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Chute deployment bags

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JimmyL

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I am looking for information on deployment bags. I have finished making an 8' chute and would like to make a deployment bag next. Searching the forum here did not turn up anything. The chute pages of Team Vatsaas are excellent. Their pattern is easy to make and sewing the chute together was a breeze. Now if I can find info on a deployment bag.

JimmyL
 

troj

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Take a look here and you'll see how to pack a parachute into a very simple deployment bag.

We refer to these bags as "beanies" because that's what they look like. Very simple, but very effective. It's basically a round piece of cordura with a skirt on it. Flip it upside down, and it looks like a straight-sided bowl.

The key is to size the parachute to the bag and the bag to the airframe you're going to use it in. A bag that works well on a 7.5" airframe may well be too large for a 6" airframe.

-Kevin
 

Slick36

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Being new to large and dangerous rocket ships, I ask :

What are chute bags and what are they for?

I am looking for information on deployment bags. I have finished making an 8' chute and would like to make a deployment bag next. Searching the forum here did not turn up anything. The chute pages of Team Vatsaas are excellent. Their pattern is easy to make and sewing the chute together was a breeze. Now if I can find info on a deployment bag.

JimmyL
 

troj

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Being new to large and dangerous rocket ships, I ask :

What are chute bags and what are they for?
A deployment bag is a bag into which the parachute is "packed" (folded), to protect it, as well as help ensure a neat, orderly deployment.

A skydiver's "container" (the thing on their back) is a form of deployment bag.

In rocketry, they're used in much the same way. The parachute is neatly folded in the bag, and held there. When the rocket deploys its recovery, the parachute unfolds out of the bag, helping keep things where they belong, reducing opening shock, and reducing the risk of entanglement.

-Kevin
 

TheAviator

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I am quite intrigued by this... Can a parachute bag help on smaller rockets, or is relegated to the realm of big L3 rockets? Also, is there a way to do this using an ejection charge that is under the main? Or also, separate at the tube coupler and pull it out of the back of the upper airframe?
 

MarkM

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I am quite intrigued by this... Can a parachute bag help on smaller rockets, or is relegated to the realm of big L3 rockets?
How small? They not are relegated to large L3 projects. I've seen them used routinely on L2, principally 4", sized rockets. Typically, they are used when doing altitude deployment using electronics. I have not seen them used when doing motor ejection though I don't see why this couldn't be done.

Also, is there a way to do this using an ejection charge that is under the main?
Of course. That's the way most deploy their main chutes with electronics; the ebay is beneath the chute so so is the ejection charge.
 

quickburst

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4" airframes are about the smallest. The motor or ejection scheme does not matter. It's all about protecting the parachute and adding some sort of order to deployment.


see: http://www.quickburst.net/ndb_4.htm




I am quite intrigued by this... Can a parachute bag help on smaller rockets, or is relegated to the realm of big L3 rockets? Also, is there a way to do this using an ejection charge that is under the main? Or also, separate at the tube coupler and pull it out of the back of the upper airframe?
 

troj

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Can a parachute bag help on smaller rockets, or is relegated to the realm of big L3 rockets?
Anything smaller than about 4", and you'll have one heck of a time packing the parachute into the bag.

Also, is there a way to do this using an ejection charge that is under the main? Or also, separate at the tube coupler and pull it out of the back of the upper airframe?
There are those who would tell you that's fine. Personally, I'd never do it that way -- you need a small drogue to pull the bag up and off of the main.

Look to skydiving, NASA, and similar setups -- they use drogues to pull the bag up and off. You can do it two ways -- a free bag, where the main isn't attached to the bag at all, or a regular bag, where the bag is attached to the parachute.

The advantage of the former is that the weight of what the drogue is attached to doesn't matter. With the latter, if you have a heavy noscone attached to that bag, it will tend to collapse your canopy.

What some folks will do (using the Gates Brothers' Jayhawk as an example), the drogue is sized for the nosecone. The drogue comes out when the nose comes off. It then pulls the bagged mains up and out of the rocket, then pulls the bag off of the mains, and entirely clear.

Bag and nosecone come down on the drogue, the main body of the rocket comes down on the mains.

I would never rely on inertia to extract a main from a bag. It's just a recipe for disaster.

Also, never shove and wad your parachute into a deployment bag -- a lot of friction is generated when the layers of nylon slip past each other, and the bag, when they're just shoved in. This leads to ruined parachutes. In the worst case, things can get jammed and not deploy properly.

It takes practice, but learn to fold your parachute into the bag. It should not be difficult to pull the parachute out. When we have our big (28 foot) parachutes in their bags, a 3 year old can easily put enough tension on the lines to extract the parachute.

-Kevin
 

ben_ullman

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It takes practice, but learn to fold your parachute into the bag. It should not be difficult to pull the parachute out. When we have our big (28 foot) parachutes in their bags, a 3 year old can easily put enough tension on the lines to extract the parachute.

-Kevin
Very good advice right there. Remember if its hard for you to yank it out think how hard it will be for a NOSECONE to pull it out.

Ben
 
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