We assembled the complete fin-can and motor mount today. We also began construction of the recovery bay and nosecone assembly from the Intellicone ((c) Public Missiles ) kit. We'll be modifying the stock intellicone significantly. The most significant change will be the addition of a HAMR threaded retaining ring on the end facing the rocket. Normally used for motor retention, we will use it to hold an aluminum plate, to which we will attach both a sled for altimeter and battery mounting and an eyebolt for attaching the tubular nylon shock cord. This is a volumetrically efficient solution which we will likely also use on the full-scale, although we are more likely to use a giant leap rocketry Slimline retainer since it is lighter. 

Our only goof so far-it turns out that one of the pistons we made yesterday is scrapped, since we made it around the stock PML strap nylon, but we need to use tubular nylon. Oops. We'll probably carve up a bunch of bulkheads and centering rings on the shopbot in the next few days, and use one of those to make a new piston. 

The only remaining steps on the nosecone and fin can (other than the machined altimeter sled and mounting plate) is to fill in the empty volume with Megafoam. We mix this two-part compound in liquid form inside a syringe, then inject it through pre-drilled access holes in the sides of the rocket/nose cone. It provides additional structural rigidity and fin adhesion to the fin can, and in the worst-case scenario (lawn dart) it will provide energy absorption to my altimeters. 

Remaining steps to complete the subscale rocket:

Machine Altimeter Sled and mounting plate

Fabricate Pistons/recovery bulkhead

Fabricate wire harnesses; thread into shock cords

Assembly recovery bays over recovery bulkhead

Assemble 'payload' bay, empty replica

Complete nosecone assembly (MegaFoam reinforcement, venting holes)

Final Assembly