Today we epoxied in the coupling rings for the motor section of the 3rd stage of the Martlet 1 rocket. We used a jig to align the rings at either end of the rocket, and to align the holes that locate the fins. There are two 6mm pins on each fin that go through the C-F airframe and into a nylon6/6 centering ring in the rocket.
The motor section is shown above with the bulkhead on top and the aluminium fin leading edges located into the airframe. The aluminium edges will be glued into C-F honeycomb and filleted onto the airframe. The edges are designed to withstand high temperature and be sharp for low drag at supersonic speed – they have already drawn blood.
The ring at the back of the motor section centres the rocket motor and provides the connection to the next stage. Inside the motor section, there are two nylon centering rings and a fibreglass wiring tunnel, to allow the staging electronics (mounted on the forward bulkhead) to ignite the rocket motor in flight.