現(xiàn)代飛行器設(shè)計(jì)理論-1

航空宇航學(xué)院Planform

Sh and

GeometryIntroductionGeometry

of

wing

planform

is

mainlydetermined

by

high

speed

considerationsPrimary

planform

parametersAspect

ratioT r

ratioSweep航空宇航學(xué)院Planform

Sh and

GeometryOther

parameters

of

wing

geometryDihedral(上反角）Angle

of

incidence（機(jī)翼安裝角）Twist

（機(jī)翼扭轉(zhuǎn)角）Secondary

planformWinglet

(翼梢小翼)Strake

(邊條翼)Cranked

trailing

edge航空宇航學(xué)院Aspect

ratio,

A

and

Wing

Span,

bDefinition– A

=b2/SS:

reference

wing

area航空宇航學(xué)院Aspect

ratio,

A

and

Wing

Span,

bConsiderations

in

terms

of

aerodynamics– The

effect

on

lift

slop: increase

of

aspect

ratio

A

results

inincrease

of

lift

slop

CL航空宇航學(xué)院Aspect

ratio,

A

and

Wing

Span,

bConsiderations

in

terms

of

aerodynamics

(cont’d)The

effect

on

dragIncrease

of

A

decrease

of

drag

duo

to

liftfor

subsonic

flightic

flightIncrease

of

A

increase

of

wave

drag

for

suThe

effect

on

angle

of

attack

at

stallingIncrease

of

A

decrease

of

angle

of

attack

at

stallingDecrease

of

A

mitigating

possibility

of

tip

stallThe

effect

on

stability

and

controlDecrease

of

A

reduction

of

the

variations of

A.C.

movementfrom

subsonic

to

su ic

flightDecrease

of

A

reduction

of

roll

dam航空宇航學(xué)院Aspect

ratio,

A

and

Wing

Span,

bConsiderations

in

terms

of

structuresIncrease

of

A

increase

of

bending

moment

at

root

increaseof

structure

weightDecrease

of

A

increase

of

root

chord

length

increase

ofchord

thickness

ease

of

structural

layoutConsiderations

in

terms

of

volumesDecrease

of

A

is

beneficial

for

provision

of

landing

gear

stowageDecrease

of

A

increase

of

fuel

volumeThe

selection

of

ACompromise

among

aerodynamics,

structures

and

volumes航空宇航學(xué)院Aspect

ratio,

A

and

Wing

Span,

bTypical

values

of

AFor

subsonic

aircraft: 5

10For

su ic

aircraft: 2

5Data

of

Some

regional

transportsAircraftpassengerspan（m）Wing

area（

m

2）ARJ7070~8526.377.38.95CRJ700ER66

~7823.368.77.90ERJ170LR7026.072.89.29728JET70~8526.675.09.43Forker7070~7928.793.58.69航空宇航學(xué)院Aspect

ratio,

A

and

Wing

Span,

bLimitation

of–

Naval

aircraft–

Airport

gatesum

span

b航空宇航學(xué)院T r

ration,

Definition

=

Ctip/Croot航空宇航學(xué)院T r

ration,

Considerations

in

terms

of

aerodynamicsSemi-elliptical

spanwise

airload

distributionIdeally,

elliptical

planform,

or

=0.4Considerations

in

terms

of

structures– Low

value

of

(high

t )

isbeneficial航空宇航學(xué)院T r

ration,

t

configurationsred

wing

for

simplicity

ofTypical

valuesof

– 0.1

0.6Higher

values

for

higher

A,

unIn

some

lightaircraft

design,

untconstructionCautions

on

unduly

highly

tred

wingHigh

local

lift

loading

tip

stallingDifficult

for

modation

of

aileronsA

guide

for

minimum

value

of

0.2

A1/4

cos21/4航空宇航學(xué)院SweepDefinition–

1/4–

LEWhy

is

wing

s t

?AerodynamicreasonTo

raise

the

critical

Mach

number

ofcompressibility

drag

(wave

drag)Layout

reasonsC.G.

locationwing

and

reduceprovision

of

stowage

volume

for

landing

gear航空宇航學(xué)院SweepIn

terms

of

structuresIncrease

of

wing

structure

(structural

penalty)In

term

of

controlPitch

up

(control

penalty)A

general

ruleKeep

sweep

as

low

as

possible航空宇航學(xué)院SweepEffect

of

sweep

at

high

subsonic

Mach

number(

MNCRIT

)3D/

(

MNCRIT

)2D

=

1

/(cos1/4)1/20o

1/4

35o(

MNCRIT

)3D/

(

MNCRIT

)2D

=

1

/

(

cos1/4)0.61/4

45o航空宇航學(xué)院SweepEffect

of

sweepat

high

subsonicMach

number航空宇航學(xué)院Summary

of

Typical

Wing

Geometry航空宇航學(xué)院DihedralDefinitionthe

upward

angle

of

the

wingfrom

the

horizontal

whenseen

from

the

front.Why

dihedralNatural

lateralstatic

stabilityLayout

requirementsGround

clearance

for

Wing-mounted

powerplant,

stores,fuel

system航空宇航學(xué)院DihedralMajor

contributions

to

positive

lateralstatic

stabilityWing

position

vertically

on

the

fuselageIt

is

beneficial

when

wings

are

located

abovethe

center

of

gravitySweep

back

of

the

wingDihedral航空宇航學(xué)院DihedralAircraft

typeWing

positionlowmidhighunsweep5o~7o2o~4o0o~2oS

t(subsonic)3o~7o-2o~2o-5o~2oS

t(su

ic)0o~5o-5o~0o-5o~0oTypical

valuesTypical

DihedralLess

dihedral

for

high

wingLess

dihedral

for

s t

wing航空宇航學(xué)院Angle

of

incidencetypical

valuestransport

jet：

1o~5.3ofighter：

-1o~3.6oDefinitionThe

angle

between

longitudinal

axis

and

airfoil

chord

line

atthe

root

section

of

the

wing.Designconsiderationsimpact

on

takeoff

distanceimpact

on

drag

at

cruise；航空宇航學(xué)院WingletWhy

wingletTo

reducedrag

due

to

liftWhen

winglet

usedAn

existing

design

is

being

developedThere

is

an

operation

wing

span

limitA330航空宇航學(xué)院StrakeWhat

is

strake

？航空宇航學(xué)院Strake(邊條翼）Why

strake–

Generate

vortex

liftvortex

lift航空宇航學(xué)院StrakeApplicationsF-16Su-27航空宇航學(xué)院Cranked

Trailing

EdgeWhy

the

trailing

edge

is

crankedTo

provide

structure

to

attach

the

landing

gearAdditional

chord

lowers

the

section

lift

coefficient

at

root,

wherewing-fuselage

interference

can

be

a

problem,

and

lower

requiredsection

lift

makes

the

design

job

easier.Boeing

757-200航空宇航學(xué)院Interaction

between

aerodynamics,structural

and

wing

volume

considerationsConsiderations

of

Spar

positionsDefinition

of

Leading

edge

and

trailing

edgeStructural

efficiencyFuel

volumeWing

box

usually

is

used

for

fuel

.420bS(t/c)(1-0.89+0.49

2)/AIf the

fuel

volume

is

not

meet

requirement,

we

should:Increase

wing

area,

or

decrease

aspect

ratio?Increase

thickness/chord

ratio

with

higher

sweep

?Need

an

optimum

solution

!航空宇航學(xué)院Interaction

between

aerodynamics,structural

and

wing

volume

considerationsStructure

massLow

wing

mass

is

associatedwith:Low

values

of

aspect

ratioLow

values

of

sweepHigh

thickness/chord

ratioLow

t r

ratioDeterminations

of

those

parameters

is

abetween

aerodynamic

and

structural

requirements.Need

compromise

and

optimization

amongaerodynamics,structures

and

fuel

volume

!Multidisciplinary

Design

Optimization

(MDO)航空宇航學(xué)院Wing

Area

(Wing

Loading)Four

fundamental

parametersTake-off

weightThrust

to

weight

ratioWing

loadingLift

to

drag

ratioWhy

they

are

fundamentalThe

performance

is

mainly

determined

bythose

parameters航空宇航學(xué)院Wing

Area

(Wing

Loading)Selection

of

the

parametersBy

the

performance

require