April 8, 2009: Saudi Arabia has ordered the new U.S. Sidewinder (AIM-9X) air-to-air heat seeking missile for use on its F-15 fighters. Nine other nations are already using some 3,000 of the 9X version Sidewinders. Saudi Arabia ordered 250 missiles for about $500,000 each, plus 96 cheaper training missiles and support gear.

Half a century ago, the Sidewinder AIM-9A scored its first kill, when a Taiwanese pilot, in an American F-86, brought down a Chinese MiG-17. The Sidewinder entered service in 1956, and has since been the most effective air-to-air missile ever produced. The latest model, the AIM-9X, entered service in late 2003, and thus missed the Iraq invasion. But over the last eight years, the 9X has been fired in over 150 tests, including many that used drone aircraft as targets, and live warheads on the Sidewinders.

The first Sidewinder (AIM-9B) was 9.28 feet long, weighed 156 pounds and had a max range of five kilometers . The most current one (AIM-9X) is 9.5 feet long, weighs 191 pounds and has a max range of over 20 kilometers. 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 Sidewinder has nearly 300 kills, world-wide, to date. Thus for every 380 Sidewinders manufactured, only one brought down an enemy aircraft. Only about one percent of all Sidewinders ever even got used in combat. The vast majority of the 110,000 built, spent their careers being carried by fighters, or stored away, waiting for a war. For that reason, the missile is designed for easy upgrades. Many of those in service have some components that are over twenty years old. The missile itself, is more like an aircraft component, than an expendable weapon.

The Sidewinder was originally conceived and developed in the shadows and off the books. The U.S. Navy engineers who created it over a ten year period, had to scrounge for money and materials, and many volunteered their labor. The basic concepts of the Sidewinder were developed during World War II, but producing a practical and reliable weapon seemed far beyond 1940s technology. But by the end of the 1950s, American air warfare experts believed that the missile was going to replace cannon as the main armament of fighters. That didn't happen right away, but gradually it did.

More powerful AESA radars, and longer range (50-100+ kilometers) missiles like AMRAAM, are put forward as the next revolution in air warfare. These missiles have built in radar, or are guided by the launching aircrafts radar. Unlike heat seeking missiles, these radar guided ones have not had as much combat experience, or success. But as more aircraft are armed with the longer range missiles and radars, more combat will take place between pilots who cannot see each other's aircraft. But history also shows that new technology does not instantly change combat tactics. Even after air-to-air missiles came into use 50 years ago, there were still situations, for over a decade, where aircraft cannon were still needed. The short range heat-seeking missile will remain useful for decades after the radar guided missiles come to dominate air combat.