SOLID ROCKET ENGINE

PURPOSE: To enable efficient propulsion according to a flying condition in lower air and upper air with lean atmosphere. and also in space. CONSTITUTION: A booster propellant 2 is charged in a combustion chamber 3. A booster nozzle 7 is operated for discharging combustion gas generated through combustion of the booster propellant 2 in the combustion chamber 2. A gas generation device 10 starts supplying of combustion gas of excessive fuel from the final period of the combustion of the booster propellant 2 to the combustion chamber 3. An oxdizing agent supply device 20 starts supplying a liquid oxidizing agent 22 to the combustion chamber 3 as air density is decreased in the outside. An air take-in port 4 is formed on the combustion chamber 3, which port 4 is opened in the final period of combustion of the booster propellant 2 and closed as time air density is decreased in the outside. A ramjet nozzle 8 is arranged for separably supporting the booster nozzle 7 in the final period of the combustion of the booster propellant 2.