Hybrid rocket engine fuel grains with radial energy compositional variations

A hybrid rocket engine comprising:

• a cylindrical fuel grain comprising multiple, concentric cylindrical layers of fuel grain material defining a combustion port extending axially through the fuel grain, in which each of the concentric layers comprises multiple beads of fuel grain material, in which the multiple beads in each of the layers are disposed adjacent to one another and bonded together, and in which adjacent concentric layers of the multiple concentric layers are bonded together,
• in which each of the beads of fuel grain material comprises a polymer based rocket fuel material and a nanoscale metallic material, and in which a size of the nanoscale metallic material in the beads of the fuel grain material, a weight percentage of the nanoscale metallic material in the beads of the fuel grain material, or both varies along a radius of the cylindrical fuel grain;
• an oxidizer source configured to provide a flow of an oxidizer through the combustion port during operation of the hybrid rocket engine;
• a valve configured to control the flow of the oxidizer through the combustion port;
• a nozzle in fluid communication with the combustion port;
• and
• a casing, in which the fuel grain, the oxidizer source, and the valve are housed within the casing, and in which the nozzle extends beyond an end of the casing.