Missile sizing for ascent-phase intercept

A computer code has been developed to determine the size of a ground-launched, multistage missile that can intercept a theater ballistic missile before it leaves the atmosphere. Typical final conditions for the interceptor are 450-km range, 60-km altitude, and 80-s flight time. Given the payload mass, which includes a kinetic kill vehicle, and achievable values for the stage mass fractions, the stage specific impulses, and the vehicle density, the launch mass is minimized with respect to the stage payload mass ratios, the stage burn times, and the missile angle-of-attack history subject to limits on the angle of attack, the dynamic pressure, and the maneuver load. For a conical body, the minimum launch mass is approximately 1900 kg. The missile has three stages, and the payload coasts for 57 s. A trade study is performed by varying the flight time, the range, and the dynamic pressure limits. A more detailed design is carried out for a particular missile to determine the heat-shield mass. The added heat-shield moss reduces the prescribed range by 100 km. Air-launching the same missile increases its range by 100 km. Finally, sizing the interceptor for air launch reduces its mass to approximately 1000 kg.