The first hot-air balloon flight

In 1783, two brothers demonstrated their invention, the hot air balloon, before a crowd of dignitaries in Annonay, France. 

Joseph-Michel and Jacques-Étienne Montgolfier, prosperous paper manufacturers (a high-tech industry at the time), experimented with lighter-than-air devices after observing that heated air directed into a paper or fabric bag made the bag rise. After several successful tests, the brothers decided to publicly demonstrate their invention.

The Montgolfiers 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, according to Encyclopedia Britannica. The balloon rose to between 5,200 and 6,600 feet (1,600 to 2,000 m) and stayed aloft for 10 minutes, traveling more than a mile
(about 2 kilometers).

The Montgolfiers’ next step was to test a balloon with a person as the passenger. On Oct. 15, 1783, the brothers launched a balloon on a tether with Jean-François Pilâtre de Rozier, a chemistry and physics teacher, aboard. He stayed aloft for almost
4 minutes, according to Encyclopedia Britannica.

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 hot air balloon. The pair flew 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 [76 m] in altitude, the intrepid voyagers lowered their hats to salute the spectators. We could not help feeling a certain mixture of awe and admiration.”

The first human passenger was also the first victim of balloon travel. Nearly two years after this flight, Pilâtre de Rozier died 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, according to the Royal Society of Chemistry.

On Jan. 19, 1784, in Lyons, France, a huge balloon built by the Montgolfiers carried seven passengers as high as 3,000 feet (914 m), according to the U.S. Centennial of Flight Commission.

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, according to the Canadian Broadcast Corp. In reality, 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 for flight were soon apparent; as the air cooled, the balloon was forced to descend. Keeping a fire burning onboard created the risk that sparks would set the bag on fire. Other means of keeping a balloon aloft were considered. On Dec. 1, 1783, less than two weeks after the first free flight, Jacques Alexandre César Charles launched a balloon containing hydrogen, according to Encyclopedia Britannica.

Today, balloons are routinely used in scientific investigations of the upper atmosphere. On occasion, specially designed high-altitude balloons have also carried people into the stratosphere; some individuals have performed parachute jumps in the extremely thin air. Balloons have been considered for space missions to Saturn, Venus and Mars, but so far, Earth is the only planet to have hosted these kinds of expeditions.

space.com