12 practice questions from the 239 in this chapter of StudyWren Aviation. Pick an answer and check it to see the explanation and its FAA source.
Wing Design & ContaminationPAR-01-220
Frost, ice, or snow with a roughness similar to medium or coarse sandpaper on a wing's leading edge and upper surface can reduce lift and increase drag by as much as approximately
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The answer is A: 30 percent and 40 percent
Wind tunnel and flight tests have shown that frost, snow, and ice on the leading edge or upper surface no thicker or rougher than coarse sandpaper can reduce lift by about 30 percent and increase drag up to 40 percent; larger accretions are worse. Even a thin layer of frost can prevent a normal takeoff.
Wind tunnel and flight tests have shown that frost, snow, and ice on the leading edge or upper surface no thicker or rougher than coarse sandpaper can reduce lift by about 30 percent and increase drag up to 40 percent; larger accretions are worse. Even a thin layer of frost can prevent a normal takeoff.
Structural ice accumulating on an airplane in flight generally causes
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The answer is C: less lift, more drag, and more weight
Ice distorts and roughens the airfoil, reducing lift and increasing drag, adds weight, and can reduce propeller efficiency (thrust). Together these raise the stall speed and degrade climb and cruise performance.
The answer is C: less lift, more drag, and more weight
Ice distorts and roughens the airfoil, reducing lift and increasing drag, adds weight, and can reduce propeller efficiency (thrust). Together these raise the stall speed and degrade climb and cruise performance.
After a summer cross-country, the wing leading edges are heavily coated with insect residue. What is the main aerodynamic effect on the next flight?
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The answer is A: More drag and a possible increase in stall speed
Roughness at the leading edge thickens and disturbs the boundary layer, increasing skin friction drag and promoting early separation, which can reduce maximum lift and raise the stall speed. Wings, especially laminar-flow wings, should be kept clean.
The answer is A: More drag and a possible increase in stall speed
Roughness at the leading edge thickens and disturbs the boundary layer, increasing skin friction drag and promoting early separation, which can reduce maximum lift and raise the stall speed. Wings, especially laminar-flow wings, should be kept clean.
A heavily loaded airplane departs from a high-elevation airport on a hot day. It lifts off but will not climb more than a few feet above the runway. What best explains this?
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The answer is C: Reduced induced drag lets it fly in ground effect but not above it
Ground effect reduces induced drag and the thrust required. A marginal airplane may have enough performance to fly within ground effect but not enough excess power to climb once induced drag increases on leaving it, a dangerous situation if obstacles lie ahead.
The answer is C: Reduced induced drag lets it fly in ground effect but not above it
Ground effect reduces induced drag and the thrust required. A marginal airplane may have enough performance to fly within ground effect but not enough excess power to climb once induced drag increases on leaving it, a dangerous situation if obstacles lie ahead.
An airplane's wings-level stall speed is 55 knots. Approximately what is its stall speed in a coordinated, constant-altitude 30° banked turn?
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The answer is B: About 59 knots
At 30 degrees, load factor = 1/cos(30) = 1.155 and stall speed rises by its square root, sqrt(1.155) = 1.075. Stall speed = 55 x 1.075 = about 59 knots. 64 knots multiplies by the load factor instead of its square root, and 78 knots applies the 60-degree factor (1.414).
At 30 degrees, load factor = 1/cos(30) = 1.155 and stall speed rises by its square root, sqrt(1.155) = 1.075. Stall speed = 55 x 1.075 = about 59 knots. 64 knots multiplies by the load factor instead of its square root, and 78 knots applies the 60-degree factor (1.414).
Holding a constant 30° bank in a level turn, a pilot doubles the true airspeed from 80 to 160 knots. By what factor does the turn radius change?
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The answer is A: It becomes four times as large
At a constant bank angle, turn radius is proportional to V^2 / tan(bank). Doubling the true airspeed multiplies the radius by 2^2 = 4. The rate of turn, which varies with 1/V, is cut in half.
At a constant bank angle, turn radius is proportional to V^2 / tan(bank). Doubling the true airspeed multiplies the radius by 2^2 = 4. The rate of turn, which varies with 1/V, is cut in half.
In level flight, an airplane accelerates from 80 knots to 120 knots. By about what factor does its parasite drag increase?
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The answer is C: About 2.25 times
Parasite drag varies with the square of airspeed: (120/80)^2 = 1.5^2 = 2.25. Using the speed ratio directly gives 1.5, and 3.4 is 1.5 cubed, which is roughly how much the power needed to overcome parasite drag increases.
Parasite drag varies with the square of airspeed: (120/80)^2 = 1.5^2 = 2.25. Using the speed ratio directly gives 1.5, and 3.4 is 1.5 cubed, which is roughly how much the power needed to overcome parasite drag increases.
During a power-off glide in still air, an airplane loses 1,000 feet of altitude while covering 1.5 NM over the ground. What is its approximate glide ratio? (1 NM = 6,076 feet)
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The answer is A: About 9:1
Horizontal distance = 1.5 x 6,076 = 9,114 feet. Glide ratio = 9,114 / 1,000 = about 9.1:1. Ignoring the 1.5 gives about 6:1, and comparing 1.5 NM with 1,000 feet without converting units gives 1.5:1.
Horizontal distance = 1.5 x 6,076 = 9,114 feet. Glide ratio = 9,114 / 1,000 = about 9.1:1. Ignoring the 1.5 gives about 6:1, and comparing 1.5 NM with 1,000 feet without converting units gives 1.5:1.
A pilot rolls from level flight into a 30° bank without increasing back pressure, so total lift stays equal to the airplane's weight. About what fraction of the weight does the vertical component of lift now support?
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The answer is B: About 87 percent
The vertical component of lift = total lift x cos(bank) = 1.0 x cos(30) = 0.866, or about 87 percent of the weight. With less upward force than weight, the airplane begins to descend unless the pilot increases the AOA. 115 percent is the load factor (1/cos 30) needed to hold altitude.
The vertical component of lift = total lift x cos(bank) = 1.0 x cos(30) = 0.866, or about 87 percent of the weight. With less upward force than weight, the airplane begins to descend unless the pilot increases the AOA. 115 percent is the load factor (1/cos 30) needed to hold altitude.
A 170-pound pilot flies a coordinated, constant-altitude 60° banked turn. Approximately how much does the pilot's body press into the seat?
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The answer is C: About 340 pounds
At 60 degrees of bank the load factor is 1/cos(60) = 2.0 G, so the pilot's effective weight is 170 x 2.0 = 340 pounds. 196 pounds corresponds to a 30-degree bank (1.15 G), and 255 pounds to 1.5 G (about 48 degrees).
At 60 degrees of bank the load factor is 1/cos(60) = 2.0 G, so the pilot's effective weight is 170 x 2.0 = 340 pounds. 196 pounds corresponds to a 30-degree bank (1.15 G), and 255 pounds to 1.5 G (about 48 degrees).
When you press the right rudder pedal, the rudder's trailing edge moves to the ___, and the nose yaws to the ___.
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The answer is A: right; right
Pressing the right pedal moves the rudder's trailing edge to the right. Airflow over the deflected rudder pushes the tail the opposite way, which rotates the airplane about its vertical axis and swings the nose to the right, the same side as the pedal. Each pedal therefore moves both the trailing edge and the nose toward its own side.
Pressing the right pedal moves the rudder's trailing edge to the right. Airflow over the deflected rudder pushes the tail the opposite way, which rotates the airplane about its vertical axis and swings the nose to the right, the same side as the pedal. Each pedal therefore moves both the trailing edge and the nose toward its own side.
A servo tab differs from a trim tab in that a servo tab
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The answer is B: is moved by the pilot's control input and its force then moves the main surface
With a servo tab, the pilot's control input deflects the tab, and the aerodynamic force on the tab moves the primary surface in the opposite direction, reducing the pilot's effort. A tab that moves in the same direction to increase force is an antiservo tab, and a trim tab is set from the cockpit to hold the surface where the pilot wants it.
The answer is B: is moved by the pilot's control input and its force then moves the main surface
With a servo tab, the pilot's control input deflects the tab, and the aerodynamic force on the tab moves the primary surface in the opposite direction, reducing the pilot's effort. A tab that moves in the same direction to increase force is an antiservo tab, and a trim tab is set from the cockpit to hold the surface where the pilot wants it.
