相关题目
Aircraft control systems are classified as primary and secondary. The primary control systems consist of those which are necessary for the safe flight of an aircraft, such as ailerons, elevator and rudder. Secondary control systems improve the performance feature of the aircraft or reduce the control forces by the pilots. Examples of secondary control systems are wing flaps and trim systems.The ailerons are located on the outboard trailing edges of both wings and are used to ro tate the aircraft around the longitudinal or roll axis. These surfaces move in opposite direc tions from each other and are controlled by rotation of the control wheel. When the control wheel is rotated to the left, the right aileron moves down and the left aileron moves up. This causes the airplane to roll to the left. When the control wheel is turned to the right, and op posite aileron movement results and the airplane rolls to the right.The pitch motion around the lateral or pitch axis is controlled by elevator moved by fore and aft movement of the control wheel. A change in position of the elevators modifies the camber of the airfoil which increases or decreases lift. When the pilot wants to raise the air craft nose, back pressure is applied on the control wheel. This moves the elevator up, result ing in a negative angle of attack. This causes the tail to move down and the nose of the air craft to move up. The rudder moves the aircraft about the vertical, or yaw axis resulting in a motion known as yaw. The movement of the rudder is to the left or to the right and is con trolled by the movement of the rudder pedal in the cockpit. Pressure applied to the right rud der pedal displaces the rudder to the right. This increases the camber on the left side of the vertical tail surface, creating a low pressure area on the left and a high pressure area on the right side. The resulting pressures cause the tail to move left and the nose of the aircraft to move right. Applying pressure to the left rudder pedal provides an opposite reaction. The rudder is used in conjunction with the ailerons to coordinate turns.1.The primary control systems include （ ） ．
Domestic airline passengers will be able to make phone calls and send e-mails from the sky from next year, a local carrier has said.Shenzhen Airlines said on Monday it has signed an agreement with Geneva-based On-Air to provide passengers with in-flight communications services on all its planes by the end of 2009. The service will be introduced on three aircraft ahead of the 2008 Olympics, on two routes——from Shenzhen to Beijing and Shenzhen to Shanghai, the airline said.Passengers will be able to use their own electronic devices to send e-mails and short messages, make calls and surf the Internet, it said. The service is expected to be of particular interest to business travelers.According to a survey at the end of last year, China had 4.55 million mobile-phone subscribers. Ninety-three percent of those polled said they wished they could send and receive e-mails and messages while on a plane.Despite the introduction of the new service, passengers will still be prevented from using their cell phones and laptops when the plane is taking off and landing, or flying at less than 3,000m above sea level, the official said.The official said the new service would not lead to an increase in ticket prices, but users of Chinese mobile-phone services will be charged the international roaming rate for any calls made from the sky.Shenzhen Airlines is the first Chinese carrier to provide such in-flight communications services. Its president, Li Kun, said installing the facilities will cost 4.5 million yuan ($596,000) per aircraft. However, the project still needs to be approved by the Civil Aviation Administration of China, a source said.5.Which is the first Chinese carrier to provide in-flight communications services?
Domestic airline passengers will be able to make phone calls and send e-mails from the sky from next year, a local carrier has said.Shenzhen Airlines said on Monday it has signed an agreement with Geneva-based On-Air to provide passengers with in-flight communications services on all its planes by the end of 2009. The service will be introduced on three aircraft ahead of the 2008 Olympics, on two routes——from Shenzhen to Beijing and Shenzhen to Shanghai, the airline said.Passengers will be able to use their own electronic devices to send e-mails and short messages, make calls and surf the Internet, it said. The service is expected to be of particular interest to business travelers.According to a survey at the end of last year, China had 4.55 million mobile-phone subscribers. Ninety-three percent of those polled said they wished they could send and receive e-mails and messages while on a plane.Despite the introduction of the new service, passengers will still be prevented from using their cell phones and laptops when the plane is taking off and landing, or flying at less than 3,000m above sea level, the official said.The official said the new service would not lead to an increase in ticket prices, but users of Chinese mobile-phone services will be charged the international roaming rate for any calls made from the sky.Shenzhen Airlines is the first Chinese carrier to provide such in-flight communications services. Its president, Li Kun, said installing the facilities will cost 4.5 million yuan ($596,000) per aircraft. However, the project still needs to be approved by the Civil Aviation Administration of China, a source said.4.It can be inferred that the new service will probably cause （ ）.
Domestic airline passengers will be able to make phone calls and send e-mails from the sky from next year, a local carrier has said.Shenzhen Airlines said on Monday it has signed an agreement with Geneva-based On-Air to provide passengers with in-flight communications services on all its planes by the end of 2009. The service will be introduced on three aircraft ahead of the 2008 Olympics, on two routes——from Shenzhen to Beijing and Shenzhen to Shanghai, the airline said.Passengers will be able to use their own electronic devices to send e-mails and short messages, make calls and surf the Internet, it said. The service is expected to be of particular interest to business travelers.According to a survey at the end of last year, China had 4.55 million mobile-phone subscribers. Ninety-three percent of those polled said they wished they could send and receive e-mails and messages while on a plane.Despite the introduction of the new service, passengers will still be prevented from using their cell phones and laptops when the plane is taking off and landing, or flying at less than 3,000m above sea level, the official said.The official said the new service would not lead to an increase in ticket prices, but users of Chinese mobile-phone services will be charged the international roaming rate for any calls made from the sky.Shenzhen Airlines is the first Chinese carrier to provide such in-flight communications services. Its president, Li Kun, said installing the facilities will cost 4.5 million yuan ($596,000) per aircraft. However, the project still needs to be approved by the Civil Aviation Administration of China, a source said.3.Passengers will still be prevented from using their cell phones in the following situations except（ ）.
Domestic airline passengers will be able to make phone calls and send e-mails from the sky from next year, a local carrier has said.Shenzhen Airlines said on Monday it has signed an agreement with Geneva-based On-Air to provide passengers with in-flight communications services on all its planes by the end of 2009. The service will be introduced on three aircraft ahead of the 2008 Olympics, on two routes——from Shenzhen to Beijing and Shenzhen to Shanghai, the airline said.Passengers will be able to use their own electronic devices to send e-mails and short messages, make calls and surf the Internet, it said. The service is expected to be of particular interest to business travelers.According to a survey at the end of last year, China had 4.55 million mobile-phone subscribers. Ninety-three percent of those polled said they wished they could send and receive e-mails and messages while on a plane.Despite the introduction of the new service, passengers will still be prevented from using their cell phones and laptops when the plane is taking off and landing, or flying at less than 3,000m above sea level, the official said.The official said the new service would not lead to an increase in ticket prices, but users of Chinese mobile-phone services will be charged the international roaming rate for any calls made from the sky.Shenzhen Airlines is the first Chinese carrier to provide such in-flight communications services. Its president, Li Kun, said installing the facilities will cost 4.5 million yuan ($596,000) per aircraft. However, the project still needs to be approved by the Civil Aviation Administration of China, a source said.2.We can learn that the new service will be introduced（ ）.
Domestic airline passengers will be able to make phone calls and send e-mails from the sky from next year, a local carrier has said.Shenzhen Airlines said on Monday it has signed an agreement with Geneva-based On-Air to provide passengers with in-flight communications services on all its planes by the end of 2009. The service will be introduced on three aircraft ahead of the 2008 Olympics, on two routes——from Shenzhen to Beijing and Shenzhen to Shanghai, the airline said.Passengers will be able to use their own electronic devices to send e-mails and short messages, make calls and surf the Internet, it said. The service is expected to be of particular interest to business travelers.According to a survey at the end of last year, China had 4.55 million mobile-phone subscribers. Ninety-three percent of those polled said they wished they could send and receive e-mails and messages while on a plane.Despite the introduction of the new service, passengers will still be prevented from using their cell phones and laptops when the plane is taking off and landing, or flying at less than 3,000m above sea level, the official said.The official said the new service would not lead to an increase in ticket prices, but users of Chinese mobile-phone services will be charged the international roaming rate for any calls made from the sky.Shenzhen Airlines is the first Chinese carrier to provide such in-flight communications services. Its president, Li Kun, said installing the facilities will cost 4.5 million yuan ($596,000) per aircraft. However, the project still needs to be approved by the Civil Aviation Administration of China, a source said.1.According to the report, passengers can（ ）on the plane by the end of 2009.
We have mentioned that at any point in the atmosphere, pressure is the weight of the air above that point. Since pressure is the weight of the air above, and since less and less air lies above a point as it moves upward through the atmosphere, pressure must decrease with increasing altitude. The greater pressure at low altitude compresses the air more than does the lesser pressure at higher altitude. Therefore, the rate of decrease (lapse rate) in pressure with height becomes less with increasing altitude. For example, from sea level to 1000ft, pressure drops about one inch of mercury; but from 19000 to 20000ft, pressure drops only about six-tenths of an inch. The rate of decrease of pressure with height, however, is not always constant. Like most substances, air contracts as it cools and expands as it becomes warmer. Therefore, when a sample of air cools, it occupies less space; when heated, it occupies more. As a result, the rate of pressure decrease with height in cold air is greater than in warm air.Since air is a gas, it may be compressed or permitted to expand. when air is compressed, a given volume contains more air, hence its density, or weight, is increased. Conversely, when air is permitted to expand, a given volume contains less air, thus its density, or weight, is decreased. Heat is a property of all matter. From early studies of science, we learned that heat is the motion of molecules. Heat is then defined as the total energy of motion of molecules. We also learned that dense air has more molecules than less dense air. The two might have the same average motion, and thus have the same temperature, but the total energy, and consequently the degree of heat is greater in the dense air with more molecules. We cannot measure heat directly, but we can measure temperature with the thermometer. 5.If the temperature is the same, the total energy of dense air is （ ） that of less dense air.
We have mentioned that at any point in the atmosphere, pressure is the weight of the air above that point. Since pressure is the weight of the air above, and since less and less air lies above a point as it moves upward through the atmosphere, pressure must decrease with increasing altitude. The greater pressure at low altitude compresses the air more than does the lesser pressure at higher altitude. Therefore, the rate of decrease (lapse rate) in pressure with height becomes less with increasing altitude. For example, from sea level to 1000ft, pressure drops about one inch of mercury; but from 19000 to 20000ft, pressure drops only about six-tenths of an inch. The rate of decrease of pressure with height, however, is not always constant. Like most substances, air contracts as it cools and expands as it becomes warmer. Therefore, when a sample of air cools, it occupies less space; when heated, it occupies more. As a result, the rate of pressure decrease with height in cold air is greater than in warm air.Since air is a gas, it may be compressed or permitted to expand. when air is compressed, a given volume contains more air, hence its density, or weight, is increased. Conversely, when air is permitted to expand, a given volume contains less air, thus its density, or weight, is decreased. Heat is a property of all matter. From early studies of science, we learned that heat is the motion of molecules. Heat is then defined as the total energy of motion of molecules. We also learned that dense air has more molecules than less dense air. The two might have the same average motion, and thus have the same temperature, but the total energy, and consequently the degree of heat is greater in the dense air with more molecules. We cannot measure heat directly, but we can measure temperature with the thermometer. 4.When air is compressed, a given volume contains （ ） when air is not compressed.
We have mentioned that at any point in the atmosphere, pressure is the weight of the air above that point. Since pressure is the weight of the air above, and since less and less air lies above a point as it moves upward through the atmosphere, pressure must decrease with increasing altitude. The greater pressure at low altitude compresses the air more than does the lesser pressure at higher altitude. Therefore, the rate of decrease (lapse rate) in pressure with height becomes less with increasing altitude. For example, from sea level to 1000ft, pressure drops about one inch of mercury; but from 19000 to 20000ft, pressure drops only about six-tenths of an inch. The rate of decrease of pressure with height, however, is not always constant. Like most substances, air contracts as it cools and expands as it becomes warmer. Therefore, when a sample of air cools, it occupies less space; when heated, it occupies more. As a result, the rate of pressure decrease with height in cold air is greater than in warm air.Since air is a gas, it may be compressed or permitted to expand. when air is compressed, a given volume contains more air, hence its density, or weight, is increased. Conversely, when air is permitted to expand, a given volume contains less air, thus its density, or weight, is decreased. Heat is a property of all matter. From early studies of science, we learned that heat is the motion of molecules. Heat is then defined as the total energy of motion of molecules. We also learned that dense air has more molecules than less dense air. The two might have the same average motion, and thus have the same temperature, but the total energy, and consequently the degree of heat is greater in the dense air with more molecules. We cannot measure heat directly, but we can measure temperature with the thermometer. 3.The lapse rate of pressure in warm air is （ ） in cold air.
We have mentioned that at any point in the atmosphere, pressure is the weight of the air above that point. Since pressure is the weight of the air above, and since less and less air lies above a point as it moves upward through the atmosphere, pressure must decrease with increasing altitude. The greater pressure at low altitude compresses the air more than does the lesser pressure at higher altitude. Therefore, the rate of decrease (lapse rate) in pressure with height becomes less with increasing altitude. For example, from sea level to 1000ft, pressure drops about one inch of mercury; but from 19000 to 20000ft, pressure drops only about six-tenths of an inch. The rate of decrease of pressure with height, however, is not always constant. Like most substances, air contracts as it cools and expands as it becomes warmer. Therefore, when a sample of air cools, it occupies less space; when heated, it occupies more. As a result, the rate of pressure decrease with height in cold air is greater than in warm air.Since air is a gas, it may be compressed or permitted to expand. when air is compressed, a given volume contains more air, hence its density, or weight, is increased. Conversely, when air is permitted to expand, a given volume contains less air, thus its density, or weight, is decreased. Heat is a property of all matter. From early studies of science, we learned that heat is the motion of molecules. Heat is then defined as the total energy of motion of molecules. We also learned that dense air has more molecules than less dense air. The two might have the same average motion, and thus have the same temperature, but the total energy, and consequently the degree of heat is greater in the dense air with more molecules. We cannot measure heat directly, but we can measure temperature with the thermometer. 2.The lapse rate of pressure （ ） with decreasing altitude.
