Overview and History of Hybrid Rocket Propulsion. Definition of propulsion: static performance of rockets for launch to space missions ; definition of thrust and drag ; equation of motion; Performance of single-stage and multistage rocket. Definition of thrust requirements for performing space missions.Definition and classification of Propellants for liquid, solid and hybrid engines. Combustion in SRE and HRE. Metals, Energetic Additives, and Special Binders Used in Solid Fuels. Solid-Fuel Pyrolysis Phenomena and Regression Rate Mechanisms. Analytical Models for Hybrid Rockets. Influence of the initial conditions of the propellant . Calculation of the temperature of combustion in conditions of chemical equilibrium. Sizing and design procedures for (a) Injection system (injectors), (b) nozzle, (c) thrust chamber. (d) feed system (E) De laval nozzle. Analytical and numerical modeling of hybrid rocket internal flow fields, transient hybrid combustion phenomena, various fuels and oxidizers used in hybrid rocket combustion, scaling effects relevant to hybrid motors, practical applications, and challenges for continued advancements in the hybrid rocket field. New launch systems: (a) gun launch to orbit ( ram accelerator and railgun ), (b) TSTO launch vehicles (c) airbreathing SSTO launch vehicles.