The majority of the 160,000 Allied troops that invaded occupied France on this day 70 years ago arrived on ships and landing vessels. But some 13,000 parachuted early on D-Day from planes flown by pilots who had already been fighting over Europe since 1940.
Their B-17 Flying Fortress and B-24 Liberator bombers flew frequent missions above 25,000 feet without pressurized or heated cabins. This presented a challenge. At that height, crews had to wear oxygen masks to remain conscious and protect themselves from temperatures so low that exposed skin could freeze to metal.
GE engineers stepped in to help. They designed a heated flying suit for high altitudes by drawing on previous experience from a successful but decisively non-military product: electric blankets.
The suit “consist[ed] of an outer garment of wool fabric with wires sewn to the inside of the cloth, and an inner lining of cotton cloth,” according to a January 1942 story in Flight magazine. The article said designers cut the wool “on the bias so that it will give freely together with the wires, which are sinuous and sewn on in parallel rows so that they give and retract with body movements.”
Three GE Copper Men posing outside the U.S. Army Research Institute of Environmental Medicine in 1968.
The suit came with “wired” boots and “a pair of fine leather gloves wired on the back and at the wrists.” The story also mentioned that “the material and design of the gloves are those commonly used in ladies’ dress gloves and give finger freedom and a delicate sense of touch essential for operation of instruments, camera adjustments, and shutter control and gun triggers.”
GE went through 50 fabric suppliers before it settled on the right material. The company tested the suits in a special cold room at Fort Monmouth, N.J. Volunteers donned the outfits and sat through temperatures reaching minus 63 degrees Fahrenheit without turning into ice cubes.
Well, maybe. GE developed a life-size dummy called the Copper Man to spare human volunteers of discomfort when testing the suit’s extremes. The dummy was 5 feet and 10 and a half inches tall, and covered with copper skin one-sixteenth inch thick. Its head, hands, torso and feet were connected by an electrical mesh that could take readings from 15 different body areas.
The suit went into mass production in 1942 and pilots used it throughout World War II. The final design could keep flyers comfortable from plus 70 F to 60 F below zero.
When it started fading out of service with the arrival of the B-29 Superfortress bomber equipped with a pressurized cabin, the GE marketing team saw an opportunity. It turned the suit technology into a cozy automatic blanket for relaxing postwar sleep.
GE advertisement explaining the postwar utility of the Copper Man in the April 1945 issue of Good Housekeeping magazine. Top Image: Testing the GE electric flying suit at 63 degrees below zero in a cold room Fort Monmouth in 1941. GIF by Kevin Weir / flux machine