Basic Aerodynamic Theory

Question 1

Static pressure

Answer 1

• Ambient pressure
• Weight of the atmosphere
• No movement
• Felt equally on all surfaces

Question 2

Dynamic pressure

Answer 2

• Pressure due to movement

Question 3

Kinetic energy formula

Answer 3

1/2mv^2

Question 4

Symbol for density

Answer 4

• P (rho)

Question 5

What measures static and dynamic air pressure?

Answer 5

• Pitot tube
• Static vent / tube

Question 6

Dynamic pressure formula

Answer 6

1/2pV^2

Question 7

Total pressure =

Answer 7

Free stream static + dynamic pressure

Question 8

Calibrated to ISA conditions

Answer 8

• IAS and TAS only the same only under ISA conditions

TAS - actual speed

IAS - speed readily available to the pilot

Question 9

Different types of aerofoils

Answer 9

• General purpose
• High lift
• High speed

Question 10

Leading edge

Answer 10

• Front of wing

Question 11

Thickness

Answer 11

Width of aerofoil

Question 12

Chord line

Answer 12

From leading edge to trailing edge in the middle

Question 13

Mean camber line

Answer 13

• Like chord line but follows the shape of the aerofoil

Question 14

Angle of attack

Answer 14

• Angle between chord line and relative airflow

Question 15

Relative airflow

Answer 15

Airflow that remains undisturbed and unaffected by the aircraft’s movement.

Question 16

Angle of incidence

Answer 16

Angle that the aerofoil is attached to the fuselage.

Measured between the chord line and the aircraft’s longitudinal axis.

Question 17

Bernoulli’s Therorem

Answer 17

In a streamline flow of an ideal fluid, the sum of all energies present must remain constant.

Question 18

Bernoulli’s theorem equation

Answer 18

Dynamic pressure + static pressure = constant total pressure

Question 19

Streamline flow

Answer 19

• Air particles in a steady airstream, follow a predictable path

Question 20

Turbulent flow

Answer 20

If air is forced to change direction abruptly

Question 21

The Venturi effect

Answer 21

As air flows through the narrower throat, it accelerates and increases dynamic pressure. This creates an area of low pressure.

Question 22

Upwash

Answer 22

Air turns upwards before reaching an aerofoil.

Question 23

Downwash

Answer 23

Downward deflection of airflow behind an aerofoil, relative to the free stream direction, occurring as the aerofoil generates lift.

Effect extends some distance behind the aerofoil and intensifies with an increase in AoA.

Essential in lift production.

Question 24

Stagnation point

Answer 24

The point at the leading edge where air is completely stationary.

Question 25

Lift

Answer 25

A force. A component of the total reaction acting through the CoP and at 90 degrees to the relative airflow. In straight and level flight lift opposes weight.

Question 26

Line of zero lift

Answer 26

- The AoA where no net lift is produced. - Lift is acting equal and opposite to each other, cancelling each other out. - Approx. 4 degrees AoA - Generally occurs when doing aerobatic manoeuvres like vertical climb/dives.

Question 27

Centre of pressure

Answer 27

- Point on an aerofoil where the total magnitude and direction of the pressure is said to act

Question 28

Movement of CoP and TR with angle of attack

Answer 28

- Shifts forward as the angle increases - Critical AoA = 16 degrees - beyond stall point, CoP moves swiftly rearward