TAV0013TAV0013BASIC AERODYNAMICBASIC AERODYNAMIC

Chapter 3:

Theory of Flight

Prepared by Zuliana Ismail for Diploma in Aircraft Maintenance, MSU

Chapter 3Chapter 3

Theory of FlightTheory of Flight

1.1.Lift AugmentationLift Augmentation

2.2.Wing PlanformsWing Planforms

3.3.Flight PhaseFlight Phase

4.4.High Speed FlightHigh Speed Flight

LIFT AUGMENTATION

Part 1

Lift Augmentation devicesLift Augmentation devices

Lift augmentation devices are used to Lift augmentation devices are used to increase the maximum lift coefficient increase the maximum lift coefficient (C(CLmaxLmax), in order to reduce the air speed at ), in order to reduce the air speed at take off and touchdown.take off and touchdown.

Devices used to augment CDevices used to augment CLmaxLmax

SlatsSlatsFlapsFlapsVortex GeneratorVortex Generator

Vortex GeneratorVortex Generator

a- SLATSa- SLATS

Slats - either automatic or controllable by Slats - either automatic or controllable by the pilot. the pilot.

With slats, CWith slats, CLmaxLmax may be increased by as may be increased by as much as 70%. much as 70%.

The effect of the slat is to prolong the lift The effect of the slat is to prolong the lift curve by delaying the stall until a higher curve by delaying the stall until a higher angle of attack.angle of attack.

The slat is use only at high angles of The slat is use only at high angles of attack , attack ,

b-FLAPSb-FLAPS

The operation of the flap is to vary the The operation of the flap is to vary the camber of the wing section. camber of the wing section.

The effect of flap is to increase the lift by The effect of flap is to increase the lift by increasing the camber increasing the camber

The flap is use at touch down and take-off.The flap is use at touch down and take-off.Types of flaps are either leading edge flap Types of flaps are either leading edge flap

or trailing edge flaps. or trailing edge flaps.

Types of FlapTypes of Flap

stalling angle: the angle relative to the stalling angle: the angle relative to the horizontal at which the flow of air around horizontal at which the flow of air around an aerofoil changes abruptly, resulting in an aerofoil changes abruptly, resulting in significant changes in the lift and drag of significant changes in the lift and drag of an aircraftan aircraft

trailing edge flap is lowered the angle of trailing edge flap is lowered the angle of attack for level flight is reduced. attack for level flight is reduced.

Effect of flaps and slats on LiftEffect of flaps and slats on Lift

c-VORTEX GENERATORc-VORTEX GENERATOR

A vortex generator (VG) is an aerodynamic surface , consisting of a small vane or bump that creates a vortex.

Vortex generators delay flow separation and aerodynamic stalling, thereby improving the effectiveness of wings and control surfaces.

WING PLANFORMS

Part 2

Wing planformsWing planforms Planform is the geometrical shape of the wing Planform is the geometrical shape of the wing

when viewed from above, and it largely when viewed from above, and it largely determines the amount of lift and drag obtainable determines the amount of lift and drag obtainable from a given area, it also has a pronounced from a given area, it also has a pronounced effect on the stalling angle of attack.effect on the stalling angle of attack.

Types of wing planforms:Types of wing planforms:Straight WingStraight WingSweepbackSweepbackDeltaDeltaSwingSwing

STRAIGHT WINGSTRAIGHT WING

Used on small, low-Used on small, low-speed airplanes.speed airplanes.

provide good lift at low provide good lift at low speeds, but are not speeds, but are not suited to high speeds. suited to high speeds.

However, the However, the straight wing provides provides good, stable flight. good, stable flight.

It is cheaper and can It is cheaper and can be made lighter, too.be made lighter, too.

SWEEPBACKSWEEPBACK

for high-speed flights.for high-speed flights.create less dragcreate less dragHeavier Structure Increased Additional

Loading Pitch up at stallnot very stable at low not very stable at low

speedsspeedsA B-52 Stratofortress showing wing with a

large sweepback angle.

DELTA WING DELTA WING (TAILLESS)(TAILLESS)

is a is a wing planform in the in the form of a triangle.form of a triangle.

so called "tailless delta", so called "tailless delta", i.e. without the horizontal i.e. without the horizontal tailplane..

gives the largest total gives the largest total wing area (generating wing area (generating useful lift) for the wing useful lift) for the wing shape, shape,

The adelta wing Avro Vulcan bomber

SWING WINGSWING WING During landing and takeoff, During landing and takeoff,

the wing swings into an the wing swings into an almost straight position.almost straight position.

During cruise, the wing During cruise, the wing swings into a sweepback swings into a sweepback position.position.

Aspect Ratio (A) Aspect Ratio (A)

Aspect ratioAspect ratio is a measure of how long is a measure of how long and slender a wing is from tip to tip.and slender a wing is from tip to tip.

The The Aspect RatioAspect Ratio of a wing is defined to of a wing is defined to be the square of the span divided by the be the square of the span divided by the wing area and is given the symbol wing area and is given the symbol AA

LOW AR Vs HIGH ARLOW AR Vs HIGH AR

Low aspect ratio High aspect ratio

LOW AR Vs HIGH ARLOW AR Vs HIGH AR

LOW ASPECT RATIO LOW ASPECT RATIO short and stubby short and stubby

wing.wing. More efficient More efficient

structurally and higher structurally and higher instantaneous roll instantaneous roll rate. rate.

They tend to be used They tend to be used by fighter aircraft. by fighter aircraft.

HIGH ASPECT RATIO HIGH ASPECT RATIO long and slender wing. long and slender wing. More efficient More efficient

aerodynamically,aerodynamically, having less induced having less induced

drag. drag. They tend to be used They tend to be used

by high-altitude by high-altitude subsonic aircraft.subsonic aircraft.

ExampleExample

Two wings with same span of 45 feet has Two wings with same span of 45 feet has an area of 265 square feet and 165 square an area of 265 square feet and 165 square feet, respectively. feet, respectively.

a)a) Calculate the aspect ratio for both wings.Calculate the aspect ratio for both wings.

b)b) Sketch their wing shapes. Sketch their wing shapes.

c)c) Compare both of the wings in terms of Compare both of the wings in terms of their aspect ratio and performance.their aspect ratio and performance.