Methods for rocket fuel grain coating and unitary manufacture

A method of making a unitary fuel grain for use in a rocket motor or gas generator, comprising:

• (a) applying a fuel grain coating upon a fuel grain core selected from a metallic fuel grain core, a non-metallic fuel grain core, or a nanoparticle fuel grain core;
• wherein the coating is substantially free of gas-permeable voids following application and has a thickness of 0.006 to 0.016 inches;
• (b) depositing a succession of coats of oxidizer depleted material onto the fuel grain coating to form a continuous fuel grain coating bonded to the fuel grain core;
• (c) wherein the fuel grain core is passivated by steps (a) and (b);
• and the passivated fuel grain is deposited into a print bed of an additive manufacturing apparatus such that it continuously self-adheres during deposition without the use of external bonding agents along a predetermined distance in a direction primarily parallel to a rocket motor central axis;
• wherein the oxidizer depleted material includes at least one atomized constituent suitable for an exothermic ignition reaction;
• (d) wherein, following deposition, the passivated fuel grain forms a unitary fuel grain having a pre-ignition segment and a post-ignition segment;
• the post-ignition segment comprising a vortex inducer channel (VIC) embedded with sensors configured to assist flight and monitoring;
• and
• (e) wherein the unitary fuel grain forms a substantially circular cross-sectional pattern upon deposition.