| BOLT-117 | |
|---|---|
 BOLT-117 on display | |
| Type | Laser guided bomb |
| Place of origin | United States |
| Service history | |
| Wars | Southeast Asia War (1961-1973)[1] |
| Production history | |
| Designer | Texas Instruments |
| Designed | 1967[2] |
| Manufacturer | Texas Instruments |
| Specifications | |
| Mass | 340 kg (750 lb) |
| Effective firing range | 4 km (2.5 mi)[1] |
TheTexas InstrumentsBOLT-117 (BOmb, Laser Terminal-117), retrospectively redesignated as the GBU-1/B (Guided Bomb Unit)[1][3] was the world's firstlaser-guided bomb (LGB). It consisted of a standardM117 750-pound (340 kg) bomb case with a KMU-342laser guidance and control kit. This consisted of agimballed laser seeker on the front of the bomb and tail and control fins to guide the bomb to the target. The latter used thebang-bang method of control where each control surface was either straight or fully deflected. This was inefficientaerodynamically, but reduced costs and minimized demands on the primitive onboardelectronics.
Originally the project began as asurface-to-air missile seeker developed by Texas Instruments (TI). When TI executive Glenn E. Penisten attempted to sell the new technology to theUnited States Air Force (USAF),Colonel Joe Davis Jr. inquired if it could instead be used as a ground attack system to overcome problems US aircraft were having with the poor accuracy of bombing in Vietnam. Davis had already witnessed a test of theUnited States Army's new laser target designator made byMartin Marietta, but no seeker existed to make use of the system. Davis had already performed tests from the back seat of anF-4 Phantom IIfighter bomber and proved that it was possible to accurately target objects from a moving aircraft. His mock testing proved correct, and during further testing with live seekers, it took just six attempts to improve the seeker accuracy from 148 feet (45 m) to within 10 feet (3.0 m) of the target. This greatly exceeded the design requirements. It was commissioned by the USAF in 1967.
The BOLT-117 andPaveway I (based on the more streamlinedMk 84 2,000-pound bomb) underwent combat evaluation with the8th Tactical Fighter Wing in Southeast Asia from May to August 1968. The first combat drop of a laser guided bomb was made using BOLT-117s on 23 May 1968.[4] Without the existence of tracking pods, the Weapon Systems Officer (WSO) in the back seat of an F-4 Phantom II used a hand-heldAirborneLaser Designator to guide the bombs,[1] but half of the LGBs still hit their targets despite the difficulties inherent in keeping the laser on the target.[5] Placement of thecontrol 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'strajectory. In the combat evaluations the BOLT-117 achieved acircular error probability (CEP) of 75 feet (23 m) while the Paveway I achieved a CEP of 20 feet (6.1 m) with one in every four bombs scoring a direct hit.[6][7] Only a limited number of BOLT-117 bombs were produced before it was discontinued in favor of the more accurate Paveway I family of guidance kits that moved the control fins to the front of the bomb. The Paveway variant was very successful and over 28,000 Paveway weapons were dropped during the war in Vietnam.
The impact of the BOLT-117 onaerial warfare was revolutionary, allowing the destruction of targets even other existing precision weapons had difficulty destroying due to having small warheads and difficulty tracking certain types of objects. Earlier electro-optical weapons such as theAGM-62 Walleye could accurately strike targets with small outlines and good contrast on camera but had difficulty hitting large oddly shaped structures like bridges. Laser-guided weapons allowed far greater precision against these types of targets, and with much larger warheads.[8][9][5]
Another equally important improvement was the ability to use add-on guidance kits to turn standard "dumb" ordnance intoprecision-guided munition yielding a considerable increase in effectiveness compared with free-falling,unguided bombs, and doing so at a fraction of the cost of other guided weapons. The cost of the add-on kits was only a few percent of the original $100,000 price goal.[5]
TheBOLT-117 featured a KMU-342 laser guidance and control kit attached toM117 750-pound bomb. The guidance system and control fins were adapted from theAGM-45 Shrike missile. The BOLT-117 was discontinued in favor of the more powerful 2,000 pounds (910 kg)GBU-10 Paveway.[1]
This article incorporates text from this source, which is in thepublic domain.