![Mark82Bomb](https://upload.wikimedia.org/wikipedia/commons/0/0a/Mark82Bomb.JPEG)
An unguided bomb, also known as a free-fall bomb, gravity bomb, dumb bomb, or iron bomb, is a conventional or nuclear
aircraft-delivered bomb that does not contain a
guidance system
A guidance system is a virtual or physical device, or a group of devices implementing a controlling the movement of a ship, aircraft, missile, rocket, satellite, or any other moving object. Guidance is the process of calculating the changes in po ...
and hence simply follows a
ballistic
Ballistics may refer to:
Science
* Ballistics, the science that deals with the motion, behavior, and effects of projectiles
** Forensic ballistics, the science of analyzing firearm usage in crimes
** Internal ballistics, the study of the proc ...
trajectory
A trajectory or flight path is the path that an object with mass in motion follows through space as a function of time. In classical mechanics, a trajectory is defined by Hamiltonian mechanics via canonical coordinates; hence, a complete traj ...
. This described all aircraft bombs in general service until the latter half of
World War II
World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...
, and the vast majority until the late 1980s.
Then, with the dramatically increased use of
precision-guided munition
A precision-guided munition (PGM, smart weapon, smart munition, smart bomb) is a guided munition intended to precisely hit a specific target, to minimize collateral damage and increase lethality against intended targets. During the First Gul ...
s, a
retronym
A retronym is a newer name for an existing thing that helps differentiate the original form/version from a more recent one. It is thus a word or phrase created to avoid confusion between older and newer types, whereas previously (before there were ...
was needed to separate "smart bombs" from free-fall bombs. "Dumb bomb" was used for a time, but many military circles felt it sounded too trite, and eventually "gravity bomb" gained popularity.
Bomb casings for unguided bombs are typically aerodynamic in shape, often with fins at the tail section, which reduce drag and increase stability after release, both of which serve to improve accuracy and consistency of trajectory.
Unguided bombs typically use a
contact fuze
A contact fuze, impact fuze, percussion fuze or direct-action (D.A.) fuze (''UK'') is the fuze that is placed in the nose of a bomb or shell so that it will detonate on contact with a hard surface.
Many impacts are unpredictable: they may involve ...
for detonation upon impact, or some milliseconds after if a penetration effect is required. Alternatives include a fuze with an
altimeter
An altimeter or an altitude meter is an instrument used to measure the altitude of an object above a fixed level. The measurement of altitude is called altimetry, which is related to the term bathymetry, the measurement of depth under water. The m ...
, to cause an
air burst at the desired altitude, and a
proximity fuze
A proximity fuze (or fuse) is a Fuze (munitions), fuze that detonates an Explosive material, explosive device automatically when the distance to the target becomes smaller than a predetermined value. Proximity fuzes are designed for targets such ...
, to cause an air burst at a specific distance from the ground or other target.
Retarded bomb
![Mk](https://upload.wikimedia.org/wikipedia/commons/b/b9/Mk._81_250-lb_and_Mk._82_Snakeye_I_500-lb.jpg)
The retarded bomb uses a mechanical method of creating increased
aerodynamic drag
In fluid dynamics, drag (sometimes called air resistance, a type of friction, or fluid resistance, another type of friction or fluid friction) is a force acting opposite to the relative motion of any object moving with respect to a surrounding fl ...
, such as a
parachute
A parachute is a device used to slow the motion of an object through an atmosphere by creating drag or, in a ram-air parachute, aerodynamic lift. A major application is to support people, for recreation or as a safety device for aviators, who ...
,
ballute
The ballute (a portmanteau of ''balloon'' and ''parachute'') is a parachute-like braking device optimized for use at high altitudes and supersonic velocities.
The original ballute configuration was invented in 1948 by the Goodyear company. The ...
, or drag-inducing petals. These deploy after the ordnance is released, slowing its fall and abbreviating its forward trajectory, giving the aircraft time to get clear of the blast zone when bombing from low altitudes or with nuclear ordnance. However, these bombs are less accurate than conventional free-fall bombs.
Generally the high-drag tail replaces the low-drag so that the same bomb can be configured for either mode of attack during weapons preparation. High-drag bombs can also be dropped in low-drag mode if the pilot selects this option in the aircraft's weapon system, and will function exactly like a low-drag weapon.
See also
*
Carpet bombing
Carpet bombing, also known as saturation bombing, is a large area bombardment done in a progressive manner to inflict damage in every part of a selected area of land. The phrase evokes the image of explosions completely covering an area, in th ...
*
Constantly computed impact point
A Constantly Computed Impact Point (CCIP) is a calculation provided by a weapon's sighting system. It is a predicted point of impact found from the launch platform's movement, the target's movement, gravity, projectile launch velocity, projectil ...
*
General-purpose bomb
A general-purpose bomb is an air-dropped bomb intended as a compromise between blast damage, penetration, and fragmentation in explosive effect. They are designed to be effective against enemy troops, vehicles, and buildings.
Characteristics ...
*
Guided bomb
A guided bomb (also known as a smart bomb, guided bomb unit, or GBU) is a precision-guided munition designed to achieve a smaller circular error probable (CEP).
The creation of precision-guided munitions resulted in the retroactive renaming of ...
*
Joint Direct Attack Munition
The Joint Direct Attack Munition (JDAM) is a guidance kit that converts unguided bombs, or "dumb bombs", into all-weather precision-guided munitions. JDAM-equipped bombs are guided by an integrated inertial guidance system coupled to a Global Pos ...
(JDAM)
*
Laydown delivery Laydown delivery is a mode of delivery found in some nuclear gravity bombs: the bomb's descent to the target is slowed by parachute so that it lands on the ground without detonating. The bomb then detonates by timer some time later. Laydown deliver ...
References
Aerial bombs
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