Hands on experience with aircraft lift augmentation devices

1. LIFT AUGMENTATION
DEVICES
Submitted to:
Mr. Anshul Bansal
Submitted By:
Pradeep Parmar (14/611)

2. Contents
Introduction -- High Lift Systems
Flaps
Trailing edgeDevices
1. plain flap
2. split flap
3. Slotted flaps
4. Fowler flap
Leading edgeDevices
SLATS AND SLOTS

3. Introduction
• Lift augmentation system is a device installed on
the wing of an aircraft to produce an increase in
lift at a given speed.
• It can be installed on the leading edge of the wing
("leading edge slats") or on the trailing edge
("wing flaps").
• It is useful at low speed because it reduce the stall
speed (the plane can fly more slowly).

4. Flaps
Trailingedge Devices
1. plain flap
2. split flap
3. Slotted flaps
4. Fowler flap

5. plain flap
The plain flap changes camber to
increase lift, but its effect is limited by
additional flow separation which occurs when it
is deflected. The additional separation occurs
because the upper surface of the deflected flap
experiences a stronger adverse pressure gradient

6. SPLIT FLAP
split flap
The split flap deflects only the underside
of the trailing edge so that, while it creates a great
deal of pressure drag, it avoids the strong adverse
pressure gradient on its upper surface and
therefore keeps the flow attached slightly longer.
This gives the split flap slightly greater lift.

7. SLOTTED FLAP
Slotted flaps
A Slotted flaps have a gap or slot in them
to allow faster-moving air from the lower surface
to flow over the upper surface. The higher-energy
air from the slot gives the boundary layer more
energy to fight the adverse pressure gradient and
delay separation

8. FOWLER FLAP
Fowler flap
The Fowler flap moves aft to increase
the wing area before deflecting downward to
increase camber. Fowler flaps usually have
one or more slots to increase their
effectiveness.

9. SLATS AND SLOTS
Leading edge Devices

10. SLOTS AND SLATS
Slats: are auxiliary airfoils fitted to the leading edge
of the wing. At high angles of attack, they
automatically move out ahead of the wing. The
angle of attack of the slat being less than that of the
main plane, there is a smooth airflow over the slat
which tends to smooth out the eddies forming over
the wing. Slats are usually fitted to the leading edge
near the wing tips to improve lateral control.
Slots: are passageways built into the wing a short
distance from the leading edge in such a way that, at
high angles of attack, the air flows through the slot
and over the wing, tending to smooth out the
turbulence due to eddies.

11. LIFT AUGMENTATION EFFECTS ONCL

12. Relative Airflow
Basic ‘Clean’ Situation
α
EFFECT OF FLAP

13. EFFECT OF FLAP
Flap Lowered
α
Maintaining the Same Lift

14. AT STALL: WEIGHT = LIFT = CLMAX ½ρ V2
STALL S
IF THIS IS THIS IS
CONSTANT
MORE LESS
Critical Angle
With FlapCl Max More
α
CL
Nose
lower
at
Stall
Without Flap
Cl Max
EFFECT OF FLAP

15. Adding flaps gives
higher CLmax
CLmax
Anderson, J. D., Introduction to Flight, 4th Edition, page 315

16. THANK
YOU