Space Shot: 1935
richard h. sstewart/national geographic2006_2_28Compared with the cutting-edge world of aerospace engineering, balloons are the essence of low tech. They need no fancy propulsion systems, their basic principles can be understood with high school science, and they haven’t really changed much since Benjamin Franklin’s day. Yet even decades after the Wright brothers, they remained the only way to explore the upper atmosphere, and today they are still the best choice for many purposes. During the nineteenth century balloons were used for adventure, research, aerial art and photography, and military reconnaissance, and in the twentieth century they acquired a broad new set of applications, including the measurement of the recently discovered cosmic rays, advancing atmospheric chemistry and physics, and the creation of maps for aviation.
Between the World Wars balloons kept getting bigger and flying higher, as aeronauts from around the world pursued scientific breakthroughs and international prestige. The hardiest pilot with the biggest balloon of them all was Albert W. Stevens, an experienced Army flier with a particular interest in photography. In 1935 he took a balloon to the stratosphere, setting a record that would last into the era of supersonic jet flight and rocket launches.
Growing up in Belfast, Maine, Stevens showed a strong bent for technology. He paid his way through the University of Maine by running an electric plant at night. He also did some newspaper work and photography on the way to earning his bachelor’s degree in electrical engineering in 1907, at the age of 21, and a master’s two years later.
After graduation, Stevens took a job at the Boston & Idaho Gold Dredging Company, setting up a power plant for the company’s mining operations on the south fork of the Payette River, in southwestern Idaho. In the summer of 1910 he remodeled a company house for his brother’s family, giving it the only indoor bathroom in the county as well as hot and cold running water, electric heat, and a darkroom in the basement. Stevens’s interest in photography would eventually lead to his pioneering ascent into the stratosphere.
In the spring of 1914 Stevens built an electric plant, which he subsequently operated, for a mining company near Nome, Alaska. He and the foreman of a company dredge once made a thousand-mile trip by dogsled up the Yukon River to Fairbanks, then south to the coast to catch a Seattle-bound ship. Eventually Stevens grew hungry for adventure of another sort, or perhaps the long journey made him want to explore the possibilities of faster travel. In any case, he became interested in aviation.
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. “The parachute jump was simply another way of getting down after the real work was done,” he later wrote. He took a few puffs from an oxygen tube on the way down, but “I was falling so fast that I soon realized that I did not need the tank, so I tucked it under one of my shoulder straps.” The parachute rocked violently in the rough air. “After ten minutes of this, I began to get awfully seasick,” he recalled. The wind was so strong that he landed in a field nearly 30 miles from where he had left the bomber.
In 1924 Stevens and Lt. John A. Macready made an eight-week, 10,000-mile trip, taking 2,000 aerial photographs of cities and scenery between Dayton, Ohio, and San Diego, California. (Macready was another distinguished flier, having already become the first to dust crops from an airplane, to make a night parachute jump, and to fly nonstop across the United States.) During the trip Stevens set another record by taking a photograph from 32,200 feet. Soon after this, Stevens, while still in the Army, joined the Alexander Hamilton Rice Scientific Expedition as its aerial photographer, to assist in mapping and exploring the upper Amazon region of Brazil.
Stevens was interested in atmospheric scientific research as well as photography. In October 1928 he and his pilot, Capt. St. Clair Streett, reached an altitude of 39,150 feet and recorded, for the first time in America, thermometer readings every few hundred feet between the earth and the stratosphere. This flight revealed some of the hazards of high-altitude flying in an unheated plane. With oxygen and fuel rapidly disappearing, Stevens wondered why Streett did not begin a descent. He recalled: “What had happened was that the intense cold during the comparatively long stay at ceiling had shrunk the metal parts of the throttle and supercharged controls so that they were immovable. That is, Captain Streett could not shut the engine off. And yet at this speed or a lower speed, it started to climb again. In short, we couldn’t get down below 34,000 feet.” When the fuel finally ran out, Streett managed a “dead stick” landing. (Streett would retire in 1952 as an Air Force major general.)
Stevens established another record in August 1929, when he photographed Mount Rainier, in Washington, from 227 miles away. This continued work he had begun in haze-penetration photography, using a combination of emulsions and filters. He broke this record on a National Geographic Society air survey of Latin America by photographing Mount Aconcagua, in Argentina, from a distance of 287 miles—the first photograph ever made that showed the curvature of the earth. In 1932 he photographed the moon’s advancing shadow over the northeastern United States during a solar eclipse.
Yet there was a limit to what Stevens, or anyone, could accomplish with this approach. In the unpressurized cockpits of the day, he and other daredevils had gone about as high as they could without being killed by the cold and lack of oxygen. 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.
The launch site not only needed good flying weather but had to be far enough west for the balloon to drift eastward 700 miles in the prevailing winds and still land in level, unforested country. It also had to be sheltered from surface winds. Kepner and Anderson searched the Western states for two weeks to find a suitable spot. When asked what they were looking for, Kepner said, “A hole 400 feet deep with vertical walls; a 500 foot square grassy meadow in the bottom, with a 20,000 volt electrical power line; a railroad and a first class truck highway running through it; and, if possible, I would also like a good trout stream running through it.”
Eleven and a half miles southwest of Rapid City, South Dakota, they found a site that had everything they were seeking, right down to the trout stream. It was soon known as the Stratobowl. The local government offered to improve the roads and install power lines. With assistance from the Army’s Fort Meade, in nearby Sturgis, a small city (which inevitably became known as the Stratocamp) was set up, complete with lighting, radio and Teletype equipment, and a weather station.
The balloon’s gondola arrived by truck from Midland, Michigan. It was an 8-foot-4-inch sphere of magnesium alloy with walls 3/16-inch thick. The floor was 60 inches across, quite spacious by ballooning standards, and around the outer edge were 8 vertical stanchions to support shelving for instruments. There were 10 portholes for observation and 2 for spectrographs.
Instrument readings were recorded with a series of cameras pointed at dials, which were illuminated with automobile lamps. 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. It was made of more than two acres of rubberized cotton fabric, and with its bands, ropes, valves, and other attachments, it weighed more than 5,000 pounds. On June 18, 1934, five engineers from the National Broadcasting Company arrived to establish two-way communication between the balloon and the ground. This would allow the mission to be broadcast over the NBC radio network.
Next, cylindrical canisters of hydrogen started arriving; they were stacked and covered with tree branches to protect them from the sun. 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. The bag was spread on a sawdust-covered, canvas-protected circular bed, and the hydrogen from the first of 1,500 cylinders began hissing into it at 7:50 p.m. 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 ground dropped away quickly, and the crew could see the thousands of people who had gathered during the night around the rim of the Stratobowl to watch the 300-foot-tall balloon take off. Stevens said it “took the bit in its teeth,” rising too fast to record the desired data. Stevens released hydrogen to reduce the rate of ascent.
In 30 minutes 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.
For more than an hour the balloon descended at about 500 feet per minute, with what Stevens described as an occasional soft swishing noise indicating a new or lengthening tear in the bag. Each member of the crew spoke on the radio during the descent. Kepner spoke twice to his wife and reported to General Westover. After he mentioned a rip in the bag “about 50 feet long and a yard wide,” the general said, “I know you’re pretty busy, and I won’t take any more of your time.”
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. The crew began to equalize pressure, first by cutting a barometer tube, then by gradually opening a manhole door until it was fully open at 18,000 feet. The crew decided to stay with the balloon as it continued down, combining the parachute effect of the bag with the lift of the remaining hydrogen to ease the descent. 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. Kepner was sitting in the rope cage atop the gondola, and Anderson was halfway out one manhole when his parachute pack accidentally opened. He gathered the folds of silk in one arm and jumped. The last altimeter reading Stevens saw was 5,000 feet above sea level, meaning they were only 3,000 feet above the ground.
Stevens wrote: “Twice I tried to push myself through the hatch of the gondola, but wind pressure around the rapidly falling sphere forced me back. So I backed up and plunged headlong at the opening. I managed to hit it fairly, and went out in a horizontal position, face down, with arms and legs outspread like a frog… . I turned over a half revolution and, as I came right side up, pulled my rip cord.” When he saw two other parachutes, he knew Kepner and Anderson were safe. “Directly below me, I heard the gondola hit with a tremendous thud, and saw a huge ring of dust shoot out. Forty seconds later I hit—fortunately with a much lighter thud.” He was near Holdrege, Nebraska, 225 miles from the launch site.
By the time the three men had rolled up their parachutes and hurried to the gondola’s crash site, Stevens said, “already a score of people were present, seemingly rising out of the very ground, and in a few minutes hundreds more were coming across the fields to the wreck.” Kepner and Stevens went to a farmhouse to use a telephone. Stevens removed his two suits of heavy woolen underwear and hung them outside over a fence. After making his calls, he returned and “found that souvenir hunters had taken my underwear!”
The gondola had been flattened, and Stevens described the instruments as “a heart-breaking mass of wreckage.” However, much of the data had been recorded photographically, and only a part of it was lost in the crash. A spectrograph that had descended on its own parachute landed undamaged. Calculations by the National Bureau of Standards indicated that Explorer had reached an altitude of 60,613 feet above sea level, missing the official world record by just 624 feet.
A review board concluded that the initial failure of the lower part of the bag was the result of “large areas of adhesion” caused by the way the bag was folded. The final disintegration of the upper part of the bag was caused by the explosion of a mixture of hydrogen and air.
Stevens said, “Our most cheering thought of the recent ascent is that we feel we have successfully solved the problems of living and working efficiently in the stratosphere.” He noted that each instrument had worked exactly as planned. “As for the balloon, we think another can be built that will go to its calculated maximum elevation without mishap.” The National Geographic Society volunteered to finance the effort, and plans were soon under way to incorporate the lessons from the flight of the Explorer .
The new balloon, called Explorer II , was to be 3,700,000 cubic feet—700,000 more than the Explorer —and 192 feet in diameter when fully expanded to a sphere. The additional volume would allow the use of heavier but nonexplosive helium as the lifting gas and would permit a bigger load of instruments to be taken. Stronger cloth was used, the balloon was folded differently, and its surface was treated with a powder to produce a dry and nonsticky surface that would not adhere to itself.
The gondola’s diameter was increased by 8 inches, to an even 9 feet. Instruments were bolted to the gondola, rather than placed on shelves, and it had fewer portholes but larger ones. The size of the two manholes was increased by 2 inches in each direction, to 20 by 22 inches. These and other changes reduced the weight of the Explorer II gondola and its fittings to 637 pounds.
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.
During inflation, early in the morning of July 12, the balloon suddenly collapsed, enveloping the gondola and three riggers. A steel guardrail kept the men from getting crushed by three tons of rubberized fabric, and they escaped with only scratches. The launch was canceled and everybody went home. An investigation showed that the accident had been caused by a fabric failure at the upper end of the rip panel, which was used to deflate the balloon quickly upon landing. After a different type of ripping device was installed, the balloon came back to the Stratocamp in early September.
The assembled civilian and military personnel waited for suitable weather through two months and three snowstorms. Lyman J. Briggs, director of the National Bureau of Standards, who chaired the flight’s scientific advisory committee, wrote that “camp life, even in heated tents, loses some of its charm in zero weather.” Finally, on November 10, the balloon was taken from its box in a heated tent and inflation began. Someone heard a slight tearing noise, and inflation stopped while crews located and repaired the 17-foot rip in the fabric.
With 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.
Kevin L. Cook is a former librarian and freelance writer in Drumright, Oklahoma.
