Air burst
{{short description|Detonation of an explosive above a target for increased pressure wave damage}}
{{Redirect|Airburst|the video game|Airburst (video game)|the air burst problem of V-2 rockets|V-2#Air burst problem|the atmospheric explosion of meteors|Meteor air burst}}
{{More citations needed|date=January 2013}}
File:UGM-109 hits target on San Clemente Island 1986.JPEG missile detonates above a test target, 1986.]]
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.
History
File:Defense.gov photo essay 111206-A-3108M-010.jpg High Explosive round]]
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 It was used in the later Napoleonic wars and stayed in use until superseded in Artillery of World War I. Modern shells, though sometimes called "shrapnel shells", actually produce fragments and splinters, not shrapnel.{{Cite journal|url= http://www.history.army.mil/faq/shrapnel.htm|title=What is the difference between artillery shrapnel and shell fragments?|date=March 1952|archive-url=https://web.archive.org/web/20170210123724/http://www.history.army.mil/faq/shrapnel.htm|archive-date= 10 February 2017|journal=Combat Forces Journal}}
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.{{Cite web |title=Weapons on Land - Artillery and Mortars |url=https://www.warmuseum.ca/firstworldwar/history/battles-and-fighting/weapons-on-land/artillery-and-mortars/ |access-date=2025-01-10 |website=Canada and the First World War}} 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 {{convert|105|mm|abbr=on}} or {{convert|155|mm|abbr=on}} shells, and "Killer Senior" when employed with larger howitzers.Major General David Ewing Ott. FIELD ARTILLERY, 1954–1973. Department of the Army. Washington, D.C., 1975.
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" {{convert|40|mm|abbr=on}} caseless grenade, which contains a secondary charge to launch it up to {{convert|1.5|m|ft|abbr=on}} 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.{{Cite web |url=https://www.orbitalatk.com/defense-systems/small-caliber-systems/30-20mmx173mm/ |title=30mm & 20mm x 173mm Munition System |access-date=2017-11-27 |archive-url=https://web.archive.org/web/20170702235536/https://www.orbitalatk.com/defense-systems/small-caliber-systems/30-20mmx173mm |archive-date=2017-07-02 |url-status=dead }}{{Cite web |url=https://www.orbitalatk.com/defense-systems/small-caliber-systems/30-20mmx173mm/docs/30-20x173_Fact_Sheet.pdf |title=Archived copy |access-date=2017-11-27 |archive-date=2017-03-29 |archive-url=https://web.archive.org/web/20170329035326/https://www.orbitalatk.com/defense-systems/small-caliber-systems/30-20mmx173mm/docs/30-20x173_Fact_Sheet.pdf |url-status=dead }}
= Nuclear weapons =
The air burst is usually {{convert|100|to|1000|m|abbr=on}} above the hypocenter to allow the shockwave of the fission or fusion driven 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 minimizes fallout by keeping the fireball from touching the ground, limiting the amount of debris that is vaporized and drawn up in the radioactive debris cloud. For the Hiroshima bomb, an air burst {{convert|550|to|610|m|abbr=on}} 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 would soon occupy the city".Nichols, K. D., The Road to Trinity pages 175, 198, 223 (1987, Morrow, New York) {{ISBN|0-688-06910-X}}
Some nuclear weapons have a contact preclusion fuzing feature to prevent the backup contact fuze from detonating the weapon if the air burst fuzing fails.{{cite report |date=August 1968 |title=History of the Mk28 |url=https://osf.io/zyktv/ |publisher=Sandia National Laboratories}}
Tactics
In conventional warfare, air bursts are used primarily against infantry in the open or unarmored targets, as the resulting fragments cover a large area but will not penetrate armor or field fortifications.
In nuclear warfare, air bursts are used against soft targets (i.e. lacking the hardened construction required to survive overpressure from a nuclear explosion) such as cities in countervalue targeting, or airfields, radar systems and mobile ICBMs in counterforce targeting.
=Killer Junior and Senior=
Killer Junior and Killer Senior are techniques of employing artillery direct fire air bursts, first developed during the Vietnam War.{{Citation |author=Major General David Ewing Ott |year=1975 |title=Field Artillery, 1954–1973 |url=http://www.history.army.mil/html/books/090/90-12/CMH_Pub_90-12.pdf |publisher=Department of the Army |location=Washington, D.C. |page=61 |access-date=2020-06-19 |archive-date=2017-06-29 |archive-url=https://web.archive.org/web/20170629145301/http://www.history.army.mil///html/books/090/90-12/CMH_Pub_90-12.pdf |url-status=dead }} The technique involves a howitzer firing a high explosive (HE) shell using a mechanical time–super quick (MTSQ) artillery fuze set to cause an airburst over a target in very close proximity to the firing gun's position. Set properly, the shell would detonate approximately {{convert|10|m|ft|abbr=off|sp=us}} above the ground at ranges of {{convert|200|to|1000|m|abbr=on}}.
The term Killer Junior was applied to this technique when used with {{convert|105|mm|abbr=on}} or {{convert|155|mm|abbr=on}} howitzers, and the term Killer Senior applied to its use with the M115 203 mm howitzer.{{Cite book |last=Gutzman |first=Philip C. |year=2002 |title=Vietnam: A Visual Encyclopedia |publisher=Herron Books |isbn=1856486389|pages=215}} The term "Killer" came from the call-sign of the battery which developed the technique. The technique was later perfected by Lieutenant Colonel Robert Dean, commander of the 1st Battalion, 8th Field Artillery Regiment, of the 25th Infantry Division Artillery.{{citation needed|date=May 2020}}
Killers Junior and Senior were developed as alternatives to the Beehive flechette rounds 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 in defilade, whereas the flechettes of a Beehive round would simply fly harmlessly over a low target.