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Legal requirements. The 1968 Vienna Convention on Road Traffic of the United Nations considers a bicycle to be a vehicle, and a person controlling a bicycle is considered a driver. The traffic codes of many countries reflect these definitions and demand that a bicycle satisfy certain legal requirements, sometimes even including licensing, before it can be used on public roads. In many jurisdictions it is an offence to use a bicycle that is not in roadworthy condition. In most jurisdictions, bicycles must have functioning front and rear lights when ridden after dark. As some generator or dynamo-driven lamps only operate while moving, rear reflectors are frequently also mandatory. Since a moving bicycle makes little noise, some countries insist that bicycles have a warning bell for use when approaching pedestrians, equestrians and other bicyclists. Wright brothers
"For some years I have been afflicted with the belief that flight is possible to man." "It is possible to fly without motors, but not without knowledge and skill." (photo: 1905) The Wright brothers, Orville (August 19, 1871 – January 30, 1948) and Wilbur (April 16, 1867 – May 30, 1912), were two Americans who are generally credited[1] with inventing and building the world's first successful airplane and making the first controlled, powered and sustained heavier-than-air human flight on December 17, 1903. In the two years afterward, they developed their flying machine into the first practical fixed-wing aircraft. Although not the first to build and fly experimental aircraft, the Wright brothers were the first to invent aircraft controls that made mechanical fixed wing flight possible. The brothers' fundamental breakthrough was their invention of "three axis-control", which enabled the pilot to steer the aircraft effectively and to maintain its equilibrium.[2] This method became standard on fixed wing aircraft of all kinds.[3] From the beginning of their aeronautical work, the Wright brothers focused on unlocking the secrets of control to conquer "the flying problem", rather than developing more powerful engines as some other experimenters did. Their careful wind tunnel tests produced better aeronautical data than any before, enabling them to design and build wings and propellers more effective than any before.[4] Their U.S. patent 821,393 claims the invention of a system of aerodynamic control that manipulates a flying machine's surfaces.[5] They gained the mechanical skills essential for their success by working for years in their shop with printing presses, bicycles, motors, and other machinery. Their work with bicycles in particular influenced their belief that an unstable vehicle like a flying machine could be controlled and balanced with practice.[6] The Wright brothers' status as inventors of the airplane has been subject to counter-claims by various parties. Much controversy persists over the many competing claims of early aviators. |
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