The functioning of booster rockets

The means by which a booster rocket is conceived in order to fulfill the requirements of a given mission is discussed, and the principle factors influencing booster performance are pointed out. The rocket mission of assuring a given velocity at a given altitude to a payload is reviewed, and forces acting on the rocket are considered, including propulsive forces, resulting aerodynamic forces and gravitational attraction to the earth. The rocket control law is examined in relation to the control variables, the choice of a predetermined control law and in-flight guidance, and the equations of rocket motion are simplified to allow for trajectory calculations neglecting the control equation. The calculation of velocity delivered to the payload and lost to steering, friction, lift and gravity is illustrated, together with the determination of the number of stages required for a given mission. Finally, examples are presented of typical orbital insertion trajectories, and the influences of the latitude of the launch area and launch azimuth are pointed out.