Aerospace Engineering Design and Project Management 8

8/10/2019 Aerospace Engineering Design and Project Management 8

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Aerospace Engineering Designand Materials

Prof Jian Wang

07/11/2013


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Chapter 5

Fuselage, Wing & Tail Layout

Practice

Provoke critical think

Get the sense of differences between creative design and classical designmethods

Learning Outcomes

Provide initial consideration of the overall criteria for fuselage design

Provide the knowledge about Fuselage layout

Provide information of size the passenger cabin & other issues for fuselage design

Provide knowledge about wing design parameters in the early stage

Describe how the wing and tail surfaces are defined

Present differences of tail design from wing design

Students should

Understand the considerations of overall criteria for design

Understand design parameters

Understand conventional design procedures

Can perform concept of fuselage and wing

Aerodynamic,

stability/controlstructure requirements


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Chapter 5


Introduction

Fuselage Layout

Passenger Cabin

Forward Fuselage

Rear Fuselage

Wing LayoutParameter Definition

Aspect Ratio

Aerofoil Section

Sweep

Taper Ratio

Thickness/Chord Ratio

Tail Layout

Tail Planform Geometry

Sizing by Tail Volume Coefficient

Content

Incidence

Dihedral

Wing Twist

High-Lift Devices

Lateral Control Surfaces


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Chapter 5


Aim & Purpose

This chapter starts our detailed consideration of the main

component parts of the aircraft.

Configuration

Characteristic parameters

Procedures

Outline

Fuselage: Container, Carrier

Wing: Lifting force providerTail: Controlling structure

Notes

Experience

Information

Introduction


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Chapter 5


Overall Parameters

Aircraft Type lf/df lfc/df fco

Business Jets 79.5 2.55 611

Regionals 5.610 24 1519

Jet Transports 6.811.5 2.64 1116

Supersonics 1225 68 29

Fuselage


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Chapter 5


Two geometrical parameters:

Diameter&Length

Layouts

PassengersDifferent classes

Seat size

Aisle arrangement

Service facilities (galleys, toilets and wardrobes)

Regulations: minimum dimensions

Loads: under floor baggage/cargo spacecontainer/pallet

Procedures

Shape of the fuselage cross-section

Number of seat abreast

Number of rows

Arrangement plan

Safety considerations: number of doors (search forinformation)

Passenger

Cabin


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Chapter 5


Elements

Flight deck (cockpit)

Front pressure bulkhead

Forward-looking radar

Nose landing gearCockpit

Working environment for the flight crew

The view of the pilot

Accommodation for the equipments

Safety of the crew

Smooth transition from the constant cross-section cabinto the forward fuselage

ForwardFuselage


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Chapter 5


Four musts

Smooth transitiondrag consideration

low side Swept uptake-off consideration

Enough strength: for supporting the tail surface/rear engine

Housing rear pressure bulk

Four noting points

A bluff rear fuselage shape has high drag and is to be avoid

For manufacturing purposes, conical shape rear fuselage

For moderate angles of up-sweep (up to about 12) theaerodynamic implications are small

Base area (any un-faired rearward facing blunt area) causesconsiderable base drag and should be avoided if possible

Fineness ratio: length of the rear section divided by thecabin diameter

RearFuselage


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Chapter 5


300 seats with 3 classes

The business/first classes are each 29 in (737 mm); aisles 28.5 in (742mm)

Economy class: 23.75 in (603 mm), aisles 20.5 in (521 mm)

Diameter= 6*737+2*742+2048=6.11 m

Length

Economy= 30 seat rows @ 36 in pitch=1080 (27.43 m)

Business= 8 seat rows @ 40 in pitch= 320 (8.13 m)

First = 2 seat rows @ 60 in pitch=120 (3.05 m)

Example

Total 38.6 m


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Chapter 5


Specialised knowledgeAerodynamics

Low speed

High speed

StructureDesign

Stress analysis

Staticdynamic

System/Control

Manufacturing

Materials

The wing placement relative to fuselage

AerodynamicsStructural

Wingfuselage attachment

Effects on cabin

Ground clearance of wing mounted engines

Service of wing mounted engines

WingLayout What affect

the wing

placement?


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Chapter 5


Undercarriage configurationSafety in the event of the aircraft striking the ground/ditching

Effects on passengers (such as cabin noise)

Primary parameters

Gross area

Aspect ratio (wing span2/area)

Aerofoil section(s)

Sweep (normally taken at chord)

Taper Ratio (tip chord/root chord)Thickness/Chord Ratio(max aerofoil section thickness to chord ratio

Additional issues

Wing mounting position relative to aircraft (high, mid, low)

Engine(s) location (if mounted on the wing)

Landing gear location/storage (if mounted on the wing)

High lift devices

Control surface for lateral control

WingLayoutContinued

Incidence

Dihedral

Wing TwistHigh-Lift Devices

Lateral Control Surfaces


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Chapter 5


Parameter definition

WingLayout

Continued

Wing aspect ratio

Taper ratio

S

bARA

2

)(or

r

t

c

c


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Chapter 5


WingLayoutContinued

- 2

b

0

2dycS

2cMAC

Examplestraight tapered wings

1

1c

3

2c

2

r

trapezoid


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Chapter 5


Aspect ratioDetermined at initial sizing stageleading to take off weight/wing area

Affects: drag, lift curve slop, span and weight

No trade study at the moment

Aerofoil section

Generated using CFD techniques; very sensible information

Our actions: select one of the NACA or NASA aerofoil

Aerofoil design parameters:

CLMAX

Lift-curve slop, a

CDat designed CL

Overall Aerodynamic characteristics of aerofoil: designed to provideacceptable compromise between

High lift L/D

Good climb performance

Good low speed lift, etc.

Critical Mach number, MCR

Pitching moment coefficient, CM(c/4)

Incidence for zero lift

WingLayoutContinued


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Chapter 5


Sweep typeZero sweep

Sweep back

Forward sweep

Sweep back

1535

Delay the drag

Reduce the pickdrag coefficient

Choice of sweep

angleWing section(aerofoil type)

Section thicknessto chord ratio

WingLayoutContinued


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Chapter 5


Taper ratioDefinition: (Tip chord)/(Aircraft central line root chord)

Ideal shape of wing planform: Elliptical Wing

Manufacturing complexities

Straight tapered planform

Simpler to manufactureTaper ratio=0.4-0.5, 2-3% less efficient than Elliptical Wing

Structural considerationbending moment: taper

Bending moment reduced to zero at wing tip

Constant stress designreduce the depth of the spar

If the same section all along the spanreduce the chord

Aerodynamic considerationtip stall

Main drawback for low taper ratiotip stall (possibly) at high angle ofattack

Twist wing section to fix the problem

WingLayoutContinued

Adequate wing tip

stiffness and sufficient

chord for ailerons


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Chapter 5


Thickness/Chord ratio

Definition:Not a constant usually:

Structural (minimum weight) and volumetric criteria: larger as possibleMore fuel

Bending and shear efficient

Aerodynamic consideration: thinner as possibleLower drag coefficient

Delay the onset of drag-rise due to shock formation

What you do

Using figure

Using equation

Wing

LayoutContinued

387.1)18.01195.0(

)10431.0(877.0 42

nL MCT des

qS

WWC FTOLdes

)4.0(


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Chapter 5


Incidence

Fuselage: angle of attackfor minimum dragWing: angle of attackfor designed lift coefficientLargely dependent on the wing sectionRefer to Table 2

DihedralProvide roll stabilitySweep back contributes to lateral stability: roughly 10% dihedral

Forward wing needs increased geometric dihedralHigh wing, high swept winged aircraft require anhedral

Select a value based on statistical data

Wing

LayoutContinued


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Chapter 5


Wing twist

Affect mainly wing-tip stall

Positive or negative

Brief discusses the purpose

High-lift DevicesReviews & discusses existing design

Discusses their respective geometries (flap chord, flap span)

Using information you obtained

Lateral control surfaces

The same applies to control surface as to high-lift devices

Wing

LayoutContinued


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Chapter 5


OverallTail design is an iterative procedure

Initial sizing method: ta il volum es

Tail configuration goes first

TailLayout


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Chapter 5


Tail Plan-form Geometry

Horizontal stabiliserpitch & rollAspect ratio

Sweep angle

Thickness ratio

Dihedral angle

Incidence angle

Control surface sizeNotes for Horizontal stabilizer

Similar to wing design

Sweep & thickness ratio are selected: Mcrit=0.05 higher than wing

Avoid jet efflux

Avoid deep stall

For canards: stalls before the wing & not alter dramatically when laminar

becomes turbulentVertical Stabilizeryaw

Select a NACA symmetrical section

Spin recovery

Their locations related to fuselage

Estimation of the required area

TailLayoutcontinued


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Chapter 5


TailLayoutcontinued

Deep stall

Sizing by tail volume coefficient

Counters the moments of each other

Proportional to area arm

Volume coefficient: a degree of consistency

Tail & wing

Tail

effectiveness

Volume

coefficient


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Chapter 5


Sizing by tail volume coefficient continued

Definitions:Tails moment arm

Areas of horizontal and vertical stabilisers

Equations 1 and 2

Your move:

Experiences:Information & knowledge

of existing aircraft

Tail

Layoutcontinued

H

H

H VL

ScS

V

V

V VL

bSS

(1)

(2)

Determine MACPosition chord

point

CG position

Iterate if necessary

Ch


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Chapter 5


Wing Data:

Roskam II pp143148

Notes and PowerPoint slides

Jenkinson

Aerospace Engineering Design and Project Management 8

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