Rubicon Motor Retention and Nose Weight

For motor retention, a simple and lightweight option was to epoxy some 2-56 threaded rods into 3 places at the back of the rocket. It only takes a nut and washer on each of these to keep all 7 motors from sliding out backwards.

Some aluminum carrier tubes and the threaded rods.

Epoxied in place on the central motor tube.

Ready to epoxy to the rest of the airframe.

Showing my Pro 24 motor case installed and held in with the washers.

Since I am going to be using 7 motors, I have to be able to balance that weight out to make the rocket stable. Unfortunately, this means adding a lot of weight because it is a short rocket. It looks like I will have to use around 16 ounces of nose weight with 7 motors installed. 

I constructed a 24mm tube with a 5/16" threaded rod down the core and epoxied it in place into the nose cone. This way I can add 5/16" washers until the proper balance is achieved and simply thread on a nut to hold the washers in place. It's basically a simpler version of the nose weight system in Positive Ascent.

Pouring the epoxy into the nose cone to hold the assembly.