I picked up my recovery gear from Gene at lunch today. When I got home I weighed everything. The main chute, parachute liner, quick links and NC shock cords weigh 12.5oz. The entire bundle takes up about 8" of the nose cone.
I updated my Open Rocket file with the accurate weights for the recovery gear. My TAPs say that I need a minimum of 1.5 calibers of stability for my certification flight. To get there I need to add 50 oz. of ballast.
I measured out the lead shot and then poured it into the nose cone. I needed to add 4" to the eyebolt so I added a section of all thread with a threaded coupler and used red Locktite to ensure that it would never come apart. I used some Proline epoxy between the nose and tip and let that dry. Then I threaded the eyebolt into the tip. Once that was dry I started working on the ballast.
I've been searching for a ratio of epoxy to lead shot for a while and I found an answer today.
1. Randomly arranged spheres will take up 64% of a given volume.
2. Cubic inches times .554 will give you fluid ounces.
I poured my ballast into a 54mm tube and found that it took up about 10.6 cubic inches. (2.125" ID x 3" depth)
10.6 x 36% = 3.83 cubic inches.
3.83 x .554 = 2.12 fluid ounces.
I mixed up 2.5 fluid ounces of 30 minute epoxy and added the shot to it. The shot was evenly covered and still pourable. Once it settled into the nose cone I cleaned up the shoulder and parachute bay with denatured alcohol. The epoxy came up to the bottom of the eye. Perfect.