External ballistics

This schlieren image of a bullet travelling in free-flight demonstrates the air-pressure dynamics surrounding the bullet.

External ballistics or exterior ballistics is the part of ballistics that deals with the behavior of a projectile in flight. The projectile may be powered or un-powered, guided or unguided, spin or fin stabilized, flying through an atmosphere or in the vacuum of space, but most certainly flying under the influence of a gravitational field.^[1]

Gun-launched projectiles may be unpowered, deriving all their velocity from the propellant's ignition until the projectile exits the gun barrel.^[2] However, exterior ballistics analysis also deals with the trajectories of rocket-assisted gun-launched projectiles and gun-launched rockets; and rockets that acquire all their trajectory velocity from the interior ballistics of their on-board propulsion system, either a rocket motor or air-breathing engine, both during their boost phase and after motor burnout. External ballistics is also concerned with the free-flight of other projectiles, such as balls, arrows etc.

^ Design for Control of Projectile Flight Characteristics, AMCP 706–242, US Army Materiel Command, 1966
^ Army (February 1965), Interior Ballistics of Guns (PDF), Engineering Design Handbook: Ballistics Series, United States Army Materiel Command, pp. 1–2, AMCP 706-150, archived from the original (PDF) on January 8, 2016

[1] Design for Control of Projectile Flight Characteristics, AMCP 706–242, US Army Materiel Command, 1966

[2] Army (February 1965), Interior Ballistics of Guns (PDF), Engineering Design Handbook: Ballistics Series, United States Army Materiel Command, pp. 1–2, AMCP 706-150, archived from the original (PDF) on January 8, 2016

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