Paladin
Statistics:
Length: 61 inches
Width: 10.7 inches
Est. Mass: ~1.7 Kg
Motors: 1x Loki I110, 3x Aerotech G64 (airstarted at 5 seconds)
I started working on Paladin by constructing the avionics bay first. It is a ~10" long coupler section that will be secured in the transition of the top payload section and connect to the main airframe with some small screws. It will have quick connects to external switches and air vents for the altimeter. The altimeter sled slides on all thread which is secured on both ends of the coupler section, enclosing everything in between. The sled itself is 5.75" so I will be able to add another if extra space is required.
The booster tubes were cut to size and sanded. A 29mm motor mount tube was inserted into Semroc's 1.4" tube, with a piece of paper wrapped around the motor mount for a snug fit. I also got my last needed 29/40-120 motor hardware for the outer cluster.
Next I cut the payload tube to size and trimmed the shoulder of the transition down to an inch. The tip of the nosecone would have to be cut off for the transition as well. All of the tubes and couplers (aside from the boosters since they are double walled) got reinforced with carbon fiber laminate. I chose carbon because of its strength/weight ratio over fiberglass. This rocket was heavy already and I wanted to keep it as light as I could but keep the stregth very high (as to not repeat the last catastrophe if something like that were to happen again).
JST quick connects were placed throughout the rocket to aid in connecting internal electronics to batteries and external switches. This was done to allow full connection of electronics that can be programmed before the need to be armed on the pad.
I had originally planned of making a silicone mold of the booster nosecone and make replicas out of plastic but due to some complications, I just ordered 2 more balsa cones and finished those; this may have been better anyway because of reduced mass.
Centering rings and bulkheads were cut using a fly cutter on a drill press. I used stepped bulkheads for the altimeter bay and U-bolts for the anchor point on all four shock cord attachments. Below you can see the altimeter bay, transition, and stepped bulkheads. The transition slides over the joined coupler tubes, which then protrude out of the bottom and allow connection into the main body of the rocket.
I came up with a better idea to attach the booster igniters to the rear rather than just have wires hanging out the back. I took a section of terminal strip and ripped it apart so it was just the internal metal pieces and then separately mounted those into the rear plywood centering ring. I then soldered on my leads to the timer quick connect. To finish with them, I drilled two small holes in the airframe to allow the screws to be used in clamping down the igniter wires, but at least they are much more permanent and a cleaner way than the bare wire leads to twist and tape. You can see the finished idea below.
Above are the shock cords with my own style of loops - the tubular nylon is slit and then passed back inside itself, sewn together, and secured with heat shrink wrap. This prevents bulky knots and a cleaner look. The electronics sleds are also pictured; you can see the timer and the MAWD connected and wired to the batteries and quick connects (note: I usually use Duracell batteries, but these were convenient at the time of the photo).