POF - Air, Atmosphere and Airspeed

Question 1

What is humidity?

Answer 1

Humidity is a measure of how much water vapour is in the atmosphere.

Question 2

If the air temperature increases, what happens to the density?

Answer 2

The air density will decrease, due to it being inversely proportionate to temperate.

Question 3

How do we convert 1 knot into m/s?

Answer 3

We would multiple knots by 0.5144 to convert it to m/s.

Question 4

What errors must be fixed to go from IAS to CAS?

Answer 4

1. Instrument Errors: this is due to the IAS being mechanical so there will be inaccuracies.
2. Position Errors: the pitot tube may not always be aligned to the air flow, which will provide inaccurate readings.

Question 5

What gases (including percentages) is the dry air within our atmosphere made up of?

Answer 5

• Nitrogen (78%)
• Oxygen (21%)
• Other gases (1%)

Question 6

What is the formula for dynamic pressure?

Answer 6

Dynamic Pressure (Q) = 1/2•rho•V^2

Question 7

As altitude increases, what happens to static pressure?

Answer 7

Static pressure will decrease as the altitude increases.

Question 8

When the density level is in ISA conditions, what is the relationship between TAS & IAS?

Answer 8

TAS = IAS, when the density level is in ISA conditions.

Question 9

What is the definition of mass flow?

Answer 9

The amount of mass of air that flows through a given volume of space.

Question 10

If humidity of the air increases, what happens to the air density?

Answer 10

Air density will decrease due to vapour particles mixing with air particles.

Question 11

When the density level is below ISA conditions, what is the relationship between TAS and IAS?

Answer 11

TAS would be more than IAS.

TAS > IAS

Question 12

What is Air?

Answer 12

Mixture of different gases.

Question 13

What is the CAS?

Answer 13

It is is the Indicated Air Speed (IAS) corrected for instrument and position errors.

Question 14

What does mass flow depend on?

Answer 14

• Speed (the greater the speed, the greater the mass flow) - this is provided by a plane.
• Air density (the denser the air, the greater the mass flow) - this is provided by the location/altitude.

Question 15

How would we convert 567m/s into knots?

Answer 15

To convert m/s into knots, you would divide the m/s by 0.5144.

So: 567 / 0.5144 = 1,102.26 knots.

Question 16

What is dynamic pressure?

Answer 16

Dynamic pressure is a pressure that’s exerted onto a body due to it being in motion.

Question 17

What is the temperature at mean sea level (MSL) in ISA conditions?

Answer 17

15 degrees Celsius

Question 18

Air density is proportionate to _____________ and inversely proportionate to ______________

Answer 18

1. Pressure

2. Temperature

Question 19

If the air pressure increases, what happens to the air density?

Answer 19

The density of the air will also increase.

Question 20

What is fluidity?

Answer 20

The ability for a liquid/gas to flow.

Question 21

What is the density at mean sea level (MSL) in ISA conditions?

Answer 21

1.225kg/m^3

Question 22

When the density level is above ISA conditions, what is the relationship between TAS and IAS?

Answer 22

TAS would be less than IAS.

TAS < IAS

Question 23

What is the TAS?

Answer 23

The True Air Speed (TAS) is the Equivalent Air Speed (EAS) that’s corrected for density.

Question 24

What are the four types of Airspeeds?

Answer 24

IAS: Indicated Air Speed

CAS: Calibrated Air Speed

EAS: Equivalent Air Speed

TAS: True Air Speed

Question 25

Calculate the dynamic pressure:

TAS = 135 kts
rho = 1 kg/m^3

Answer 25

Dynamic pressure = 2,411 Pa

Question 26

What is the definition of static pressure?

Answer 26

Static pressure is pressure that’s exerted on an object from all given directions

Question 27

What is the EAS?

Answer 27

The Equivalent Air Speed (EAS) is the Calibrated Air Speed (CAS) that’s corrected for compressibility issues.

Question 28

How do we calculate airspeed?

Answer 28

We calculate airspeed by measuring the amount of dynamic pressure being exerted into the pitot tube.