power-driven Aviation. Future designers would avoid placing the petrol engine so near the flammable hydrogen balloon.
Austrian engineer David Schwarz was also attempting to harness the petrol engine to an airship, which was highly unusual and ahead of its time in being made of sheet aluminum, an eight thousandth of an inch thick, which was supported internally by an aluminum frame braced with wires (Fig, 3). The airship was 47.5 m long and had a capacity of 3,700 m³. Power was provided by a 12-hp Daimler engine, driving four propellers, two of which were for steering and the remaining other two for propulsion. Schwarz’s mechanic had the dubious honor of testing his employer’s novel brainchild. The airship made its maiden voyage from Tempelhof, Berlin, on November 3, 1897. It did several successful circles, but then started to descend rapidly before it struck the ground and broke up. This time, the pilot was able to walk away, without any bruises,
The Balloon Brésil was the first aircraft designed and built by Santos-Dumont and was ahead of its time. Instead of Chinese silk, he employed in its construction the Japanese one (Santos-Dumont, 1904). This resulted in a much smaller and lighter balloon compared to the existing ones with the same payload. The common sense at that time advised the use of Chinese silk, but Santos-Dumont correctly calculated that Japanese silk would enable a lighter balloon.
After his brief experiments with balloons, Alberto Santos-Dumont released his first dirigible in 1898, one year after David Schwarz’s crash. He christened it Santos-Dumont number1 (Fig, 4). It was made of lightweight Japanese silk, had a capacity of 186 m³, and was powered by a 3.5-hp internal combustion engine. Similar to many other Santos-Dumont designs, the number 1 was no bigger than was strictly necessary to lift its pilot. Santos-Dumont did not even have room to sit down in the tiny wicker basket. After a takeoff attempt, Dumont’s number 1 crashed on September 18, 1898 (Santos-Dumont, 1904). The airship hit the trees of Jardin D’Acclimatation in Bois de Boulogne and was extensively damaged. Santos-Dumont repaired it and took off again a couple of days later. Using the incidence-changing mechanism he had designed, he was able to reach a 400 m height. At the highest altitude attained by Santos-Dumont, the pressure drop accounted by hydrogen leakage, which was caused by the porosity of the hull, could not be compensated by Dumont’s mechanism anymore. The graceful dirigible was out of control and began to fall. With serenity and self-control, Dumont shouted out for some boys below to catch the hanging rope and maneuvered the airship against the wind (Santos-Dumont, 1904). The landing was then almost perfect.
In May 1889, number 2 (Fig. 4) was ready to flight. Santos-Dumont’s second airship was strongly based on the number 1 configuration. Despite the rain, windy weather and low temperature, he decided to fly. Short after takeoff the airship hit some trees and broke into two pieces. Winds then threw the airship against the trees.
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On November 13, 1889, Santos-Dumont finally performed a controlled flight with the number 3 airship (Fig. 4), which was lifted by hydrogen and powered by an internal combustion engine. The determined Brazilian modified his design to prevent envelope failure. In this time, a long sausage shape was rejected in favor of an elliptical envelope, similar to the one Giffard and his friend Tissandier (Fig. 4) had used long before. Since it was thicker in the middle of its length, it was unable to fold up on itself. The number 3 was the first successful aircraft to be propelled by an internal combustion engine. Besides hydrogen, Santos-Dumont also considered to employ illumination gas for lifting the number 3 airship. The main idea behind this was to design a low-cost aircraft, which could be easily manufactured to be employed as a general transportation.
Henri Deutsch de la Meurthe established the Deutsch de la Meurthe Prize of 100 000 fraces (US$ 20 000, in 1901 dollar) in 1900 to grant the first person to fly around the Eiffel Tower, leaving from and returning to the Saint Cloud field within 30 minutes. The entire city of Paris watched as Santos-Dumont performed his aviation milestone in October 1901, piloting his airship number 6 (Fig. 5).
