Lift Augmentation

Question 1

What is the benefit of lowering flap on an aircraft?

Answer 1

Lowering flap will reduce the Vs of the aircraft
Generate more lift at low speeds (good for takeoff)
Reduce the nose attitude at low speed, as more lift is produced
Fly a steeper approach due to more drag
reduce the landing ground roll due to more drag

Question 2

What does leading edge flap do?

Answer 2

The leading edge flap has the same effect as lowering trailing edge flap. Only if used alone, it will increase the stalling AOA.

Question 3

What is the purpose of slots and slats?

Answer 3

When a slat is deployed at high AOA’s, a slot is formed between the slat and the aerofoil. This allows airflow to travel through the slot and re-energise the boundary layer, thus delaying separation and therefore the stall.

Slats/slots increase both the CL max and the stalling AOA.

Question 4

What is the effect of lowering trailing edge flaps?

Answer 4

Lowering trailing edge flaps will increase camber, and therefore lift.

This will result in greater CL max and Cl values.

Drag is also increased, resulting in a decreased L/D ratio.

Centre of pressure moves rearwards.

Geometric stalling AOA is reduced, as the nose is lowered to compensate for more lift being produced in level flight.

Question 5

What are the 2 types of leading edge flaps?

Answer 5

Leading Edge Droop
Krueger

Question 6

What are the different types of flaps in ascending order of CL max.

Answer 6

Basic Flap
Split Flap
Slotted Flap
Fowler Flap

Question 7

What is the effect of deploying slats and slots.

Answer 7

Increased CL max and stalling AOA.