The Origin of Human Flight

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The Origin of Human Flight

Overview

For centuries humans dreamed of flying. The ancient Greek myth of Icarus, killed attempting to fly when the wax on his artificial wings melted, was an early expression of this desire. This myth also reflected the realization that human flight would be difficult, perhaps impossible. Yet the dream persisted. Writers who speculated about future societies often included controlled human flight in their utopian fiction. Cyrano de Bergerac (1619-1655) described interplanetary journeys in several of his stories, while Jonathan Swift (1667-1745) made a huge flying island the focus of the third voyage in Gulliver's Travels. Medieval and renaissance scholars Roger Bacon (1220?-1292) and Leonardo da Vinci (1452-1519) speculated on the possibility of human flight. Da Vinci even designed a heavier-than-air machine and a parachute. But human flight remained unachieved until 1783.

Background

By the seventeenth century, scientists realized the earth was surrounded by heavy gas. They assumed that this ocean of air could be navigated, just as ships sailed across water. Various devices were invented to achieve flight, such as artificial wings and crafts relying on muscle power. The repeated failures of these devices led to investigations of lighter-than-air balloons. This decision now seems mistaken, since heavier-than-air craft are clearly superior to lighter-than-air vessels in terms of carrying capacity and control. But the paucity of aerodynamic knowledge and the lack of an adequate engine gave eighteenth-century inventors no choice in the matter.

Three developments in the eighteenth century made human flight possible. The first was when the English scientist Henry Cavendish (1731-1810) discovered hydrogen in 1766. He found that iron placed in a dilute solution of sulfuric acid produced a gas fourteen times lighter than air. Because it was so combustible, it was called "inflammable air." One problem of using hydrogen in terms of flight was that it easily seeped through cloth and so apparently could not be contained in lightweight materials. It was also expensive to make on a large scale and it was very dangerous; a spark of static electricity could set it on fire.

The second eighteenth-century condition that led to human flight was not scientific, but rather social in nature. Middle-class men began taking a great interest in science. In part, this was a result of the growing application of science to the industries owned by the middle classes. Interest in science was also an indication of higher social status. Pursuing scientific experiments, even as a dilettante, was evidence that an individual possessed the leisure time and income necessary for such pursuits. It was no accident that the men most responsible for the early development of human flight were middle-class scientific amateurs.

A final factor leading to successful human flight was the influence of the enlightenment, an eighteenth-century intellectual movement based on the belief that if reason and scientific inquiry were applied to physical and social conditions, the laws governing those conditions could be discovered. Following these laws would lead to unlimited progress. This faith in progress was very strong in France, especially after the publication of Denis Diderot's (1713-1784) Encyclopédie, a summary of the scientific and technological advances of the century. It created an optimistic belief that the riddle of human flight could be solved.

Impact

The first major step toward human flight occurred on June 4, 1783, when Joseph (1740-1810) and Etienne (1745-1799) Montgolfier made a public scientific demonstration in the main square of Annonay, a small town in southern France near Lyon. They inflated a 35-foot (10.7-m) paper-covered cloth globe, which floated upward about 6,000 feet (1,829 m) and landed a mile and a half (2.4 km) away. Although it carried no passengers, the Montgolfiers had succeeded in achieving the first large-scale balloon voyage in history, bringing human flight much closer to reality.

The Montgolfier brothers were middle-class businessmen, not scientists. Their father was a wealthy paper manufacturer who supported his sons' scientific dabblings. They became interested in the problems of flight in 1782. Their experiments with silk and paper models led them to conclude that hydrogen could not be contained long enough to permit flight. But they did discover that heated air became sufficiently rarefied (less dense) to lift a balloon and it did not diffuse through its cover. They erroneously believed that the smoke of the fire, not the heated air, provided the lifting power and spent weeks experimenting with different types of fuel to get the "ideal smoke," eventually settling on a mixture of wet straw and wool. So two scientific amateurs had inadvertently provided a solution to the problem of lifting a heavy craft off the ground for an extended period of time.

The Montgolfiers immediately notified the scientific establishment of their success and Etienne went to Paris seeking a grant to cover their expenses. The family also hoped their fame would result in lucrative government contracts for their paper business. News of their success galvanized the capital. A popular science lecturer, Jacques-Alexandre-César Charles (1746-1823) decided to compete with the Montgolfiers in an effort to be the first to achieve human flight. Assisted by two clever instrument makers, the brothers A.J. and M.N. Robert, Charles set out to make a workable hydrogen balloon.

Charles and the Roberts succeeded in making enough hydrogen for an unmanned flight from Paris on August 27, 1783, although they needed half a ton of iron filings, a quarter of a ton of acid, and several days to do so. They also managed to make a leak-proof sack of taffeta covered with a rubberized paint to hold the gas. Charles's other contributions to the development of hydrogen balloons are equally important: the valve line to release gas allowing immediate descent (in a hot air balloon, descent occurs only when the air cools); the "appendix" (an opening through which gas expanding at higher altitudes can automatically escape before bursting the balloon); the use of bags of sand for ballast and of a grapnel (anchor) to aid in landing; the "nacelle" or gondola (a wicker basket suspended beneath the balloon).

A few weeks later, Etienne Montgolfier launched a hot air balloon from Versailles with Louis XVI and his court in attendance. It carried aloft a rooster, duck, and sheep and all three survived, making human flight the next logical step. There were now two successful techniques of ascending, one physical and one chemical: a balloon utilizing the Montgolfiers' method of relying on heated air would be called a montgolfière, while a balloon using a gas different from air would be labeled a charlière. In 1783 the Montgolfiers' method was the simplest and cheapest; Etienne only needed 90 pounds (40.8 kg) of straw and wool in the Versailles flight to lift a load of 1,000 pounds (454 kg). Its disadvantages for human flight were that a montgolfière could not rise as high as a hydrogen balloon, its fire needed constant tending, and it could not descend as quickly or safely.

Etienne won the race for the first human flight in an untethered, freed balloon. On November 21, 1783, a montgolfière carrying two men ascended from the Bois de Boulogne and flew over Paris for about 20 minutes. The two passengers were Jean François Pilâtre de Rozier (1757-1785) and François Laurent, marquis d'Arlandes (1742-1809). They were the first aeronauts, and the first humans to ride freely in the air. It was d'Arlandes's only ascent; Etienne Montgolfier himself never ascended in an untethered balloon. On December 1, 1783, Charles and the older Robert brother ascended from the Tuileries in Paris in a new charlière. By now a balloon mania had seized Paris and half the population of the city turned out for the flight. Charles and Robert flew for over 2 hours and covered 25 miles (40 km). After landing, Charles took off again in history's first solo flight. He reached 10,000 feet (3,048 m) when the cold drove him back to earth. Although this was Charles's only flight, he proved that there was a height barrier to balloon flights. He also showed that hydrogen balloons were far superior in range (both distance and height) to hot air balloons. In addition, landings usually destroyed montgolfières, while the smaller and more durable charlières could be used repeatedly. As soon as cheaper and quicker means to manufacture hydrogen were developed, the montgolfières became quite scarce.

Meanwhile, Joseph Montgolfier was in Lyon constructing a monster balloon to carry multiple passengers. On January 19, 1784, he and six other men made a successful ascent, his first and last. On June 4, 1784, a Madame Thible made the first free flight by a woman when she and a male companion ascended in a montgolfière from Lyon. Another aeronautic milestone was reached on January 7, 1785, when a Frenchman named Jean Pierre Blanchard (1753-1809) flew from England to France in history's first overseas flight. Pilâtre de Rozier tried to cross the English Channel in the other direction on June 15, 1785, but his balloon caught fire and he was killed. Thus, the first man to fly was also the first to be killed in an aerial accident.

After de Rozier's death, advances in ballooning slowed considerably. Although observers from a tethered balloon helped the French win the battle of Fleurus in 1794, it was not until the American Civil War that balloon observations took on military significance. Nor were any scientific advances achieved through flight in the next half-century. The inability to control the flight direction of a balloon reduced it to purely entertainment uses throughout the early nineteenth century. No fair or civic celebration was complete without a balloon ascent, with acrobats performing dangerous stunts high above the sensation-seeking public; a parachute descent usually ended the show. After the first night ascent in Paris on June 18, 1786, fireworks set off from balloons became common (and risky because of the hydrogen). Samuel Johnson's (1709-1784) remark about balloons remained accurate: "In amusement, mere amusement, I am afraid it must end, for I do not find that its course can be directed so that it shall serve any useful purpose in communication." Even famous nineteenth-century aeronauts such as Gaston Tissandier (1843-1899) realized the future of flight lay in the development of heavier-than-air machines.

ROBERT HENDRICK