We made a rounded dowel that fit perfectly inside of a 1" PVC pipe. In order to do this, we got Jay to go chipmunk on the end of one of the dowels and then stuck a hole down the middle for the 1/8" steel rod to go into. Then we put the brass tubing on top of that rod. Then we stuck washers on the outside of the rod. If the ID of the washers wasn't snug around the OD of the brass tubing, we put duct tape around the brass tubing until it was snug, but not too tight. If the dowel wasn't thick enough to occupy all of the space inside of the PVC pipe without wiggling side to side, we put masking tape on the outside.

Then we put a perfect 3/4" hole into an endcap using a small drill bit and then moving up to a 3/4" drill bit. Starting with the large bits will give an un centered hole. If the hole gets messed up, we use scissors to adjust the diameter as seen here:

Chipmunk Jay

Using scissors to correct nozzle diameter.

Then we glued the end cap to the PVC pipe using PVC primer and cement. Then we put the dowel into a vice such that when the PVC pipe w/end cap nozzle-to-be was stuck on the dowel, the edge of the hole in the end cap was at a point 7/8" up the brass tubing. Cement was poured in. As the cement begins to dry, the brass tubing is taken off of the steel rod. Since the cement is mostly dry, the washers stay in there. Their purpose is to reinforce the concrete during burn, so that erosion is limited.

A knife is taken to the still not quite dry cement, and the hole is widened to 1/2". (a paper cut out can be used to determine what 1/2" is). This is the divergent section of the nozzle. Now you let it dry.

Setting the Nozzle

Setting the Nozzle

The rocket motor is made from 1" Schedule 40 PVC piping.

Casing and method of attachment to the test stand.

The conduit hangers are used to hold the PVC piping, which is the motor. The conduit hangers have inserts screwed into them that will make them slide nicely into the extrusion.