1970s Airbags become standard (Airbags, introduced in some models in the 1970s, become standard in more cars. Originally installed only on the driver's side, they begin to appear on the front passenger side as well. 1970s Fuel prices escalate, driving demand for fuel-efficient cars (Fuel prices escalate, driving a demand for fuel-efficient cars, which increases the sale of small Japanese cars. This helps elevate the Japanese automobile industry to one of the greatest in the world. 1980s Japanese popularize "just in time" delivery of auto parts (The Japanese popularize "just in time" delivery of auto parts to factory floors, thus reducing warehousing costs. They also popularize statistical process control, a method developed but not applied in the United States until the Japanese demonstrate how it improves quality.
1985 Antilock braking system (ABS) available on American cars (The Lincoln becomes the first American car to offer an antilock braking system (ABS), which is made by Teves of Germany. ABS uses computerized sensing of wheel movement and hydraulic pressure to each wheel to adjust pressure so that the wheels continue to move somewhat rather than "locking up" during emergency braking. 1985 Antilock braking system (ABS) available on American cars (The Lincoln becomes the first American car to offer an antilock braking system (ABS), which is made by Teves of Germany. ABS uses computerized sensing of wheel movement and hydraulic pressure to each wheel to adjust pressure so that the wheels continue to move somewhat rather than "locking up" during emergency braking.1992 Energy Policy Act of 1992 encourages alternative-fuel vehicles (Passage of the federal Energy Policy Act of 1992 encourages alternative- fuel vehicles. These include automobiles run with mixtures of alcohols and gasoline, with natural gas, or by some combination of conventional fuel and battery power.1997 First American carmaker offers automatic stability control (Cadillac is the first American carmaker to offer automatic stability control, increasing safety in emergency handling situations.
Not a single human being had ever flown a powered aircraft when the 20th century began. By century's end, flying had become relatively common for millions of people, and some were even flying through space. The first piloted, powered, controlled flight lasted 12 seconds and carried one man 120 feet. Today, nonstop commercial flights lasting as long as 15 hours carry hundreds of passengers halfway around the world. Not a single human being had ever flown a powered aircraft when the 20th century began. By century's end, flying had become relatively common for millions of people, and some were even flying through space. The first piloted, powered, controlled flight lasted 12 seconds and carried one man 120 feet. Today, nonstop commercial flights lasting as long as 15 hours carry hundreds of passengers halfway around the world.
The first of aviation's hurdles—getting an airplane off the ground with a human controlling it in a sustained flight—presented a number of distinct engineering problems: structural, aerodynamic, control, and propulsion. As the 19th century came to a close, researchers on both sides of the Atlantic were tinkering their way to solutions. But it was a fraternal pair of bicycle builders from Ohio who achieved the final breakthrough. The first of aviation's hurdles—getting an airplane off the ground with a human controlling it in a sustained flight—presented a number of distinct engineering problems: structural, aerodynamic, control, and propulsion. As the 19th century came to a close, researchers on both sides of the Atlantic were tinkering their way to solutions. But it was a fraternal pair of bicycle builders from Ohio who achieved the final breakthrough.Orville and Wilbur Wright learned much from the early pioneers, including Paris-born Chicago engineer Octave Chanute. In 1894, Chanute had compiled existing information on aerodynamic experiments and suggested the next steps. The brothers also benefited from the work during the 1890s of Otto Lilienthal, a German inventor who had designed and flown several different glider models. Lilienthal, and some others, had crafted wings that were curved, or cambered, on top and flat underneath, a shape that created lift by decreasing the air pressure over the top of the wing and increasing the air pressure on the bottom of the wing. By experimenting with models in a wind tunnel, the Wrights gathered more accurate data on cambered wings than the figures they inherited from Lilienthal, and then studied such factors as wing aspect ratios and wingtip shapes.
Lilienthal and others had also added horizontal surfaces behind each wing, called elevators, that controlled the glider's pitch up and down, and Lilienthal used a vertical rudder that could turn his glider right or left. But the third axis through which a glider could rotate— rolling to either left or right—remained problematic. Most experimenters of the day thought roll was something to be avoided and worked to offset it, but Wilbur Wright, the older of the brothers, disagreed. Wilbur's experience with bicycles had taught him that a controlled roll could be a good thing. Wilbur knew that when cyclists turned to the right, they also leaned to the right, in effect "rolling" the bicycle and thereby achieving an efficient, controlled turn. Wilbur realized that creating a proper turn in a flying machine would require combining the action of the rudder and some kind of roll control. While observing the flight of turkey vultures gliding on the wind, Wilbur decided that by twisting the wings—having the left wing twist upward and the right wing twist downward, or vice versa—he would be able to control the roll. He rigged a system that linked the twisting, called wing warping, to the rudder control. This coordination of control proved key. By 1902 the Wrights were flying gliders with relative ease, and a year later, having added an engine they built themselves, Orville made that historic first powered flight—on December 17, 1903.
Do'stlaringiz bilan baham:
|
