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A Record That Lasted Into The Jet Age

In 1935 Albert W. Stevens, an experienced Army flier with a particular interest in photography, took a balloon to the stratosphere, setting a record that would last into the era of supersonic jet flight and rocket launches. In 1917 Stevens enlisted as a private in the aviation section of the U.S. Army Signal Corps. After training at Cornell University, he was commissioned a first lieutenant and sent to France with the photographic section of the 88th Observation Squadron. He was cited twice for his dangerous work in photographing enemy positions. Following the Armistice, he stayed in Europe, taking pictures of the now silent battlefields. He returned to the United States in 1919 and assisted in making the first large photomosaic map for the Army Air Service and the Geological Survey.

Stevens continued his military work in photographic mapmaking, flying at ever-increasing altitudes. On June 12, 1922, he was in a Martin bomber when it established a new three-passenger altitude record of 24,306 feet. On that same flight he made a record high-altitude parachute jump from 24,200 feet.

Balloons, however, with their tightly sealed gondolas, were already topping 40,000 feet, and they provided a stable platform and tranquil working conditions for their occupants. If Stevens wanted to go any higher, he knew it would have to be in a balloon. In 1933 he initiated an ambitious venture with the National Geographic Society and the U.S. Army Air Corps. The goal was to explore the stratosphere, which begins at an elevation of about 50,000 feet. First Stevens asked the Goodyear-Zeppelin Corporation to determine what altitudes could be reached with balloons of various capacities. After securing support and cooperation from public and private sources, he ordered a 3,000,000-cubic-foot balloon, three times as large as any ever before built. Karl Arnstein, Goodyear-Zeppelin’s vice president in charge of engineering, estimated that a balloon of that size could reach 79,000 feet with a useful load of one ton.

Brig. Gen. Oscar Westover, assistant chief of the Army Air Corps, assigned Maj. William E. Kepner as pilot and commanding officer of the flight. Kepner, decorated for his World War service, was a frequent contestant in major balloon races and had won the James Gordon Bennett trophy in 1928 for distance covered in a balloon. Capt. Orvil A. Anderson, who had considerable lighter-than-air flying experience, was named alternate pilot and operations officer. He would be responsible for rigging, inflating, and launching the balloon.

Eleven and a half miles southwest of Rapid City, South Dakota, they found a launch site. It was soon known as the Stratobowl. The balloon’s gondola arrived by truck from Midland, Michigan. One purpose of the flight was to collect data on cosmic rays and air composition at various altitudes. Another, said National Geographic Magazine, was to gather information on “the mysterious ozone layer of the upper air, which some scientists assert is a sheath that saves life on earth from destruction by ultra-short light rays.”

A few days after the gondola arrived, another truck brought the balloon bag. On July 6 a ground crew consisting of troops from Fort Meade performed a practice inflation using a 35,000-cubic-foot balloon. The next day another test was conducted with Kepner, Stevens, and Anderson sealed inside the gondola. (It had become clear that the flight was a three-man job, so Anderson joined Kepner and Stevens in the crew.) Now it was just a matter of waiting for suitable weather: clear skies stretching several hundred miles east from the launch site.

At 1:30 P.M. on July 27 it was decided to begin inflating the balloon for a flight the next day. To allow for expansion of the lifting gas at high altitudes and the heating effect of the sun, the balloon was inflated to only 7.5 percent of its capacity. It was expected to expand from its carrotlike shape at takeoff to a 179-foot sphere at 65,000 feet. Early the next morning Stevens and Anderson got into the gondola while Kepner climbed into the rope cage on top of it to direct the takeoff. Eighty pounds of lead ballast were removed, and the Explorer, as it had been christened, started to rise at 5:45 a.m. The balloon reached equilibrium at 14,500 feet. Stevens crawled outside to help Kepner lower a 125-pound spectrograph on a 500-foot rope. At about 10:00 a.m. the crew closed the two manholes and released another 280 pounds of lead ballast. The Explorer rose to 40,500 feet over the next hour.

At 1:15 p.m. and 57,000 feet, the crew heard a noise overhead. When they looked through the top porthole, they saw a 30-foot rip and three smaller tears in the lower part of the bag. The balloon had not yet fully expanded, and the crew allowed it to rise to 60,000 feet while they took instrument readings. Then they valved off hydrogen to begin a descent. By 3:00 p.m. the rate of descent had increased to about 700 feet per minute and the balloon had reached 25,000 feet. Just after 3:30 p.m. the bottom of the balloon bag suddenly dropped off. The remnants of the balloon were still acting as a parachute, but with a load of three tons, Kepner believed it could fail at any minute. Kepner had just given the order to prepare to jump when a final burst created a large hole in the top of the bag.

The new balloon (The National Geographic Society volunteered to finance the effort), was called Explorer II, Major Kepner was scheduled for duty with the Air Corps’ Tactical School, at Montgomery, Alabama, so Stevens became commanding officer of the flight and Anderson became the pilot. Capt. Randolph P. Williams was designated alternate pilot and officer in charge of ground operations. The gondola arrived at the reconstituted Stratocamp in mid-May 1935, and the balloon arrived soon after. No suitable weather arrived until July.

The assembled civilian and military personnel waited for suitable weather through two months and three snowstorms. The two-man crew wearing helmets borrowed from Rapid City’s high school football team, Explorer II lifted off at 7:01 a.m. on November 11. The balloon rose quickly at first, then began to settle. To avert a crash, Anderson and Stevens had to release 750 pounds of lead-shot ballast onto the heads of spectators, who ducked, covered their heads, and ran.

At 11:40 a.m. Stevens opened an instrument case and found that the barometric pressure was slightly greater than one inch, compared with about 30 inches at sea level. The two men estimated their altitude at 73,000 feet. They made observations and took samples, and Stevens released a spore-collecting apparatus, which would fall to earth on its own. At 12:20 p.m. they valved gas to start the descent. On reaching 40,000 feet the balloon began to drop more rapidly, so they discharged some ballast.

At 3:14 p.m. Stevens and Anderson landed safely 12 miles south of White Lake, South Dakota. No human would match their official altitude of 72,395 feet (13.7 miles) until August 15, 1951, when William B. Bridgman reached 79,494 feet in a rocket-powered Douglas D-558-II belonging to the National Advisory Committee for Aeronautics (NACA). On the balloon flight’s twentieth anniversary in 1955, Dr. Hugh L. Dryden, director of NACA, said that it had produced new data on cosmic rays, the chemical composition, electrical conductivity, and living spore content of the air above 70,000 feet, the ozone layer, and radio transmission from high altitudes. More important, he said, was the “convincing demonstration that man could protect himself from the environment of the stratosphere.”

Gen. H. H. (“Hap”) Arnold, commander of the U.S. Army Air Forces during World War II, said that Explorer II’s flight had contributed to the Allied victory. He cited advances in the use of magnesium alloys, pressurization techniques, and personal equipment, such as heated flying suits. “Many other items of equipment and methods were improved,” he said, “which later played important parts in giving American airmen superiority in the skies of Berlin and Tokyo.”

Orvil A. Anderson retired from the Air Force as a major general in 1950. Albert W. Stevens continued his work in aerial photography, taking the first photograph of the globular corona of the sun during an eclipse over the Peruvian Andes in 1937. He was named director of the Army Aeronautical Museum, now the National Museum of the United States Air Force, then headed the photographic department of the Air Corps Technical School, at Lowry Field, near Denver, until his medical retirement at the rank of lieutenant colonel in 1942. And more than 70 years after Explorer II’s flight, balloons, now usually unmanned, are still a mainstay of atmospheric researchers, who literally travel to the ends of the earth (the Arctic and Antarctic are favorite launch sites) to study meteorology, cosmic rays, astrophysics, and solar behavior—as well as the continuing deterioration of the same fragile ozone layer that the original Explorer missions did so much to explore.

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