USA Weapons - Machtres Fighters

GBU-1/B, GBU-2/B, GBU-3/B, GBU-5/B, GBU-6/B, GBU-7/B, GBU-10/B, GBU-11/B, GBU-12/B

History and General Description

In 1965, the USAF's Armament Development and Test Center at Eglin AFB began the evaluation of laser guidance systems for free-fall bombs. Such systems generally consist of a laser illuminator, which marks the target with a laser beam (typically with a near-infrared wavelength), and a seeker, which detects the laser's reflection and guides a weapon towards it. In April 1965, the first successful drop of an LGB (Laser-Guided Bomb) using a guidance system from Texas Instruments (TI) occurred. The Air Force subsequently began the Paveway (originally Pave Way) program for full-scale LGB development, and TI received a contract to produce KMU-342/B laser guidance add-on kits for the 750 lb class M117 general purpose bomb. M117s with a KMU-342/B kit were known as "BOLT-117" (BOLT = Bomb, Laser, Terminal Guidance), and were first used operationally over Vietnam in 1968.

Laser guidance not only improved the accuracy of the bombs by about 100 times, but the added stand-off range also often allowed the bombers to stay outside air defense range. After the initial success, Paveway laser guidance kits were designed and produced for a variety of bombs, including the widely used 2000 lb MK 84 and 500 lb MK 82 bombs and several types of cluster munitions (see Variants section below for a detailed rundown of all versions). The original Paveway system was renamed Paveway I after the Paveway II follow-on program had been started in 1972.

A Paveway I add-on kit consisted of a gimballed seeker head, a Computer Control Group (CCG), and a set of airfoils. The latter were made up of fixed cruciform tailfins (also referred to as wings) and four movable canards (except for the KMU-342/B, which had the moving surfaces on the tail). The airfoils of the GBU-2/B, GBU-10/B (MXU-600( )/B) and GBU-12/B (MXU-602( )/B) came in two different versions, with "short wings" and "long wings". The latter had wing extensions for slower delivery speed but higher stand-off range (the extensions could optionally be removed before the mission). The LGB's seeker head was fitted with a ring airfoil which kept it aligned with the bomb's flight path. The CCG had a relatively simple "bang-bang" autopilot, i.e. the control surfaces were either deflected fully or not at all, resulting in a sub-optimal flight path (this drawback was not addressed before the introduction of the Paveway III LLLGB (Low-Level LGB) system). The big advantage of the Paveway concept is that virtually no modifications on the delivery aircraft are necessary. The laser designators, e.g. the early AN/AVQ-10 PAVE KNIFE, or the later AN/AVQ-23 PAVE SPIKE and AN/AVQ-26 PAVE TACK, can be carried either by the delivery aircraft itself or by other aircraft in the strike group. There are also portable laser designators for ground troops.
More than ten thousand Paveway I LGBs were used with great success by the U.S. Air Force over South East Asia. The U.S. Navy hesitated longer to adopt LGBs on a large scale, and dropped only a few hundred Paveway I bombs in that conflict. The reason for this reluctance is the fact that when a sortie is cancelled after the aircraft are already in the air, bombs are normally jettisoned over water for safety reasons before returning to the aircraft carrier. Throwing away relatively expensive electronic guidance kits was considered undesirable. The Navy didn't take full advantage of LGB technology until the introduction of the cheaper Paveway II system. In U.S. military service, all Paveway I guidance kits have been retired in favour of the Paveway II, but residual Paveway I kits have been used for training for some time.

Variants
Early Paveway and Pave Storm versions
The first Paveway LGBs were usually referenced by the KMU-xxx/B designations of the guidance kits, and not by GBU numbers. In some cases it is not even clear if GBU designations for the all-up rounds were ever assigned. The name Pave Storm was sometimes used for cluster bombs with Paveway guidance, especially for the GBU-2/B. The following weapons could be fitted with Paveway I guidance kits:
"   M117: 750 lb class general purpose bomb
"   M118E1: 3000 lb class demolition bomb (see GBU-11/B section below)
"   MK 82: 500 lb class LDGP (Low-Drag General Purpose) bomb (see GBU-12/B section below)
"   MK 83: 1000 lb class LDGP (Low-Drag General Purpose) bomb
"   MK 84: 2000 lb class LDGP (Low-Drag General Purpose) bomb (see GBU-10/B section below)
"   MK 20 "Rockeye": 500 lb cluster bomb, consisting of a MK 7 MOD 2 dispenser filled with 247 MK 118 0.9 kg (2 lb) anti-tank bomblets
"   CBU-74/B: Cluster bomb, consisting of a SUU-51/B dispenser filled with 48 BLU-87/B 6.1 kg (13.4 lb) anti-personnel fragmentation bomblets
"   CBU-75/B: 2000 lb cluster bomb, consisting of a SUU-54A/B dispenser filled with 1800 BLU-63/B 0.45 kg (1 lb) APAM (Anti-Personnel/Anti-Materiel) fragmentation bomblets
"   CBU-79/B: Cluster bomb of the "Gator" family, using 2 kg (4.3 lb) BLU-91/B anti-tank and 1.7 kg (3.7 lb) BLU-92/B anti-personnel mines
"   CBU-80/B: Cluster bomb (details not available)

GBU-10/B, GBU-12/B, GBU-16/B, GBU-17/B, GBU-48/B, GBU-49/B, GBU-50/B, GBU-51/B

History and General Description

The Paveway I laser-guided bombs had been used by the USAF very successfully in the later phases of the Vietnam war. The Paveway II follow-on development rectified two major shortcomings of the first version: the Computer Control Group (CCG) was significantly simpler and therefore cheaper, and the fixed tailfins were replaced by foldable ones. The latter feature combined the advantages of both the "long wing" and "short wing" versions of the Paveway I airfoil groups - high speed delivery and long stand-off range. It also allowed for easier ground handling and more compact storage and carriage. Prototype testing of Paveway II guidance kits started in 1974, and production began in 1977.
Paveway II guidance kits were produced for the 2000 lb class MK 84 and BLU-109/B, the 1000 lb MK 83 and the 500 lb MK 82 bombs (see Variants section below for a detailed rundown of all versions). Including foreign sales, more than 100000 Paveway II kits have been built, and production and upgrades are still continuing. The primary manufacturer for Paveway II is Raytheon, building the MAU-169( )/B series of CCGs. In the early 2000s, Lockheed Martin established itself as a second source, and currently produces the MAU-209( )/B CCG, which is interchangeable with the MAU-169( )/B. The current version of the MAU-209 is the MAU-209B/B, which has completely replaced the original MAU-209/B.

In good conditions, a Paveway II LGB has an accuracy of about 6 m (20 ft) CEP. However, laser guidance doesn't work very well in bad weather, and when the illuminating laser is switched off for any reason, guidance is completely lost. To overcome these shortcomings, a GPS-aided inertial add-on package for Paveway II LGBs was developed (as was done for Paveway III). GPS/INS-enabled LGBs are frequently referred to as EGBUs (E = Enhanced). So far, Raytheon-built Paveway II EGBUs have primarily been produced for export, and have already been used in combat by the British Royal Air Force over Afghanistan and Iraq.
Lockheed Martin has developed its DMLGB (Dual-Mode LGB) GPS/INS upgrade for Paveway II, and in November 2005, the company received a U.S. Navy contract for further development and eventual production of DMLGB kits to upgrade the Navy's Paveway II stockpile. Primary focus is on the 500 lb GBU-12/B series, but the 1000 lb GBU-16/B and 2000 lb GBU-10/B are planned to follow.

Variants
GBU-10/B, GBU-50/B
The GBU-10/B series covers Paveway I and Paveway II LGBs with warheads in the 2000 lb class. The following warheads are used in GBU-10/B series LGBs:
"   MK 84: Standard 2000 lb LDGP (Low-Drag General Purpose) bomb
"   BLU-109/B: 2000 lb class penetrator warhead
"   BLU-117/B: In place of the MK 84, the U.S. Navy also uses the BLU-117/B warhead. The BLU-117/B is externally identical to the MK 84, but uses the PBXN-109 thermally insensitive explosive and has external protective coating.

The designation GBU-50/B covers Raytheon Enhanced Paveway II GPS/INS-equipped GBU-10/B variants, which are informally also known as EGBU-10.

GBU-17/B
The GBU-17/B was to be a HSM (Hard Structure Munition) penetrator warhead with a Paveway II guidance kit, but this version was not built.
GBU-51/B
The GBU-51/B is a 500 lb class Paveway II laser guided bomb, which uses the BLU-126/B LCDB (Low Collateral Damage Bomb) warhead. The BLU-126/B is externally identical to the BLU-111( )/B, but is filled with less explosives for a reduced fragmentation pattern blast radius. The LCDB was developed by the U.S. Navy for use in situations where friendly forces and/or civilians are close to the target.
Inert Paveway II LGBs
The LGTR (Laser Guided Training Round) is an inert cylindrical bomb body of 10 cm (4 in) diameter with a Paveway II guidance kit, and emulates the GBU-10( )/B, GBU-12( )/B and GBU-16( )/B live munitions. It is used by the U.S. Navy for operational Paveway II training to preserve the stockpile of live bombs and their guidance kits.
The LGTR comes in several versions, including the BDU-57/B, BDU-59/B, BDU-59A/B, BDU-59B/B, BDU-60/B and BDU-60A/B (the BDU-60( )/B series is usually referred to as LGTR II). Since 1992, Lockheed Martin has delivered more than 50000 LGTRs to the U.S. Navy, and production is continuing.

GBU-21/B, GBU-22/B, GBU-23/B, GBU-24/B, GBU-27/B, GBU-28/B, GBU-33/B
History and General Description

By the late 1970s, Paveway II laser-guided bombs were standard precision-attack air-to-ground weapons in the U.S. inventory. However, they were not well suited to release at low level for several reasons. To achieve a worthwhile stand-off range from a low-level launch, the LGB had to be released in a pull-up manoeuver to send the bomb on a lofted trajectory. But when the Paveway II's seeker detected the laser reflection too soon after release, the simple control logic would immediately pop down the bomb, which would then have insufficient range to reach the target. Because low-level attacks were mandatory in the presence of capable air-defense systems, Texas Instruments received a development contract in 1980 for a low-level LGB (LLLGB) guidance package, labeled Paveway III.
The Paveway III GCU (Guidance and Control Unit) has a microprocessor-based autopilot, which implements proportional control in place of the cruder "bang-bang" (either full deflection of control surfaces or none at all) autopilot of earlier Paveways. This provides for a much smoother and therefore more efficient flight path. Furthermore, the scanning laser seeker has a larger field of view, and the tailfins have been enlarged for higher manoeuverability and aerodynamic efficiency. The improvements enable a Paveway III LGB to maintain level flight at low altitude for effective ranges of more than 18 km (10 nm). Other delivery options include high-altitude drops (with a range of about 30 km (16 nm) from 10000 m (33000 ft) altitude) or long-range low-altitude launches using a lofted trajectory.
Originally, Paveway III guidance kits were to be built for four different warheads: a new HSM (Hard Structure Munition), which didn't materialize, and the 500 lb MK 82, 1000 lb MK 83 and 2000 lb MK 84 standard bombs. Of these only the MK 84 version was procured for operational service as the GBU-24/B, but later other warheads were also adopted for Paveway III guidance (see Variants section below for a detailed rundown of all versions). Paveway III entered service with the U.S. military in 1983, and has since been operationally used in all U.S. air offensives. More than 10000 kits have been procured by the U.S. military so far. Because Paveway III guidance kits are significantly more expensive than Paveway II kits, the latter are nevertheless still in service and won't be retired in the near future. Current prime contractor for all Paveway III guidance systems is Raytheon.

In optimum conditions, a Paveway III LGB can have an accuracy of 1 m (3.6 ft) CEP. However, laser guidance doesn't work very well in bad weather, and when the illuminating laser is switched off for any reason, guidance is completely lost. To overcome these shortcomings, the development of a GPS-aided inertial add-on package for Paveway III GCUs began in the late 1990s. Flight tests began in 1999, and GPS/INS-enabled Paveway III LGBs became available for operational service in 2000. GPS/INS-enabled LGBs are frequently referred to as EGBUs (E = Enhanced). The general homing method of EGBUs is to use the GPS/INS unit for mid-course guidance (giving the control logic a whole new set of options for optimum flight paths, and greatly expanding the delivery envelope) and the laser seeker for terminal homing. Should laser designation and/or GPS reception fail, the accuracy is degraded but not completely lost.

Variants
GBU-21/B
The GBU-21/B was to be a 2000 lb class HSM (Hard Structure Munition) warhead with a Paveway III guidance kit, but this version was not built.
GBU-22/B
The GBU-22/B is a 500 lb MK 82 bomb with a Paveway III guidance kit. It uses a BSU-82/B airfoil group, and can be fitted with all standard Paveway III GCUs (WGU-12( )/B, WGU-39( )/B and WGU-43( )/B series). The GBU-22/B was not produced for the U.S. military, but it is included by Raytheon in the list of available Paveway III variants.
GBU-23/B
The GBU-23/B was to be a 1000 lb MK 83 bomb with a Paveway III guidance kit. This version was not built.
GBU-24/B
The GBU-24/B series covers Paveway III LGBs with warheads in the 2000 lb class. These bombs are by far the most important and numerous Paveway III weapon. The following warheads are used in GBU-24/B series LGBs:
"   MK 84: Standard 2000 lb LDGP (Low-Drag General Purpose) bomb
"   BLU-109/B: 2000 lb class penetrator warhead
"   BLU-116/B: 2000 lb class AUP (Advanced Unitary Penetrator) warhead
It can be assumed that other 2000 lb warheads, which use MK 84 or BLU-109 casings, can also be fitted with GBU-24 series Paveway III guidance kits. This includes e.g. the BLU-118/B and BLU-121/B thermobaric bombs.

The original GCU of the 2000 lb Paveway III LGBs was the WGU-12/B, later followed by the WGU-39/B. The WGU-39A/B GCU adds a GPS/INS unit, and GBU-24s so equipped are informally known as EGBU-24.
Apart from the GBU-24/B series of the U.S. military, which uses suffix letters to distinguish between variants, there is also a GBU-24(V)/B series. These designations are applied to 2000 lb Paveway IIIs for export, which all use GCUs in the WGU-43( )/B series. The WGU-43/B is the original GCU of the UK's GBU-24/B bombs, and was possibly also known as WGU-39(UK). The WGU-43A/B is another UK version with different laser PRF (Pulse Repetition Frequency) codes, while the WGU-43B/B is for export to non-NATO countries, and includes only commercial PRF codes. The WGU-43G/B is the GPS/INS-enhanced GCU in this series. It is a derivative of the WGU-39A/B for export to NATO countries, and contains all NATO-cleared PRF codes. The WGU-43H/B is a modification of the WGU-43G/B, and contains limited PRF codes for non-NATO countries.
GBU-27/B
The large fins of the GBU-24/B series weapons don't fit into the bomb bay of the F-117A Nighthawk, and therefore the USAF developed the GBU-27/B, a specially configured 2000 lb class Paveway III for use by the F-117. The primary difference from the GBU-24/B is that the GBU-27/B uses a Paveway II-type airfoil group, and slightly more compact suspension logs. All GBU-27/B series weapons use penetrating warheads, either the BLU-109/B or the BLU-116/B. When fitted with GPS/INS-enabled WGU-39A/B GCUs, the GBU-27/B LGBs are informally referred to as EGBU-27. The GBU-27/B entered service in 1987, and about 3200 rounds have been produced.
GBU-28/B
During Operation Desert Storm in early 1991, the U.S. Air Force had to find out that the deepest and most hardened Iraqi bunkers could not be defeated by the BLU-109/B penetrator warhead. Therefore a much more powerful "bunker buster" warhead was urgently needed. Several options were discussed, but even the quickest possible alternative (an upscaled BLU-109) was estimated to have a development time of at least 4-5 weeks. Finally, USAF engineers at Eglin AFB came up with the idea to drop a very heavy guided bomb from high altitude, creating a powerful kinetic energy penetrator. The USAF eventually opted for the development of a 4500 lb bomb with Paveway III laser guidance.
GBU-28/B
To save time, practically all parts of the new bomb, designated GBU-28/B, were modified off-the-shelf components. The body of the BLU-113/B warhead was made of surplus U.S. Army M201 howitzer gun barrels, the nose cone and the explosive was from the BLU-109/B, and the WGU-36/B guidance package was a GBU-24/B Paveway III GCU with software modifications to handle the different aerodynamics of the new LGB. The final decision to go ahead with development and deployment of the weapon came on 13 February 1991, followed only 11 days later by the successful drop test of the first prototype. Another three days later, GBU-28/B prototypes number three and four were dropped on an Iraqi bunker.
Only the initial batch of BLU-113/B warheads was made from howitzer gun barrels, and later purpose-build warheads were designated BLU-113A/B. The latest warhead used in the GBU-28/B series is the BLU-122/B, which was developed under the BLU-113 P3I (Pre-Planned Product Improvement) program. It has unspecified improvements in warhead design and explosives, to enhance penetration capability and general effectiveness. Like other Paveway III GCUs, the GBU-28/B's WGU-36/B has also been enhanced with a GPS/INS package. This is included in WGU-36B/B and later versions, and GBU-28s so equipped are informally referred to as EGBU-28. The primary delivery aircraft for the GBU-28/B series LGBs is the F-15E Eagle.

Source: Raytheon-Global Security