BOLT-117
Encyclopedia
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| BOLT-117 (GBU-1/B) | |
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| Primary Function: | 750 lb (340 kg) unpowered guided weapon |
| Length: | |
| Diameter: | |
| Range: | ca. 4 km |
The Texas Instruments
Texas Instruments
Texas Instruments Inc. , widely known as TI, is an American company based in Dallas, Texas, United States, which develops and commercializes semiconductor and computer technology...
BOLT-117 (BOmb, Laser Terminal-117), retrospectively redesignated as the GBU-1/B (Guided Bomb Unit) was the world's first laser-guided bomb
Laser-guided bomb
A laser-guided bomb is a guided bomb that uses semi-active laser homing to strike a designated target with greater accuracy than an unguided bomb. LGBs are one of the most common and widespread guided bombs, used by a large number of the world's air forces.- Overview :Laser-guided munitions use a...
(LGB). It consisted of a standard M117
M117 bomb
The M117 is an air-dropped general-purpose bomb used by United States military forces. It dates back to the time of the Korean War of the early 1950s. Although it has a nominal weight of 750 lb , its actual weight, depending on fuze and retardation options, is around 820 lb . Its explosive content...
750-pound bomb case with a KMU-342 laser guidance
Laser guidance
Laser guidance is a technique of guiding a missile or other projectile or vehicle to a target by means of a laser beam. Some laser guided systems utilise beam riding guidance, but most operate more similarly to semi-active radar homing . This technique is sometimes called SALH, for Semi-Active...
and control kit. This consisted of a gimbal
Gimbal
A gimbal is a pivoted support that allows the rotation of an object about a single axis. A set of two gimbals, one mounted on the other with pivot axes orthogonal, may be used to allow an object mounted on the innermost gimbal to remain immobile regardless of the motion of its support...
led laser seeker on the front of the bomb and tail and control fins to guide the bomb to the target. These latter used the bang, bang method of control where each control surface was either straight or fully deflected. This was inefficient aerodynamically
Aerodynamics
Aerodynamics is a branch of dynamics concerned with studying the motion of air, particularly when it interacts with a moving object. Aerodynamics is a subfield of fluid dynamics and gas dynamics, with much theory shared between them. Aerodynamics is often used synonymously with gas dynamics, with...
, but reduced costs and minimized demands on the primitive on-board electronics
Electronics
Electronics is the branch of science, engineering and technology that deals with electrical circuits involving active electrical components such as vacuum tubes, transistors, diodes and integrated circuits, and associated passive interconnection technologies...
.
It was commissioned by the United States Air Force
United States Air Force
The United States Air Force is the aerial warfare service branch of the United States Armed Forces and one of the American uniformed services. Initially part of the United States Army, the USAF was formed as a separate branch of the military on September 18, 1947 under the National Security Act of...
in 1967 and successfully completed a combat evaluation in 1968. The Weapon System Officer in the back seat of a F-4 Phantom II fighter bomber
Strike fighter
In a current military parlance, a strike fighter is a multi-role combat aircraft designed to operate primarily in the air-to-surface attack role while also incorporating certain performance characteristics of a fighter aircraft. As a category, it is distinct from fighter-bombers...
used a hand-held Airborne Laser Designator
Laser designator
A laser designator is a laser light source which is used to designate a target. Laser designators provide targeting for laser guided bombs, missiles, or precision artillery munitions, such as the Paveway series of bombs, Lockheed-Martin's Hellfire, or the Copperhead round, respectively.When a...
to guide the bombs, but half of the LGBs hit their targets despite the difficulties inherent in keeping the laser on the target. Placement of the control surfaces on the rear of the bomb proved to be less than ideal as it limited the ability of the fins to control the bomb's trajectory
Trajectory
A trajectory is the path that a moving object follows through space as a function of time. The object might be a projectile or a satellite, for example. It thus includes the meaning of orbit—the path of a planet, an asteroid or a comet as it travels around a central mass...
. Only a limited number of BOLT-117 bombs were produced before it was discontinued in favour of the more accurate Paveway I
Paveway
Paveway is a generic term for Laser Guided Bombs .Pave or PAVE is sometimes used as an acronym for precision avionics vectoring equipment; literally, electronics for controlling the speed and direction of aircraft...
family of guidance kits that moved the control fins to the front of the bomb.
The impact of the BOLT-117 on aerial warfare
Aerial warfare
Aerial warfare is the use of military aircraft and other flying machines in warfare, including military airlift of cargo to further the national interests as was demonstrated in the Berlin Airlift...
was revolutionary. Laser guidance kits turned standard "dumb" ordnance into "smart bombs," yielding a 100-fold increase in effectiveness compared with free-falling, unguided bombs.