Chute Release - Early Deploy

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First time using my JL Cute Release this weekend. Chute was packed and rolled just like the videos suggest and ground testing worked fine. Upon launch however my chute popped at deployment. Recovered the rocket with no issues and the pin on the chute release was out. Rubber band showed no damage. I was set to deploy at 400 feet. Apogee was at 1450.

Can anyone think of a reason why this would have happened? I'm counting on user error of some kind but would like to try and narrow down the cause so I can try not to repeat it.

Some factors: Flight data from my Altimeter 3 shows that the ejection was early, so the deployment velocity was very likely considerable. The Chute Release was tethered to the same swivel the chute itself was. Could that have popped the pin out?
 

noffie79

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My guess is that the chute simply slipped out of the band. Last month I had a very late deployment and the chute was attached to the same U-bolt as my harness. It's a 50" chute and everything held together just fine. It may take some practice to get just right. Maybe you used the larger band when the smaller one would've worked? Here's a video of my flight.
https://youtu.be/lT2RknQJ6xQ
 

woferry

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One other thought would be whether you had any reason to open your rocket after you armed the CR, and if so how much (if any) ventilation you have in the main parachute section. I've had two early releases, one was a broken band, the other one I don't have any proof what happened, but it was the only time the tightness of my nose fit got questioned by the RSO, so I pulled the nose off at the RSO desk, and while I have a vent hole for that section I think I could have created enough of a vacuum in the tube to look like a higher altitude (the nose is a pretty tight fit, and you can hear the air rushing in/out of the hole when you install/remove the nose). So the fact that the one time of several flights that I separated the rocket after arming the CR was the one time it released early inexplicably seems more than coincidental to me.
 

EXPjawa

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I have one parachute that repeatedly has done this to me. Its a standard 1.7oz nylon Top Flight 24" chute, whereas most of my others are thin-mil nylon. I can only guess that the chute in question is slipperier than the thin material, and is more prone to slipping out of the band with regards to how I have to pack it to fit within the tube it goes in (a 2" Estes PS2 body tube). Of course, by the time I recover it, the CR has released, so there is no evidence of the chute slipping the band. But I think it comes back to testing the band fit to make sure that the chute stays in when you whip it around, and that the the band pops off with some authority when released...
 

PatB

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Just remember that if your chute slips out of the rubber band that it may seem that it got released prematurely. That's because the CR will still function normally and release the rubber band when it hits its set altitude. Granted, it may not always release if there's no pressure on it, but the relative wind may also pull it out. So once you find it on the ground it will look as if though it had deployed the chute, rather than the chute having been pulled out due to too fast of an ejection. With larger chutes, we use to CRs with interlocking rubber bands and have had 100% success keeping larger chutes constrained.
 

rstaff3

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First time using my JL Cute Release this weekend. Chute was packed and rolled just like the videos suggest and ground testing worked fine. Upon launch however my chute popped at deployment. Recovered the rocket with no issues and the pin on the chute release was out. Rubber band showed no damage. I was set to deploy at 400 feet. Apogee was at 1450.

Can anyone think of a reason why this would have happened? I'm counting on user error of some kind but would like to try and narrow down the cause so I can try not to repeat it.

Some factors: Flight data from my Altimeter 3 shows that the ejection was early, so the deployment velocity was very likely considerable. The Chute Release was tethered to the same swivel the chute itself was. Could that have popped the pin out?

I assume ground testing included a shake test?
 

Flyfalcons

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Flew my CR on several models this weekend, including a 4" Sea Wolf with a 40" Recon chute that wads up pretty big. Used the larger rubber band and it worked perfectly. I did use a drogue on this model with its very heavy nose cone. I probably wouldn't have flown that model as high as I did without the Chute Release. But a shake test and release test on this new configuration were very important to ensure success.
 
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Ok you got me. Ground testing did not include a vigorous shake test. And as it happens it's the same (or nearly identical) 24" chute Rick mentions above that he says had problems with. Seems to me like chute slippage is the culprit here. If indeed the case, lesson learned.
 

Swissyhawk

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The Chute Release was tethered to the same swivel the chute itself was. Could that have popped the pin out?

There shouldn't be any force on the tether when the bundle is out. I could see this pulling the CR off the parachute. Try a longer tether or connect it to one of the shroud lines instead of the swivel.
 
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