Air burst

"Airburst" redirects here. For the video game, seeAirburst (video game).For the air burst problem of V-2 rockets, seeV-2 § Air burst problem.For the atmospheric explosion of meteors, seeMeteor air burst.

UGM-109 Tomahawkmissile detonates above a test target, 1986.

Anair burstorairburstis the detonation of anexplosive devicesuch as ananti-personnelartillery shellor anuclear weaponin theairinstead of on contact with the ground or target. The principal military advantage of an air burst over aground burstis that the energy from the explosion (as well as any shell fragments) is distributed more evenly over a wider area; however, the peak energy is lower atground zero.

History

The airburst fuzing system on a modernCarl Gustav recoilless rifleHigh Explosive round

Air burst artillery has a long history. Theshrapnel shellwas invented byHenry Shrapnelof the British Army in about 1780 to increase the effectiveness ofcanister shot.It was used in the laterNapoleonic warsand stayed in use until superseded inArtillery of World War I.Modern shells, though sometimes called "shrapnel shells", actually producefragments and splinters,not shrapnel.

Air bursts were used in theFirst World Warto 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 and troops in the open. The time fuses for the shells could be set to function on contact or in the air, or at a certain time after contact.

Earlyanti-aircraft warfareused time fuses to function when they reached the estimated altitude of the target. DuringWorld War IIa "proximity fuze"was developed for antiaircraft use, controlled by aDoppler radardevice within the shell that caused it to explode when near the target. The idea was later adapted for use against ground targets.

During theVietnam War,air bursting shells were used to great effect to defend bases. This tactic was known as "Killer Junior" when referring to 105 mm or 155 mm shells, and "Killer Senior" when employed with largerhowitzers.

Some anti-personnelbounding minessuch as Germany's World War II "Bouncing Betty"fire agrenadeinto the air, which detonates at waist level, increasing the blastradiusand harm inflicted by detonation, shock wave, and flying splinters.

A relatively recent example of airburst munitions is theVOG-25P"jumping" 40 mm caseless grenade, which contains a secondary charge to launch it up to 1.5 meters above its point of impact before the main charge detonates. Another recent development are computer programmableair burst grenadeswithfire control system.Grenade launchersusing this technology include theXM29,XM307,PAPOP,Mk 47 Striker,XM25,Barrett XM109,K11,QTS-11,Norinco LG5 / QLU-11andMulti Caliber Individual Weapon System.

Orbital ATKdeveloped air burst rounds forautocannons.

Nuclear weapons

A blast wave reflecting from a surface and forming a mach stem

The air burst is usually 100 to 1,000 m (330 to 3,280 ft) above thehypocenterto allow theshockwaveof thefissionorfusiondriven explosion to bounce off the ground and back into itself, combining two wave fronts and creating a shockwave that is more forceful than the one resulting from a detonation at ground level. This "mach stem"only occurs near ground level, exists around the entire perimeter of the expanding wave front near ground level, and is similar in shape to the letter Y when viewed from the side (see sliced view). Airbursting also minimizesfalloutby keeping thefireballfrom touching the ground, limiting the amount of debris that is vaporized and drawn up in the radioactive debris cloud. For theHiroshima bomb,an air burst 550 to 610 m (1,800 to 2,000 ft) above the ground was chosen "to achieve maximum blast effects, and to minimize residual radiation on the ground as it was hoped U.S. troops wouldsoon occupy the city".

Some nuclear weapons have acontact preclusionfuzing feature to prevent the backup contact fuze from detonating the weapon if the air burst fuzing fails.

Tactics

In conventional warfare, air bursts are used primarily againstinfantryin the open or unarmored targets, as the resulting fragments cover a large area but will not penetrate armor or field fortifications.

Innuclear warfare,air bursts are used against soft targets (i.e. lacking the hardened construction required to surviveoverpressurefrom a nuclear explosion) such as cities incountervaluetargeting, or airfields, radar systems and mobile ICBMs incounterforcetargeting.

Killer Junior and Senior

Killer JuniorandKiller Seniorare techniques of employingartillerydirect fireair bursts, first developed during theVietnam War.The technique involves ahowitzerfiring ahigh explosive (HE) shellusing a mechanical time–super quick (MTSQ)artillery fuzeset to cause an airburst over a target in very close proximity to the firing gun's position. Set properly, the shell would detonate approximately 10 meters (33 feet) above the ground at ranges of 200 to 1,000 meters.

The termKiller Juniorwas applied to this technique when used with 105 mm or 155 mm howitzers, and the termKiller Seniorapplied to its use with theM115 203 mm (8-inch) howitzer.The term "Killer" came from thecall-signof thebatterywhich developed the technique. The technique was later perfected by Lieutenant Colonel Robert Dean, commander of the 1st Battalion,8th Field Artillery Regiment,of the25th Infantry DivisionArtillery.

Killers Junior and Senior were developed as alternatives to theBeehiveflechetterounds previously used against nearby enemy troops. The advantage of the Killer techniques over Beehive is that the airburst projects fragments in all directions, and is able to wound enemies crawling or lying indefilade,whereas the flechettes of a Beehive round would simply fly harmlessly over a low target.

See also

• Airburst round
• Laydown delivery
• Toss bombing
• Munition fuzes
• Meteor air burst