin to the rubberband has needle sharp ends (at least mine does) and it traveled a couple of inches and embedded itself into the chute protector material and got stuck, thus preventing the chute from releasing.

I had this EXACT failure mode on my crayon bank rocket. The edge of the keyring snaged a single tiny fiber in one of the shroud lines, but it was after most of the rubberband tension was relieved, so it wasn't able to pull free. It was amazing how little effort it took to keep the parachute nicely bundled once the initial deployment shock is over.

Despite the concern of the same sharp end damaging the rubber band, I carefully locate the rubber band attachment to shield that sharp end of the ring. I just carefully inspect the rubber band before packing up the chute to make sure there are no nicks in the rubber band.

 

[Jim Hinton]

It has happened to me as well, fortunately, pretty uncommon. I use the JLCR on pretty much every flight that isn't dual recovery. I've experienced that failure twice in about five years. I have taken ti tying two JLCRs together in series on flights where the band tension is high and when space in the airframe allows. If either device releases, the chute deploys. On the plus side, the devices themselves have triggered properly every time. I have experienced premature triggering, I believe inside the airframe. This seems to have been caused by a weak battery. One thinks that is a 'fail safe' designed into the unit.

Jim

 

[KevinT]

I really like the product too; just need find an alternate to the mini keyring.

 

[SkyFire]

I quit using rubber bands and started using a 3/4" elastic band, as suggested by someone on this forum. Functions better because the elastic band doesn't stick to the fabric like the rubber band, it's easily adjustable for different size chutes, and the band covers the sharp ends of the ring.

 

[KevinT]

That's awesome and covers the keyring as well.

 

[rcktnut]

Jolly Logic Chute Release | The Rocketry Forum Post #50 and beyond. I bring it up every time a JLCR thread like this comes up simply because the method works great. Ditch the rubber!!!

 

[Buzzard]

I use the fabric covered elastic hair rings that women use for ponytails. They come in various sizes. I used a large one at the last launch on a DG&A Arrow on a H123 with a 48" parachute. Worked well. One other tip is to make sure that the pin can release close to straight down out of the connector to prevent it binding.

Chas