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Pilot Chute Attachment Point

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fyrfytr310

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I'm sure this has been discussed ad nauseam but a quick search didn't yield the results I was looking for.

I'm going to employ a deployment bag in my current project because of the large chute dimensions relative to the ID of the airframe.

My question: It seems that the pilot is to be connected directly to the bag but is it logical to connect the pilot to the nose and have the bag pulled out via shock cord?
 

rharshberger

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That's the method I used on my L3 CherokeeD, pilot and d- bag connected to NC, chute connected to 3rd loop (Onebadhawk harness), harness z-folded, make sure length of harness between connection points is longer than length of shroud lines and taut pulled canopy.
 

Bat-mite

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As usual with rocketry, there is no single right answer. My chute is a military silk with a webbing at the top. I attached the internal loop of the Fruity Chutes D-bag to the webbing, and the pilot chute to the top of the D-bag. Chute attaches to the U-bolt on the NC bulkhead.
 

fyrfytr310

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This is my first run with a D-bag (hate that abbreviation btw) so i'll be ground testing the heck out of it. As such, I'll likely try a couple of different configurations. At the end of the day through, as long as the pilot makes it out and the bag freely moves in the airframe, I should be good to go in terms or laundry exit.
 

Bat-mite

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This is my first run with a D-bag (hate that abbreviation btw) so i'll be ground testing the heck out of it. As such, I'll likely try a couple of different configurations. At the end of the day through, as long as the pilot makes it out and the bag freely moves in the airframe, I should be good to go in terms or laundry exit.
First flight was scary for me, because, as you have realized, there is no way to test whether or not the chute is going to come out of the bag. So with a rocket and components coming in at over $1k, I had to "wing it." Good ground test on getting everything apart and out, and then you just have to trust gravity to do its job with the bag.

Happy to say, it has worked every time.
 

fyrfytr310

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I really like the idea of connecting the bag to the nose. My af is pretty about 2' longer than the bag will be so this should keep the laundry from lodging at the rear of the compartment.

I have a feeling i'll be practicing the packing and attachment methods quite extensively.
 

Handeman

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I use a pilot that brings the nose cone down about 5 ft/sec slower then the main drops the rest of the rocket. The pilot has about a 6 ft line to the nose cone and that has a 3 ft line to the d-bag. Inside the d-bag is a 100 ft z-folded 150 lb Dacron line connected between the d-bag and the crown of the main chute.

When the main deploys, all that is required is the nose cone seperates enough so the pilot gets into the air stream and inflates. Once that happens, everything else happens in sequence. The pilot pulls the nose cone up and the d-bag out of the payload (if it didn't come out with the ejection charge)(the rest of the rocket is dropping on drogue so the slow decent of the pilot and nose cone pulls that d-bag out). The d-bag is pulled up by the pilot and all of the shroud lines of the main pull out of the elastic straps on the d-bag and when they are fully stretched out, the chute pulls out of the d-bag. The main is stretched out well and opens very quickly, much faster then the pilot chute can pull that 100 ft of Dacron line out of the d-bag. The main opens and slows the whole rocket and the pilot is dropping the nose cone at a slightly slower rate, but the Dacron line keeps them together so the nose cone doesn't drift off from the main rocket.
 

mpitfield

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A successful deployment is what counts and there is no "one" way to do this. I would consider the rocket design and recovery conditions before I made my choice. What I would do for a 3" 15lb rocket in a farmers field surrounded by trees, vs. an 8" 100lb rocket on the open playa would likely be different.

This is something I am considering for an 8" project at this stage, but I have used D-Bags in many configurations with 4" and 3" air-frames so I have some confidence with the technology and my techniques at this stage. Beyond the config choices you mention and what others have mentioned such as tethering, there is also sizing of the pilot, pilot tether extension harness, and what is called a slider ring to consider.

With larger projects a technique that I have observed is what I have heard referred to as "free bag". This is, as you partly described, the D-Bag is connected to the pilot as well as the nosecone and when the main is deployed the two parts descend independently. With smaller projects such as the ones I have done, I keep everything tethered together.

A great source of good reliable information is Gene from Fruity Chutes (fruitysales@fruitychutes.com)
 
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