# JL Chute release question

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#### tOD

##### Sinking in the quicksand of HPR
TRF Supporter
I'm going to make my first flights with a
chute release this weekend. Does the compartment containing the device need to be vented?

#### ep29030

##### Mark N.
TRF Supporter
Well, it is always a good idea to vent the parachute area with a small hole, to relieve pressure build-up in upper airframe. For model rockets, a single 1/16 to 1/8" hole works. But once your engine kicks it out at apogee with ejection charge, then CR is in open air.

#### Eric

##### Well-Known Member
I have flown the chute release in both types. Most of the Estes kits never had a vent when built, so they never got one.

Chute Release still opened perfectly either way. But it never hurts to just add a small hole.

#### kuririn

##### BARGeezer
TRF Supporter
Not necessary. Vent holes are only needed for devices that sense atmospheric pressure while in the rocket. The altimeter portion of the JLCR senses atmospheric pressure and releases the pin, rubber band, and chute at your programmed elevation while free falling after ejection.

Best invention ever. I'm still waiting for the JLCR II that can fit inside a BT-20 tube.

#### tOD

##### Sinking in the quicksand of HPR
TRF Supporter
So I guess it established it's ground level reference on power- up and then calculates the release altitude from there?

#### Jozef

##### Well-Known Member
So I guess it established it's ground level reference on power- up and then calculates the release altitude from there?
Exactly..

#### tOD

##### Sinking in the quicksand of HPR
TRF Supporter
I'm eager to try this. I have two rockets I want to use it in tomorrow, wind at the launch site is forecast for 10-15 mph, and I don't think the corn's been cut. The corn is planted in strips with fallow areas in between so it's 50/50 a rocket will land in the clear. I think I'll release at 200' and see how it goes

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#### afadeev

##### Well-Known Member
TRF Supporter
I'm eager to try this. I have two rockets I want to use it in tomorrow, wind at the launch site is forecast for 10-15 mph, and I don't think the corn's been cut. The corn is planted in strips with fallow areas in between so it's 50/50 a rocket will land in the clear. I think I'll release at 200' and see how it goes
BTDT, spent 2 days looking for a rocket in the corn field.
Found it on day #2 by flying a drone over the adjacent fields and (luckily) spotted the orange chute peaking out between corn stalks.
It's deceptively difficult to estimate depth over corn fields, and most of my fruitless foot grid searching was too close to the launch pad. 200 foot JLCR deploy worked perfectly, and against me, since the rocket weather cocked into the wind, and super short open chute time did not bring it back.
YMMV.

Have fun with JLCR - it's a great tool that make dual-deploy flying easy, quick, and fun!

a

P.S.: I hate corn fields!

#### smugglervt

##### Vermont BAR
TRF Supporter
Best to include a loud buzzer/beacon to it. Corn is a pain in the butt to try and find a rocket when the corn is over 7' tall.

#### Zeus-cat

##### Well-Known Member
BTDT, spent 2 days looking for a rocket in the corn field.
Found it on day #2 by flying a drone over the adjacent fields and (luckily) spotted the orange chute peaking out between corn stalks.
It's deceptively difficult to estimate depth over corn fields, and most of my fruitless foot grid searching was too close to the launch pad...
People almost always underestimate how far a rocket has drifted. I've done it numerous times. I've recovered rockets that other people gave up on because they didn't go out far enough. My rule is just keep looking until you are ridiculously far away from the launch pad and only then turn around.

P.S.: I hate corn fields!
I love corn fields... when they don't have corn in them.

#### tOD

##### Sinking in the quicksand of HPR
TRF Supporter
Best to include a loud buzzer/beacon to it. Corn is a pain in the butt to try and find a rocket when the corn is over 7' tall.
Any suggestions for a buzzer I might be able to get ahold of today?

#### smugglervt

##### Vermont BAR
TRF Supporter
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#### crossfire

##### Lifetime Supporter
TRF Lifetime Supporter
Not necessary. Vent holes are only needed for devices that sense atmospheric pressure while in the rocket. The altimeter portion of the JLCR senses atmospheric pressure and releases the pin, rubber band, and chute at your programmed elevation while free falling after ejection.

Best invention ever. I'm still waiting for the JLCR II that can fit inside a BT-20 tube.
Do you think a JCR for BT20 size rocket would be a big seller for John? A $129.00 item in a$20 rocket.

#### kuririn

##### BARGeezer
TRF Supporter
Do you think a JCR for BT20 size rocket would be a big seller for John? A $129.00 item in a$20 rocket.

#### snrkl

##### Well-Known Member
TRF Supporter
I didn't see anyone else state the obvious... so here goes -

When in doubt, RTFM. Read the FACTORY manual. (what did you think it stood for?!?)

If you do read it, you will learn what is and is not recommended. Lots of good info in there. I can see why you might think venting could be required... and venting is (in general terms) not a bad idea for high flying rockets that experience a large change in air pressure as they reach a high altitude.

Anyhoo... check this out - https://www.jollylogic.com/wp-content/uploads/2015/12/JollyLogicChuteReleaseWeb.pdf
Yes. Vent it. I’ve seen the JLCR take the NC going on as a pressure change that then triggered the release on the pad. (Fortunately we heard the servo and it release on the pad as my club mate was doing it) - quick cordless drill vent hole and all good.