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DEPLOYMANT BAG FOR MAIN CHUTE ATTACHED TO NOSECONE. CONE HAS OWN CHUTE.
#1
Quote:     Deployment bag advice please.
Rocket is large...12" diameter.. low and slow flight with one apogee event.
Main chute is in a deployment bag, it's shock cord attached to the bulkhead below it that contains ejection charges.
Nosecone chute sits above the main chute bag and it's shock cord is attached to the nosecone ubolt.
I want to attach the main's bag to the nosecone so that when the cone is ejected it helps pull the main bag out of the rocket and carries away the bag.
I have used the 2 chute deployment just using the ejection charge..and using a pilot chute on the main's bag... but have had a failure where the main chute remained in the bodytube and only the cone and it's chute were ejected.
The picture below is from Giant Leap.

Your thoughts and experiences please..basics of where and how to connect the deployment bag and the nosecone....what orientation to place the bag in the body tube..length of the cord from bag to cone..
Tom Cohen

MDRA...Maryland
MARS...Geneseo N.Y.
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#2
Lots of variables and not a lot of information. How is the main wrapped and secured in the bag? How is the bag held closed? Is the nosecone chute of sufficient size to deploy the main? Will the main and bag easily slide out of the body tube for deployment?

I would attach the bag on a shock cord far enough below the nosecone as to allow the nosecone chute (I'm jumping to conclusions that the nosecone chute is the pilot chute you are referring to) to fully deploy independent of the bag and main coming out of the body tube.

You could try a reefing device for the bag and main but that adds a level of complexity to your configuration.

Hope this helps.
Joe Southworth
NAR 98381
Southern Colorado Rocketeers (SCORE)
Level 1 Modified Initiator
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#3
I usually attach a parachute to the NC and use the same quick link to connect the deployment bag.
The deployment bag has the loops on the side to z-fold the parachute lines.

How much shock cord and how big of a charge you using?
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#4
My dual deploy uses the engine ejection charge to deploy the drogue and then I use two archtype cable cutters to release the main from the bag. The cable cutters use about 1/2 a gram of BP. The shock cord is about 43" long and is kevlar. The drogue is about 30" from the body tube and the main is attached to the nose cone. All of the electronics are in the nose cone. This is set up in a modified Initiator flying H133s.
Joe Southworth
NAR 98381
Southern Colorado Rocketeers (SCORE)
Level 1 Modified Initiator
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#5
I would worry that a large rocket only flying to 800" would not have enough time to pull the chute out of the bag and fully open it before it hit the ground.....
it seems to me that the free bagging technique although much safer takes 400 - 500" to happen.

just my 2 cents


Bill Clune L3 | NAR#88583
Been a launch Director
Founded a Club
MARS Club|SRC|MDRA - Forever
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#6
(01-05-2016, 09:28 PM)wclune Wrote: I would worry that a large rocket only flying to 800" would not have enough time to pull the chute out of the bag and fully open it before it hit the ground.....
it seems to me that the free bagging technique although much safer takes 400 - 500" to happen.

just my 2 cents

The chute deployment needs to happen at apogee...I don't think there will be time for a free bag setup.
The main chute in it's own bag and the cone chute likewise..both with pilot chutes and both immediately out at apogee is the goal.
We are now gound testing a piston to get everything out and open at apogee with no delay...
Tom Cohen

MDRA...Maryland
MARS...Geneseo N.Y.
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#7
Anything less than 1000 ft ;I'd consider it under powered....
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