On the 27h of April 1972 USAF F-4D’s of the 8th Fighter Wing (8TFW) attacked and severely damaged the heavily defended Thanh Hoa bridge in North Vietnam. What made this bombing raid different from all of the other that had been made on this important strategic target before, was that on this occasion the bombers were armed with a new type of bomb.
PAVE (Precision Avionics Vectoring Equipment) laser guided bomb (LGB) was introduced in 1965 as a series of add-on laser honing kits, with laser seekers, fixed wings and canards that could be fitted to either a standard 2,000-lb Mk.84 low-drag bomb (GBU-10A1) or the 500 lb Mk.82 general purpose bomb (GBU-12A). Paveway I, which became operational by the US in 1967, would provide a massive leap in accuracy when used in conjunction with airborne or ground laser designators. Whilst the LGB was only used in small numbers during the Vietnam War (0.2٪ of all bombs used), they were still able to destroy some highly important and well defended targets (notably the Paul Doumer Bridge in North Vietnam).
The second generation, Paveway II, entering US service in 1973, was distinguishable from the earlier type by their ‘pop-out’ wings which made handling and carrying easier. These new wings also increased maneuverability and range, plus the guidance system on these new bombs had been simplified (which made them cheaper to produce).In addition to the laser guiding attachments to the Mk,82 and Mk.84 bombs the Paveway II was also adapted to the BLU-109 bomb for penetrating the interior of hardened targets before exploding. Two other versions specific for the US Navy were the GBU-16, mated to the Mk.83 general purpose bomb (regularly carried by the Navy’s F-18 and F-14 strike aircraft) and the GPU-123 fitted to a British 1,000-lb bomb for attacks on hardened aircraft shelters were also manufactured. US laser guided bombs carried by F-117s were used against targets in Grenada during Operation Urgent Fury in 1983, and again on the night of 14/15 April 1986 when US F-111Fs struck targets in Libya (Operation Dorado-Canyon) in reprisal for alleged acts of terrorism. In this latter operation several of the LGBs missed their target, but those that did hit home did so with such convincing results that it was clear that the LGB was a weapon of the future.
The Paveway III which began replacing the earlier versions in 1987 has increased performance and enhanced effectiveness. Paveway III has microprocessor controls and digital autopilot, and was developed for use under European conditions where an ability to operate in poor weather and on a high threat battlefield were the main operational considerations. It can be released at low level in either level flight or a climb, and is therefore fitted with high lift folding wings. In addition it can also be dropped at high altitude or in dives as steep as 60˚. All of these features make Paveway III far more flexible than its predecessors. Typically mated to either a 2,000 lb general purpose bomb (GPU-24) or the BLU-109 for attacks on hardened targets such as concrete bunkers (GBU-245A) the system is also employed on the GBU-27A, which is a. development of the GBU-24A that incorporates clipped wings and canards to enable the bomb to be stored in the relatively small bay of the F-117. Stealthfighter. This model has a shorter range than the conventional Paveway III bombs but this problem is largely neutralized by the F-117’s ability to reach its target undetected and, then from close range, drop its weapons accurately.
The most recent version of the Paveway III series of laser guided bombs is the GBU-27 with the BLU-109 penetration warhead fitted to the GBU-27A enabling it capable of penetrating some 6 ft of concrete before exploding. This capability was utilized during the Gulf war when F-117s attacked hardened bunkers housing Iraqi military personnel and equipment (and once, infamously, civilians), with great success. Some 2,000 tons of GBU-27 were dropped during the war achieving a claimed 80-90٪ hit ratio.
Perhaps the most famous weapon during the Gulf war was the GBU-28 ‘BLU-113’ which is to date the most powerful non-nuclear penetration weapon yet designed. It was developed, deployed and used in combat in only 17 days and earned itself the nickname ‘Deep Throat’. The weapon was machined from spare 8-in naval gun barrels and resembles a very long BLU-109. When dropped from high altitude at supersonic speeds it is able to penetrate 100 ft of earth or 20 ft of concrete, thus earning its nickname. Only two were dropped during the Gulf war, both by F-111Fs and both on bunkers at Al Taji air base in Iraq. Currently only the F-15E is capable of carrying this weapon.
The main drawback of the Laser guided Bomb is its unit cost, which is about 50 times as much as a conventional free-fall ‘Dumb’ bomb; but since it is usually only employed on high importance targets which might take a considerable number of conventional ‘dumb’ bombs to destroy the accuracy that a single LGB allows outweighs the expense.