The Forgotten Flight That Sparked the Modern Age of Hot Air Ballooning
On the morning of November 18, 1960, in a narrow valley south of Rapid City known as the Stratobowl, a small team of engineers stood in the frozen grass and waited for a balloon to rise. The sky was hard blue, the air thin and still. A propane burner hissed beneath a domed envelope of nylon—the first of its kind built to withstand its own heat. Slowly the balloon filled and lifted free. It drifted above the dark ridges of the Black Hills for an hour and thirty-five minutes before touching down miles away.
Frank Heidelbauer, an employee at Raven Industries and amateur photographer, caught the moment on Kodachrome. On the cardboard mount he wrote, “First sustained hot air balloon flight; Black Hills in background. Nov 1960.” It was a modest note for what would become a defining photograph in aviation history—one that now sits comfortably within the broader legacy of flight chronicled by institutions like the Smithsonian National Air and Space Museum. I’ve held this slide in my own hands. It still glows brightly when held to the light, its edges browned by time.
A Secret Within a Cereal Company
To understand why that flight mattered, one has to return to a most unlikely setting: the General Mills headquarters in Minneapolis. During the early Cold War, behind the public face of cereal brands and smiling cartoon mascots, General Mills housed one of the most secretive research facilities in the country. Inside the Aeronautical Research Division, engineers built high altitude balloons under contract to the U.S. Air Force and Office of Naval Research. What no one knew outside of two engineers was that the balloon program sponsor was none other than the CIA (J-171 Manned Balloon Program, CIA Internal A-171), according to a declassified memorandum titled “General Mills Aeronautical Research Laboratory — Balloon Trials” (Central Intelligence Agency, Jan. 27 1954, Document C05415896, cia.gov
The CIA’s partnership was hidden in plain sight. From the outside, it appeared to be a food manufacturer experimenting with weather and unmanned balloons. The division worked as a secret research base. It developed advanced balloon technology, including polyethylene film and guidance systems for spy balloons. These balloons drifted over the Soviet Union to take intelligence pictures—part of a network of Cold War spy balloons that paved the way for space exploration. The projects were called Moby Dick and Genetrix. Among those engineers was a quiet innovator named Ed Yost. The helium and hydrogen gas balloons he helped build were costly, dangerous, and single-use. Yost began imagining something reusable—a craft that could heat the air inside its own envelope, rise gently, and return safely to the ground.
The Navy Contract In 1955
Ed Yost left General Mills. With his government contacts still intact, he approached the Office of Naval Research (ONR) with a proposal for a man-carrying hot air balloon that could be reheated, refueled, and recovered. The ONR agreed. Under Project A-134, Yost received funding for the “modern hot air balloon project.” The work needed flexible manufacturing outside a secret military base. So, he and three former General Mills engineers named James Black, Max Anderson, and John Olson started Raven Industries. They founded it in Sioux Falls, South Dakota on February 8, 1956. Raven worked as both a government contractor and a private lab for Yost’s experiments. It connected military secrecy with civilian invention.
The First Leap: Nebraska, October 22 1960
After years of prototypes, Yost launched his first manned balloon from a field near Bruning, Nebraska.
Nearly two centuries earlier, in 1783, French inventors Joseph and Étienne Montgolfier astonished Paris with the first human flight in a hot air balloon Their paper and fabric aircraft rose above the city, powered only by fire, carrying the first humans ever to fly — Jean-François Pilâtre de Rozier and François Laurent, the Marquis d’Arlandes.
In fact, the word “pilot” itself is believed to trace back to Pilâtre’s name — a linguistic nod to one of history’s first aeronauts.
Now, in Nebraska, Yost was about to do what the Montgolfier brothers could not. He created a controllable and reusable hot air balloon capable of true, sustained flight.
The balloon envelope was made of a Mylar-nylon laminate, a remnant of the CIA’s stratospheric surveillance work. Earlier experiments in flight—dating back to when the hot air balloon was first invented—laid the groundwork for Yost’s Cold War-era breakthroughs. The flight lasted twenty five minutes—the first free hot air flight of the modern era, according to the New York Times obituary of Ed Yost (June 4, 2007, nytimes.com). It was enough to prove that heated air could lift a human being safely, but the laminated film softened under continuous heat. Yost knew that to achieve longer, practical flights he would need an entirely new material.
A Cold Morning in the Stratobowl: November 18, 1960
Less than a month later, the Raven team gathered again, this time in the Stratobowl, a natural amphitheater famous for record-setting ascents in the 1930s. The new balloon’s envelope was made entirely of nylon, a fabric strong enough to withstand hours of direct heat. When the burner ignited, the balloon rose smoothly from the valley floor. For one hour and thirty-five minutes, it remained aloft, stable, controllable, and undamaged. It was the first sustained hot air flight in history, transforming a fragile experiment into a practical aircraft. The Nebraska flight showed that the idea worked. The Stratobowl flight proved it could endure.
From Spycraft to Skycraft
The irony was striking. The same chemistry and materials that once carried cameras above hostile borders now lifted people peacefully into the sky. What began in a hidden CIA research lab inside a cereal company had become an instrument of curiosity and joy. Within a decade, Raven Industries balloons were flying around the world. Scientists used them for atmospheric research; adventurers used them to cross mountains and deserts. By the early 1970s, bright nylon domes filled the morning skies at balloon festivals from Albuquerque to Switzerland. Technology once meant for secrecy had become the quiet poetry of flight.
The Legacy of a Slide
Frank Heidelbauer’s photograph from that cold morning in 1960 represents more than a successful experiment—it captures a shift in purpose. What began as classified research at General Mills evolved into the birth of modern hot air ballooning. The technology that once served the Cold War became a symbol of exploration and freedom. When Yost’s balloon lifted over the Black Hills, it carried not only a man, but the enduring proof that the human spirit always finds its way back to the sky.
About This Story
Seattle Skies produced this piece. It is a nonprofit organization dedicated to preserving and sharing ballooning history by digitizing archival collections and connecting historical documents through AI. Seattle Skies makes these resources available to aviation historians, balloon museums, and the public.
The article was written by Eliav Cohen, Director of Seattle Skies, a balloon historian, world-level hot-air-balloon competitor, commercial pilot, and owner of Seattle Ballooning. The featured slide comes from the Richard Douglas Collection, preserved and digitized by Seattle Skies.
