Atmosphere

Question 1

What’s density?

Answer 1

The number of molecules and how closely packed they are in a given volume of a substance or mass per unit volume.

Question 2

How does density affect AC performance?

Answer 2

Lower density can reduce lift and engine efficiency whereas higher density can increase lift and engine efficiency.

Question 3

Best weather conditions for favorable density?

Answer 3

High pressure
Low humidity
Low temperature

Question 4

How does humidity affect density.

Answer 4

Humidity is the amount of water vapour in the air. Water vapour has less mass then molecules of dry air therefore reducing its density.

Warm air typically contains more WV then cool so at higher humidities density changes can become significant.

Question 5

What’s the most important determinant of how well an aircraft an its engine can perform?

Answer 5

Temp and pressure have the biggest affect as they are what combine to represent density which significantly influences aerodynamic performance.

Question 6

How does density affect the IAS/TAS relationship?

Answer 6

Density affects the Indicated Airspeed (IAS) and True Airspeed (TAS) relationship. At higher altitudes with lower density, IAS reads lower than TAS due to reduced air density impacting the pitot-static system, which measures IAS.

Question 7

What effects the aircraft more per unit pressure or temp?

Answer 7

Temp as the lapse rate for it is 1º per 120ft whereas pressure is only 1hPa per 30ft