Drag

Question 1

What does skin friction drag + form drag equal?

Answer 1

Profile drag

Question 2

What does a low Reynolds number indicated about shere/viscous forces?

Answer 2

High forces.

Question 3

In laminar flow, what level is the Reynolds number?

Answer 3

Low.

Question 4

What does inertial forces over viscous forces give you?

Answer 4

Reynolds number.

Question 5

What happens to the laminar flow on a wing if the maximum thickness is moved backwards?

Answer 5

More likely to occur on more of the wing.

Question 6

What happens to the position of the transition point as the angle of attack increases?

Answer 6

It moves forward.

Question 7

How is the coefficient of lift and velocity proportional?

Answer 7

CL & 1/v^2

Question 8

How is the stall speed proportional to weight?

Answer 8

Vstall & -/weight

Question 9

How do you measure the load factor?

Answer 9

Lift/weight.

Question 10

Why does form drag occur?

Answer 10

Due to pressure gradient.

Question 11

By reducing the frontal area of an aircraft, you can reduce what type of drag?

Answer 11

Form drag.

Question 12

What is free stream flow?

Answer 12

Air not affected by an aircraft.

Question 13

What would you say about turbulent airs velocity gradient?

Answer 13

Steep velocity gradient.

Question 14

Compared to laminar flow, does turbulent flow have more or less energy?

Answer 14

More energy.

Question 15

What type of airflow is less likely to cause stalling?

Answer 15

Turbulent flow.

Question 16

Why does the air have to be turbulent post the point of max thickness?

Answer 16

Pressure gradient opposes the airflow.

Question 17

What happens if the air travelling over the wing losses more energy than the energy needed to oppose the adverse pressure gradient shere forces?

Answer 17

Seperation.

Question 18

What type of airflow is resistant against separation?

Answer 18

Turbulent airflow.

Question 19

Given a constant load factor, which of these statements about the variation of induced drag with changes of speed and mass are correct or incorrect?

1. When speed decreases, induced drag decreases.
2. When mass decreases, induced drag increases.

Answer 19

Both incorrect.

Question 20

True or false : Assuming no flow separation, the strength of wing tip vortices increases as the angle of attack increases.

Answer 20

True

Question 21

What kind of drag will you find on a wing with no lift?

Answer 21

Parasite

Question 22

What is the point on the wing about which the pitching moment created by the lift does not change with changes in AoA.

Answer 22

Aerodynamic centre

Question 23

True or false : the aerodynamic centre cannot move.

Answer 23

True

Question 24

At subsonic flight, what percentage of MAC is the aerodynamic centre located at?

Answer 24

25%

Question 25

At supersonic flight, what percentage of MAC is the aerodynamic centre located at?

Answer 25

50%