As we see coalition fighters loaded down with laser guided bombs (LGBs) on their way into Iraq and Syria, we mustn't forget where this technology began- the BOLT-117. This granddaddy of LGBs paved the way for the legendary 'Paveway' series of guided munitions that have changed the course of modern warfare as we know it.
A RAF Tornado GR4 tanks from a RAF Voyager tanker during operations against ISIS. Seen under its belly are the latest Paveway IV dual-mode laser/GPS guided 500lb bombs (by Cpl Neil Bryden RAF Crown copyright 2014)
The BOLT-117 (standing for BOmb Laser, Terminal), later known as the GBU-1, was born out of a great need during the Vietnam War to be able to accurately hit highly defended, key logistical targets, such as bridges, on a single mission. Traditionally, massive strike packages of aircraft had to be risked to attack a single, highly defended target with standard "dumb" bombs. With this in mind, the promise of relatively inexpensive laser guidance kits that can be strapped on to off-the-shelf bombs was truly a dream for mission planners and aircrews who were sick of sending dozens of good men and expensive hardware on dangerous missions with no guarantee that the target would even be destroyed.
The BOLT-117 utilized a standard 750lb Mk117 bomb with a tail guidance kit and a nose mounted laser seeker. The laser seeker would lock onto to a laser spot and the tailfins would maneuver the weapon directly at that spot. Launched from an F-4 Phantom, the Weapon System Officer in the back cockpit utilized a cumbersome and less than stable hand-held target designator to give the bomb's laser seeker a point to home in on. The BOLT-117 worked via the "bang-bang" over-correction guidance concept, where the bomb kit's tail fins would fully deflect rapidly to keep the laser spot in its cross-hairs, instead of deflecting proportionately based on how far off course the weapon was. Although not the most efficient method aerodynamically, the concept is still in use on some guided munitions today.
The BOLT117's rear mounted maneuvering fin configuration proved less than ideal as the rear mounted control surfaces had a tough time providing enough directional authority to control the bomb's course. This design deficiency was corrected on later laser guided bombs via placing the control surfaces on the nose of the bomb, near the laser seeker head.
Overall, the weapon system (bomb, guidance kit and laser designator) had a success rate of about 50% under real world battlefield conditions of SE Asia. Although fairly dismal by today's "smart weapons" standards, the technology proved very promising, as was realized in the hugely successful Paveway series of laser guided bombs and pod mounted, gyro-stabilized laser designators that were borsighted to TV and infrared sensor systems. These included the Vietnam era massive Pave Knife pod, the smaller daytime-only Pave Spike pod flown on F-4s at the very end of the Vietnam War, and later the much more capable, day and night capable Pave Tack pod, which flew on F-4s and more famously in a semi-recessed fashion on the F-111 Aardvark.
The BOLT-117, and its legendary successor, the Paveway GBU-10, GBU-12 and GBU-16, changed the way modern wars are fought. On the tactical level, attacking aircrews would no longer have to put their lives at great risk by using comparatively ineffective dive or toss bombing methods when attacking their targets, which also left the attacking aircraft very vulnerable to enemy fire. With the introduction of LGBs, the launching aircraft could standoff from over flying the target directly, thus making the whole exercise more survivable. Additionally, a single fighter or attack aircraft could hit not just one target (if they were lucky), but multiple individual targets on a single mission with a high probability of success. This means smaller air forces were needed to achieve the same strategic goals during an air campaign.
On a strategic level, laser guided munitions allowed for one or two aircraft to destroy high value targets with a good probability of success, an outcome that once took tens, or even hundreds of aircraft and multiple strike attempts. In effect, LGBs would allow for air campaigns that would have taken months or years to complete, to be executed in a matter of weeks or even days. A truly game-changing evolution in air power.
Additionally, without the BOLT-117s and its successors, there would have been a much smaller case for tactical stealth technology as seen in the pioneering F-117 Nighthawk, whose stealth shaping and coatings were only one facet of the whole low-observable, deep precision strike concept. The fact of the mater is that stealth technology, the Paveway class of LGBs and a infrared laser designation system that had finally come of age were the right weapon systems, fused into the right design, at the right time. Collectively they gave birth to the world of stealth combat aircraft as we know it today.
Over 45 years after its introduction into combat, the laser guided bomb continues to be a weapon of choice for aircrews around the world who need precision attack capabilities at a reasonable cost, and are especially useful when needing to hit a moving target or a target of opportunity. As this is being written, laser guided weapons are flying on the wings of American and coalition fighters high over Iraq and Syria, as well as laser guided AGM-65 Mavericks, laser Hellfires, Brimstones, laser guided rockets, and what some see as the holy grail of guided weapons, the new Laser Joint Direct Attack Muinition and the dual-mode Paveway IV.
The new dual-mode Paveway IV series and the Laser JDAM series of precision guided weapons pack the best features of both GPS and laser guidance, and melds them into one weapon that can be used for almost any air-to-ground and even air-to-surface engagement. Navy Hornets and Super Hornets seem to have defaulted to the GBU-54 500lb Laser JDAM, along with the laser targeted version of the venerable AGM-65 Maverick missile for combat flights over Iraq. Meanwhile, the Royal Air Force's Tornadoes, which just began flying missions over Iraq, are sticking to their love affair with the Paveway series of munitions, packing the dual-mode 500lb Paveway IV along with the highly capable Brimstone missile.
Both the Paveway IV and the Laser JDAM can work in various modes, using strictly GPS guidance if a target area is obscured by clouds or smoke, or if it needs to be attacked a standoff ranges (up to about 15 miles), such as when attacking anti-aircraft emplacements. The other major mode uses pinpoint laser guidance backed up by the bomb's on-board inertial navigation system (INS) that is coupled with a GPS receiver and an autopilot. In this mode, if the bomb's seeker were to lose contact with the laser spot, it would fly to the last known laser coordinates autonomously.
The almost universal adaptability of these new dual mode weapons means that only one type of bomb kit would have to be procured to provide both laser guided and GPS guided bomb attacks. This takes stress of logistical chains while also lowering unit cost. Additionally, it means that an attack mission, with its many moving parts, would not have to be scrubbed because a fighter or bomber does not have weapons capable of hitting moving vehicles or executing attacks on targets obscured by clouds. Finally, because of these weapons' on-board INS system and autopilot, they are more accurate than their predecessors and their modular nature may allow new components to be added in the future, such as wing kits that will provide the ability to strike at much greater standoff ranges.
For now, wing kits like the JDAM-ER are GPS guided, but a multi-mode capability could be introduced for enhanced accuracy and re-targeting. This could be especially useful while supporting special forces deep inside enemy territory as they could 'paint' targets with their laser designators which a winged Laser JDAM, having glided the majority of the way to the target area using its GPS/INS guided autopilot, could then lock onto the laser spot during the terminal phase of its attack. Even rocket assisted, "smart" artillery rounds could be guided in a similar manner.
A RAF Tornado awaits loading of a 500lb Paveway IV for a anti-ISIS sortie over Iraq. (Cpl Neil Bryden RAF, Crown Copywright 2014)
The ability to point a laser at a target from tens of thousands of feet in the air and have literally a ton of TNT fly to it and explode with remarkable reliability has changed the very idea of aerial warfare. Waves of attack aircraft no longer have to thrown at a single target, and "carpet bombing" has largely become an archaic, brutal and wasteful tactic. Even the very notion of what a 'air campaign' is, and its duration, have been irreversibly changed via the advent of the laser guided bomb and its successors.
This revolutionary technology has saved the lives of countless aircrews, non-combatants and friendly forces, while killing the enemy with an efficiency once only dreamed of in science fiction. Unmanned combat aircraft, and the controversial "drone war" associated with them, would have never been possible without laser guided munitions.
Some say that America's air power is our greatest techno-strategic advantage over our enemies. Such a claim would hold much less weight if it were not for the history changing BOLT-117, which is truly the granddaddy of laser guided munitions and the concept of 'smart bombs' in general.
Tyler Rogoway is a defense journalist and photographer who maintains the website Foxtrot Alpha for Jalopnik.com You can reach Tyler with story ideas or direct comments regarding this or any other defense topic via the email address Tyler@Jalopnik.com