Closing Off and Attaching the Balloon

I have not found any really good references anywhere on how to attach your balloon to the rig below. They talk about zip ties and cord and such, but no one has said, "just do it this way".

So I am making this up, and your mileage may vary.  I will update as I get closer.

First I was concerned about the possibility of any cord cutting through the latex nozzle after it had been attached, so I was looking for something smooth and larger in diameter to make the interface. I originally was looking at carabiners, and then I remembered these little babies:

This is a chain "quick link" that you can get at Home Depot in a variety of sizes.  Not only are they rated for extreme weights ( I have been working with 200lbs as my working weight so I didn't have any issues) but they also screw together so there is almost no chance of them coming apart.

My plan is to fill the balloon with a steel ring (on the same racks as the quick links) already around the nozzle.  I don't want to risk tearing the balloon while putting this on after the balloon is filled.

I will then take the loose end of the fill nozzle and fold it up towards the half attached to the balloon with the ring at the bottom.  Then using two or three zip ties I will seal off the balloon and lock the quick link onto the balloon.

This then becomes a perfect attaching point for the swivel and grommets to attach to using a quick link.  I went with these:

http://www.amazon.com/gp/product/B003IHBER0/ref=oh_details_o02_s00_i00

Then I will remove a grommet from one end of the swivel, and that will slip right into the quick link, attach a string to the grommet on the bottom, and then the string can attach to the parachute below.  The string used here needs to break at under 50lbs to stay in the exempt category for free balloons as per the FAA regulations.  As I understand it, this is not static load, but under a sharp load such as a drop.

The swivel is necessary.  If you have seen any videos of these flights online, you can see they spin quite wildly at times, and you don't want the cord to twist to its breaking point.

I have some mason's twine available at home that should fit this description nicely, and it should still be strong enough that I don't have an issue with it breaking prematurely.

 

Balloon to Parachute Mason's Twine Connection

Note that I labelled the connections.  I don't want to have to be sitting there on launch day trying to figure out what goes where while I am trying to do everything else.