A previous article described fabricating PVC motors using couplings and endcaps to secure the bulkheads. Figure 1: PVC fitting used to retain grains in 2" diameter PVC motor with cork liner. In an effort to make the motors more flyable, the motors have been redesigned without those elements. First attempts consisted of drilling a series of 4-6 radial holes and casting the rockite into the holes. This provide insufficient to retain the bulkheads in 4/6 tests, and none of the successful tests exceeded 150 psi. Figure 2: Note the forward bulkhead and nozzle bulkheads are extruded out from the pvc. The next attempt was to cut a 0.25" section 1 1/4" PVC pipe, slit it and glue it into the end of the 1 1/2" pipe. The Rockite was cast with this lip retaining it. This was successful in 1/4 tests, but the successful test did hold 380 psi, and the other tests failed at above 300psi. Here is the data from the...