Air burst

An air burst or airburst is the detonation of an explosive device such as an anti-personnel artillery shell or a nuclear weapon in the air instead of on contact with the ground or target. The principal military advantage of an air burst over a ground burst is that the energy from the explosion, including any shell fragments, is distributed more evenly over a wider area; however, the peak energy is lower at ground zero.

The shrapnel shell was invented by Henry Shrapnel of the British Army in about 1780 to increase the effectiveness of canister shot. It was used in the later Napoleonic wars and stayed in use until superseded in Artillery of World War I. Modern shells, though sometimes called "shrapnel shells", actually produce fragments and splinters, not shrapnel.

Air bursts were used in the First World War to shower enemy positions and men with shrapnel balls to kill the largest possible number with a single burst. When infantry moved into deep trenches, shrapnel shells were rendered useless, and high-explosive shells were used to attack field fortifications. The time fuses for the shells could be set to function on contact or in the air, or at a certain time after contact.

Early anti-aircraft warfare used time fuses to function when they reached the estimated altitude of the target. During World War II a "proximity fuze" was developed for antiaircraft use, controlled by a Doppler radar device within the shell that caused it to explode when near the target. The idea was later adapted for use against ground targets.

During the Vietnam War, air bursting shells were used to great effect to defend bases. This tactic was known as "Killer Junior" when referring to 105 mm (4.1 in) or 155 mm (6.1 in) shells, and "Killer Senior" when employed with larger howitzers.

Some anti-personnel bounding mines such as Germany's World War II "Bouncing Betty" fire a grenade into the air, which detonates at waist level, increasing the blast radius and harm inflicted by detonation, shock wave, and flying splinters.

A relatively recent example of airburst munitions is the VOG-25P "jumping" 40 mm (1.6 in) caseless grenade, which contains a secondary charge to launch it up to 1.5 m (4.9 ft) above its point of impact before the main charge detonates. Another recent development is a computer programmable air burst grenade with fire control system. Grenade launchers using this technology include the XM29, XM307, PAPOP, Mk 47 Striker, XM25, Barrett XM109, K11, QTS-11, Norinco LG5 / QLU-11, and Multi Caliber Individual Weapon System.

Orbital ATK developed air burst rounds for autocannons.