The modern era of flight lifted off in 1783 when two brothers demonstrated their invention, the hot-air balloon, before a crowd of dignitaries in Annonay, France. Joseph-Michael and Jacques-Ètienne Montgolfier, prosperous paper manufacturers (a high-tech industry at the time), began experimenting with lighter-than-air devices after observing that heated air flowing directed into a paper or fabric bag made the bag rise. After several successful tests, they decided to make a public demonstration.
The Montgolfier brothers built a balloon made of silk and lined with paper that was 33 feet (10 meters) in diameter and launched it — with nobody aboard — from the marketplace in Annonay on June 4, 1783. The balloon rose 5,200-6,600 feet (1,600-2,000 meters), stayed aloft for 10 minutes and traveled more than a mile — about 2 kilometers.
Word of their success quickly spread, and a demonstration for the king was planned. For this flight, the brothers enlisted the help of Jean-Baptiste Réveillion, a successful wallpaper manufacturer. They constructed a balloon about 30 feet (9 meters) in diameter made of taffeta and coated with a varnish of alum for fireproofing. Réveillion’s influence was apparent as the balloon was decorated with golden flourishes, zodiac signs, and suns (symbolizing King Louis XVI).
There was some concern about the effects of high altitude on living beings. The king proposed a test using prisoners, but the Montgolfiers instead suspended a basket below the balloon containing a sheep, a duck, and a rooster. It was actually a scientifically sound idea. The sheep’s physiology was thought to be similar to a human’s. The high-flying duck was unlikely to be harmed, so it was used as a control. The rooster was included as a further control because while it was also a bird, it did not fly at high altitudes.
The balloon and its passengers lifted off on Sept. 19, 1783. The flight lasted 8 minutes and was witnessed by King Louis XVI, Marie Antoinette, and a crowd of 130,000. The balloon flew about 2 miles (3.2 km) and landed safely.
First manned flight
The Montgolfiers’ next step was to put a person in the basket. On Oct. 15, 1783, they launched a balloon on a tether with Jean-François Pilâtre de Rozier, a chemistry and physics teacher, aboard. He stayed aloft for almost four minutes.
About a month later, on Nov. 21, Pilâtre de Rozier and the Marquis d’Arlandes, a French military officer, made the first free ascent in a balloon, flying from the center of Paris to the suburbs, about 5.5 miles (9 km) in 25 minutes. Benjamin Franklin wrote in his journal about witnessing the balloon take off:
« We observed it lift off in the most majestic manner. When it reached around 250 feet in altitude, the intrepid voyagers lowered their hats to salute the spectators. We could not help feeling a certain mixture of awe and admiration. »
Ironically, the first human passenger was also the first victim of balloon travel. Pilâtre de Rozier was killed on June 15, 1785, when his balloon, filled with a combination of hydrogen and hot air, exploded during an attempt to fly across the English Channel.
On January 19, 1784, in Lyons, France, a huge balloon built by the Montgolfiers carried seven passengers as high as 3,000 feet (914 meters).
The Montgolfier brothers’ success caused a sensation. The events were commemorated with engravings and illustrations. Chairs were designed with balloons carved into the back. Crockery came decorated with pictures of balloons. Clocks were made with the dials set in a replica of a balloon.
Advances in ballooning
At the time, the Montgolfiers believed they had discovered a new gas (which they called Montgolfier gas) that was lighter than air and caused the inflated balloons to rise. In fact, the gas was merely air, which became more buoyant as it was heated. The balloon rose because the air within was lighter and less dense than the surrounding atmosphere, which pushed against the bottom of the balloon.
The limitations of using air were soon realized because as the air cooled, the balloon was forced to descend. Keeping a fire burning meant the risk of sparks setting the bag on fire. Other means were considered, and less than two weeks after the first free flight, on Dec. 1, 1783, Jacques Alexandre César Charles launched a balloon containing hydrogen.
With this and other advancements, balloon flight was firmly established.
The Montgolfier brothers continued with their experiments. They were honored by the French Académie des Sciences. During their careers, they published books on aeronautics, Joseph invented a calorimeter and the hydraulic ram, and Jacques developed a process for manufacturing vellum.
Joseph died on June 26, 1810. Jacques died on Aug. 2, 1799.
— Tim Sharp, Reference Editor