There was never supposed to be a Sidewinder. The Navy did not ask for one and the Air Force did not want one.

It exists because a physicist at a desert laboratory in California decided the official requirements were wrong, worked on it out of the wrong budget under a deliberately misleading project name, and kept going after being told to stop.

Seventy years later it is still the air-to-air missile everybody buys.

The man

William Burdette McLean was born in 1914, the son of a Protestant clergyman who believed in self-reliance. His mother taught him to knit, crochet and use a sewing machine before he started school. As a boy he built surfboards, canoes, rafts and his own photographic enlarger, and at eleven he helped his family build a house.

He was good at science and maths and bad at English and history, which got him into Caltech, where he took three degrees in physics and a doctorate in 1939. One of his professors observed that McLean sometimes seemed more interested in the laboratory equipment than in the measurements it produced.

The war put him at the National Bureau of Standards designing arming devices for proximity fuzes — objects that must work at the target and at no other moment. Jacob Rabinow, who worked under him there and went on to hold 225 patents, called him the best engineer he had ever known.

At the end of the war McLean went out to the Naval Ordnance Test Station at China Lake for what he expected to be a two-month visit. He stayed twenty-three years.

The argument nobody wanted

In 1946, running the station’s Aviation Ordnance Division, McLean was working on aiming systems for unguided air-to-air rockets. He worked out that no aiming system, however perfect, could let an unguided rocket hit a target that was free to accelerate unpredictably. The weapon would have to steer itself.

Radar sets of the period were far too bulky for the nose of a rocket. Infrared detectors were about the size of a dime.

The rest of the guided-missile community had reached the opposite conclusion, because infrared cannot see through cloud, and both services had written requirements for all-weather missiles. McLean had come to distrust requirements at the Bureau of Standards; he thought they often asked for the impossible and sometimes failed to ask for what was feasible. His view was that a requirement should be written after the thing existed.

He also knew that bombers attack from above twenty thousand feet, where cloud is scarce, and that a weapon working nine times out of ten beats one too complicated to work and too expensive to buy.

Local Fuze Project 602

In 1949 McLean proposed a “heat-homing rocket”. The last word was the argument: an aircraft is maintained continuously for repeated use, whereas ordnance is stored and then fired. If the missile was ordnance, it had to be simple and sturdy, and McLean thought it should cost a few hundred dollars when everyone else assumed hundreds of thousands.

There was no requirement, so there was no money. For two years he ran the work on the station’s internal discretionary funds plus Navy fuze money, under the name Local Fuze Project 602 — the rationale being that the seeker head was, if you squinted, a fuze that got the missile closer before it went off. Later it became Feasibility Study 567, which was, as Howard Wilcox put it, another obfuscation.

Meanwhile the Bureau of Aeronautics was building the Sparrow and letting it be known that all guided missiles should be its business. McLean recruited volunteers from around the station instead.

The design decisions that made it

McLean believed that with a good enough steering servo you could fly a barn door, so the first missile had rectangular wings and fins. They flew reasonably well. His aerodynamicist eventually won that argument and the production version got swept leading edges.

A technician named Sidney Crockett solved the roll problem with rollerons: solid gyroscope wheels on flaps at the rear fin tips, rims notched so the airstream spins them, so that any roll forces the flaps out into the airflow to oppose it. No electronics, no power, no commands. Just a spinning wheel that does not want to be turned.

The torque-balance servo commanded a twisting force on the fin rather than an angle, which automatically compensated for changes in speed and altitude. The team’s boast was that their missile was independent of aerodynamics.

The telemetry was built from Heathkits, because laboratory-grade equipment was expensive and fragile. An engineer taught a group of women at the station to assemble the kits; once they were good at that, he had them build seeker heads.

The cigarette trick

Officials from Washington kept arriving to see whether any of this was real. The team developed a demonstration: mount a seeker head on the antenna of a surplus radar van, wire the seeker’s output to steer the antenna, and let visitors watch the whole assembly track an aircraft overhead — or a man standing at a distance holding a lit cigarette.

In 1951 Rear Admiral William S. “Deak” Parsons, deputy chief of the Bureau of Ordnance, came to look.

He also decreed that the project would be run from China Lake rather than from Washington. Three million dollars followed. The missile already had a name, suggested by McLean’s colleague Gilbert Plain after the rattlesnake that hunts by body heat.

Six inches

By 1953 more than two hundred people at the station were on the project and more than a dozen shots had failed. On 11 September a carefully prepared round passed within six inches of a drone, and Wilcox wired Washington calling it a virtual hit. McLean threw a beer party. At two in the morning somebody telephoned a former commanding officer with the news, could not make himself understood, and was asked to put on someone sensible — who turned out to be up on the roof.

The first test pilot on the programme was a young Navy lieutenant named Walter Schirra, who later went to space.

Holloman, 1955

The Air Force did not know the Sidewinder existed until McLean and Wilcox ambushed an assistant secretary over breakfast in Pasadena. He agreed to commission a study, told them what conclusion it would reach, and required a shoot-off against the Air Force’s own Falcon.

The visiting team readied four rounds in four hours and left them on the aircraft overnight, which with a Falcon would have been unthinkable. They asked for a flashlight and a small multimeter. They were then shown the Falcon test rig: dials, gauges and meters along forty feet of wall, with the missiles trolleyed past on a series of stations.

The first Sidewinder flew up the drone’s exhaust pipe and blew it apart without a warhead. The pilot celebrated with a victory roll that broke the sound barrier and was formally cautioned for it.

And afterwards

The Sidewinder was released to the fleet on the first working day of 1956, and two years later Chinese Nationalist Sabres used it over the Taiwan Strait in the first successful air-to-air missile engagement in history — a story with its own sting in the tail, since one round lodged in a MiG without exploding and gave the Soviet Union a complete design to copy.

McLean stopped running the project in 1954 when he became technical director. He went on to satellites, then submersibles, and found that the further he got from missiles the less anyone wanted to hear from him. Shortly before he died in 1976 he complained that innovation had been easier in the old days at China Lake.

Several hundred thousand Sidewinders and foreign copies have been built — more than any other air-to-air missile. It remains the cheapest one America makes.

Sources: Howard A. Wilcox and Ron Westrum, “Sidewinder”, Invention & Technology, Fall 1989; Ron Westrum, Sidewinder: Creative Missile Development at China Lake; National Academy of Sciences biographical memoir of William B. McLean; Naval Air Weapons Station China Lake.