Unit 5

Question 1

What is the most important factor that affects airplane performance?

Answer 1

Air density

Question 2

As density altitude increases & air density decreases, does performance improve or worsen?

Answer 2

worsens

Question 3

As air temp increases, air density?

Answer 3

decreases

Question 4

As altitude increases, air density?

Answer 4

decreases

Question 5

As barometric pressure increases, air density?

Answer 5

increases

Question 6

As humidity increases, air density?

Answer 6

decreases

Question 7

Density altitude

Answer 7

measurement of air density expressed in terms of altitude

(theoretical value)

Question 8

What is density altitude used for?

Answer 8

determining plane’s performance capabilities

Question 9

Humidity

Answer 9

amount of water vapor in the air

(affects engine power)

Question 10

Relationship between humidity & engine performance?

Answer 10

Increase humidity = decrease performance

(less air enters cylinders)

Question 11

What is the general rule for takeoff distance in humid environments?

Answer 11

add 10% to takeoff distance

Question 12

What should you do if density altitude is above 5,000ft or power setting is less than 75%?

Answer 12

lean out engine for max power

Question 13

Minimum takeoff distance

Answer 13

min safe speed that allows for sufficient safety margin above stall speed, provides control, & initial rate of climb

Question 14

What is the affect of gross weight on takeoff performance?

Answer 14

increase gross weight = decrease in takeoff performance

(more takeoff speed, mass to accelerate, drag)

requires longer takeoff distance

Question 15

Takeoff speed

Answer 15

min speed at which plane can become airborne

Question 16

What would happen if takeoff speed were too low?

Answer 16

plane stalls & very low initial rate of climb

Question 17

What would happen if takeoff speed were too high?

Answer 17

initial rate of climb better, but require LONGER takeoff distance

Question 18

What does a plane’s climb performance depend on?

Answer 18

reserve thrust & reserve power

Question 19

Climb Performance

V_X

Answer 19

greatest gain in altitude for distance traveled on the ground (clear obstacles)

(most reserve thrust)

Question 20

Climb Performance

V_Y

Answer 20

greatest gain in altitude over a period of time

(most reserve power available)

Question 21

What variables affect climb performance?

Answer 21

Weight, altitude

Question 22

How does weight affect climb performance?

Answer 22

increase weight → plane must fly at greater AOA to maintain given altitude/speed

Question 23

How does altitude affect climb performance?

Answer 23

increase power required for climb & decrease in power available

(greater altitude = higher V_X lower V_Y)

Question 24

Range

Answer 24

ability of plane to convert fuel energy into flying distance

Question 25

**Power**

Answer 25

work per unit time

Question 26

Cruise is based on what % of power?

Answer 26

65%

Question 27

What does a **quartering** crosswind mean?

Answer 27

directly across runway

Question 28

Does the landing distance change at different altitudes & temperature? If so why?

Answer 28

Yes b/c change in air density

Question 29

Does the **indicated airspeed** for landing change at different altitudes & temperature? If so why?

Answer 29

No

Question 30

General rule for approximating landing distance based on density altitude?

Answer 30

add 3.5% of landing distance for every 1,000ft of altitude

Question 31

**arm**

Answer 31

horizontal distance (in) from reference datum to CG

Question 32

**Basic empty weight**

Answer 32

standard empty weight + optional equipment installed

Question 33

**Center of gravity (CG)**

Answer 33

point of balance along longitudinal axis

Question 34

**CG limits**

Answer 34

extreme (forward & aft) CG locations within which plane must be operated at a given weight

Question 35

**Max ramp weight**

Answer 35

max weight approved for ground maneuvers

Question 36

**Moment**

Answer 36

force that tries to cause an object to rotate

Question 37

**Moment index**

Answer 37

moment divided by a reduction number (100 or 1000) make # smaller and reduce chance of mathematical errors in computing CG

Question 38

**Payload**

Answer 38

total weight of occupants, cargo, luggage

Question 39

Standard weights for gasoline, oil, and water?

Answer 39

* Gasoline: 6 lb / US gal * Oil: 7.5 lb / US gal * Water: 8.35 lb / US gal

Question 40

**Useful load**

Answer 40

diff between takeoff weight & basic empty weight

Question 41

**Total weight**

Answer 41

basic weight + everything loaded on it

Question 42

**Datum**

Answer 42

arbitrary point established by plane designers

Question 43

What should the pilot do before every flight?

Answer 43

determine weight & balance condition of aircraft

Question 44

Equation for **center of gravity (CG)**

Answer 44

total moments / total weight

Question 45

Equation for calculating **moment**

Answer 45

weight x arm = moment

Question 46

As air temperature increases, density altitude will

Answer 46

increase

Question 47

What effect does high density altitude, as compared to low density altitude, have on propeller efficiency and why?

Answer 47

Efficiency is reduced because the propeller exerts less force at high density altitudes than at low density altitudes.