The Birth of the AIM-9 Sidewinder: A Tale of Innovation and Determination

Christian Baghai
4 min readMay 16, 2024

Some inventions, despite a rocky start, end up changing the world in unimaginable ways. The story of the AIM-9 Sidewinder, the world’s first heat-seeking missile, is a testament to this. This revolutionary piece of military technology might never have come to fruition if not for a small, dedicated group of engineers who defied the odds, working in their own time and scraping together experimental funding wherever they could find it. Let’s dive into the fascinating history of the Sidewinder and the relentless determination that brought it to life.

The Spark of an Idea

The year was 1946, and the world was still reeling from the aftermath of World War II. Amidst the chaos, US Navy physicist William McLean was working on a novel idea at the Naval Ordnance Test Station (NOTS) in Inyokern, California. He envisioned using a lead-sulphide proximity fuse sensitive to infrared radiation to create a missile that could home in on the heat signature of an enemy aircraft. This idea was groundbreaking; it proposed a missile that could guide itself to its target, a significant leap from the traditional unguided ballistic rockets used during aerial combat.

Early Challenges and Rivalries

World War II had seen aerial dogfights where pilots had to get close enough to their targets to use guns, cannons, or rockets effectively. Once fired, these projectiles followed a simple ballistic path, hoping to hit their mark. McLean’s vision aimed to revolutionize this by creating a missile that could track and follow a moving target, making it far more effective in combat.

However, McLean’s project faced significant hurdles from the start. The US Navy had two Bureaus dealing with rockets and missiles: the Bureau of Aeronautics (BuAer) and the Bureau of Ordnance (BuOrd). BuAer, responsible for naval aircraft and related systems, preferred contracting out work to external companies, while BuOrd handled in-house projects. This bureaucratic division created a rivalry that nearly killed the Sidewinder project before it even began.

BuAer had contracted out the design of the Falcon missile, a complex and costly project built by outside contractors. In contrast, McLean’s team at NOTS, under BuOrd, was developing the “Heat Homing Rocket” in-house. Despite the promising advancements, BuAer managed to get the project canceled through the Department of Defense.

Persistence Pays Off

Refusing to let their work go to waste, McLean and his team continued developing the missile in their spare time, using whatever resources they could scrounge up. Their dedication paid off. By 1951, the project had advanced enough to demonstrate its potential to the Deputy Chief of BuOrd. In 1952, the missile was officially named the Sidewinder, almost as a jab at BuAer for their previous attempts to shut it down.

Despite initial disinterest from the Air Force, proponents of the Sidewinder managed to arrange a shoot-off against the Falcon. The results were clear-cut: the Sidewinder, with its simplicity and reliability, outperformed the Falcon, which struggled with technical issues. This success proved the Sidewinder’s worth and set the stage for its adoption by the military.

Design Innovations and Field Success

One of the keys to the Sidewinder’s success was its innovative design. It required no onboard batteries, generating its own electrical power with a tiny turbine driven by a hot gas generator. This simplicity extended to its stabilization system, using rollerons — small air-driven wheels that acted as gyros on the rear canards. These features made the Sidewinder cost-effective, reliable, and easy to produce.

Initially, the Sidewinder was limited to targeting enemy aircraft from behind, where the heat signature of the engines was most intense. However, later versions overcame this limitation, allowing for more versatile use in combat. The missile’s first real test came in 1958 during a conflict between Taiwan and Communist China. Taiwanese F-86 Sabres, armed with Sidewinders, managed to shoot down several Soviet-supplied MiGs, showcasing the missile’s effectiveness and altering the course of the conflict.

The Missile Wars and Legacy

The Sidewinder’s success caught the attention of the Soviet Union, which managed to reverse-engineer a captured missile, creating their own version, the Vympel K-13. This marked the beginning of the missile arms race, with both sides continually developing new and improved versions of their air-to-air missiles.

The Sidewinder went through several iterations, each improving on the last. Versions such as the AIM-9B, AIM-9D, and AIM-9L incorporated advancements that made the missile even more effective in combat. By the time of the Vietnam War, the Sidewinder had proven itself as a reliable and deadly weapon, far surpassing the Falcon in performance.

Today, the Sidewinder remains in service, a testament to McLean’s original design principles of simplicity, reliability, and cost-effectiveness. With over 110,000 units produced and an estimated 270 aircraft kills, the Sidewinder is the most widely used air-to-air missile in the Western world. Its continued updates and support contracts ensure that it will remain a key component of military arsenals until at least 2055.


The story of the AIM-9 Sidewinder is one of perseverance, innovation, and the power of a dedicated team to overcome bureaucratic obstacles. William McLean and his team’s vision and determination not only brought the first heat-seeking missile to life but also set a standard for future air-to-air combat technology. Their legacy lives on in every Sidewinder missile fired, a fitting tribute to their groundbreaking work over six decades ago.