fuselagem design

1Fuselage Design

ITA 2009 – Version 10 - Prof. Bento S. de Mattos

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Functions of FuselageFunctions of Fuselage

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Functions of fuselage: provision of volume for

payload (passengers & cargo).

provide overall structural integrity.

possible mounting of landing gear, powerplant and antennas.

Functions of FuselageFunctions of Fuselage

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Primary Primary ConsiderationsConsiderations


Primary considerations when designing the airplane's fuselage are as follows:Primary considerations when designing the airplane's fuselage are as follows:

• Low aerodynamic drag

• Minimum aerodynamic instability

• Comfort and attractiveness in terms of seat design, placement, and storage space

• Safety during emergencies such as fires, cabin depressurization, ditching, and proper placement of

emergency exits, oxygen systems, etc.

• Ease of cargo handling in loading and unloading, safe and robust cargo hatches and doors

• Structural support for wing and tail forces acting in flight, as well as for landing and ground operation forces

• Structural optimization to save weight while incorporating protection against corrosion and fatigue

• Flight deck optimization to reduce pilot workload and protect against crew fatigue and intrusion by

passengers

• Convenience, size, and placement of galleys, lavatories, and coat racks

• Minimization of noise and control of all sounds so as to provide a comfortable, secure environment

• Climate control within the fuselage including air conditioning, heating, and ventilation

• Provision for housing a number of different sub-systems required by the aircraft, including auxiliary power

units, hydraulic system, air conditioning system, etc.

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Layout ProcedureLayout Procedure

Primary DecisionsPrimary Decisions

Pressurization requirements or not?

Affects fuselage section

Powerplant system internally mounted or not?

If yes then dominant effect

Does payload occupy most of the fuselage volume?

If yes then use payload as starting point for fuselage layout.

Are there any special considerations?

twin boom, flying boat, V/STOL, etc.

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Local Layout DecisionsLocal Layout Decisions

Vertical location of wing

Low, mid or high?

Horizontal tail surface location

Fuselage or fin?

Landing gear mounting/stowage required on fuselage?

Fuel tanks in fuselage?

Avionics location?

APU accommodation?

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Layout ModulesLayout Modules

Follow on from primary & local layout decisions.

May be considered separately & then matched together

to form unified fuselage layout.

Aim of integration is to derive fuselage configuration

which makes most use of total internal volume with

appropriate aerodynamic form & minimum of structural

difficulties.

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Layout Modules (Cont.)Layout Modules (Cont.)

Modules include:

payload

powerplant installation

crew compartment

wing carry-through box structure

avionics volume, APU & air conditioning equipment

landing gear stowage & mounting

tail section

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Common practice is to modularize layout:Common practice is to modularize layout:

crew compartment, powerplant system, payload

configuration, fuel volume, landing gear stowage,

wing carry-through structure, empennage, etc.

or simply into front, center and rear fuselage section

designs.


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Primary ConsiderationsPrimary ConsiderationsEE--170 Fuselage Sections170 Fuselage Sections

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Primary ConsiderationsPrimary Considerations

Most of the fuselage volume is occupied Most of the fuselage volume is occupied

by the payload, except for:by the payload, except for:

Single & two-seat light a/c.

Trainer & light strike a/c.

Combat a/c with weapons carried on

outer fuselage & wing.

High performance combat a/c.

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Payload includes:Payload includes:

Passengers & associated baggage.

Freight.

Internal weapons (guns, free-fall bombs, bay-

housed guided weapons.

Crew (significant for anti-sub and early-

warning a/c).

Avionics equipment.

Flight test instrumentation (experimental a/c).

Fuel (often interchangeable with other payload

items on a mass basis).


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Access Panels

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PressurizationPressurization

If required, has a major impact upon overall shape.

Overall effect depends on level of pressurization required.

Low Differential Pressurization

Defined as no greater than 0.27 bar (4 psi).

Mainly applicable to fighters where crew are also equipped with pressure suits.

Cockpit pressurization primarily provides survivable environment in case of suit failure at high altitude.

Also used on some general aviation a/c to improve passenger comfort at moderate altitude.

Pressure compartment has to avoid use of flat surfaces.


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Normal (High) Differential PressurizationNormal (High) Differential Pressurization

Usual requirement is for effective altitude to be no more

than 2.44 km (8000 ft) ISA for passenger transports.

Implied pressure differentials are:

0.37 bar (5.5 psi) for a/c at 7.6 km (25,000 ft).



High pressure differential required across most of

fuselage for passenger transports so often over-riding

fuselage structural design requirement.


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Normal (High) Differential Pressurization (Cont.)Normal (High) Differential Pressurization (Cont.)

Particular need to base outer shell cross-section on circular arcs to

avoid significant mass penalties.

Pure circular sections best structurally but “double-bubbles”

sometimes give best compromise with internal layout.

Circular

section

examples


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Fuselage Layout Fuselage Layout

Considerations Considerations -- TransportsTransports

“Double“Double--Bubble” Fuselage XBubble” Fuselage X--Section ExamplesSection Examples

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Cross SectionCross Section

ERJ 145 CRJ 200 DHC 8 Dornier 328

ATR 42 / 72 Saab 340 / 2000 EMBRAER 170/190

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Cabin Width & CrossCabin Width & Cross--SectionSection

DoubleDouble--Deck Airbus A380Deck Airbus A380

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PowerplantPowerplant LocationLocation

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If powerplant is located within fuselage, this is a

primary consideration for fuselage layout.

Three main powerplant arrangements affecting

fuselage layout.

Nose-mounted.

Central or central/rear location.

Rear fuselage location.


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NoseNose--Mounted EngineMounted Engine

Either piston or turbine-driven propeller.

Significantly influences geometry and cross-section of

front fuselage.


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Rear Fuselage Location Common for supersonic combat aircraft

with low aspect ratio wings.

Major advantage is reduced length of

exhaust tail pipe.

Wing carry-through structure passes ahead

of powerplant, easing access and removal.

Complicates design of empennage

attachment structure, though OK if a

canard configuration.


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WingWing--Mounted or FuselageMounted or Fuselage--Mounted Engines?Mounted Engines?


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WingWing--Mounted or FuselageMounted or Fuselage--Mounted Engines?Mounted Engines?

Rear MountedRear Mounted

• May suffer from boundary layer ingestion

• Bleed air supply more complicated

• Difficult to inspect by the crew and maintenance team

• Thrust line above the cg

• Critical for stretched versions

• Larger tailplane

• Lower cabin noise level

• Rear mounted engines often require soft (rubber/fluid) engine mounts to absorb vibration and

blade off loads. For wing mounted engines the flexible wings act as effective dampers thus allowing

engines to use cheaper hard mount arrangements

• Heavier aft fuselage structure

• Ice shed from the wing and aircraft nose can be ingested by the engine

• There is the possibility of high drag from the convergent/divergent channel formed between the

nacelle and the fuselage wall on rear mounted engine installations

• Aft fuselage mounted engines reduce the rolling moment of inertia. This can be a disadvantage if

there is significant rolling moment created by asymmetric stalling. The result can be an excessive

roll rate at the stall

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Recontouring of the aft fuselage to

improve propeller efficiency


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ThreeThree--engine Arrangementsengine Arrangements

A center engine is always a

difficult problem. Early DC-10

studies examined 2 engines on

one wing and one on the other,

and 2 engines on one side of

the aft fuselage and one on the

other, in an effort to avoid a

center engine. Neither of these

proved desirable. The center

engine possibilities are shown

at left.


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ThreeThree--engine Arrangementsengine Arrangements

Solutions to the DC-10 tail engine maintenance

problems include built-in work platforms and

provisions for a bootstrap winch system utilizing

beams that are attached to fittings built into the

pylon structure. Although currently companies are

developing virtual reality systems to evaluate

accessibility and maintenance approaches,

designers considered these issues before the

advent of VRML. The figure at left is an artist's

concept of a DC-10 engine replacement from a

1969 paper entitled "Douglas Design for

Powerplant Reliability and Maintainability".


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Central or Central/Rear Location

Advantageous layout for jet-powered

military strike/trainer a/c of moderate

aspect ratio wings.

Associated side or ventral intakes may also pass through wing center

structure.

Major consideration is engine removal – usually downwards via

access panels/doors.

Exhaust gases ejected via rear of fuselage to alleviate acoustic fatigue

problems.


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General ConfigurationGeneral Configuration

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AircraftAircraftOverall Length Overall Length

(m)(m)

Fuselage Width Fuselage Width

(m)(m)Length / WidthLength / Width

A319 33.84 3.95 8.57

A320-200 37.57 3.95 9.51

B737-200 30.53 3.76 8.12

B737-400 36.11 3.76 9.60

B757-200 47.32 3.76 12.59

MD-81 39.75 3.4 11.69

MD-83 45.0 3.4 13.24

Narrow Body Jet Transports

Typical Aircraft Fuselage DimensionsTypical Aircraft Fuselage Dimensions

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Typical Aircraft Fuselage DimensionsTypical Aircraft Fuselage Dimensions


(m)(m)

Fuselage Width Fuselage Width

(m)(m)Length / WidthLength / Width

A310-200 45.13 5.64 8.00

A300-600 53.3 5.64 9.45

A330-600 63.65 5.64 11.29

A340-200 59.4 5.64 10.53

B747-400 68.63 6.6 10.40

B767-200 48.51 5.03 9.64

B777-200 62.78 6.2 10.13

L1011-250 54.17 5.97 9.07

DC10-30 51.97 6.02 8.63

MD-11 58.65 6.02 9.74

Wide Body Jet TransportsWide Body Jet Transports

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(m)(m)

Fuselage Fuselage

Width (m)Width (m)Length / WidthLength / Width

An-32 23.8 2.9 8.21

BAe Jetstream 41 18.25 1.98 9.22

Embraer EMB 120 18.73 2.28 8.21

SAAB 340B 19.73 2.31 8.54

Shorts 330-200 17.69 2.24 7.89

Regional TurbopropsRegional Turboprops

Typical Aircraft Typical Aircraft

Fuselage DimensionsFuselage Dimensions

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Local Layout AspectsLocal Layout Aspects

Wing Wing -- Vertical LocationVertical Location

Compromise between aerodynamic, structural &

operational considerations – also covered in

“Configuration” presentation.

Can occasionally be an over-riding configurational

issue, particularly regarding:

propeller ground clearance.

powerplant removal on V/STOL a/c.

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Wing Vertical Location Wing Vertical Location –– Aerodynamics ConsiderationsAerodynamics Considerations

Mid-wing position gives lowest interference drag, especially good for

supersonic a/c.

Top-mounted wing minimises trailing vortex drag, especially good for low-

speed a/c.

Low wing gives improved landing gear stowage & more usable flap area.

Local Local Layout AspectsLayout Aspects

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Wing Vertical Location – Structural Considerations

Primary wing structure should be continuous across fuselage

– rules out use of mid-wing position when requirement

for single payload volume to occupy most of fuselage.

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Wing - Vertical Location – Operational Issues

Clearance & ground access

high wing best if using wing-mounted props.

also improved loading/unloading for freight a/c.

stores handling difficult if lower surface > 1.5 m above

ground.

Crashworthiness

low wing best for water evacuation.

high wing best for wheels-up landing.

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Wing Wing -- Vertical Location Vertical Location –– Operational Issues (Cont.)Operational Issues (Cont.)

Landing gear

high wing gives long/heavy landing gear or fuselage

mount & retract into fairings.

Internal Cabin Layout

High wing gives headroom problems.

Low wing provides better freight capacity.

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Wing Wing -- Vertical Location Vertical Location –– Summary of ApplicationsSummary of Applications

High wing

Freight a/c, small prop-powered transport a/c, most single

engine light a/c, some combat a/c (especially if V/STOL),

unmanned a/c, flying boats, tilt wing/rotor a/c.

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Wing Wing -- Vertical Location Vertical Location –– Summary of Applications (Cont.)Summary of Applications (Cont.)

Mid wing

High performance combat a/c, multi-deck large transport a/c, weapons

systems dedicated a/c with long internal bay.

Low wing

Most passenger transport a/c, some light single/twin engine trainers,

canard configured combat a/c.

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Fuselage Fuselage –– Local Layout AspectsLocal Layout Aspects

Empennage Layout Empennage Layout –– Vertical Surface(s)Vertical Surface(s)

Single, central fin most common arrangement, positioned as far aft as

possible.

Sometimes ahead of horizontal tail on fighters & trainers to improve spin

recovery.

Twin fin arrangements used for:

twin boom fuselage layout a/c;

a/c with high stealth requirement;

freight a/c with large rear ramp loading door.

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Empennage Layout Empennage Layout –– Horizontal SurfaceHorizontal Surface

Efficiency affected by wing downwash, thus vertical location

relative to wing important.

Usually mounted higher than wing except on high wing design

or with small moment arm – low tail can give ground clearance

problems.

Local Local Layout AspectsLayout Aspects

http://www.airliners.net/open.file/536356/L/

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Canard LayoutCanard Layout

Canard should be located higher than wing – spacing is

critical design feature.

• Sometimes just behind

cockpit, high on fuselage.

• Or often in front though it

then obstructs pilot’s view.



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Avionics & APUAvionics & APU

Including navigation, comms. & flight control/management

equipment.

Provision necessary for adequate volume in correct location

with ease of access.

Location of radar, aerials, etc also important

sensors often have to face forward/down in a/c nose.

long range search & early warning scanners sometimes

located on fuselage.

Auxiliary power unit (APU) commonly located at extreme

rear of fuselage on transport a/c.

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E3 Sentry

E2 Hawkeye

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Fuel

Not normally located within fuselage of passenger

transport a/c

exceptions are freight bay extended range tanks and

CG balancing tanks.

Many other a/c classes store fuel in fuselage.

Results in awkward-shaped tanks on high-performance

combat a/c.

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Weapons Bay(s)Weapons Bay(s)

Disposable load should be

carried so that overall CG is

close to that of a/c as a whole.

Greater layout flexibility conferred if more than one

bay used:

may facilitate landing gear stowage;

reduced structural cut-out problems.

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Gun InstallationGun Installation

Common on combat a/c.

Mounted in forward region of

a/c, adjacent to crew

compartment.

Major factor in nose layout,

especially when allowing for

ammunition stowage & spent

cartridge collection.

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A350XWB Nose LayoutA350XWB Nose Layout

The cockpit fuselage section will be

constructed from aluminum lithium, with

Airbus deciding against adopting a one-

piece carbonfibre structure that it had

been evaluating previously.

A350 XWB chief engineer Gordon

McConnell said that the nose redesign

was made partly for improved

aerodynamics and also to enable the

overhead crew rest to be installed further

forward and eliminate any encroachment

in the passenger cabin. He adds that

strength requirements for birdstrike

protection were partly behind the

decision to adopt a metallic nose

structure. "If we went for a composite

structure we'd have to reinforce the area

above the cockpit with titanium which is

expensive," he says.

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A350XWB Nose Further RedesignA350XWB Nose Further Redesign

Emirates has become the first A350

customer to release images of the XWB

with the revamped nose and cockpit

window arrangement adopted by Airbus as

it refines the aircraft's design from the

original 2006 concept. The revised nose,

which dispenses with the dramatic four-

window panel layout illustrated on all

artists' impressions released of the A350 in

May 2008, was adopted last year when

Airbus decided to incorporate the A380's

nose structural design.

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A350XWB All Out of DirectionA350XWB All Out of Direction

In June 2008 Airbus released computer-aided design model images of the

A350 that showed its latest thinking on the fuselage and nose shape. The

four windows panels are back in business. At this point and according to

Airbus the XWB's wing design was also further refined, among other

changes also incorporating a streamwise flap motion design to reduce drag

and seven-spoiler configuration instead of the six previously planned.

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Typical Nose Layouts Typical Nose Layouts ––

Single Seat Combat A/CSingle Seat Combat A/C

Fairchild Republic A-10A Warthog

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Typical Nose Layouts Typical Nose Layouts ––

Single Seat Combat A/CSingle Seat Combat A/C

McDonnell Douglas F-15A/C Eagle

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Nose LayoutNose Layout

Crew AccommodationCrew Accommodation

TwinTwin--Seat Combat & Trainer A/CSeat Combat & Trainer A/C

Tandem or side-by-side twin seating

arrangements possible:

Side-by-side has:

simpler layout, eased communications, wide fuselage,

increased drag, complicated ejection.

Tandem seating arrangement generally preferred.

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Typical Nose LayoutsTypical Nose Layouts

TwinTwin--SeaterSeater Combat A/CCombat A/C

Panavia TornadoPanavia Tornado

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Typical Nose LayoutsTypical Nose Layouts

TwinTwin--Seater Combat A/CSeater Combat A/C

Blackburn Buccaneer

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Typical Nose Layouts Typical Nose Layouts –– Military Transport A/CMilitary Transport A/C

Lockheed C-130 Hercules

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Design Design constraintsconstraints

Nose landing-gear

housingRoom for flight

controls

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Landing gear compartment shall

accommodate both E-170 and E-190 wheel

and associate systems.

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RadomeRadome

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Crew AccommodationCrew Accommodation

Civilian Passenger Transport A/CCivilian Passenger Transport A/C

Typical flight deck layout

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Typical Nose Layout: Boeing 747Typical Nose Layout: Boeing 747

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CD

Mach number

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Passengers & BaggagePassengers & Baggage

General Comments

Primary consideration regarding fuselage layout for civil

airliners.

Adequate provision required for passengers, baggage &

freight – according to specification.

Cabin length & width mainly determined by passenger

& associated services.

Cross-section depth also influenced by accommodation

of standard containers.

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General Comments (Cont.)

For typical subsonic single-deck airliner, passenger cabin

approximately 70% of total length.

Larger nose and tail length on supersonic airliner – usable

cabin length approximately 55% of total.

Multi-deck arrangements (e.g. Boeing 747, Airbus A380)

introduce flexibility.

Once cross-section is fixed, different passenger

requirements met by stretching or shortening the fuselage.

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Passengers’ PreferencesPassengers’ Preferences

Main concerns are comfort& safety.

Emotional aspects

As expected?

Aesthetically pleasing?

Feels friendly & safe?

Entertainment & boredom avoidance

In-seat entertainment.

Comfortable conversation possible.

Undisturbed reading, working, etc.

Eating & drinking.

Sleep & relaxation.



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Passengers’ Preferences (Cont.)

Physical aspects

Tidy?

Efficient air-conditioning?

Odour-free?

Quiet & vibration-free?

Non-smoking?

Cramped space?

Disturbance of & by others.

Carry-on baggage facility convenience.

Proper lighting


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Cabin LengthCabin Length

Determined by combination of:

Seat pitch, typically:

charter, 0.7 to 0.775 m

economy, 0.775 to 0.85 m

business, 0.9 to 0.95 m

first, 0.95 to 1.5 m

Galley floor area, typically 1 to 2 m by 0.7 m

Toilet floor area, typically 1 m by 1 m

Number of cross aisles

Number of passengers and distribution across cabin.


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Seating & passenger layout considerations:Seating & passenger layout considerations:

Minimise passenger fore & aft movements to reduce

CG variations during flight.

Dispose passengers, baggage & freight equally

about nominal CG position.

Avoid seating in line with plane of propellers

(noise, psychology).

More space required for seats facing bulkheads.

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Passengers & Baggage (Cont.)Passengers & Baggage (Cont.)

Forward facing seats generally best.

Large number of small windows gives versatile viewing arrangement.

Doors required for passengers, galley access, toilet services, freight/baggage

stowage, emergency exits.

Overhead lockers for passengers’ light baggage.

Headroom minimum 1.8 m, 2.0 m in aisles.

Typical economy class requirements:

1 toilet per 40 to 50 pax.

1 galley per 60 to 120 pax.

77


Shape mainly dictated by structural requirements for pressurisation.

circular best structurally but may give too much unusable

space above & below cabin.

problem overcome by using several inter-connecting circular

sections (mass penalty).

78


Commuter Airplanes CabinsCommuter Airplanes Cabins

79

Cabin Width & Cabin Width &

CrossCross--Section (Cont.)Section (Cont.)

Size should be small enough to reduce mass &

drag but big enough to provide passenger

comfort.

Main decision is choice of number of seats

across a/c and consequential aisle arrangement.

Need to provide headroom for passengers next

to wall sometimes constrains shape & moves

seat position inwards from edge of floor.

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Cabin Width & Cabin Width &

CrossCross--Section (Cont.)Section (Cont.)

Seat arrangementsSeat arrangements

Seat widths (typically):

charter, 0.4 to 0.42 m


business, 0.575 to 0.625 m

first, 0.625 to 0.7 m

Many seating possibilities but passenger should

be no more than 2 seats away from aisle.

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Cabin Width & CrossCabin Width & Cross--Section (Cont.)Section (Cont.)

Aisle width typically:


first, > 0.6 m

Possibilities include:

2/2, 3/3, 2/3/2, 2/4/2,

2/5/2, 3/4/3, 3/5/3

Boeing 777 possibilities

Seating arrangements (cont.)Seating arrangements (cont.)

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Cabin Length (Cont.)Cabin Length (Cont.)

Typical split of classes:

8% first, 13% business, 79% economy

Extra “flip-up” seats also required for cabin attendants

in vicinity of emergency doors/exits, typically;

economy, 1 per 30 to 40 pax

business, 1 per 20 to 25 pax

first, 1 per 10 to 15 pax.

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Cabin Width EstimationCabin Width Estimation

Internal width for economy seating approximately:

[0.5 p + 0.55 a] m,

where:

p = number of seats across cabin

a = number of aisles

External cross-section estimation

Maximum external width includes allowance for trim &

structure, typically 0.2 to 0.3 m added to cabin width.


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Cabin Length EstimationCabin Length Estimation

Total length in any given unit of accommodation for single Total length in any given unit of accommodation for single

deck layout approximatelydeck layout approximately

[(P/p +g) s + t + 0.8 w] m, where:

P = total number of passengers in unit

p = number of seats across cabin width

g = number of galleys across length

s = seat pitch (m)

t = number of toilets across length

w = number of cross aisles

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Fuselage Fineness RatioFuselage Fineness Ratio

Depends on choice of seating layout, i.e. number

of seats across width and number of rows.

Should typically aim for a subsonic fineness ratio

of about 9 (see above):

lower values give drag penalty

higher values give dynamic instability and

reduces future stretch potnential.

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Fuselage Fineness Ratio (Cont.)Fuselage Fineness Ratio (Cont.)

Effect of cabin layoutEffect of cabin layout

87

Fuselage Fuselage –– Mass EstimationMass EstimationTransport AircraftTransport Aircraft

where

and

wf = fuselage width (ft)

hf = fuselage height (ft)

ln = tail arm of the horizontal tail (ft)

VD = dive speed (knots)

(weight provided in lb)

(ft2)f

ff w

Lλ

2

3/2

ff

11

2-1 L D

ff

gsfS

88

Fuselage Fuselage –– Mass EstimationMass EstimationFighter PlaneFighter Plane

where

lf = fuselage length (ft)

hf = fuselage height (ft)

WTO = takeoff weight (lb)

(weight provided in lb)

(ft2)

89

Innovative Cabin LayoutInnovative Cabin Layout

Patented Diagonal SeatingPatented Diagonal Seating

90

Innovative Cabin LayoutInnovative Cabin Layout

The Sky is the Limit for FantasyThe Sky is the Limit for Fantasy

91

Baggage & FreightBaggage & Freight

Typical baggage provision is 16~20 kg per

passenger (density approximately 160 kg/m3).

This is in addition to personal items placed in

overhead (or sometimes side) lockers.

92

Baggage & Freight (Cont.)Baggage & Freight (Cont.)

Usual arrangement is to carry passengers’ baggage

plus freight, loaded in standard LD containers

and located in under-floor freight holds.

93


Hold usually split into separate fore and aft areas,

divided by wing carry-through structure.

Boeing 767

94


Sometimes freight & passengers accommodated in

main cabin in separate sections (“combi”) –

needs large freight access door.

95

1995

Same

ERJ 145

front

fuselage

Employ ERJ 145 fuselage sections

EMBRAER 170EMBRAER 170

A ) DERIVAÇÃO DO ERJ 145, ALARGANDO-SE AS PARTES CILÍNDRICAS DA FUSELAGEM :

B ) FUSELAGEM ‘4-ABREAST’ CIRCULAR, MOTORES NA FUSELAGEM, ASA DERIVADA DO ERJ 145 :

EMBRAER 170EMBRAER 170

98

Same front fuselage from older versions (reduce costs)

Airbus concept for the A380 Airliner (year 2000)Airbus concept for the A380 Airliner (year 2000)

No wingtips

Two A-300 fuselage sections joined by plain segments

Drawback: any

door in this

region is costly

to manufacture

99

Dornier 228Dornier 228

Dornier 328JetDornier 328Jet

100

Fuselage AerodynamicsFuselage Aerodynamics

101

Typical Flow PatternTypical Flow Pattern


Here is not a good location for probes

Upwash caused by the wing

102

GoalsGoals

Aim is to achieve reasonably streamlined form together with

minimum surface area to meet required internal volume.

Both drag and mass heavily influenced by surface area.

Require absence of steps and minimum number of

excrescences.

Fundamental differences between subsonic and supersonic

applications.

Concerned with: cross-section shape, nose shape & length,

tail shape/length, overall length.


103

Should not be unduly “bluff”.

Local changes in cross-section needed

to accommodate windscreen panels.

Windscreen angle involves compromise

between aerodynamics, bird-strike,

reflection and visibility requirements.

Windscreen panel sizes should be less

than 0.5 m2 each.

Shape of the NoseShape of the Nose




104

Starting point for front fuselage

layout is often satisfactory position

for pilot’s eye.

Reasonable nose length is about:

1.1 to 2.0 x fuselage diameter

(subsonic).

4 x fuselage diameter

(supersonic).


Shape of the Nose (Cont.)Shape of the Nose (Cont.)

http://www.airliners.net/open.file?id=526349&WxsIERv=Qm9laW5nIDc1Ny0zMzA=&WdsYXMg=VGhvbWFzIENvb2sgKENvbmRvcik=&QtODMg=QWxpY2FudGUgKC0gRWwgQWx0ZXQpIChBTEMgLyBMRUFMKQ==&ERDLTkt=U3BhaW4=&ktODMp=RmVicnVhcnkgMjAwNA==&BP=0&WNEb25u=RGFlbXMgR3V5&xsIERvdWdsY=RC1BQk9L&MgTUQtODMgKE=Tm9zZSBkZXRhaWwuIChEMTAwKQ==&YXMgTUQtODMgKERD=NjI=&NEb25uZWxs=MjAwNC0wMy0wOA==&ODJ9dvCE=&O89Dcjdg=&static=yes



105

Subsonic


106

Example of Fuselage DesignExample of Fuselage Design

Armstrong Whitworth 650 Argosy Armstrong Whitworth 650 Argosy

Vortex Generators to reattach the flow

107

The aircraft

flies in the

transonic

regime

108

Experiment

Transonic

Shock wave causes flow separation in

this region. Vortex generators fix

problem. However, shock wave

remains causing drag and

considerable.

109

Mach number contours

Navier-Stokes Simulation

M∞ = 0.85

110

Shock causes flow

separation

111

Flow

separation

CBACBA--123123

113

No flow stagnation at the

windshield-nose junction

Mach = 0.80

Euler Calculations

114

Mach = 0.85

Weak shock wave with no flow separation

116

Center Fuselage & Overall Length

Subsonic Aircraft

Theoretically minimum drag for streamlined body with fineness

ratio (length/diameter) of 3.

In reality, typical value is around 10, due to:

need to utilise internal volume efficiently.

requirement for sufficiently large moment arm for

stability/control purposes.

suitable placement of overall CG.


117

Constant cross-section

preferable for optimized

volume utilization and ease of

manufacture.

Not too critical

aerodynamically, but should:

avoid sharp corners;

provide fairings for

protuberances


Cross section Shape for Subsonic A/CCross section Shape for Subsonic A/C



118


Supersonic AircraftSupersonic Aircraft

Overall length/diameter ratio very important because

of wave drag problems – typically around 20.


119

“Area-ruling” needed to:

reduce wave drag;

increase critical Mach number (Mcrit)

Combined wing/fuselage section area should vary smoothly

along length.


Cross section Shape for Supersonic A/CCross section Shape for Supersonic A/C

120

Tail ShapeTail Shape

Smooth change in section required, from maximum

section area to ideally zero.

Minimisation of base area especially important for

transonic/supersonic a/c.

Typical tail section lengths are:

2.5 to 3.0 x diameter (subsonic)

6 to 7 x diameter (supersonic)


Tail ShapeTail Shape


121

Important parameter for determining tail

upsweep angle is ground clearance required for

take-off and landing rotation.

Typically 12o to 15o.

Tail Tail ShapeShape


Pylon

Engine Pylon

Axed Configuration

For the ERJ-145 Airliner

+ Fluent

Wind Tunnel

123

Upsweep angle can be a particular design problem for

transport a/c with large rear ramp loading doors (up to 25o).

Tail Tail ShapeShape




124

Avoid flow separation and improve rudder effectiveness


Mutual interferenceMutual interference

125

Fuselage Fuselage –– Local Layout AspectsLocal Layout Aspects

Strakes Stablets

EMBEMB--145SA145SA

Solving Poor DutchSolving Poor Dutch--Roll Behavior Caused by Antenna Instalation Roll Behavior Caused by Antenna Instalation


fuselagem design

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