The Chrysler Air Raid Siren was the size of a car. It measured twelve feet long and six feet high, and weighed an estimated 3 short tons. The gigantic siren was powered by a 180 horsepower eight-cylinder gasoline engine, that drove a two-stage air compressor and a rotary chopper. The compressor pushed 2,610 cubic feet of air a minute, at nearly 7 PSI, through a rotating chopper that sliced the air into pulses to create sound. The compressed air exited through six giant horns with a velocity of 400 miles per hour. This resulted in an incredibly loud sound of 138 dB, measured 100 feet from the siren. The loudness of this siren remains unmatched by any warning device ever produced.

Men testing the Chrysler-Bell Victory Siren in RCA, New York. Photo credit: Marie Hansen/The LIFE Picture Collection

The main objective of the Chrysler Air Raid Siren was to alert the public, in the most jarring and attention-grabbing way, in the event of a nuclear attack by the Soviets during the Cold War. The siren was built by the automobile company Chrysler in collaboration with Bell Telephone Laboratories. Bell developed a new sound generation design that used a direct flow of pressurized air through a chopper rotor and Chrysler put that design into production.

Chrysler produced three popular air raid sirens based on the Bell design. The first generation of these, called the Chrysler-Bell Victory Siren, was manufactured in the early 1940s, and more than a hundred were sold all over the United States. The early designs used a 140 horsepower engine. An improved version of the Chrysler Air Raid Siren with a 180 horsepower engine was introduced in 1952.

The United States government helped selected state and county law enforcement agencies to buy these sirens and install them at key locations in populated areas. Los Angeles County, for instance, bought six of these, and another ten were sold to other government agencies in the state of California. The “Big Red Whistles”, as they were nicknamed, were sounded only a few times during routine tests. Its scream was reportedly heard 25 miles away.

The Chrysler Air Raid Siren was so powerful that it was utilized to disperse fog by the US Navy during World War 2. Fog was a serious aviation hazard at that time when aircrafts were less sophisticated and the pilots relied more on visibility than on the instruments on his craft. Both the US Navy and RAF engineers experimented with different techniques of fog dispersal. The British eventually used fires to evaporate the fog away. Another method employed a series of Chrysler Air Raid Sirens installed about 100 feet apart along the plane’s approach. The sound waves produced by these great siren caused the suspended fog particles to merge with each other and precipitate as rainfall.

The major disadvantage of the sonic method of fog dispersal was the ear-drum shattering sound the sirens produced, that left the men dazed and nauseated. Personnel who worked on the airfield protected their ears with cotton covered with sponge rubber, but these were not enough to keep out the terrific changes in air pressure. The noise was also harmful to animals and birds in the sky. An article published by Mechanix Illustrated during the 1940s suggested that ultrasonic waves could be employed to produce the same effect on fog without the discomfort on men and animals.

The last Chrysler Air Raid Siren was manufactured in 1957. Existing sirens remained in service into the 1970s, after which lack of use and maintenance caused them to fall into disrepair. Many sirens were pulled down from the top of watchtowers and buildings and repurposed into hot rod engines. Others were sold for scrap. A handful of them exist at their original location, but rusted and beyond salvage. For example, there is one in downtown Greenville, South Carolina on top of Westin Poinsett hotel, and another one atop the Rochester Fire Department Maintenance Building in Rochester, New York.

Superintendent of the Office of Civil Defense, Los Angeles, California, examining the Chrysler Air Raid Siren in January 22, 1954. Photo credit: gsjansen/Flickr

Men testing the Chrysler-Bell Victory Siren in RCA, New York. Photo credit: Marie Hansen/The LIFE Picture Collection