Jolly Logic Chute Release

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NewtonsLaws
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Jolly Logic Chute Release

Postby NewtonsLaws » Sat Mar 25, 2017 8:22 am

Wrong place, wrong time!
I was picking up an order from AusRocketry when I spied the new Jolly Logic Chute Release.
I had seen these on the web and thought "that will be awesome!)

and I am in the middle of a L1 build and getting worried about altitude on an H motor causing a lost rocket.

So being sucker for new toys, bought one!

Here are some photos of the unboxing.
Aiming to try it out soon, will let you know how it goes.....

QUESTION for the Forum:
Do you think that I need to have pressure equalisation holes in the body tube for this unit to work right?
Manual does not indicate that it is needed.

Just have to size my drogue chute now!

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Hot of the shelf, it was too cool to walk past!
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Back of the Box


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First reveal


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The full contents.


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Close up of Chute Release
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The spares!
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More rubber bands (the big ones)


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Fully assembled ready to use
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AMRS #134 L2 RSO / LCO

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OverTheTop
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Re: Jolly Logic Chute Release

Postby OverTheTop » Sat Mar 25, 2017 8:39 am

I have seen questions on pressure equalisation holes for the JLCR devices somewhere else on forums. I think the answer was that they are not needed, as the JLCR is actually out in the air when it is expected to work anyway.

Do you need equalisation holes for other reasons is what you should be asking. As the rocket ascends the air inside tries to get out. As the pressure difference builds it can easily blow the NC off, or other separation points apart, resulting in a premature deployment. This is one of the things that change as rocketry progresses from LPR to MPR to HPR. Bigger airframes and faster ascents putting more pressure (literally) on the rocket components from the inside.

So, two questions arise:
Do I need equalisation holes (in each airframe section)?
Do I need to use shear pins for retention on the moveable sections of airframe?

My opinion is "yes" to both.

Enjoy the JLCR. Many people love them!
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Re: Jolly Logic Chute Release

Postby OverTheTop » Sat Mar 25, 2017 8:43 am

Just have to size my drogue chute now!


That is just the main with the JLCR keeping it closed, isn't it?

There are a few ways to set up your recovery, some will need drogues, some won't.
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Re: Jolly Logic Chute Release

Postby SpaceManMat » Sat Mar 25, 2017 9:04 am

NewtonsLaws wrote:QUESTION for the Forum:
Do you think that I need to have pressure equalisation holes in the body tube for this unit to work right?
Manual does not indicate that it is needed.


From reading the manual, I suspect it would work without venting, but...
1. It is a Baro based unit so flight data will be much more acurate with a vented body.
2. Flights going high enought to use DD should have a vent to avoid early deployment.
QRS: 124
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Re: Jolly Logic Chute Release

Postby SpaceManMat » Sat Mar 25, 2017 9:08 am

SpaceManMat wrote:
NewtonsLaws wrote:QUESTION for the Forum:
Do you think that I need to have pressure equalisation holes in the body tube for this unit to work right?
Manual does not indicate that it is needed.


From reading the manual, I suspect it would work without venting, but...
1. It is a Baro based unit so flight data will be much more acurate with a vented body.
2. Flights going high enought to use DD should have a vent to avoid early deployment.


Edit. Looks like OTT beat me to it :)
QRS: 124
AMRS: 32 L2 RSO
Highest Altitude: 13,647 feet
Fastest Flight: Mach 1.55
Largest Motor: CTI 1115J530 IM
Current Project: X Wing

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Re: Jolly Logic Chute Release

Postby NewtonsLaws » Sat Mar 25, 2017 2:14 pm

Thanks OTT and SMM!

The motor ejection charge will deploy the drogue chute and then the Chute release will deploy the main chute at apogee.

Just SIMming up the rocket now and looking at a 12inch drogue . any smaller and Openrocket does not like the decent velocity for opening the main chute it seems.

Thank you for ideas re vent holds for body tube!

and upon reflection, yes obviously the Chute Release works on decent so vent tubes (hopefully) would not be relevant for the device anyway.
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AMRS #134 L2 RSO / LCO

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Re: Jolly Logic Chute Release

Postby OverTheTop » Sat Mar 25, 2017 2:38 pm

The motor ejection charge will deploy the drogue chute and then the Chute release will deploy the main chute at apogee.


Consider running the main (reefed by the JLCR) as the drogue. This is a common configuration. That doesn't mean you have to do it though :)
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Re: Jolly Logic Chute Release

Postby Lamp » Sun Mar 26, 2017 7:10 am

OTT is correct, the reefed main will act as a drogue and depending on the type, configuration and length of your shock chord, your shock chord will also lower your decent speed. These things will not be taken into account by any of the simulation programs and they will all indicate you need a drogue. I have never used a chute release but I have seen a few used, from memory I don't think I have seen anyone use a drogue with it.

I sometimes launch my 54mm fiberglass "Little Dog" as a Dual Deploy with drogueless recovery. The shockchord deployed at apogee is about 20' (6m) of 1/4" flat tubular kevlar and the typical decent velocity is around 60fps. Sometimes I will use a streamer (4" by 48") just to make it more visible. Both Rocksim and Open Rocket predict quite different decent velocities but in reality the decent velocities are pretty similar!
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Re: Jolly Logic Chute Release

Postby NewtonsLaws » Thu Mar 30, 2017 2:37 pm

Received this feedback from Jolly Logic:

From: John Beans [mailto:john@jollylogic.com]
Sent: Sunday, 26 March 2017 1:03 PM
To:NewtonsLaws
Cc: support@jollylogic.com
Subject: Re: Questions on Jolly logic in general and Chute Release

For Altimeters: yes to vents. If just Chute Release, no vent needed. 

Drogue is personal preference. They can make the "stack" descend on a more repeatable, predictable manner, but sometimes they speed up the descent if the ticket would have tumbled flat. 
Do a RocketryForum.com search on "chute release drogue". Great discussions, including my thoughts. 

Kind regards,
--John Beans
    President
    Jolly Logic

On Mar 25, 2017, at 6:45 PM, wrote:
HI John
 
Thank you for your previous reply regarding 2 stage rockets.
 
Two questions:
1. For Jolly Logic products in general, should I have a pressure equalising hole in my body tube so pressure at height is known inside the rocket?
 
2. For the chute release (just picked up from AusRocketry), I thought it would need a drogue chute or streamer. But I see that no one is using a drogue and you do not reference in your instructions/website.
Should I use a drogue or not in your view?
Primary target for this unit is high power rockets.
 
Thank you for your time.
QRS #184
AMRS #134 L2 RSO / LCO


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