Two of the most popular and effective air weapons used in the current bombing campaign in Iraq and Syria are British. The Paveway IV (a laser or GPS guided bomb) and Brimstone (a Hellfire variant that can be used by jet fighters). Both weapons were also widely used in Libya in 2011 and there Brimstone was particularly effective.
As a result of the Libya success a recent upgrade to the Eurofighter Typhoon fighter-bomber included a new three rail launcher for the Brimstone missiles along with several upgrades and improvements to the Typhoon fire control system for Brimstone and smart bombs in general. The new launcher enables a Typhoon to carry up to 18 Brimstones. The new Brimstone 2 version has range (fired from jets) increased from 20 kilometers to 60 kilometers along with improvements in accuracy and reliability. At the new max range the Brimstone takes up to three minutes to reach its target.
Originally developed as an upgraded version of the American Hellfire, Brimstone ended up as a Hellfire in general shape only. Weighing the same as the Hellfire (48.5 kg/107 pounds), Brimstone was designed to be fired by fighter-bombers, not just (as with Hellfire) from helicopters and UAVs. Aircraft can carry a lot of these lightweight missiles. These are perfect for small targets, including vehicles, which need to be hit, without causing injuries to nearby civilians or friendly troops. Brimstone entered service in 2005 and only a few thousand were produced. Use was low in Afghanistan, but was much higher in Libya. And that caused other nations to pay attention and seek to get Brimstone for their own use. This was a problem because production was unable to rapidly increase and production lines were already in the midst of retooling for a new version which included a dual-mode (radar and laser) seeker to its Brimstone missiles. The Brimstone radar seeker makes it easier to use the missile in "fire and forget" mode. The laser seeker is more accurate (to within a meter or two of the aim point.) The nine kilogram (20 pound) Brimstone warhead is sufficient to destroy vehicles, without causing a lot of casualties to nearby civilians. British fighter pilots have become quite good at coming in low and taking out individual vehicles with Brimstone missiles. Carrying a dozen or more Brimstones, a fighter-bomber can easily use all of them in one sortie, all the while staying out of range of ground fire.
Britain also recently (late 2014) certified (configured and tested) their Paveway IV smart bomb to operate from their new Typhoon fighter bombers. The Paveway IV was developed in Britain and is not used by the U.S. Air Force or Navy. Introduced in 2008, over a thousand 500 pound (228 kg) Paveway IVs have been dropped in combat so far. These were dropped by the older Tornado fighter-bomber. Saudi Arabia, the one export customer for Paveway IV has used them on their Typhoons recently against targets in Syria and is very satisfied with these new, for the Saudis, smart bomb.
In the U.S. JDAM and other GPS-only weapons are much more popular, although some Paveway I, II, III type bombs are still used. The original Paveway laser guided smart bombs were developed in the United States but a British manufacturer obtained a license to develop a variant (Paveway IV) that met standards the Royal Air Force wanted (like GPS and inertial guidance in addition to the original laser guidance). The JDAM is a later and cheaper guided bomb design that uses GPS rather than laser. Paveway was developed in the 1960s, when there were no GPS satellites but lasers were new and it was now possible to use laser guidance in a bomb. GPS did not become available until two decades after the first Paveway entered service.
The U.S. and Britain jointly develop more upgrades for the Paveway IV. These include a low explosive model (to limit collateral damage), another model has a penetrator cap (to hit underground bunkers) which is a novel feature for a 228 kg bomb. There are also improvements in the American anti-jamming technology as well as the laser seeker technology.
The Paveway system is actually a kit that is attached to an unguided bomb. The 50.5 kg (111 pound) Paveway kit contains guidance electronics, computers, and battery powered winglets. But to work the carrying aircraft must have a fire control system that enables the pilot to get the GPS data (received from troops on the ground) into the Paveway IV equipped bomb.
Once attached to a one ton, half ton, or quarter ton (500 pound) bomb, the Paveway IV can achieve precise (within a meter or less) accuracy using a laser designator. Now there is also GPS guidance to land within ten meters (31 feet) of the aiming point. Earlier versions of Paveway did not have GPS. Most just only had laser guidance. Britain has since added GPS to Paveway IV. While more accurate, laser guidance requires that someone on the ground or in the air be shining a laser on the target. The Paveway then homes in on the reflected laser light (of a particular frequency). GPS guided bombs can hit the target under bad weather conditions and only have to worry about jamming of the GPS satellite signal.
The U.S. firm that manufactures the Paveway bombs, Raytheon, has produced over 250,000 kits so far, of which about twenty percent have been used in combat with great success. Britain was caught short by the popularity of Paveway IV and Brimstone in Libya and almost ran out. Rather than have stocks of these two weapons get dangerously low again more are being ordered now. Exact numbers were not revealed but from media accounts appears that both British and Arab fighter pilots favored the 228 kg (500 pound) Paveway IV because there are more structures to attack this time around compared to 2011 when most of the targets were individual vehicles or small groups of gunmen.