Density and Performance

Question 1

What is the standard that aircraft performance is normally based on?

Answer 1

ISA or International Standard Atmosphere

Question 2

What are the two main factors that affect air density?

Answer 2

Ambient temperature and pressure

Question 3

How does a higher density of air affect thrust??

Answer 3

Reduced thrust/power available

Question 4

How does a higher air density affect control effectiveness?

Answer 4

Reduces control effectiveness and stability

Question 5

How does a higher density altitude effect Groundspeed, turn radius, momentum?

Answer 5

• Increases groundspeed
• Increases turn radius
• Increases momentum

Question 6

What is SALR?

Answer 6

Saturated adiabatic lapse rate = 1.5/1000 ft

Question 7

What is DALR?

Answer 7

Dry adiabatic lapse rate = 3/1000 ft

Question 8

What is ELR?

Answer 8

The actual rate of change of temperature in the atmosphere

Question 9

What is ISA lapse rate?

Answer 9

2 C/1000 ft

Question 10

How does humidity effect air density?

Answer 10

Increased humidity reduces density

Question 11

What are the ISA values for pressure, density and temperature?

Answer 11

P  = 1013.25 hPa
T = 15 C
Density = 1.225 kg/m^2

Question 12

What is pressure altitude?

Answer 12

Altitude at which 1013 is set on the altimeter

Question 13

What is density altitude?

Answer 13

Pressure altitude corrected for non standard temperature