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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.
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. 1.The pressure above a point （ ） with decreasing altitude.
In addition to the important factors of proper technique, many other variables affect the landing performance of an airplane. Any item which alters the landing speed or deceleration rate during the landing roll will affect the landing distance.The effect of gross weight on landing distance is one of the principal items determining the landing distance of an airplane. One effect of an increased gross weight is that the airplane will require a greater speed to support the airplane at the landing angle of attack and lift coefficient.The minimum landing distance will vary in direct proportion to the gross weight. For example, a 10 percent increase in gross weight at landing would cause:(1) a 5 percent increase in landing velocity.(2) a 10 percent increase in landing distance.The effect of wind on landing distance is large and deserves proper consideration when predicting landing distance. Since the airplane will land at a particular airspeed independent of the wind, the principal effect of wind on landing distance is due to the change in the ground speed at which the airplane touches down. The effect of wind on deceleration during the landing is identical to the effect on acceleration during the takeoff.A headwind which is 10 percent of the landing airspeed will reduce the landing distance approximately 19 percent but a tailwind which is 10 percent of the landing speed will increase the landing distance approximately 21 percent.The effect of pressure altitude and ambient temperature is to define density altitude and its effect on landing performance. An increase in density altitude will increase landing speed but will not alter the net retarding force. Since an increase in altitude does not alter deceleration, the effect of density altitude on landing distance would actually be due to the greater TAS (true airspeed).The minimum landing distance at 5000ft would be 16 percent greater than the minimum landing distance at sea level. The approximate increase in landing distance with altitude is approximately 3 and a half percent for each 1000ft of altitude. Proper accounting of density altitude is necessary to accurately predict landing distance.The effect of proper landing speed is important when runway lengths and landing distances are critical. The landing speeds specified in the airplane’s flight handbooks is generally the minimum safe speeds at which the airplane can be landed. Any attempt to land at below the specified speed may mean that the airplane may stall, be difficult to control, or develop high rates of descent. On the other hand, an excessive speed at landing may improve the controllability slightly, but will cause an undesirable increase in landing distance.5.Landing at below minimum safe speeds may result in （ ） ．
In addition to the important factors of proper technique, many other variables affect the landing performance of an airplane. Any item which alters the landing speed or deceleration rate during the landing roll will affect the landing distance.The effect of gross weight on landing distance is one of the principal items determining the landing distance of an airplane. One effect of an increased gross weight is that the airplane will require a greater speed to support the airplane at the landing angle of attack and lift coefficient.The minimum landing distance will vary in direct proportion to the gross weight. For example, a 10 percent increase in gross weight at landing would cause:(1) a 5 percent increase in landing velocity.(2) a 10 percent increase in landing distance.The effect of wind on landing distance is large and deserves proper consideration when predicting landing distance. Since the airplane will land at a particular airspeed independent of the wind, the principal effect of wind on landing distance is due to the change in the ground speed at which the airplane touches down. The effect of wind on deceleration during the landing is identical to the effect on acceleration during the takeoff.A headwind which is 10 percent of the landing airspeed will reduce the landing distance approximately 19 percent but a tailwind which is 10 percent of the landing speed will increase the landing distance approximately 21 percent.The effect of pressure altitude and ambient temperature is to define density altitude and its effect on landing performance. An increase in density altitude will increase landing speed but will not alter the net retarding force. Since an increase in altitude does not alter deceleration, the effect of density altitude on landing distance would actually be due to the greater TAS (true airspeed).The minimum landing distance at 5000ft would be 16 percent greater than the minimum landing distance at sea level. The approximate increase in landing distance with altitude is approximately 3 and a half percent for each 1000ft of altitude. Proper accounting of density altitude is necessary to accurately predict landing distance.The effect of proper landing speed is important when runway lengths and landing distances are critical. The landing speeds specified in the airplane’s flight handbooks is generally the minimum safe speeds at which the airplane can be landed. Any attempt to land at below the specified speed may mean that the airplane may stall, be difficult to control, or develop high rates of descent. On the other hand, an excessive speed at landing may improve the controllability slightly, but will cause an undesirable increase in landing distance.4.The minimum landing distance at 5000ft would be 16 percent greater than the minimum landing distance at sea level because （ ） ．
In addition to the important factors of proper technique, many other variables affect the landing performance of an airplane. Any item which alters the landing speed or deceleration rate during the landing roll will affect the landing distance.The effect of gross weight on landing distance is one of the principal items determining the landing distance of an airplane. One effect of an increased gross weight is that the airplane will require a greater speed to support the airplane at the landing angle of attack and lift coefficient.The minimum landing distance will vary in direct proportion to the gross weight. For example, a 10 percent increase in gross weight at landing would cause:(1) a 5 percent increase in landing velocity.(2) a 10 percent increase in landing distance.The effect of wind on landing distance is large and deserves proper consideration when predicting landing distance. Since the airplane will land at a particular airspeed independent of the wind, the principal effect of wind on landing distance is due to the change in the ground speed at which the airplane touches down. The effect of wind on deceleration during the landing is identical to the effect on acceleration during the takeoff.A headwind which is 10 percent of the landing airspeed will reduce the landing distance approximately 19 percent but a tailwind which is 10 percent of the landing speed will increase the landing distance approximately 21 percent.The effect of pressure altitude and ambient temperature is to define density altitude and its effect on landing performance. An increase in density altitude will increase landing speed but will not alter the net retarding force. Since an increase in altitude does not alter deceleration, the effect of density altitude on landing distance would actually be due to the greater TAS (true airspeed).The minimum landing distance at 5000ft would be 16 percent greater than the minimum landing distance at sea level. The approximate increase in landing distance with altitude is approximately 3 and a half percent for each 1000ft of altitude. Proper accounting of density altitude is necessary to accurately predict landing distance.The effect of proper landing speed is important when runway lengths and landing distances are critical. The landing speeds specified in the airplane’s flight handbooks is generally the minimum safe speeds at which the airplane can be landed. Any attempt to land at below the specified speed may mean that the airplane may stall, be difficult to control, or develop high rates of descent. On the other hand, an excessive speed at landing may improve the controllability slightly, but will cause an undesirable increase in landing distance.3.If an aircraft landing at 150 knots in calm wind uses 1000ft to make a full stop, it will require （ ） （ ）ft to stop in 15 knots headwind.
In addition to the important factors of proper technique, many other variables affect the landing performance of an airplane. Any item which alters the landing speed or deceleration rate during the landing roll will affect the landing distance.The effect of gross weight on landing distance is one of the principal items determining the landing distance of an airplane. One effect of an increased gross weight is that the airplane will require a greater speed to support the airplane at the landing angle of attack and lift coefficient.The minimum landing distance will vary in direct proportion to the gross weight. For example, a 10 percent increase in gross weight at landing would cause:(1) a 5 percent increase in landing velocity.(2) a 10 percent increase in landing distance.The effect of wind on landing distance is large and deserves proper consideration when predicting landing distance. Since the airplane will land at a particular airspeed independent of the wind, the principal effect of wind on landing distance is due to the change in the ground speed at which the airplane touches down. The effect of wind on deceleration during the landing is identical to the effect on acceleration during the takeoff.A headwind which is 10 percent of the landing airspeed will reduce the landing distance approximately 19 percent but a tailwind which is 10 percent of the landing speed will increase the landing distance approximately 21 percent.The effect of pressure altitude and ambient temperature is to define density altitude and its effect on landing performance. An increase in density altitude will increase landing speed but will not alter the net retarding force. Since an increase in altitude does not alter deceleration, the effect of density altitude on landing distance would actually be due to the greater TAS (true airspeed).The minimum landing distance at 5000ft would be 16 percent greater than the minimum landing distance at sea level. The approximate increase in landing distance with altitude is approximately 3 and a half percent for each 1000ft of altitude. Proper accounting of density altitude is necessary to accurately predict landing distance.The effect of proper landing speed is important when runway lengths and landing distances are critical. The landing speeds specified in the airplane’s flight handbooks is generally the minimum safe speeds at which the airplane can be landed. Any attempt to land at below the specified speed may mean that the airplane may stall, be difficult to control, or develop high rates of descent. On the other hand, an excessive speed at landing may improve the controllability slightly, but will cause an undesirable increase in landing distance.2.The major effect of wind on landing distance derives from the change in the （ ） at which airplane touchdown.
In addition to the important factors of proper technique, many other variables affect the landing performance of an airplane. Any item which alters the landing speed or deceleration rate during the landing roll will affect the landing distance.The effect of gross weight on landing distance is one of the principal items determining the landing distance of an airplane. One effect of an increased gross weight is that the airplane will require a greater speed to support the airplane at the landing angle of attack and lift coefficient.The minimum landing distance will vary in direct proportion to the gross weight. For example, a 10 percent increase in gross weight at landing would cause:(1) a 5 percent increase in landing velocity.(2) a 10 percent increase in landing distance.The effect of wind on landing distance is large and deserves proper consideration when predicting landing distance. Since the airplane will land at a particular airspeed independent of the wind, the principal effect of wind on landing distance is due to the change in the ground speed at which the airplane touches down. The effect of wind on deceleration during the landing is identical to the effect on acceleration during the takeoff.A headwind which is 10 percent of the landing airspeed will reduce the landing distance approximately 19 percent but a tailwind which is 10 percent of the landing speed will increase the landing distance approximately 21 percent.The effect of pressure altitude and ambient temperature is to define density altitude and its effect on landing performance. An increase in density altitude will increase landing speed but will not alter the net retarding force. Since an increase in altitude does not alter deceleration, the effect of density altitude on landing distance would actually be due to the greater TAS (true airspeed).The minimum landing distance at 5000ft would be 16 percent greater than the minimum landing distance at sea level. The approximate increase in landing distance with altitude is approximately 3 and a half percent for each 1000ft of altitude. Proper accounting of density altitude is necessary to accurately predict landing distance.The effect of proper landing speed is important when runway lengths and landing distances are critical. The landing speeds specified in the airplane’s flight handbooks is generally the minimum safe speeds at which the airplane can be landed. Any attempt to land at below the specified speed may mean that the airplane may stall, be difficult to control, or develop high rates of descent. On the other hand, an excessive speed at landing may improve the controllability slightly, but will cause an undesirable increase in landing distance.1.A 40 percent increase in gross weight at landing would result in （ ） ．
The effect of pressure altitude and ambient temperature is to define primarily the density altitude and its effect on takeoff performance. While subsequent corrections are appropriate for the effect of temperature on certain items of power plant performance, density altitude defines specific effects on takeoff performance. An increase in density altitude can produce a two-fold effect on takeoff performance: (l) greater takeoff speed and (2) decreased thrust and reduced net accelerating force. If an airplane of given weight and configuration is operated at greater heights above standard sea level, the airplane will still require the same dynamic pressure to become airborne at the takeoff lift coefficient. Thus, the airplane at altitude will take off at the same indicated airspeed as at sea level, but because of the reduced air density, the true airspeed will be greater.The effect of density altitude on power plant thrust depends much on the type of power plant. An increase in altitude above standard sea level will bring an immediate decrease in power output for the unsupercharged reciprocating engine. However, an increase in altitude above standard sea level will not cause a decrease in power output for the supercharged reciprocating engine until the altitude exceeds the critical operating altitude. For those power plants which experience a decay in thrust with an increase in altitude, the effect on the net accelerating force and acceleration rate can be approximated by assuming a direct variation with density. Actually, this assumed variation would closely approximate the effect on airplanes with high thrust-to-weight ratios.Proper accounting of pressure altitude and temperature is mandatory for accurate prediction of takeoff roll distance.5.Which of the following statements is not true?
