5B - Performance and Limitations - Aircraft Performance

Question 0

A

Answer 0

“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.”

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Question 1

A

Answer 1

“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”

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Question 2

A

Answer 2

“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).”

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Question 3

A

Answer 3

“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.”

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Question 4

5

Answer 4

“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.”

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Question 5

6

Answer 5

“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.”

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Question 6

7

Answer 6

“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.”

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Question 7

8

Answer 7

“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.”

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Question 8

9

Answer 8

“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.”

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Question 9

10

Answer 9

“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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Question 10

11

Answer 10

“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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Question 11

12

Answer 11

“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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Question 12

13

Answer 12

“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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Question 13

14

Answer 13

“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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Question 14

15

Answer 14

“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.”

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Question 15

16

Answer 15

“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.”

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Question 16

17

Answer 16

“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.”

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Question 17

18

Answer 17

“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.”

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Question 18

19

Answer 18

“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”

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Question 19

20

Answer 19

“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.”

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Question 20

21

Answer 20

“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.”

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Question 21

22

Answer 21

“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.”

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Question 22

23

Answer 22

“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.”

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Question 23

24

Answer 23

“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.”

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Question 24

25

Answer 24

“25.	What does the term 75% brake horsepower mean? (FAA-H-8083-25)
Brake horsepower (BHP) is the power delivered at the propeller shaft (main drive or main output) of an aircraft engine. 75% BHP means you are delivering 75 percent of the normally rated power or maximum continuous power available at sea level on a standard day to the propeller shaft.”

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Question 25

26

Answer 25

“26. Explain how 75% BHP can be obtained from your engine. (FAA-H-8083-25)
Set the throttle (manifold pressure) and propeller (rpm) to the recommended values found in the cruise performance chart of your POH.”

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Question 26

27

Answer 26

“27. When would a pilot lean a normally-aspirated direct-drive engine? (FAA-P-8740-13)

a. Lean anytime the power setting is 75 percent or less at any altitude.
b. At high-altitude airports, lean for taxi, takeoff, traffic pattern entry and landing.
c. When the density altitude is high (Hot, High, Humid).
d. For landings at airports below 5,000 feet density altitude, adjust the mixture for descent, but only as required.
e. Always consult the POH for proper leaning procedures.”

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Question 27

28

Answer 27

“28. What are the different methods available for leaning aircraft engines? (FAA-P-8740-13)
Tachometer Method—For best economy operation, the mixture is first leaned from full rich to maximum power (peak rpm), then the leaning process is slowly continued until the engine starts to run rough. Then, enrich the mixture sufficiently to obtain a smoothly firing engine.
Fuel Flowmeter Method—Aircraft equipped with fuel flowmeters require that you lean the mixture to the published (POH) or marked fuel flow to achieve the correct mixture.
Exhaust Gas Temperature Method—Lean the mixture slowly to establish peak EGT then enrich the mixture by 50° rich (cooler) of peak EGT. This will provide the recommended lean condition for the established power setting.”

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Question 28

29

Answer 28

“29. Define the following airplane performance speeds. (FAA-H-8083-25)
VS0—The calibrated power-off stalling speed or the minimum steady flight speed at which the airplane is controllable in the landing configuration.
VS1—The calibrated power-off stalling speed or the minimum steady flight speed at which the airplane is controllable in a specified configuration.
VY—The calibrated airspeed at which the airplane will obtain the maximum increase in altitude per unit of time. This best rate-of-climb speed normally decreases slightly with altitude.
VX—The calibrated airspeed at which the airplane will obtain the highest altitude in a given horizontal distance. This best angle-of-climb speed normally increases slightly with altitude.
VLE—The maximum calibrated airspeed at which the airplane can be safely flown with the landing gear extended. This is a problem involving stability and controllability.
VLO—The maximum calibrated airspeed at which the landing gear can be safely extended or retracted. This is a problem involving the air loads imposed on the operating mechanism during extension or retraction of the gear.
“VFE—The highest calibrated airspeed permissible with the wing flaps in a prescribed extended position. This is because of the air loads imposed on the structure of the flaps.
VA—The calibrated design maneuvering airspeed. This is the maximum speed at which the limit load can be imposed (either by gusts or full deflection of the control surfaces) without causing structural damage.”
VNO—The maximum calibrated airspeed for normal operation or the maximum structural cruising speed. This is the speed at which exceeding the limit load factor may cause permanent deformation of the airplane structure.
VNE—The calibrated airspeed which should never be exceeded. If flight is attempted above this speed, structural damage or structural failure may result.”

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Question 29

30

Answer 29

“30. The following questions are designed to provide you with a review of some of the basic information you should know about your specific airplane before taking a flight check or review.

a. What is the normal climb-out speed?
b. What is the best rate-of-climb speed?
c. What is the best angle-of-climb speed?
d. What is the maximum flap extension speed?
e. What is the maximum gear extension speed?
f. What is the maximum gear retraction speed?
g. What is the stall speed in the normal landing configuration?
h. What is the stall speed in the clean configuration?
i. What is the normal approach-to-land speed?
j. What is the maneuvering speed?
k. What is the red-line speed?
l. What speed will give you the best glide ratio?
m. What is the maximum window-open speed?
n. What is the maximum allowable crosswind component for the aircraft?
o. What takeoff distance is required if a takeoff were made from a sea level pressure altitude?”

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