Air Weapons: Little Wonders No One Expected


December 10, 2011: Air operations in Libya made it clear that smaller is often better. Smaller missiles and bombs reduce civilian casualties and enable aircraft to carry more weapons (and hit more targets). The star of this category in Libya was the British 55 kg (109 pound) Brimstone. The Brimstone missile appeared years ago as an American Hellfire that was modified to launch from fast moving jets, rather than just helicopters and propeller driven UAVs. But there is competition. The 119 kg (261 pound) SDB (small diameter bomb) was developed by the U.S. Air Force to provide a smaller and more versatile (SDB can penetrate bunkers) bomb. Then there is something no one expected; the use of the Sidewinder air-to-air missile for attacking surface targets.

Four years ago, the U.S. Air Force asked the manufacturer of the 85.3 kg (188 pound) AIM-9X Sidewinder air-to-air missile if the weapon could be adapted to hit ground targets (including ground vehicles and small boats). The manufacturer got to work and, two years ago, conducted several successful tests of the modified AIM-9X. The mods apparently were mainly in the fire control software, and the details are being kept secret. The target was a large speedboat, a target that gives off a lot of heat in the midst of a much cooler environment (the ocean.)

The AIM-9 is a heat seeking missile, and the heat sensors have become much more sensitive since the first AIM-9 entered service half a century ago. The current versions of the missile work by detecting a heat source at the point where the pilot is looking. This is done using the JHMCS ( Joint Helmet Mounted Cueing Systems), which allows a pilot to see, displayed on his visor, critical flight and navigation information. Sort of like a see-through computer monitor or Head Up Display. Most importantly, the pilot can turn his head towards a target, get an enemy aircraft, or ground target, into the crosshairs displayed on the visor, and fire a missile that will promptly go after target the pilot was looking at. For Sidewinder, the pilot has to be looking at something giving off enough heat to catch the attention of the missiles heat sensor.

The JHMCS is already used with some air-to-ground missiles, although it was revealed that no special air-to-ground software was needed for Sidewinders fired at ground targets. Instead, the air-to-air software was modified. This is important, because one of the reasons for this mod was to give the F-15C, which carries no air-to-ground weapons (it's strictly an air-to-air fighter) some air-to-ground capability. In addition, fighter-bombers (like the F-18, F-16, F-22 and F-35) will now be able to use their air-to-air weapons, in a pinch, once all their actual air-to-ground weapons are gone. But the air force did not order any of these air-to-ground systems (which appear to be mainly software changes.) At least no one is talking about it.

Although over half a century old, the Sidewinder has been the most effective air-to-air missile ever produced. The first Sidewinder (AIM-9B) was three meters (9.3 feet long), weighed 71 kg (156 pounds) and had a max range of five kilometers. The most current model, the AIM-9X, is 3.1 meters (9.5 feet) long, weighs 85.3 kg and has a max range of over 20 kilometers. All models have a warhead weighing about ten kg (22 pounds) The AIM-9X can go after the target from all angles, while the AIM-9B could only be used from directly behind the target. The AIM-9X is about seven times more likely to bring down the target than the AIM-9B. The 9X entered service in 2000, but the older 9M is nearly as accurate, although more expensive to upgrade. Current Sidewinders cost about $100,000 each, versus $170,000 for Brimstone. It’s believed that Sidewinders are not as accurate or reliable in hitting ground targets as Brimstone.




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