Created by a small team of engineers on a shoestring budget, the Sidewinder nevertheless became one of the most influential and widely used missiles in history, being the first missile in the world to use passive infrared homing guidance. The AIM-9B, the first production model, entered operational military service in 1956. It was made of sections of aluminum tubing with a seeker head packed full of vacuum tubes. Its solid-rocket motor could accelerate the missile to Mach 2.5 in 2.2 seconds. The Sidewinder was simple, easy to match with different aircraft, and cheap to build. Unfortunately, the uncooled seeker head had a tendency to lock-on to the sun or reflections off of lakes or rivers, and had difficulty acquiring a signal in bad visibilty, clouds or rain. The Nationalist Chinese were the first to use the Sidewinder in combat, downing several Communist Chinese MiG-17's in October 1958.
