Solid fuel and hybrid rocket

A hybrid rocket, comprising:

• a solid fuel in which openings are formed on both end surfaces in a length direction, the solid fuel defining therein a flow channel communicating between the opening of a starting end surface that is one end surface in the length direction and the opening of a terminating end surface that is another end surface;
• a liquid oxidizer supply device that supplies a liquid oxidizer that causes the solid fuel to oxidize to the flow channel through the opening of the starting end surface of the solid fuel, thereby causing the solid fuel to combust in a mode in which a flow of combustion gas, flowing in a direction from the starting end surface toward the terminating end surface, is produced in the flow channel;
• a casing that houses the solid fuel;
• and
• a nozzle that is connected to an end of the casing and that jets the combustion gas, wherein the solid fuel includes;
• a readily combustible portion including a readily combustible exposed surface exposed to the flow channel, and
• a combustion-resistant portion covering an outer surface, opposite the readily combustible exposed surface in a direction orthogonal to the length direction, of the readily combustible portion, the combustion-resistant portion comprising a material that is more resistant to combustion than the readily combustible portion and including an inner surface that is exposed to the flow channel after the readily combustible portion burns out, thereby combusting slower than the readily combustible portion while protecting the casing;
• and
• the combustion-resistant portion includes a stopper that prevents peeling of the readily combustible portion in the direction from the starting end surface toward the terminating end surface.