5. Devices For Modyfing Lift And Drag

Question 1

What devices are used to modify lift?

Answer 1

TRAILING EDGE DEVICES
- Flaps
LEADING EDGE DEVICES
- Slots, slats, flaps
SPOILERS / AIRBRAKES

Question 2

Name 2 leading edge high lift devices?

Answer 2

Slats
Slots

Question 3

What are Spoilers?

Answer 3

Spoilers are small, hinged plates on the upper surface of wings.
The airflow over the wing is disturbed by the
spoiler, so the drag of the wing is increased,
and the lift is decreased.

Question 4

When are spoilers most frequently used?

Answer 4

On landing.

They are normally ‘armed’ during final approach and deploy automatically when weight and rotation is sensed on the landing gear.

Question 5

What affect will FAILURE of high lift devices have?

Answer 5

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

Question 6

How do flaps increase lift?

Answer 6

This difference in velocity results from the curvature, or ‘camber’ of the wing.
Camber is directly related to how much lift the wing produces.
By changing the shape of the wing, its increased camber will result in an increase in lift.

Question 7

What are speed brakes?

Answer 7

Used on some aircraft to increase drag without directly effecting lift

Question 8

What limits the use of Flaps and Slats?

Answer 8

Limited by the speed of the aircraft.
Deploying flaps beyond the ‘flaps extended’ or VFE speed could result in structural damage to the airframe.