AIM-9 Sidewinder: China Lake Rollerons, a Captured Dud and FrankenSAM

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In February 2023 an F-22 shot down the suspected Chinese spy balloon off South Carolina with an AIM-9X Sidewinder, a missile whose origins date to 1946. At the Naval Ordnance Test Station at China Lake, California, physicist William B. McLean started the heat-seeking project with leftover lab funds and volunteer help, calling it Local Fuze Project 602, and named it for the Mojave sidewinder rattlesnake, which senses prey by its body heat. Instead of heavy active roll stabilization, his team used rollerons, air-spun wheels on the tail fins that act as gyroscopes, and proportional guidance that leads the target to a future intercept point. On September 24, 1958, during the Second Taiwan Strait Crisis, Taiwanese F-86 Sabres modified by U.S. Marines ambushed high-flying Chinese MiG-17s with AIM-9Bs, scoring the first successful air-to-air missile kills.

One AIM-9B lodged unexploded in a MiG-17 that landed safely, and the Soviet Union reverse engineered it as the Vympel K-13, NATO's AA-2 Atoll. The uncooled, rear-aspect AIM-9B had a 4-degree field of view and could lock onto the sun. In Vietnam, 452 Sidewinders were fired with an 18 percent kill probability, against 65 percent predicted in testing, as humidity, ground clutter and hard-turning MiGs defeated the seeker. After the Red Baron and Ault reviews, the argon-cooled, all-aspect AIM-9L entered full production in 1977, and in the 1982 Falklands War British Sea Harriers fired 24, scoring 21 hits and destroying 19 Argentine aircraft. The AIM-9X of 2003 added a 128-by-128 imaging infrared array, thrust vectoring for 60 g turns and aiming by helmet through the Joint Helmet Mounted Cueing System.

• Soviet engineers called the captured missile a university course in missile design.
• The AIM-9X can leave the rail without a lock and acquire a target behind the launching jet by data link.
• Its thermal imaging lets the missile recognize an aircraft's shape and ignore magnesium flares.
• The Army has ground-launched Sidewinder variants since the MIM-72 Chaparral, and today in the 15-round Multi-Mission Launcher and NASAMS.
• Since late 2022 the FrankenSAM program has fitted stored AIM-9Ms to improvised Ukrainian ground launchers, and in May 2025 Ukraine's military intelligence chief said Magura V5 drone boats used Sidewinders to down two Su-30s.