History of Flight — 3-Part Series

• Part 1: The Invention of the Hot Air Balloon (current)
• Part 2: The Age of Airships
• Part 3: The Invention of the Airplane

The Invention of the Hot Air Balloon: Humanity’s First Flight

On September 19, 1783, a crowd gathered in the plaza before the Palace of Versailles. King Louis XVI and Marie Antoinette were among them. What rose into the sky that day was not a human being — it was a sheep, a duck, and a rooster. And that was enough. When it was confirmed that the three animals had survived after flying roughly three kilometers over eight minutes and landing safely, thousands of spectators understood: living creatures could travel through the air.^[1]

Two months later, a human being took that place.

Experiments That Began in a Paper Factory

The story of the hot air balloon’s invention is said to have begun by chance. The protagonists were Joseph-Michel Montgolfier (1740–1810) and Jacques-Étienne Montgolfier (1745–1799), brothers from a papermaking family in Annonay, in the south of France.^[2]

According to the legend passed down, Joseph-Michel was inspired one day when he watched a shirt inflate over a fire. However, this anecdote has likely been embellished over time. In reality, the brothers began systematic experiments in late 1782. They started by filling small pouches made of silk and thin paper with hot air to test whether they would rise.^[3] The results were encouraging.

In the early stages of experimentation, the brothers believed they had discovered a new kind of gas. They thought a mixture of smoke and water vapor produced a special buoyancy, which they called “Montgolfier gas.”^[4] In fact, it was simply heated air. Hot air is less dense than cold air, which is why it rises — but the brothers did not fully understand this principle and continued their experiments regardless. Not knowing the reason did not stop them from making the discovery.

The First Public Flight: Annonay, June 1783

On June 4, 1783, the brothers held their first public demonstration in their hometown of Annonay.^[5] With local gentlemen and officials looking on, a spherical balloon roughly eleven meters in diameter, constructed from paper and linen, was filled with smoke over a fire. When the ropes were released, it shot upward into the sky. After flying for about ten minutes and traveling approximately two kilometers, it landed.

News spread quickly to Paris. At the time, a group of scientists in the city were working to develop lightweight balloons using hydrogen gas, which had been isolated by Henry Cavendish. Physicist Jacques Alexandre César Charles, upon hearing news of the Montgolfiers’ demonstration, began accelerating his own development of hydrogen balloons.^[6] The Annonay demonstration not only opened the age of the balloon but acted as a catalyst — through competition — for the advancement of balloon technology as a whole.

The Animal Passengers at Versailles

Following the success at Annonay, the brothers attracted the attention of the Royal Academy of Sciences in Paris and were given the opportunity to demonstrate before the royal court. This became the historic animal-passenger flight at Versailles on September 19, 1783.^[1]

It is important to note that this experiment was not merely a spectacle. At the time, scientists did not know what would happen to living creatures at high altitudes, where the air grows thin. Sending a human being first was considered too dangerous. A sheep was chosen because it was thought to share physiological similarities with humans; a duck served as a baseline comparison as an animal capable of flight; and a rooster was selected as a creature that can fly but is not accustomed to altitude.^[7]

The flight was a success. The balloon rose to an altitude of roughly 460 meters, flew for eight minutes over approximately 3.2 kilometers, and landed in a forest about three kilometers from the palace. All three animals survived. The rooster’s wing was slightly broken — one account suggests it had been stepped on by the sheep during landing.^[1] Whatever the cause, the fact that high-altitude flight was not lethal to living creatures had been established.

The First Crewed Flight in History: November 21, 1783

With the animal experiment a success, it was time for a human to board. But a dispute arose — not over who would fly, but over how the first passenger should be chosen. Louis XVI suggested that a condemned prisoner be used. The reasoning was that it would be appropriate to use a criminal as the subject of a dangerous experiment.^[8]

One man strongly opposed this proposal: Jean-François Pilâtre de Rozier (1754–1785). He volunteered to go himself. A natural philosopher and passionate promoter of science, de Rozier argued that the historic honor of being “humanity’s first aviator” could not be handed to a criminal.^[8] In the end, de Rozier and army officer François Laurent d’Arlandes, Marquis d’Arlandes, were chosen as passengers.

At 1:54 in the afternoon on November 21, 1783, the balloon lifted off from the garden of the Château de la Muette in Paris.^[9] It climbed to an altitude of roughly 900 meters. The two men kept the flight going by using wet sponges to douse sparks before they could reach the balloon’s surface. After flying approximately nine kilometers over around 25 minutes, they landed on the Butte-aux-Cailles hill on the other side of Paris.^[9]

It was humanity’s first free crewed flight. Among those who witnessed it was Benjamin Franklin, one of the Founding Fathers of the United States and the American diplomatic envoy to France at the time.^[10] The story goes that after watching the flight, when a skeptic asked Franklin “What use is it?”, he replied: “What use is a newborn baby?”

The Rivalry with the Hydrogen Balloon: Charles’s Challenge

At the same time the Montgolfier brothers were launching balloons with hot air, an entirely different type of balloon was being developed in Paris. This was the hydrogen balloon, built by Jacques Charles and the Robert brothers.^[6]

Hydrogen is far lighter than hot air. With the same volume, a hydrogen balloon could fly higher and longer. On August 27, 1783, Charles’s unmanned hydrogen balloon launched from Paris, flew for 45 minutes, and traveled roughly 21 kilometers.^[6] When the farmers who first found the balloon at its landing site saw it, they were so terrified that they destroyed it with scythes and pitchforks.

On December 1 of the same year, Charles himself boarded a hydrogen balloon and flew 36 kilometers over two hours at an altitude of roughly 550 meters.^[11] After landing, he took off alone again and ascended to approximately 3,000 meters, at which point he experienced excruciating pain in his ears — a result of the rapid change in air pressure. This experience convinced Charles never to board a balloon again.

The competition between hot air balloons and hydrogen balloons ultimately came down to a question of trade-offs. Hot air balloons were economical because they needed only fuel, but their flight duration was limited. Hydrogen balloons could fly higher and longer, but hydrogen was expensive to produce and posed a risk of explosion. In the nineteenth century, coal gas balloons emerged as a practical compromise.

Tragedy and Pioneering: The End of de Rozier

Pilâtre de Rozier, who had become humanity’s first aviator, would mark another milestone in balloon history — this time a tragic one.

As attempts to cross the English Channel mounted, de Rozier devised a hybrid balloon capable of longer flights. It combined a hot air balloon on the lower section with a hydrogen balloon on the upper section.^[12] The design — later known as the “Rozière balloon” — was conceptually clever, but carried a fatal flaw: open flame in close proximity to hydrogen.

On June 15, 1785, de Rozier and his companion Pierre Romain lifted off from Boulogne-sur-Mer in France. About 30 minutes later, flames broke out on the balloon, and the two men fell from an altitude of roughly 520 meters. The first person to fly in a crewed balloon had become the first victim of an aviation accident.^[12]

De Rozier’s death served as a stark reminder of the dangers of balloon flight, but it did not extinguish the spirit of exploration. The balloon bearing his name — the Rozière — was continuously refined through the nineteenth and twentieth centuries, and in 1999 it was the design used by Bertrand Piccard and Brian Jones to complete the first nonstop round-the-world balloon flight.^[13]

Military Applications: Eyes on the Battlefield

Within a decade of its invention, the hot air balloon was being put to military use. In 1794, during the Battle of Fleurus in the French Revolutionary Wars, French forces used a balloon for reconnaissance purposes.^[14] An observer would board the balloon, survey the enemy’s positions and movements, and relay that information to the ground below. The French won the battle, and the tactical value of balloon reconnaissance was demonstrated.

This was the starting point of military aviation. During the American Civil War (1861–1865), both sides operated reconnaissance balloons. General Ulysses Grant noted that balloon reconnaissance was useful for directing artillery fire.^[15] During the Franco-Prussian War (1870–1871), when Paris was besieged by Prussian forces, around 65 balloons were used to carry mail and personnel out of the city past the enemy lines. It was an early form of airmail service.^[14]

Beyond military use, balloons were actively employed for meteorological observation and scientific exploration. Nineteenth-century scientists rode balloons to collect data on temperature, air pressure, and magnetic fields at various altitudes. In 1804, Joseph Louis Gay-Lussac ascended by balloon to an altitude of 7,016 meters — a record height at the time — to study the composition of the atmosphere.^[11]

Understanding the Principle: The Science Explained Later

When the Montgolfier brothers invented the balloon, they did not fully understand why it floated. The dominant theory in European science at the time held that a hypothetical element called “phlogiston” was released during combustion.^[4] The brothers believed it was smoke rich in phlogiston that lifted the balloon.

The correct explanation lies in the principle of Archimedes. The same principle that governs buoyancy in liquids — that an object submerged in a fluid is buoyed up by a force equal to the weight of the fluid it displaces — applies equally to gases.^[3] When air is heated, its molecules move more vigorously and the air becomes less dense, making it lighter than the same volume of cool air. When the total weight of the heated air inside the balloon is light enough relative to the same volume of outside air, the balloon rises.

Modern hot air balloons are designed around this principle. Burners heat the air inside the envelope to between 100 and 120 degrees Celsius, and the burners are kept running continuously during flight to maintain that temperature.^[16] To descend, pilots can allow the air to cool or open a vent at the top of the balloon to release hot air. The principle itself is simple, but using the wind’s direction to navigate toward a desired destination still demands considerable skill and experience.

The Modern Hot Air Balloon: From Sport to Record-Breaking

In the mid-twentieth century, the hot air balloon shed its role as a military and scientific tool and transformed into popular leisure and sport. The catalyst was a technological innovation in the United States in the 1960s. Ed Yost, working on a research contract with the U.S. Navy, developed the modern hot air balloon in the early 1960s by combining a propane gas burner with a nylon envelope.^[16] Whereas earlier balloons used burning straw or wool to generate the smoke that kept them aloft, the new design used a precisely controllable gas burner. For the first time, the hot air balloon became a safe and repeatable piece of sporting equipment.

Today, balloon-based leisure flights and competitions are held around the world. The Albuquerque International Balloon Fiesta in New Mexico, USA, is the world’s largest balloon festival, where hundreds of balloons fill the sky simultaneously every October.^[17] Meanwhile, record attempts continue. In 2012, Austrian skydiver Felix Baumgartner ascended in a specially built helium balloon to an altitude of approximately 38,969 meters, then jumped and broke the sound barrier in freefall, setting a new world record.^[13]

Conclusion

Return for a moment to that day at Versailles in 1783 when a sheep, a duck, and a rooster rose into the sky. With a king and queen looking on, the scientists chose to send animals up first — because they were afraid. More precisely, because there was so much they did not know. No one understood what would happen to a living creature at altitude.

The Montgolfier brothers themselves did not fully understand why the thing they had built actually flew. They launched a balloon into the sky while holding an incorrect understanding of the underlying principle. De Rozier risked his life to become the first aviator, and in losing that life became the first victim of aviation. The history of the hot air balloon shows, from its very beginnings, that it is possible to act without complete understanding — and that such action can sometimes change the world.

A hundred and twenty years before the airplane, humanity was already in the sky. With nothing but flame and cloth.

The history of flight that began with hot air balloons continues into the age of airships. Continued in Part 2: The Age of Airships.