The Chimera project has ordered a batch of eight plastic rods, 500mm in length, and in different materials and thicknesss (30mm, 32mm and 35mm). We need a plastic material that is easy to drill clean holes in, and easy to machine. Acetal Resin is good for machining, but unheard of as a hybrid fuel rod. Why is this?
Other materials we have ordered include PVC, PE (polypropylene), HDPE (high density polyethylene) and UHMWPE (ultra high molecular weight polyethylene).
PVC and PE are used in SkyRipperSystems commercial Hybrid motors. HDPE has been used in hybrid design. UHMWPE might offers advantages of more material being ejected, and therefore higher thrust. Presumably, this is all to do with the density of the plastic. Some of these plastics may be very difficult to machine or drill. This is why Chimera will be doing some experiments.