Performance and Limitations

Question 1

How is aircraft performance reduced as air becomes less dense?

Answer 1

Power-engine takes in less air
Thrust-propeller less efficient in less dense air
Lift-thin air exerts less force on airfoils

Question 2

What is the standard atmosphere at sea level?

Answer 2

15C or 59F

29.92”Hg or 1013.2 millibars

Question 3

What are the standard temperature and pressure lapse rates?

Answer 3

2C or 3.5F per 1000’

1”Hg per 1000’

Question 4

Define pressure altitude.

Answer 4

Height above the standard datum plane

Read from altimeter when set to 29.92

Question 5

Define density altitude.

Answer 5

Pressure altitude corrected for non-standard temperature

Question 6

How does density altitude affect aircraft performance?

Answer 6

Airplane performance decreases with an increase in density altitude

Question 7

What factors affect density altitude?

Answer 7

Temperature increase increases density altitude
Humidity increase increases density altitude
Pressure decrease increases density altitude

Question 8

Define service ceiling.

Answer 8

Maximum density altitude at which a 100fpm climb can be maintained at max weight

Question 9

Define absolute ceiling.

Answer 9

Altitude at which climb is no longer possible

Question 10

What is power loading?

Answer 10

Total weight of airplane divided by engine horsepower

Determines takeoff and climb capabilities

Question 11

What is wing loading?

Answer 11

Total weight of airplane divided by wing area

Determines landing speed

Question 12

Define maximum range.

Answer 12

Maximum distance an airplane can fly at L/Dmax for a given fuel supply

Question 13

Define maximum endurance.

Answer 13

Maximum amount of time an airplane can fly at minimum power for a given fuel supply

Question 14

What is ground effect?

Answer 14

Interference of airflow around airplane when flown within one wingspan of ground
Reduction of upwash/downwash, wingtip vortices=reduction of induced drag

Question 15

What problem might ground effect cause during landng?

Answer 15

Excess speed/reduced drag may cause significant float

Question 16

What problem might ground effect cause on takeoff?

Answer 16

Airplane leaving ground effect with too little airspeed may settle back to runway

Question 17

What is the region of reversed command?

Answer 17

Low speed phases of flight
Higher airspeed requires a lower power setting
Lower airspeed requires a higher power setting

Question 18

What are some phases of flight in which the airplane would be operated in the region of reversed command?

Answer 18

Low airspeed, high pitch, powered short-field approach

Attempting to climb out of ground effect on a soft-field takeoff before attaining proper climb pitch/airspeed

Question 19

What effect does a high gross weight have on takeoff and landing performance?

Answer 19

Higher liftoff and landing speeds
Slower acceleration/deceleration
Increased drag/ground friction
Longer takeoff/ground roll

Question 20

What effect does an increase in density altitude have on takeoff and landing performance?

Answer 20

Increased takeoff distance/higher takeoff TAS
Reduced rate of climb
Increased TAS on approach and landing
Increased landing roll

Question 21

When should a normally aspirated, direct-drive engine be leaned?

Answer 21

Anytime power is less than 75%, at any altitude
Taxi, takeoff, traffic pattern, and landing at high altitude airports
High density altitude (hot, high, humid)
According to POH procedures

Question 22

Define arm (moment arm).

Answer 22

Horizontal distance from reference datum line to the CG of an object

Question 23

Define basic empty weight.

Answer 23

Standard empty weight of an aircraft+any equipment installed

Question 24

Define center of gravity (CG).

Answer 24

Point at which the aircraft would balance if it were suspended at that point
All weight is considered to act through the CG

Question 25

Define CG limits.

Answer 25

Specified forward and aft points within which the CG must be located during flight

Question 26

Define CG range.

Answer 26

Distance between forward and aft CG limits

Question 27

Define datum.

Answer 27

Imaginary vertical plane or line from which all arm measurements are taken

Question 28

Define licensed empty weight.

Answer 28

Empty weight + optional equipment + unusable fuel + un-drainable oil

Question 29

Define moment.

Answer 29

Product of the weight of an item and its arm

Question 30

Define moment index.

Answer 30

Moment divided by a common figure (10, 100, 1000, etc.) to simplify calculations

Question 31

Define station.

Answer 31

Location of an item in an aircraft designated in inches from the datum

Question 32

Define useful load.

Answer 32

Weight allowable for pilot, passengers, baggage, fuel, oil | Maximum takeoff weight - basic empty weight

Question 33

How would being over maximum gross weight affect performance?

Answer 33

``` Longer takeoff run/higher takeoff speed Reduced rate and angle of climb Lower maximum altitude Shorter range Reduced cruising speed Reduced maneuverability Higher stalling speed Higher landing speed/longer landing roll Excessive weight on nosewheel ```

Question 34

What effect does a forward CG have on flight characteristics?

Answer 34

Higher stall speed (increased wing loading) Slower cruise speed (increased drag, greater angle of attack required) More stable Greater back elevator pressure required

Question 35

What effect does an aft CG have on flight characteristics?

Answer 35

Lower stall speed (less wing loading) Higher cruise speed (less drag, smaller angle of attack) Less stable (stall/spin recovery more difficult)

Question 36

What basic equation is use for weight and balance problems?

Answer 36

Weight x Arm = Moment

Question 37

What basic equation is used to calculate CG when weight has been shifted?

Answer 37

(weight shifted x distance moved) / aircraft gross weight = CG