ACFT - Devices for Modifying Lift & Drag

Question 1

What devices modify Lift & Drag? (3)

Answer 1

1. Trailing Edge devices - Flaps
2. Leading Edge devices - Slots, slats, flaps
3. Spoilers / Airbrakes

Question 2

What happens when you deploy Flaps? (2)

Answer 2

• Increases Lift
• Increases Drag

Question 3

What are the benefits of Flaps for Take-off? (3)

Answer 3

1. Generates lift for the A/C
2. Airborne at slower speeds
3. Reduces runway distance, and take-off time

Question 4

Why is it advantageous to use flaps for steeper climbs & approaches? (2)

Answer 4

• A steep descent requires less thrust, which reduces noise impact
• A greater angle of climb or descent enables better obstacle clearance

Question 5

B747 “Fowler” flap system diagram

Answer 5

Question 6

What types of Leading Edge devices are available? (4)

Answer 6

1. Leading edge slots
2. Leading edge slats
3. Leading edge flaps
4. Krueger flaps

Question 7

What are Spoilers? (3)

Answer 7

1. Small, hinged plates on the upper surface of wings
2. When the pilot activates the spoilers, the plates flip up into the air stream
3. Airflow over the wing is disturbed by the spoiler, so the drag of the wing is increased, and the lift is decreased

Question 8

How does the Failure of high lift devices effect A/C performance? (5)

Answer 8

1. Higher approach speed (needed to generate adequate lift)
2. Shallower approach and climb gradient (problems with obstacle clearance)
3. Longer take-off and landing roll (needed to attain and reduce speed)
4. Less efficient braking (hot brakes, tyre failures, runway excursion)
5. Flap asymmetry (results in rolling movement)