The development of the rudder was one of the most important sea navigational inventions that have ever been invented. Before the twelfth century in northern Europe, ships were steered by a quarter-rudder mounted on the stern side of the vessel. Up until the fourteenth century the use of the quarter rudder persisted in the Mediterranean. Two quarter-mounted steering oars were used. By age of exploration, the pintle-and-gudgeon rudder, hung from the sternpost had replaced quarter-rudder. The rudder brought great changes to the world. The voyages of Christopher Columbus may have never occurred if the Chinese had not of invented the rudder in first century AD.
The action of a rudder is basically very simple, The passage of the ship through the water causes water to flow past the rudder, and the angle at which the rudder is inclined to the direction of the flow is called the angle of attack. The steering action is dependent on the pressure distribution between the two hydrodynamic surfaces of the rudder. The pressure on the downstream side is less than the static pressure of the surrounding water while the pressure on the upstream side is greater. The result of this is an out ward force on the downstream side of the rudder, and this can be regarded as being made up of a list force at right angles to the direction of flow, and a drag force directly opposing the direction of flow. The variation of the lift and drag forces for different angles of attack is extremely important in rudder design as it is the lift forces which creates the turning effect. At a certain angle of attack, called the critical angle, the rudder stalls: a phenomenon called burbling occurs and the rudder force is suddenly reduced.
The Essay on Magnetic Fields And Magnetic Force
1. What happens to the distribution of magnetic flux lines when the iron ring was placed in between the U-magnets? The distribution of magnetic flux lines when the iron ring is placed in between the magnets, the iron ring is included in the distribution of flux lines. Instead of connecting to the other pole, the ring affects its distribution and some of it is attracted to the iron ring. 2. How ...
Burbling is caused by a breakdown in the streamlined flow, on the downstream side of the rudder there is a swirling irregular eddying flow. Rudders on merchant vessels are normally expected to operate up to an angle of 35 degrees from the centerline to port or starboard. When a ships rudder is turned the ship first moves a small distance sideways in the opposite direction to the turn that was intended then moves around a circular path until it eventually faces the opposite direction. The distance moved forward from the point at which the ship is at right angles to its original direction is called advance. Transfer is the sideways distance between these two points, and the diameter of the circular path followed by the ship is called the tactical diameter. During the turn the bow of the vessel lies always inside the turning curve, so that a drift angle is formed between the centerline of the vessel and the tangent to the turning curve.
The tactical diameter is a measure of the ability of the rudder to turn the vessel. It is important for warships, because they frequently execute complicated turning maneuvers. With a simple rudder arranged to turn around the edge nearest the ship, the force produced by the rudder will act to return the rudder to the straight-ahead position. To avoid excessive steering forces a balanced rudder arrangement is employed with the turning axis being positioned some way along the rudder near to the center of pressure of the center of pressure of the turning forces. The earliest rudder in China was a balanced rudder. This means that part of the blade projected in front of the post.
These rudders were easier to use, but Europeans did not adopt them until the nineteenth century. One of the earliest ships to use such a rudder was the Great Britain of 1843. The British were in the forefront when it came to adopting Chinese inventions for naval use, with this as well as the square-pallet chain pump as a bilge pump and water tight compartments in hulls. It is no exaggeration to say that the superiority of the British Navy was to a large extent due to its readiness to adopt Chinese invention more rapidly than other European powers. Chinese seagoing rudders grew to many times the size of a man. Huge ships with enormous rudders were used on the Chinese voyages of discovery, which proceeded the European ones. The Chinese sailed round the cape Good Hope in the opposite direction to that taken by the Europeans and at an earlier time.
The Essay on Story Of A Chinese Immigrant
After 12 hours of hard labor work, Wong is exhausted and was fast asleep right after he finish every other mine workers laundry. Wong is a Chinese immigrant from China. Back in China he was a farmer peasant, who works 13 hours a day to earn some food for his family. But 13 hours of work was not enough, the crops that he grew is only enough to pay the debt for the land lords, he did not have any ...
They were also the first to discover Australia; landing at the site now called Port Darwin. Chinese trade with the Philippines and Indonesia was common; and trade with the eastern coast of Africa was so extensive that pieces of broken Chinese porcelain are to be found scattered all up and down the beaches of Tanzania and Mozambique, data back for centuries. The Chinese also made voyages to the American continents, though it is questionable whether they were return voyages. Many Asian influences have been identified in ancient America by Needham and others. But the Chinese who arrived were quite possibly stranded, unable to return home, owing to the greater difficulty of sailing westward across the Pacific. Another traditional Chinese invention was the fenestrated rudder, which is simply a rudder with holes made in it. The Chinese soon discovered that while easing the task of turning the rudder through the water, the holes did not appreciably lower its steering function.
Until that time, a coal-fired torpedo boat traveling at 30 knots was unable to turn its rudder at speed. Fenestration made this possible. A Chinese boat called Hangchow Bay freighter had a rudder and tiller. The rudder was balanced, meaning it curves round somewhat in the front of the post. This rudder is also slung by a tackle; it can be raised or lowered by the hoisting windlass. It is possible to pull the rudder entirely up above water level and pass over shallows without damaging the rudder. Until Europeans adopted the rudder from the Chinese, Western ships had to make do with steering oars.
If you steer with oars then this meant that long voyages of discovery by Europeans were impossible. The famous voyages of Christopher Columbus, Vasco da Gama, and others of their time were only made possible by the adoption of Chinese nautical technology. The oldest Western evidence for rudders is found in church carvings of about the year 1180. This is within a few years of the first European evidence for the ships compass. Rudders and compasses seem to have reached Europe at about the same time, since they were so closely associated. It could probably be safely said that the Chinese were the greatest sailors in history.
The Essay on Chinese Exclusion Act European Jews
Chinese Exclusion Act Be it enacted, That from and after the expiration of ninety days next after the passage of this act, and until the expiration of ten years next after the passage of this act, the coming of Chinese laborers to the United States be, Suspended; and During such suspension it shall not be lawful for any Chinese Laborer to come, or, having so come after the expiration of Said ...
For nearly two millennia they had ships and sailing techniques so far in advance of the world that comparisons are embarrassing. When the West finally did catch up with them, it was only by adopting their inventions in one way or another. For most of history, Europeans used ships, which were drastically inferior to Chinese ships in every respect imaginable. They had no rudder, no leeboards, no watertight compartments, single masts, and square sails, which left them at the mercy of the winds to an extent which today we would consider ludicrous. This continued to be the case even into the nineteenth century. As Needham says: As late as 1800 they sometimes had to wait as long as three months at Hamoaze in order to get into Plymouth Sound, and this was long after the introduction of a lateen sail on the mizzen mast. When Europeans eventually made their way to China and saw the way to China and saw the Chinese ships, with their many mast and their fore-and aft rigs, they were really impressed. The first attempt to copy what they saw was the adoption in Europe of multiple masts on ships, with square sails on the fore masts but a fore-and aft rig for the mizzen mast at the rear of the ship.
Since the Arab lateen sail was ready to hand, it was the lateen, which was fitted to the mizzen of the European three-masters commencing about 1304, not long after Marco Polos time in China. But the idea was slow to be assimilated, and only a couple of centuries later did such ships really come into their own. In1492 Christopher Columbus sailed in such a ship to America. All the Western three masters of the sixteenth and seventeenth centuries carried lateen sails aft. After that, the more efficient gaft sail replaced the lateen on the mizzen mast of a typical European ship. The actual Chinese lug sail did not apparently make an appearance in Europe before the sixteenth century in the sixteenth century in the Adriatic.
Certain traditional Venetain boats with lug sails appear to be direct copies of Chinese vessels in other respects as well, having rerly flat bottoms and enormous Chinese-style rudders. After an interval of least thirteen hundred years, Europeans thus adopted Chinese concepts of rigging. In every way, whether for navigation, propulsion, or steering, Europeans were dependent upon Chinese ideas in order to be capable of the Great Voyages of Discovery. The Great colonial powers of the West, the Portuguese, British, French, and other Empires, were the direct result of the adoption by Europeans of Chinese technology on the high seas.
The Essay on Qing China And Tokugawa Japan Respond To The Coming Of The Europeans
How did Qing China and Tokugawa Japan respond to the coming of the Europeans, and what explains the differences? What impact did European contacts have on these two East Asian civilizations through the end of the eighteenth century? China under the Ming and early Qing dynasties reached its cultural peak and was much admired by its neighbors as well as Europeans. The Tokugawa shogunate in Japan ...
