AY Honors/Hot Air Balloons/Answer Key

Jacques Étienne Montgolfier

The Montgolfier brothers, Joseph Michel Montgolfier (August 26, 1740 – June 26, 1810) and Jacques Étienne Montgolfier (January 6, 1745 – August 2, 1799), invented the montgolfière, or hot air balloon. Their invention was the first aircraft to carry humans into the sky.

Early years

The brothers were born into a family of successful paper manufacturers in Annonay, south of Lyon, France. Their father, Pierre (1700-1793), established his eldest son Raymond (1730-1772) as his successor. As a result, the younger sons were initially sent away to school to learn other professions.

Joseph possessed a typical inventor's temprement -- a maverick and dreamer but impractical in terms of business and personal affairs. Clever and highly inventive by nature, he was rebellious towards his formal education -- twice running away from school. Nonetheless, his natural curiosity led him to a very successful self-education in the then emerging physical sciences. He eventually returned to the family homestead, but was only peripherally involved in the family paper-making business.

Étienne (as Jacques Étienne was more generally known) had a much more even and businesslike temperament than Joseph. He was initially sent to Paris to train as an architect. However, after the sudden and unexpected death of Raymond in 1772, he was recalled to Annonay to run the family business (no serious consideration was given to the elder Joseph in this role, given his uneven behaviour.) In the subsequent 10 years, Étienne applied his talent for technical innovation to the family business (papermaking was a high tech industry in the 18th century.) He suceeded in incorporating the latest innovations of the day into the family mills. His work led to recogonition by the government of France as well as the awarding of a government grant to establish the Montgolfier factory as a model for other French papermakers.

Initial experiments

Of the two brothers, it was Joseph who first contemplated building flying machines.

There is no definitive account of when Joseph first started contemplating lighter-than-air flight. Some accounts put it as early as 1777 when Joseph observed laundry drying over a fire incidentally form pockets that billowed upwards.

Joseph made his first definitive experiments in November of 1782 while living in Avignon. He reported, some years later, that he was watching a fire one evening while contemplating one of the great military issues of the day -- an assault on the fortress of Gibralter, which had proved impregnable by both sea and land. Joseph mused on the possiblity of an air assault using troops lifted by the same force that was lifting the embers from the fire.

As a result of these musing, Joseph set about building a box-like chamber (3 foot by 3 foot by 4 foot) out of very thin wood and covering the sides and top with lightweight taffeta cloth. Under the bottom of the box he crumpled and lit some paper. The contraption quickly lifted off its stand and colided with the ceiling.

Joseph then recruited his brother to balloon building by writing the prophetic words: "Get in a supply of taffeta and of cordage, quickly, and you will see one of the most astonishing sights in the world." From that point forward, the brothers worked as a team.

Early in next month, December 1782, Joseph repeated his experiment out of doors in a garden near the family homestead with his entire family as witness. On this ocassion, the box-like balloon lifted to some 70 feet in the air and remained aloft for a full minute.

The two brother then set about building a contraption 3 times larger in scale (9 times larger in volume). The lifting force was so great that they lost control of their craft on its very first test flight on December 14, 1782. The device floated nearly 2 kilometers (about 1.5 miles). It was destroyed after landing by, what Etienne later called, the "indiscretion" of passersby.

Public demonstrations

Given these initial successes, the brothers decided to make a public demonstration of a balloon in order to establish their claim to its invention.

constructed globe-shaped balloon (there are no reports as to whether the balloon was plain or decorated) of sackcloth with three thin layers of paper inside. The envelope could contain nearly 28,000 cubic feet of air and weighed 500 lbs. It was constructed of 4 pieces (the dome and 3 lateral bands) held together by some 1,800 buttons. A reinforcing "fish net" of cord covered the outside of the envelope.

On June 4, 1783 (many sources incorrectly fix the date as June 5), they flew this craft as their first public demonstration

Human flight

With the successful demostration at Versailles, and again in collaboration with Réveillon, Etienne started construction of a 60,000 cubic foot balloon for the purpose of making flights with humans. The balloon was once again decorated with flourishes and was 75 feet tall and 46 feet in diameter.

The balloon was tested in tethered flights later in 1783 on October 15, 17, and 19. At different times, Etienne and Pilâtre de Rozier on board. On occasion, these tethered flights reached the limits of the 324 foot long retaining ropes.

On November 21, 1783, the first free flight by humans was made by Pilâtre de Rozier and the marquis d'Arlandes, who flew aloft for 25 minutes about 100 metres above Paris for a distance of nine kilometres. The flight began in the courtyard of the château de la Muette in the western outskirts of Paris and landed between the windmills on the Butt-aus-Cailles. Enough fuel remained on board at the end of the flight to have allowed the balloon to fly four to five times as far. However, burning embers from the fire were scrotching the balloon fabric and had to be daubed out with sponges. Thus the pilots decided to land as soon as they were over open contryside.

The ascensions made a sensation. Numerous engravings commemorated the events. Chairs were designed with balloon backs, and mantel clocks were produced in enamel and gilt-bronze replicas set with a dial in the balloon.

Following years

Only one of the brothers (which one is unknown) ever flew in a balloon himself, and then only once.

In 1766, the British scientist Henry Cavendish had discovered hydrogen gas, by adding sulphuric acid to iron, tin, zinc shavings. The development of gas balloons proceeded almost in parallel with the work of the Montgolfiers. This work was led by Messr. Charles. Work on each type of balloon was spurred on by the knowledge that there was a competing group and alternative technology.

For a variety of reasons, including the fact that the French government chose to put a proponent of hydrogen in charge of balloon development, hot air balloons were superseded by hydrogen gas balloons.

Hydrogen balloons became the predominent technology for the next 180 years. They were used for all major ballooning accomplishments such as the crossing of the English Channel on January 7, 1785, by Jean-Pierre Blanchard and John Jeffries.

Revival of the hot air balloon

Balloons using heated air rather than lighter-than-air gasses did not return until the 1960s, when Ed Yost improved the safety of the classic Montgolfier design by using ripstop nylon for the envelope and propane gas as the burner fuel.

External links

• "Lighter than air: the Montgolfier brothers"
• "Balloons and the Montgolfier brothers"
• "Karl Friedrich Meerwein"