5B - Performance and Limitations - Aircraft Performance Flashcards
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“2. What is the relationship of lift, weight, thrust and drag in steady, unaccelerated, level flight? (FAA-H-8083-25)
For the airplane to remain in steady, level flight, equilibrium must be obtained by a lift equal to the airplane weight and powerplant thrust equal to the airplane drag.”
Excerpt From: Michael D. Hayes. “Commercial Oral Exam Guide.” Aviation Supplies and Academics, Inc., 2013-08-23. iBooks.
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A
“1. What are some of the main elements of aircraft performance? (FAA-H-8083-25)
a. Takeoff and landing distance
b. Rate-of-climb
c. Ceiling
d. Payload
e. Range
f. Speed
g. Maneuverability
h. Stability
i. Fuel economy”
Excerpt From: Michael D. Hayes. “Commercial Oral Exam Guide.” Aviation Supplies and Academics, Inc., 2013-08-23. iBooks.
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A
“3. What are the two types of drag? (FAA-H-8083-25)
Total drag may be divided into two parts: the wing drag (induced), and drag from everything but the wings (parasite).”
Excerpt From: Michael D. Hayes. “Commercial Oral Exam Guide.” Aviation Supplies and Academics, Inc., 2013-08-23. iBooks.
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A
“4. Define induced drag. (FAA-H-8083-25)
Induced drag is the part of total drag created by the production of lift. Induced drag increases with a decrease in airspeed. The lower the airspeed, the greater the angle of attack required to produce lift equal to the airplane’s weight, and therefore the greater the induced drag.”
Excerpt From: Michael D. Hayes. “Commercial Oral Exam Guide.” Aviation Supplies and Academics, Inc., 2013-08-23. iBooks.
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5
“5. Define parasite drag. (FAA-H-8083-25)
Parasite drag is the part of total drag created by the form or shape of airplane parts. It is the sum of pressure and friction drag due to the airplane’s basic configuration and is independent of lift. It is greatest at high airspeeds and is proportional to the square of the airspeed: if the airspeed were doubled, the parasite drag would be quadrupled.”
Excerpt From: Michael D. Hayes. “Commercial Oral Exam Guide.” Aviation Supplies and Academics, Inc., 2013-08-23. iBooks.
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6
“6. How much will drag increase as airplane speed increases? (FAA-H-8083-25)
If an airplane in a steady flight condition at 100 knots is then accelerated to 200 knots, the parasite drag becomes four times as great, but the power required to overcome that drag is eight times the original value. Conversely, when the airplane is operated in steady, level flight at twice as great a speed, the induced drag is one-fourth the original value, and the power required to overcome that drag is only one-half the original value.”
Excerpt From: Michael D. Hayes. “Commercial Oral Exam Guide.” Aviation Supplies and Academics, Inc., 2013-08-23. iBooks.
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7
“7. Climb performance is a result of using the aircraft’s potential energy provided by one, or a combination of two, factors. What are those two factors? (FAA-H-8083-25)
a. Use of excess power above that required for level flight. An aircraft equipped with an engine capable of 200 horsepower (at a given altitude) but using 130 horsepower to sustain level flight (at a given airspeed) has 70 excess horsepower available for climbing.
b. Use of the aircraft’s kinetic energy. An aircraft can trade off its kinetic energy and increase its potential energy by reducing its airspeed. The reduction in airspeed will increase the aircraft’s potential energy, making the aircraft climb.”
Excerpt From: Michael D. Hayes. “Commercial Oral Exam Guide.” Aviation Supplies and Academics, Inc., 2013-08-23. iBooks.
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8
“8. Define the term “service ceiling.” (FAA-H-8083-25)
Service ceiling is the maximum density altitude where the best rate-of-climb airspeed will produce a 100 feet-per-minute climb at maximum weight while in a clean configuration with maximum continuous power.”
Excerpt From: Michael D. Hayes. “Commercial Oral Exam Guide.” Aviation Supplies and Academics, Inc., 2013-08-23. iBooks.
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9
“9. Will an aircraft always be capable of climbing to and maintaining its service ceiling? (FAA-H-8083-25)
No. Depending on the density altitude, an airplane may not be able to reach it published service ceiling on any given day.”
Excerpt From: Michael D. Hayes. “Commercial Oral Exam Guide.” Aviation Supplies and Academics, Inc., 2013-08-23. iBooks.
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10
“10. What is the definition of “absolute ceiling”? (FAA-H-8083-25)
Absolute ceiling is the altitude at which a climb is no longer possible.”
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11
“11. What is meant by the terms “power loading” and “wing loading”? (FAA-H-8083-25)
Power loading is expressed in pounds per horsepower and is obtained by dividing the total weight of the airplane by the rated horsepower of the engine. It is a significant factor in the airplane’s takeoff and climb capabilities.
Wing loading is expressed in pounds per square foot and is obtained by dividing the total weight of the airplane in pounds by the wing area (including ailerons) in square feet. It is the airplane’s wing loading that determines the landing speed.”
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12
“12. Define the terms “maximum range” and “maximum endurance.” (FAA-H-8083-25)
Maximum range is the maximum distance an airplane can fly for a given fuel supply and is obtained at the maximum lift/drag ratio (L/DMAX). For a given airplane configuration, the maximum lift/drag ratio occurs at a particular angle of attack and lift coefficient, and is unaffected by weight or altitude.
Maximum endurance is the maximum amount of time an airplane can fly for a given fuel supply and is obtained at the point of minimum power required since this would require the lowest fuel flow to keep the airplane in steady, level flight.”
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13
“13. What is ground effect? (FAA-H-8083-25)
Ground effect occurs due to the interference of the ground surface with the flow pattern about the airplane in flight, when the airplane is flown at approximately one wingspan above the surface. Especially with low-wing aircraft, it is most significant when the airplane is maintaining a constant attitude at low airspeed and low altitude. For example: during landing flare before touchdown, and during takeoff when the airplane lifts off and accelerates to climb speed. A wing in ground effect has a reduction in upwash, downwash, and tip vortices. With reduced tip vortices, induced drag is reduced. When the wing is at a height equal to one-fourth the span, the reduction in induced drag is about 25 percent, and when the wing is at a height equal to one-tenth the span, this reduction is about 50 percent.”
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14
“14. What major problems can be caused by ground effect? (FAA-H-8083-25)
During landing—At a height of approximately one-tenth of a wing span above the surface, drag may be 50 percent less than when the airplane is operating out of ground effect. Therefore, any excess speed during the landing phase may result in a significant float distance. In such cases, if care is not exercised, the pilot may run out of runway and options at the same time.
During takeoff—Due to the reduced drag in ground effect, the aircraft may seem capable of takeoff well below the recommended speed. However, as the airplane rises out of ground effect with a deficiency of speed, the greater induced drag may result in very marginal climb performance, or the inability of the airplane to fly at all. In extreme conditions such as high gross weight and high density altitude, the airplane may become airborne initially with a deficiency of speed and then settle back to the runway.”
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15
“15. What does “flight in the region of normal command” mean? (FAA-H-8083-25)
It means that while holding a constant altitude, a higher airspeed requires a higher power setting, and a lower airspeed requires a lower power setting. The majority of all airplane flying (climb, cruise, and maneuvers) is conducted in the region of normal command.”
Excerpt From: Michael D. Hayes. “Commercial Oral Exam Guide.” Aviation Supplies and Academics, Inc., 2013-08-23. iBooks.
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16
“16. What does “flight in the region of reversed command” mean? (FAA-H-8083-25)
It means that a higher airspeed requires a lower power setting, and a lower airspeed requires a higher power setting to hold altitude. It does not imply that a decrease in power will produce lower airspeed. The region of reversed command is encountered in the low-speed phases of flight. Flight speeds below the speed for maximum endurance (lowest point on the power curve) require higher power settings with a decrease in airspeed. Because the need to increase the required power setting with decreased speed is contrary to the “normal command” of flight, flight speeds between minimum required power setting (speed) and the stall speed (or minimum control speed) is termed the region of reversed command. In the region of reversed command, a decrease in airspeed must be accompanied by an increased power setting in order to maintain steady flight.”
Excerpt From: Michael D. Hayes. “Commercial Oral Exam Guide.” Aviation Supplies and Academics, Inc., 2013-08-23. iBooks.
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17
“17. What are examples of where an airplane would be operating in the region of reversed command? (FAA-H-8083-25)
a. An airplane performing a low airspeed, high-pitch attitude, powered approach for a short-field landing.
b. A soft-field takeoff and climb where the pilot attempts to climb out of ground effect without first attaining normal climb pitch attitude and airspeed, is an example of inadvertently operating in the region of reversed command at a dangerously low altitude.”
Excerpt From: Michael D. Hayes. “Commercial Oral Exam Guide.” Aviation Supplies and Academics, Inc., 2013-08-23. iBooks.
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18
“18. Explain how runway surface and gradient affect performance. (FAA-H-8083-25)
a. Runway surface—Any surface that is not hard and smooth will increase the ground roll during takeoff. This is due to the inability of the tires to smoothly roll along the runway. Although muddy and wet surface conditions can reduce friction between the runway and the tires, they can also act as obstructions and reduce the landing distance.
b. Braking effectiveness—The amount of power that is applied to the brakes without skidding the tires is referred to as braking effectiveness. Ensure that runways are adequate in length for takeoff acceleration and landing deceleration when less than ideal surface conditions are being reported, as it affects braking ability.
c. Runway gradient or slope—A positive gradient indicates that the runway height increases, and a negative gradient indicates that the runway decreases in height. An upsloping runway impedes acceleration and results in a longer ground run during takeoff. However, landing on an upsloping runway typically reduces the landing roll. A downsloping runway aids in acceleration on takeoff resulting in shorter takeoff distances. The opposite is true when landing, as landing on a downsloping runway increases landing distances.”
Excerpt From: Michael D. Hayes. “Commercial Oral Exam Guide.” Aviation Supplies and Academics, Inc., 2013-08-23. iBooks.
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19
“19. What factors affect the performance of an aircraft during takeoffs and landings? (FAA-H-8083-25)
a. Air density (density altitude)
b. Surface wind
c. Runway surface
d. Upslope or downslope of runway
e. Weight
f. Powerplant thrust”
Excerpt From: Michael D. Hayes. “Commercial Oral Exam Guide.” Aviation Supplies and Academics, Inc., 2013-08-23. iBooks.
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20
“20. What effect does wind have on aircraft performance? (FAA-H-8083-25)
Takeoff—A headwind increases airplane performance by shortening the takeoff distance and increasing the angle of climb. However, a tailwind decreases performance by increasing the takeoff distance and reducing the angle of climb. The pilot must carefully consider the decrease in airplane performance before attempting a downwind takeoff.
Landing—A headwind increases airplane performance by steepening the approach angle and reducing the landing distance. A tailwind decreases performance by decreasing the approach angle and increasing the landing distance. Again, the pilot must take the wind into consideration prior to landing.
Cruise flight—Winds aloft have a somewhat opposite effect; a headwind decreases performance by reducing ground speed, which in turn increases the fuel requirement for the flight. A tailwind increases performance by increasing the ground speed, which in turn reduces the fuel required for the flight.”
Excerpt From: Michael D. Hayes. “Commercial Oral Exam Guide.” Aviation Supplies and Academics, Inc., 2013-08-23. iBooks.
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21
“21. How does weight affect takeoff and landing performance? (FAA-H-8083-25)
Increased gross weight can produce these effects:
a. Higher liftoff and landing speed required;
b. Greater mass to accelerate or decelerate (slow acceleration/deceleration);
c. Increased retarding force (drag and ground friction); and
d. Longer takeoff and ground roll.
The effect of gross weight on landing distance is that the airplane will require a greater speed to support the airplane at the landing angle of attack and lift coefficient resulting in an increased landing distance.”
Excerpt From: Michael D. Hayes. “Commercial Oral Exam Guide.” Aviation Supplies and Academics, Inc., 2013-08-23. iBooks.
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22
“22. What effect does an increase in density altitude have on takeoff and landing performance? (FAA-H-8083-25)
An increase in density altitude results in:
a. Increased takeoff distance (greater takeoff TAS required).
b. Reduced rate of climb (decreased thrust and reduced acceleration).
c. Increased true airspeed on approach and landing (same IAS).
d. Increased landing roll distance.
An increase in density altitude (decrease in air density) will increase the landing speed but will not alter the net retarding force. Thus, the airplane will land at the same indicated airspeed as normal but because of reduced air density the true airspeed will be greater. This will result in a longer minimum landing distance.”
Excerpt From: Michael D. Hayes. “Commercial Oral Exam Guide.” Aviation Supplies and Academics, Inc., 2013-08-23. iBooks.
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23
“23. Planning for a rejected takeoff is essential to the safety of every flight. What calculation must be made prior to every takeoff? (FAA-H-8083-25)
Prior to takeoff, the pilot should have in mind a point along the runway at which the airplane should be airborne. If that point is reached and the airplane is not airborne, immediate action should be taken to discontinue the takeoff. If properly planned and executed, the airplane can be stopped on the remaining runway without using extraordinary measures, such as excessive braking that may result in loss of directional control, airplane damage, and/or personal injury.”
Excerpt From: Michael D. Hayes. “Commercial Oral Exam Guide.” Aviation Supplies and Academics, Inc., 2013-08-23. iBooks.
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24
“24. Why does the manufacturer provide various manifold pressure/prop settings for a given power output?
The various power MAP/rpm combinations are provided so the pilot has a choice between operating the aircraft at best efficiency (minimum fuel flow) or operating at best power/speed condition. An aircraft engine operated at higher rpms will produce more friction and, as a result, use more fuel. On the other hand, an aircraft operating at higher and higher altitudes will not be able to continue to produce the same constant power output due to a drop in manifold pressure. The only way to compensate for this is by operating the engine at a higher rpm.”
Excerpt From: Michael D. Hayes. “Commercial Oral Exam Guide.” Aviation Supplies and Academics, Inc., 2013-08-23. iBooks.
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