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Sidewinder – the Missile that Changed Aerial Combat

During World War II pilots had to get up close and personal with their adversaries to have any chance of making a kill. 

Though the heavy machine guns and cannons in most aircraft were capable of firing accurately well past 500 yards, this usually involved aviators in classic warbirds like Spitfires, Mustangs, Me 109s and A6M Zeros screaming through the sky less than 100 yards off their enemy’s tails.

As dramatic as it was, just a few short years after the war ended, previously unimaginable advances in air-to-air weaponry led Navy and Air Force brass to conclude that guns and cannons would eventually be unnecessary, thanks to a new breed of weapons poised to revolutionize aerial combat. 

Fast forward two decades to the skies over Taiwan, when the venerable Sidewinder missile made its debut. 

Now instead of squeezing a trigger and hoping to down the enemy in a hail of lead, jet-age pilots relied on a supersonic missile that tracked targets from great distances using superheated engine exhaust as a homing beacon. 

Though early Sidewinders were used extensively in Vietnam too, they weren’t as effective as the Navy hoped they’d be, but over the following decades they’d go on to become the world’s preeminent air-to-air weapons.  


The AIM-9 Sidewinder is a short-range air intercept missile that’s been around since the mid-’50s. 

Originally adopted by the Navy in 1956, Sidewinders also entered service with the Air Force in 1964 just before America got involved in Vietnam. 

AIM 9L Sidewinder (modified).
AIM 9L Sidewinder (modified). By David Monniaux, is licensed under CC-BY-SA

Though original Sidewinders were a far cry from today’s variants, in more than a few ways they were surprisingly similar.  

But though they weren’t introduced until the ‘50s, the concept and development began in the ‘40s, and much of the technology on which the missiles were ultimately based originated in Nazi Germany where researchers had designed cutting edge infrared guidance systems for long-range rockets. 

The Nazi’s tracking systems were revolutionary, but much of the work of mating them to actual weapons had gone undone by war’s end. 

Immediately after the war, intelligence teams from Britain, America and the Soviet Union began collecting data from these projects and whisking it back to their respective countries, along with many of the engineers who’d developed it. 

This information was analyzed by the military and quietly disseminated to trusted companies in the weapons and aircraft fields, a few of which already had fledgling missile projects in the works.  

Sidewinder development officially began in 1946 at the Naval Ordnance Test Station in Inyokern, California, known now as the Naval Air Weapons Station China Lake. 

Designated “Local Fuze Project 602,” the program was the brainchild of US Navy physicist William Burdette McLean who’s credited with being the “father” of the heat-seeking Sidewinder missile.

Later McLean worked with big defense contractors like Ford Aerospace and the Loral Corporation, but in the early going the project didn’t have official funding, but it progressed on a relatively small budget with a mostly volunteer workforce. 

The program was officially funded in 1951, and the name Sidewinder was selected after the venomous rattlesnakes found across much of the American Southwest, which use heat-detecting sensory organs to hunt warm-blooded prey like mice, rats and ground squirrels.

Originally called the Sidewinder 1, after years of relatively slow and tedious development, the first live firing took place in early September of 1952, but the new weapon wouldn’t actually intercept a slow moving drone until a year later.  

It was a huge milestone, and over the following year more than four dozen additional tests were carried out with moderate success. 

The military was sufficiently impressed to authorize production in 1955, and Sidewinders were first used operationally in 1956 on Navy Grumman F9F-8 Cougars and FJ-3 Furies.


These days Sidewinders are nearly 10 feet (3.1 m) long, have diameters of 5 inches (127 mm) and weigh just a hair under 190 pounds (87 kg).

Most variants carry a 20.8 pound (9.4 kg) annular blast-fragmentation warheads that detonate when they get close to their targets. 

The resulting explosion sends a field of shrapnel over a relatively large area like a shotgun blast, which increases the likelihood of making a kill.  

Since fast, high-flying jets are elusive targets, this type of warhead is common on anti-aircraft and anti-missile missiles. 

The detonation mechanism is an infra-red sensing proximity fuze similar to those used in American anti-aircraft shells during the Second World War. 

Powered by a single solid-fuel rocket, Sidewinders can reach speeds of up to Mach 2.5 (1918 mph or 3086 km/h), and their ranges stretch from just 6/10ths of a mile (.96 km) out to nearly 22 miles (35.4 km). 

But contrary to popular belief, Sidewinders aren’t actually guided to their target’s actual location, but instead to its anticipated change in position, which is calculated multiple times per second using factors like speed and course. 


Sidewinders first saw combat during the Second Taiwan Strait Crisis in September of 1958 with the Republic of China Air Force (ROCAF), which as a respectful reminder is the name of Taiwan’s air force. 

It’s a long story, but during the conflict ROCAF F-86 Sabres were routinely engaged in air battles with MiG-17s from the People’s Republic of China over the Taiwan Strait. 

Republic of China Air Force North American F-86F Sabre

Republic of China Air Force North American F-86F Sabre. By Toshiro Aoki, is licensed under CC-BY-SA

The MiGs were faster, had better climb rates and higher service ceilings, which meant that they could fly out of harm’s way above their counterparts and choose when and where they wanted to engage.

This scenario was maddenning and embarrassing for the Americans and Taiwanese, but since the Sabres were only equipped with cannons there wasn’t anything they could do about it.

That said, the first ever air-to-air missile engagement took place on September 24, when ROCAF Sabres packing secretly “procured” Sidewinders fired on unsuspecting MiG-17s that’d been cruising smugly above them. 

All told, more than 100 PLAAF MiGs clashed with nearly three dozen F-86s. 

When the proverbial smoke cleared, 25 MiGs had been downed – all by the revolutionary missiles that weren’t even supposed to be there in the first place. 

Though the conflict lasted into October, only six more MiGs were shot down, compared to only two F-86s lost, making it one of the most lopsided air wars of the 20th century. 

However, though the moment was historic, just weeks later another similar engagement ended in disaster from a transfer of technology standpoint, when an AIM-9B fired from a Sabre stuck in the fuselage of a MiG-17 and failed to explode.  

Along with his potentially deadly prize, the MiG pilot gingerly guided his plane home, and the dud missile wound up in the hands of Soviet engineers who considered the unexpected gift a “free university course,” or more accurately, a postdoctoral degree in missile technology. 

Big shocker, the Sidewinder was reverse engineered into the Vympel K-13/R-3S missile which entered Soviet service more than a decade later. 

Rumor has it that the AIM-9 was copied so closely that the Soviets didn’t even bother changing the part numbers. 

As they say, if it ain’t broke don’t fix it, and, imitation is the sincerest form of flattery

Vietnam War

According to official statistics, 452 Sidewinders were fired during the Vietnam War resulting in less than 100 kills.   

By comparison, in World War II Army Air Forces pilots scored more than 15,000 aerial victories, and in Korea, F-86s shot down nearly 800 enemy aircraft.  

In short, air dominance was slipping, largely because Sidewinders had kill probabilities of less than 20%, despite America’s better training and tactics, and arguably better airplanes. 

The MiGs flown by the Vietnam People’s Air Force were small and nimble, and like the Chinese did over Taiwan, Vietnamese pilots usually avoided confrontation until the conditions swung to their advantage, which wasn’t very often. 

These days Sidewinders are the most well-known of all western air-to-air missiles, but they weren’t the only ones streaming through the skies over Vietnam. 

In fact, of all Air Force kills, nearly 60% were made with radar guided AIM-7 Sparrows, while Navy pilots made all of theirs with heat seeking AIM-9 Sidewinders.

But in the early going when Sidewinders were fired from F-4s, the pilots had no backup if their missiles failed to hit their marks, because at that time Phantoms weren’t equipped with cannons. 

This was corrected later, and Navy pilots increasingly relied on guns especially in close range situations. 



The next major advance in Sidewinder development came with the AIM-9L “Lima” in the ‘70s. 

The new Limas were the first true “all aspect” missiles, which meant that they could be fired from any orientation in relation to their targets, including from 90-degree angles and when the two aircraft were closing head-on. 

AIM-9Ls first saw combat in 1981, when two Navy F-14s – think Top Gun – downed two Libyan Su-22s over the Gulf of Sidra. 

In the hands of RAF pilots during the Falklands War in 1982, nearly 80% of Sidewinder AIM-9L launches ended in kills, and 20 Argentinian aircraft were downed. 


The AIM-9X entered service in late 2003, years after a competition between Hughes Electronics and Raytheon. 

The Hughes model won out, after which Raytheon purchased its competitor in a classic case of, “if you can’t beat ‘em, buy ‘em.”

Used by Air Force F-15s and Navy F-18s, the new missiles featured substantial upgrades, one of the most prominent of which was a new thrust-vectoring system that significantly increased maneuverability.  

The 9Xs were also compatible with the new US Joint Helmet Mounted Cueing System (JHMCS) which allowed pilots to lock onto targets simply by looking at them. 

These new Sidewinders also included internal cooling systems and more streamlined aerodynamics which translated into improved reliability, range and speed. 

But perhaps most importantly, the AIM-9X Block II demonstrated “lock-on after launch” capability. 

Previous variants had to acquire their targets before being fired, which wasn’t a problem when they were stored on external hardpoints, but the new development allowed for the possibility of deployment from the internal bomb bays of stealth aircraft like F-35s and F-22s, and at least theoretically from submarines. 

In 2008 AIM-9Xs were also tested for air-to-ground applications at China Lake, where they proved effective at taking out tanks and other armored vehicles. 

Then in 2015, the Army successfully fired Block II missiles from their new Multi-Mission Launcher – a 15-missile truck-mounted battery capable of simultaneously tracking multiple targets 

In this new role Block IIs used a passive infrared seeker that was nearly invisible to detection devices on anti-missile missiles, and though they were more than capable of taking out enemy aircraft, they were also adept at shooting down drones and other missiles themselves. 

Raytheon continued developing Sidewinders into the 2000s, and what might have been the Block III variant would have had longer range and a more powerful warhead.

Sadly for Raytheon shareholders however, the Block III never was, though some of its features were incorporated into later variants. 

For decades the naysayers have been claiming that the Sidewinder was living on borrowed time, but continuous upgrades have made it lethally efficient and surprisingly inexpensive when compared to the cost associated with developing an entirely new missile system. 

In addition, it’s the weapon most capable of dealing with 5th-generation Russian and Chinese jets, unmanned aircraft and other missiles, so it’s not going anywhere any time soon. 

The Diamondback

Though it never made it past the concept phase, the Diamondback was a nuclear-armed Sidewinder variant considered by the Navy in the ‘50s.

Perhaps it never saw the light of day, because even by American standards, firing a nuclear-tipped missile at a relatively small enemy aircraft just seems like overkill.  

Still Going Strong

With more than 100,000 units produced since the mid-’50s, Sidewinders are the oldest, most reliable and widely produced air-to-air missiles in the world, and they’re found in the arsenals of dozens of countries around the world. 

Though less than 1% have been used in combat, they’re responsible for more than 300 kills, and at just $400,000 a pop they’re even affordable for countries like Thailand, Ethiopia and Cameroon which have relatively small military budgets compared to western nations like America and Britain. 

In the early 2000s the old missile turned fifty.

Huge contracts to manufacture and support Sidewinders well into the 2050s in America and abroad keep rolling in to companies like Boeing and Raytheon, and according to the Air Force they’ll be in service until at least 2055, and perhaps decades longer.  

If so, Sidewinders will join a very exclusive club of weapons that remain in use after hitting the century mark, like the M1 Black Dragon howitzer, which in case you missed it, was recently featured on Mega Projects. 

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