081.01 SUBSONIC AERODYNAMICS .01 (basics)

Question 1

Taper ratio is the ratio of (tip/root) chord to (tip/root).

Answer 1

Taper ratio is the ratio of (tip) chord to (root).

- Taper Ratio: Tip/Root -

Question 2

Angle of incidence is the angle between (…) and (…).

Answer 2

• Angle of incidence* is the angle between (aeroplane longitudinal axis) and (wing root chord line).
  source: https://en.wikipedia.org/wiki/Angle_of_incidence_(aerodynamics)#/media/File:Aircraft_Angle_of_Incidence_(improved)–1080x660–25Mar2009.jpg

Question 3

Angle of attack of a wing is the angle between (…) and (…).

Answer 3

Angle of attack is the angle between (chord line) and (relative airflow).

source: https://aviation.stackexchange.com/questions/21799/why-does-the-vortex-created-by-wing-affects-its-own-angle-of-attack

Question 4

Wing loading is (…) devided by(…). The unit is (…).

Answer 4

Wing loading is (aircraft weight) devided by (wing area). The unit is (N/m²).

Question 5

Aspect ratio = (…) ÷ (…)

or

Aspect ratio = (…) ÷ (…)

Answer 5

Aspect ratio = (wingspan²) ÷ (wing area)

or

Aspect ratio = (wingspan) ÷ (mean geometric chord)

Question 6

List the SI unit for the following:

• mass
• acceleration
• weight
• velocity

Answer 6

List the SI unit for the following:

• mass = kg (kilogram)
• acceleration = m/s² (meter per second squared)
• weight = N (newton)
• velocity = m/s (meter per second)

Question 7

List the SI unit for the following:

• energy
• density
• temperature
• pressure

Answer 7

List the SI unit for the following:

• energy = J (joule)
• density = kg/m³ (kilogram per cubic meter)
• temperature = K (kelvin)
• pressure = Pa (pascal) → non-SI units: PSI (pounds per square inch)

Question 8

List the SI unit for the following:

• force
• wing loading
• power

Answer 8

List the SI unit for the following:

• force = N (newton)
• wing loading = N/m² (newton per meter squared)
• power = W (watt) → non-SI units: J/s (joules per second) = Nm/s (Newton meter per second)

Question 9

kg•m/s² is expressed in the SI-unit system as (…).

Answer 9

kg•m/s² is expressed in the SI-unit system as (Newton).

Question 10

Dihedral of a wing is the angle between the (leading edge/trailing edge/quarter chord line) of the wing and the (horizon/vertical axis/lateral axis).

Answer 10

• Dihedral* of a wing is the angle between the (0.25 chord line) of the wing and the (lateral axis).
• “The angle between the wing plane and the horizontal with the aeroplane in an unbanked, level condition.”*
  source: https://nl.pinterest.com/pin/703617141762264820/

Question 11

Wing sweep angle is the angle between the (leading edge/trailing edge/quarter chord line) of the wing and the (horizon/normal axis/lateral axis).

Answer 11

• Wing sweep angle* is the angle between the (quarter chord line) of the wing and the (lateral axis).
  source: https://aviation.stackexchange.com/questions/4992/why-are-swept-wings-better-for-breaking-the-sound-barrier

Question 12

An aeroplane’s angle of attack can be defined as the angle between its (longitudinal axis/lateral axis/speed vector) and (horizontal plane/longitudinal axis).

Answer 12

An aeroplane’s angle of attack can be defined as the angle between its (speed vector) and (longitudinal axis).

Question 13

State he formula for dynamic pressure (q).

Answer 13

½ • ρ • v²

Question 14

State Bernoulli’s equation for incompressible flow.

Answer 14

P_s + ½ • ρ • v² = constant

Question 15

Mean geometric chord of a wing is the (aspect ratio/wing area/wingspan²) divided by (wingspan/wing area/ taper ratio).

Answer 15

Mean geometric chord of a wing is the (wing area) divided by (wingspan).

Question 16

relative thickness of an aerofoil is expressed in (meters / % chord / camber).

Answer 16

relative thickness of an aerofoil is expressed in (% chord).

Question 17

Define indicated airspeed (IAS) and how it is derived.

Answer 17

Airspeed read directly from the airspeed indicator. It uses the difference between total pressure and static pressure.

Question 18

TAS is IAS corrected for (instrument/position/compressibility/density) error(s).

Answer 18

TAS is IAS corrected for (instrument, position, compressibility and density) errors.

Question 19

EAS is IAS corrected for (instrument/position/compressibility/density) error(s).

Answer 19

EAS is IAS corrected for (instrument, position and compressibility) errors.

Question 20

CAS is IAS corrected for (instrument/position/compressibility/density) error(s).

Answer 20

CAS is IAS corrected for (instrument and position) errors.

Question 21

State Newton’s first law.

Answer 21

A body will remain a rest or in uniform motion unless acted on by an external force

Question 22

State Newton’s second law.

Answer 22

The force on an object is equal to its mass times its acceleration (F = m • a)

Question 23

State Newton’s third law.

Answer 23

Every action has an equal and opposite reaction.

Question 24

Compared to a two-dimensional airflow, in a three-dimensional airflow a (…) component exsist in addition to the chordwise speed component.

Answer 24

Compared to a two-dimensional airflow, in a three-dimensional airflow a (spanwise) component exsist in addition to the chordwise speed component.

- from wing root to wing tip -

Question 25

Lift acts perpendicular to (…).

Answer 25

Lift acts perpendicular to (the relative airflow).

Question 26

If an aerofoil has a positive pitching moment, the AoA (increases/decreases).

Answer 26

If an aerofoil has a positive pitching moment, the AoA (increases).

Question 27

A symmetrical aerofoil has (no/a positive/a negative) pitching moment at zero lift.

Answer 27

A symmetrical aerofoil has (no) pitching moment at zero lift.

Question 28

A positively cambered aerofoil has (no/a positive/a negative) pitching moment at zero lift.

Answer 28

A spositively cambered aerofoil has (a negative) pitching moment at zero lift.

Question 29

A negatively cambered aerofoil has (no/a positive/a negative) pitching moment at zero lift.

Answer 29

A negatively cambered aerofoil has (a positive) pitching moment at zero lift.