P Bradshaw
Skill Group Leader
Airbus Future Projects
Low Fare Airline – Design Project 2006-2007
University of Southampton
3rd November 2006
EDXCW/PR/PB/20808A
Design Project Aim
Enable design teams:
• To bring together knowledge of individual engineering
disciplines into a complete aircraft project
• To combine ‘conceptual design’ with some more focussed
engineering.
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• To work efficiently in teams – Compete with other teams,
not each other
• Develop process of working, managing and controlling the
Project Design for an aircraft.
EDXCW/PR/PB/20808A
The Problem
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Background:
• Current short-range aircraft developed to meet the
requirements of flag carriers.
• Next generation of SR aircraft will probably be operated by
Low Fare Airlines
The Task ?
• Design a SR aircraft to meet the specific requirements of
LFA’s
• Two aircraft family:
150
pax HD
1800nm and 3000nm versions
EDXCW/PR/PB/20808A
Objective
• Each team is to propose a
short-range aircraft primarily
designed for Low Fare
Airlines.
• EIS 2015
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• Generate initial technical
specification to support a
possible launch decision.
Based on current and emerging technology and materials
Novel configurations are not excluded
Realistic approach to technology and risk
EDXCW/PR/PB/20808A
Design Targets
•
•
•
•
Performance (P, R, Mcr, TOFL, TAT)
Manufacturing and Assembly considerations ?
Reliability and Maintenance
Cost
 To
Manufacturer
– Non-Recurring Cost
– Recurring Cost
 To
- NRC
- RC
Customer
– Operating Cost (direct and indirect)
– Life Cycle Costs
• Timescale
and Development
 Manufacturing Cycle Time – Build rate ?
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 Design
• Marketability:
 What
appeals ?
• Business Case:
 IRR vs Investment
 Expected MSN to break even ?
EDXCW/PR/PB/20808A
The Design Specification
UB2007-SR
Passenger Capacity (1-cl HD)
-
Design Range (still-air)
nm
Design Cruise Speed
Take-Off Field Ln. (MTOW at S-L, ISA+15)
Time To Climb (1500ft to ICA at ISA+10)
150
1800
3000
Mach
0.80
m
2000
min
Result
 25
Initial Cruise Altitude (ISA+10)
ft
35000
Maximum Cruise Altitude
ft
41000
kts CAS
 135
Landing Field Length (MLW, S-L, ISA)
ft
1600
One Engine Inoperative Altitude
ft
Approach speed (MLW, S-L, ISA)
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UB2007-ER
VMO / MMO
Result
kts CAS / Mach
Result
360 / 0.84
Equivalent Cabin Altitude (at 41000ft) (4.9)
ft
Turn-Around Time
-
Airport compatibility limits
-
ICAO Code ‘C’
ACN (Flexible B)
-
40
DOC target
ETOPS capability (at EIS)
EDXCW/PR/PB/20808A
$/seat-nm
mins
8000
Minimum
Minimum
Minimum
Minimum
90
What are Customers’ Needs ?
• Future concept selection will be chosen to fulfill the
requirements to be met…………
Range
Payload
Noise
Safety
Operating cost – (Profit for airlines !)
Manufacturing Cost (Profit for us !)
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Cheap to maintain (DMC)
Reliable etc etc etc (OI, MMEL)
•That means understanding the options available to us, and the challenges
ahead – does the latter infer that particular technologies have to be used,
whether we like it or not ??
EDXCW/PR/PB/20808A
Method of Working
•
•
Initially you will be ‘swamped’ with information - don’t panic.
Things will get clearer as all topics are delivered and you will see how
they fit together.
THEN:
1. Organise yourselves:
•
•
Everyone cannot do everything, so allocate responsibilities
Ensure everyone knows their roles and tasks (and is fully aware of the
roles and tasks of others) – focus on problems early – support eachother.
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2. Plan your project:
•
•
•
•
Identify major deliverables (internal / external), dates and owners
Identify activities with realistic timescales
Keep the plan current & feasible.
Ensure everone agrees & aims to adhere to it
3. Communicate
• Share information early – decide what’s improtant/ what isn’t
• Single failure=Collective failure
EDXCW/PR/PB/20808A
General Tips – Some Do’s and Don’ts
• Understand the question:
Differentiate
between the “hard” and “soft” requirements
Identify key drivers
Assess the ‘cost’ of each requirement
Challenge if appropriate -
• Understand the importance of a design decision – Ensure
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technical evidence justifies it.
• Ensure design solutions are driven by the requirements
• Be realistic in your assessment of risk – Wild arsed
guesses may kill your product.
EDXCW/PR/PB/20808A
General Tips – Some Do’s and Don’ts
• If you go for an unconventional design, always assess
against an equivalent conventional design.
• Only include technology if it buys it’s way onto your aircraft.
• Focus on the engineering – The marketeers will do the
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marketing
(…..and understand the difference between the two)
• Always be aware of the regulations and ensure your
design meets them (eg minimum ROC margin @ top of
climb, Vapp rules in terms of Vst....).
EDXCW/PR/PB/20808A
General Tips – Some Do’s and Don’ts
Always reference your design against a known solution
Sanity
check
Calibration
• Gain a feel for the configurational influences and exchange
rates.
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• Don’t squeeze the last drop from your design – you’ll regret
it later on !
EDXCW/PR/PB/20808A
General Tips – Some Do’s and Don’ts
• Ensure you draw, maintain and use a GA of the aircraft
design change traceability
Assists in understanding of scale & ‘fit’
Unique definition of the configuration and geometry
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Gives
EDXCW/PR/PB/20808A
General Tips – Some Do’s and Don’ts
• Use methods appropriate to the stage of the design and
the input data available
Don’t obsess with accuracy of numbers – the nth
decimal place is completely unrealistic – Get OM
understood.
Use quick and dirty methods where appropriate
Always ‘sanity check’ results – does it look/ feel right ?
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"Tools don't design aircraft, engineers do”
EDXCW/PR/PB/20808A
Presentation of Results
• Ensure content, style and level of detail are appropriate.
• Clearly describe the main features of the aircraft and its
components.
• Justify all design decisions made.
• Demonstrate the multidisciplinary balance and integration
of your design.
• Describe the process by which you approached the design.
• Demonstrate:
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Good
team working
Good project management
Good control of the project design
• Make your points as clearly as you can – peer review your
chapters before submission.
EDXCW/PR/PB/20808A
The Question
• Requirements drive the solution
• Payload and Range define some major aircraft parameters
e.g.
150 pax / 3000nm
• These will form a significant part of the design drivers
Payload
Design mission
should be typical
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Max Payload by HD
mission
Fuel Volume by design
mission fuel or other
requirement (e.g.
approach speed)
Max Payload Limit
Fuel Volume Margin
MTOW Limit
Fuel Volume Limit
MTOW driven by design
mission
Range
EDXCW/PR/PB/20808A
Design Process
• Design is iterative
You
can’t unpick the ends to untie the knot
You can’t work out a solution from the question in a straight
line
• ‘Cut the Gordian Knot’
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Choose
a concept
Analyse it
Assess it
Change it
Start again…
EDXCW/PR/PB/20808A
The Iterative Design Process
Initial Cardinal Geometry
Configuration: Size, Position ...
Design Weights,
Engine Size, CLmax,
Minimise Cost
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Refine Config
Space Allocation
(Fuel Volume, LG, Hi-Lift...)
Component
Weights Aerodynamics
Component Weights
Aerodynamics
Performance
& Cost
Cost
Performance &
‘Actual’ V ‘Targets’
(Wing area,  MTOW, ..)
No
EDXCW/PR/PB/20808A
OK?
Yes
Example of Simplified Calculation
Wing Area or Thrust
Weight
Take-Off Dist = aP + b
T/Off Dist.
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T/Off Dist.
• Take-Off Field Performance
Parametric No (P)
EDXCW/PR/PB/20808A
Sizing Process - Design Weights
• MTOW = ZFW + Fuel
• ZFW = Payload + OWE
• MLW = z * MZFW
• 1st order: MTOW/OWE = fn(Range)
• Range (Breguet)= y * (V*(L/D)/sfc) * log (MTOW/ZFW)
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• Initial L/D value: Compare with other a/c
• Calibrate z & y against known aircraft
EDXCW/PR/PB/20808A
Sizing Process: Component Sizing
• Wing Area = fn (MLW, CL, Vapp)
or fn (MTOW, CL, TOFL, Thrust)
or fn (Cruise Weight, CL, Height, Speed)
or fn (Fuel Volume)
• Wing Sweep, t/c => see aerodynamics section
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• Fin Area = fn (Wing Area, Span, Moment Arm)
• Tail Area = fn (Wing Area, Chord, Moment Arm)
• Thrust = fn (MTOW, CL, TOFL, Thrust)
or fn (Cruise Weight, Height, Speed, L/D)
EDXCW/PR/PB/20808A
Sizing Process: Component Weights
• Fuselage = fn (Length, Cross-Section)
• Wing = fn (Area, MTOW, Sweep, Span, t/c, MZFW)
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• Fin & Tail = fn (Area)
• Engines = fn (Thrust)
• Undercarriage = fn (MTOW)
• Systems = Fixed
• Furnishings = fn (Length, Cross-Section)
• Operator’s Items = fn (No Pax)
EDXCW/PR/PB/20808A
Sizing Process: Aerodynamics
• CD = CD0 + K.CL² +CDM
• CD0 = fn (Surface Area)
= fn (Fuse len. & diam., wing, fin & tail area, eng. size)
• K = fn (AR, sweep)
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• CDM = fn (AR, sweep, t/c)
• CLmax = fn (flap type)
EDXCW/PR/PB/20808A
Sizing Process: Performance
• Range = y * (V*(L/D)/sfc) * log (MTOW/OWE)
• Vapp = fn(Wing Area,MLW, CL)
• TOFL = fn (Wing Area, MTOW, CL, TOFL, Thrust)
• Thrust = fn (MTOW, CL, TOFL, Thrust)
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or fn (Cruise Weight, Height, Speed, L/D)
EDXCW/PR/PB/20808A
Fuselage & Cabin
• Preliminary – scale from existing known aircraft
• Define seat-abreast and cross-section (incl. number of
decks)
• Calculate required number of:
(by class)
Galleys / Lavatories / Attendants / Crew rest areas etc
Doors (based on highest density layout)
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Seats
• Layout cabin to determine length (and iterate)
• Add nose and tail (length based on scaling of existing
aircraft)
EDXCW/PR/PB/20808A
Door distribution requirements
due to
 certification requirements
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max. door spacing is 60ft=18m
EDXCW/PR/PB/20808A
EDXCW/PR/PB/20808A
uniform distribution of exits due to
passenger distribution in the cabin
chart 25
Door distribution requirements
due to
 certification requirements
 emergency slide function
spacing to flaps
min. door spacing= 4.5m
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spacing to engines
EDXCW/PR/PB/20808A
EDXCW/PR/PB/20808A
Landing gear definition
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Functions:
• carry aircraft max gross weight to take off runway
• withstand braking during aborted take off
• retract into compact landing gear bay
• damp touchdown at maximum weight- and sink rate-landing
Characteristics:
• size and number of wheels
• retraction path / stowed position
• impact on ground surface (cracks, damage and fatigue)
• maximum braking energy capability
Main parameters fix the development potential quite early.
Small changes can be introduced later in the programme
EDXCW/PR/PB/20808A
LG continued
• Ensure wing & LG integration with rest of aircraft;
NLG impact on high speed landing (A/C attitude too nose down
on touchdown?) – resolve through body setting angle or more
powerful high lift devices ?
Tail tip on loading – MLG too far forward.
Wing (& MLG) too far aft – rotation @ T/O may be difficult.
Longitudinal constraints: Tail-scrape on rotation (LG length
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or longitudinal position/ rear fuselage shape/ ‘Power’ of High
Lift Devices)
Lateral constraints: x-wind landing, turnover angle theta < 30
degrees typically
Position NLG & MLG to retain at least 5% MTOW over NLG in static
balance about CG, to ensure steering feasibility.
EDXCW/PR/PB/20808A
LG
Ensure
LG leg integration feasibility
– NLG, BLG, MLG volume requirements for sensible leg positions & tyre
quantity & size (family growth version ?)
– ACN – pavement loading – set by Airfield classification (requirement).
–Greater root chord?
–Inner TE kink?
–Thicker section @ root?
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–Re-twist at root?
EDXCW/PR/PB/20808A
Standard Clearances for LG Concept Studies
• Weight:Total LG weight typically 3% of MTOW for commercial airliners
• Tyre clearances:Spinning Tyre to airframe = 80mm minimum for nominal static
structure (50mm after tolerances and deflections)
Landing gear structure to airframe = 50mm minimum for
nominal static structure (25mm after tolerances and
deflections)
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• Airframe skin thickness:Wing skin thickness = 50mm
Belly fairing thickness = 100mm
Nose bay skin thickness = 100mm
EDXCW/PR/PB/20808A
Results in an Envelope for LG Fairing Sizing
Tyre clearance illustration for stowed
Spinning tyre
Main Gear.
+80mm clearance to structure
+100mm belly fairing thickness
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+180mm total offset
Structure
+50mm clearance to structure
+50mm Wing skin thickness
+100mm total offset
EDXCW/PR/PB/20808A
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Section through stowed leg in wing
Wing surfaces
EDXCW/PR/PB/20808A
Landing Gear - Aerodrome reference code
• The purpose of the Aerodrome reference code is to match aerodrome facilities
to the A/C. It is a two part code.
 The first part relates to the A/C reference field length
 The second to the A/C wing span and L/G outer wheel span.
• The details regarding the aerodrome reference code for L/G outer wheel span
can be found in the ICAO aerodrome design manual Part 2 Chapter 1
(Taxiways).
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• The code elements are reproduced as follows;
EDXCW/PR/PB/20808A
Landing gear layout
retraction into compact landing gear bay
including free-fall capability
(number, size & spacing)
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load per wheel under
nominal and special conditions
to be less than tire’s allowables
(number, size & ply rating)
volume for brake discs
inside wheel
(number & size)
EDXCW/PR/PB/20808A
attachment to wing & fuselage
to guide static and braking loads
(available space between spars & flaps)
“equivalent single wheel load”
to estimate impact on ground surface
by scaling of pavement test results
(number, size , pressure & spacing)
Landing gear characteristics
number of wheels
load / wheel / diameter / width
20
50
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maximum “ground pressure”
16
40
12
30
8
20
4
10
0
0
0
100
200
300
400
500
600
0
100
200
300
400
MTOW [t]
Number and size of wheels driven by max gross weight
and ground impact requirement
EDXCW/PR/PB/20808A
500
600
MTOW [t]
Powerplant Positioning & Integration
Powerplant position:
– Gulled wing ? (local increase in dihedral at root)
–+/ - 5 degree disc burst cones for fuel tank boundaries and feeds to
Engine.
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–MLG longitudinal position on NLG collapse to ensure engine
clearance.
EDXCW/PR/PB/20808A
Engine installation constraints
17.5°
Door 7
position
Toe-in
1.7°
110mm margin
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3°
5°
Fan burst criteria :
 3° opposite wing side fan
burst trajectory / rear I/B pickup point
 5° same wing side fan burst
trajectory / rear I/B pick-up
point
Safety requirements bound optimisation window
EDXCW/PR/PB/20808A
Wing planform definition
• Wing aerodynamic performance depends on
 Sectional
shape
 Wing area, span, sweep, thickness, taper
 Spanwise lift distribution
 Flap size and type
• Wing weight depends on
weights
 Design speed
 Wing area, span, sweep, t/c, taper
 Spanwise lift distribution
 Box size / flap size and type
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 Design
• Weight & drag require different planforms
• The wing must also carry landing gear & engines, and integrate into the
fuselage
EDXCW/PR/PB/20808A
We must find the best balance
for the overall aircraft
Wing Sizing
• Develop understanding of component level sizing & links
to OAD;
•Wing planform versus drag & economics;
TR, Span, t/c, S – which gives the best multidisciplinary balance ?
Span versus Area
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Sweep versus t/c
TR versus CoP
Check fuel volume requirement is met in wing.
Value of Weight versus Drag for Economics terms – Which most influences ?
Is aero benefit of elliptical lift distribution more powerful than BM relief due to
more inboard position of CoP ?
EDXCW/PR/PB/20808A
Wing Area Selection
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constant AR
• Lower wing weight
• Lower drag
• Lower cost
• Smaller fin & tailplane
• Fuselage integration easier
• Increased fuel volume
• Increased high speed lift
(better buffet margin)
• Increased low speed lift
(lower approach speed)
•Gear installation easier
Minimum Area for capability and
growth potential
EDXCW/PR/PB/20808A
Aspect Ratio (AR) Definition
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constant wing area
• More fuel volume
• Better engine & gear installation
• Lower wing weight:
Wwing = fn(span3)
• Possibly tip stall problems
• Quieter aircraft
• Improved aerodynamic performance:
Induced drag = fn(span –2)
Balance between aerodynamic performance and wing
weight depends on aircraft requirements (range etc.)
EDXCW/PR/PB/20808A
Sweep Angle Selection
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constant
wing area and AR
• Improved low speed performance
• Lower wing weight
• Improved high speed performance
• Easier engine segregation
• Easier gear installation
Balance between high speed and low speed
performance
EDXCW/PR/PB/20808A
Spanwise Lift Distribution
Triangular
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Elliptical
• Minimum induced drag
• Higher induced drag
• Lower wing weight
Optimum depends on the requirements –
Range in particular
EDXCW/PR/PB/20808A
Span vs Area vs Block Fuel
Span and Area Trades
Mission Efficiency
6
15
Design Mission (500 nm)
DOCM Block Fuel Change
[%]
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4
Area
10
Span
Vapp limit
2
5
const. AR
33.4m
Baseline
0
0
TTC limit
2
145m
-2
-5
-4
-10
38.7m
2
125m
Fuel limit boundary 3500nm
-6
EDXCW/PR/PB/20808A
-15
Weight and Drag Balance
D.O.C. [Range = 6000nm]
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1.02
1.01
1.02
1.01
+5dc
1.00
1.00
datum
+2t
0.99
0.99
+1t
drag
datum
-5dc
0.98
-1t
-2t
MWE
Minimising Operating Cost means balancing
weight and drag benefits
EDXCW/PR/PB/20808A
0.98
Span vs Area vs DOC/ Weight
Span and Area Trades
Weight
15
Area
38.7m
Wing Weight Change
[%]
10
Span
5
Baseline
0
145m
2
wing weight for iso Vapp
-5
33.4m
125m
2
-10
Span and Area Trades
Operator Cost
0.7
Design Mission (500 nm)
145m
0.6
2
6
Span
0.4
4
CoC
Other key trades include:
•DOC vs A/C price vs Fuel price
0.3
EDP Change
[%]
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0.5
2
0.2
•Fuel margin vs Area vs Span
0.1
0
0
Baseline
-0.1
125m
-0.2
Area
2
-2
33.4m
-0.3
38.7m
-0.4
EDXCW/PR/PB/20808A
Fuel Price assumened at 0.7 $/Gal
-4
•Aircraft Price vs Area vs Span
Requirements for High Lift Devices
•Provide sufficient lift to meet Vapp
•Avoid tail-strike @ touch down
•Avoid NLG first impact @ touchdown for High speed landing
Max Alpha case - Tailscarape
CL
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Clmax limit
Overspeed
cases –
Alpha min
Vapproach = 1.23 x Vs1g + 5 kts
CLapproach = f(CLmax)
Vapproach
CL0
NLG First
Impact
cruis
e
Tailstrike
Alpha
EDXCW/PR/PB/20808A
= 1.23 x Vs1g + 15 (20) kts
Useable Rotation Angle – Take-off & Landing
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• For landing, the compressed main gear is a useful
de-rotation axis for measuring allowable alpha
• For take off, calculation benefits can be drawn from
taking the extended main gear (including rocking bogie)
as the rotation axis for measuring allowable alpha and
calculating safe lift off speed
EDXCW/PR/PB/20808A
Different Ways to Meet LS Targets
Trailing Edge:
Split Flap
Plain Flap
Single Slotted
double Slotted
Triple Slotted
Improved Aerodynamics
Increased Weight, Cost, Maintenance
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Leading Edge:
Plain
EDXCW/PR/PB/20808A
Slat
Krueger
Hinged
Actuation Mechanism
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Trailing Edge - Three principle mechanism types:
Drop-hinge (pure rotation)
Track & Lever
4-Bar Link
Low weight
Low cost
Limited deployment
Poor lap & gap
Heavier weight
Higher cost
Excellent deployment
Excellent lap & gap control
Medium weight
Medium cost
Good deployment
Good lap & gap control
Selection is a balance of all characteristics
at the aircraft level
EDXCW/PR/PB/20808A
Some Sanity Checks - 1
• Effect of Engine wear: Equivalent to 4 – 6% FB increase.
• Weights: (Check out Niu/ Raymer/ Roskam/ Shevell/ Torenbeek)
Weight  W/S, b3, c/t, / 
Top Cover: 7000 srs Al (550 Mpa FTU)
Bottom Cover: 2000 srs Al (300 MPa FTU) with fatigue reduction.
Covers approx 45% - 50% wing weight
Ribs & Spars approx 25% wing weight
FLE & Movables approx 5% - 10%
FTE & Movables approx 15% - 20%
• Disk burst: All subject to rational analysis to decrease cone size if
possible;
Turbine blades: +/- 15º
Compressor blades:
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Covers
– 1/3rd of a disk; +/ - 3 º
– Intermediate fragment; +/ - 5 º
EDXCW/PR/PB/20808A
Some Sanity Checks - 2
• Fuel Volume Availability
© AIRBUS S.A.S. All rights reserved. Confidential and proprietary document.
Gross
volume - Outside skin line
Nett Volume – What is available to use
Remember: Limiting mission + 200 nm diversion, 5% trip fuel
allowance + 30 minute hold @ 1500 ft AGL +10% margin is what you
will need.
Items that reduce fuel volume availability:
– Structural volume
– Thermal expansion
– Unusable fuel
– Trapped air
– In-tank equipment (pumps, probes, pipes)
Gross – Nett: Should be approx 10 – 15% difference, subject to
above items.
EDXCW/PR/PB/20808A
© AIRBUS S.A.S. All rights reserved. Confidential and proprietary document.
Economics
EDXCW/PR/PB/20808A
Why we’re Producing Aircraft ?
© AIRBUS S.A.S. All rights reserved. Confidential and proprietary document.
Making money
is the reason why most
companies are in the
aerospace industry
Operating Costs
are an important criterion
used by airlines when
choosing new aircraft
Operating Cost
methods give engineers
a useful multi-disciplinary
assessment tool in the
sizing process
Consider economics throughout, not just as a result
EDXCW/PR/PB/20808A
Low Cost Operator TAT (Hub vs. Destination)
TAT process
45%
TAT –time in between „blocks on“ and „blocks off“
40%
Gatwick (Hub)
35%
Toulouse (Destination)
•Passenger deplaning/ boarding
•Cargo unloading/ loading
•Refuelling process
30%
•Catering
25%
•Cabin Cleaning
•Freshwater service
20%
15%
10%
•Lavatory water service
•Inspection/ maintenance
•Security check
•Deicing
0%
Timeclass [min]
015
20
-2
5
25
-3
0
30
-3
5
35
-4
0
40
-4
5
45
-5
0
50
-5
5
55
-6
0
60
-6
5
65
-7
0
70
-7
5
75
-8
0
80
-8
5
85
fro
-9
m
0
9
12
00
up 120
m
or to
3
e
th 00
an
30
0
© AIRBUS S.A.S. All rights reserved. Confidential and proprietary document.
5%
Data for many different airports and airlines available
for analysis
EDXCW/PR/PB/20808A
Operating Costs - COC, DOC & IOC (1/2)
Direct Operating Cost (DOC)
• Financial Costs
Depreciation
Interest
Insurance
Cash Operating Cost (COC)
• Flying Costs
© AIRBUS S.A.S. All rights reserved. Confidential and proprietary document.
Fuel
Landing fees
Cockpit crew
Cabin crew
Navigation charges
• Maintenance Costs
Airframe
Engines
Dependent on aircraft design
EDXCW/PR/PB/20808A
Total Operating Cost (TOC)
Indirect Operating Cost (IOC)
•Ground Property & Equipment
Depreciation
& Maintenance
•Administration & Sales
Servicing
administration
Reservations & sales
Advertising & publicity
General
•Servicing
Passenger
services
Aircraft services
Traffic services
Dependent on airline operations
Operating Costs - COC, DOC & IOC (2/2)
• Cash Operating Cost (COC):
Flight-related
costs
 Highlights aircraft-use and variable cost trends – Useful to airlines
 Doesn’t account for aircraft cost - If used as the target function, it
drives design to a high-tech solution to reduce fuelburn
• Direct Operating Cost (DOC):
+ Aircraft price (or cost) related costs
 Large price/cost component masks flight-related cost trends which
are important for airlines
 Realistically accounts for the cost of aircraft design and technology
© AIRBUS S.A.S. All rights reserved. Confidential and proprietary document.
COC
• Indirect Operating Costs (IOC):
Airline
infrastructure costs
 Highly airline dependent – No reliable quantitative method
• Calculate COC for “airline” a/c comparisons
• Calculate DOC for technical trade studies
• Assess IOC issues qualitatively
EDXCW/PR/PB/20808A
AEA Method - Inputs, Assumptions & Results
Inputs
Assumptions
• Mission data:
 Stage Length (nm)
 Block Fuel [BF] (lb)
 Block Time [BT] (hr)
 Passengers [Pax]
 Fuel Density = 6.7 lb/USgal
 Labour Rate [R] = 66 $/hr
• Financial Costs:
 Depreciation [DEP]
 Interest [INT]
 Insurance [INS]
• Weight data:
 MTOW (t)
 MWE (t)
 Engine Weight
• Maintenance Costs:
(t)
© AIRBUS S.A.S. All rights reserved. Confidential and proprietary document.
• Engine parameters:
AEA DOC
Method
 Number of Engines [NE]
 SLST [T] (t)
 Bypass Ratio [BPR]
 Overall Pressure Ratio [OPR]
 No. of compressor stages [NC]
• Price data:
 Engine Price [ENP] ($)
 Manufacturers Study Price
 Airframe Cost [AFC] ($)
 Fuel Price ($/USgal)
EDXCW/PR/PB/20808A
Results
[MSP] ($)
 Airframe
Maintenance
[AMC]
 Engine Maintenance
[EMC]
• Flight Costs:
 Cockpit Crew [CPC]
 Cabin Crew [CAC]
 Navigation Charges
C
O
C
[NAV]
 Landing Fees [LAF]
 Fuel [FUE]
(All costs calculated as $/trip)
D
O
C
AEA Method - Study Mission (COC & DOC)
The Study mission is not the same as the Design mission
• Aircraft are sized by their Design mission Payload-Range requirements
• Operational routes are typically much shorter than the Design mission
• For representative operating costs it is important to use a
representative (average) mission.
© AIRBUS S.A.S. All rights reserved. Confidential and proprietary document.
Use the values from the following table:
Design Mission (nm)
Range <= 3000
3000 < Range <= 5000
5000 < Range <= 7000
Range > 7000
Aircraft Category
Short Range
Medium Range
Long Range
Very Long Range
Study Mission (nm)
500
1000
3000
4000
Note:
DOC mission payload is usually the aircraft design payload (Standard Passenger Payload)
For DOC, use Study Mission with Standard Payload
EDXCW/PR/PB/20808A
AEA Method - Utilisation (DOC)
Utilisation (U) = Number of trips in a year
= Available hours in year / (Block Time + Turn Around Time)
Where:
Available Hours in year is not simply 24 hours × 365 days
Turn Around Time [TAT] = fn(Loading, Maintenance, Refuelling, etc.)
These values depend on the aircraft type and operation
© AIRBUS S.A.S. All rights reserved. Confidential and proprietary document.
Use the values from the following table for your aircraft’s study mission:
Study Mission
(nm)
Range < 1000
1000 <= Range <= 2000
Range > 2000
Available Hours
per Year (hours)
4000
5100
6500
Turn Around Time
(hours)
0.5
1.4
3.0
Use your calculated turn-around time
(The average of the three cases specified)
Increased utilisation = More trips = More fares = 
EDXCW/PR/PB/20808A
AEA Method - Total Investment (DOC)
Total Investment [TI] = Cost of aircraft and initial spares
= Manufacturer’s Study Price [MSP]
Typically a study variable (see later)
+ Airframe spares
= 10% of airframe price (or airframe cost)
= 0.10 × (MSP – (Engine Price [ENP] × No. of engines [NE]))
© AIRBUS S.A.S. All rights reserved. Confidential and proprietary document.
+ Spare Propulsion Units
= 30% of total engine price
= 0.30 × (Engine Price [ENP] × No. of engines [NE])
EDXCW/PR/PB/20808A
AEA Method - Financial Costs (DOC)
Total Financial Costs = Financial Overheads
= Depreciation [DEP]
= Depreciation of aircraft value
= Total Investment / (14 × Utilisation)
+ Interest [INT]
= Payment of aircraft financing
= 0.05 × Total Investment / Utilisation
© AIRBUS S.A.S. All rights reserved. Confidential and proprietary document.
+ Insurance [INS]
= Cost of insuring aircraft
= 0.006 × Manufacturer’s Study Price / Utilisation
EDXCW/PR/PB/20808A
AEA Method - Crew Costs (COC & DOC)
Total Crew Costs = Cost of current and reserve crews
= Cockpit Crew Cost [CPC]
= 380 × Block Time
Assumes a 2 person cockpit at $380 per block hour
+ Cabin Crew [CAC]
© AIRBUS S.A.S. All rights reserved. Confidential and proprietary document.
= 60 × NCAB × Block Time
Assumes $60 per block hour per cabin crew member
For a commercial airliner, the number of cabin crew [NCAB] is a
function of the comfort standard.
– Typically 1 per 35 pax, rounded up to the next whole number
EDXCW/PR/PB/20808A
© AIRBUS S.A.S. All rights reserved. Confidential and proprietary document.
EDXCW/PR/PB/20808A
AEA Method - AF Maintenance Costs (COC & DOC)
Airframe Maintenance Costs [AMC]
= Airframe Labour
=

 350  
 0.09  AFW  6.7  
   0.8  0.68  t  0.25  R
 AFW  75  

+ Airframe Materials
© AIRBUS S.A.S. All rights reserved. Confidential and proprietary document.
= AFP × (4.2 + 2.2 × (t - 0.25))
Where:
AFW = Airframe Weight (tonnes) = MWE less Weight of the Engines
R = Labour Rate = 66 $/hour
MWE = Manufacturers Weight Empty (tonnes)
t = Block time (hours)
AFP = Airframe Price = MSP less Price of the Engines ($M)
EDXCW/PR/PB/20808A
AEA Method - Eng Maintenance Costs (COC & DOC)
Engine Maintenance Costs [EMC]
The
Turbojet or Turbofan
Contra-Turboprop or Propfan
LT = 0.21 × C1 × C3 × (1+T )0.4 × R
LT × 0.152 × C3 × (1+N)0.4 × R
LP = 0.072 × B × (1+N/2)0.4 × R
[Core]
[Props]
Material: MT = 2.56 × (1+T)0.8 × C1 (C2+C3)
MT = 1.65 × (1+N)0.8 × (C2+C3)
MP = 0.56 × (1+N/2)0.8 × B
[Core]
[Props]
Labour:
Total:
© AIRBUS S.A.S. All rights reserved. Confidential and proprietary document.
method depends on the engine type:
EMC = NE × (LT + MT) × (tƒ+1.3)
EMC = NE × (LT+MT) × (tƒ+1.3)
+ NE × (LP+MP) × (tƒ+0.5)
Where:
C1 = 1.27 - 0.2 x BPR0.2
C2 = 0.4 × (OPR / 20)1.3 + 0.4
C3 = 0.032 × NC + 0.57
A = 8.5 × (N / 3 × P + 28)0.5 + 0.9
B = (0.05 × P + 0.6) × (0.4 × (D / A) + 0.6)
T = Sea Level Static Thrust (tonnes)
NC = No. of Compressor Stages
tƒ = Flight time = Block time - 0.25 (hrs)
BPR = Bypass Ratio
OPR = Overall Pressure Ratio
P = No. of Propeller Blades
EDXCW/PR/PB/20808A
N= Take Off SHP×10-3
D= Prop Diameter (m)
AEA Method - Fuel Price (COC & DOC)
Fuel cost [FUE]
= Block Fuel (lb) / 6.7 × Fuel Price ($/USGal)
Assumed fuel density = 6.7 lb/USGal (~0.803 kg/l)
Current price
>2 $/USgal
© AIRBUS S.A.S. All rights reserved. Confidential and proprietary document.
Historic price
~1 $/USgal
• The price of fuel varies
considerably
• A tax on fuel is likely to
be the method of
taxing aircraft
emissions in the future
• Fuel price is typically
considered a study
variable (... see later)
Source: IATA website, 03 October 2006
EDXCW/PR/PB/20808A
http://www.iata.org/whatwedo/economics/fuel_monitor/price_development.htm
Cost Estimation - Understanding Price & Cost
• The Manufacturer’s Study Price [MSP] is a major DOC input
= Airframe Price [AFP] + Engine Price [ENP]
( = Aircraft Cost + Manufacturer’s Profit)
• The Price is what the airline is willing to pay for the aircraft
Market
driven, big discounts
• The Cost is what it costs the manufacturer to build the aircraft
© AIRBUS S.A.S. All rights reserved. Confidential and proprietary document.
= RC + (NRC / Number of a/c produced)
Where:
RC = Recurring Cost = Cost of building one aircraft. Includes materials,
man-hours, transportation, bought items, energy, etc.
NRC = Non Recurring Costs = Cost of design and set up for manufacture
of a new aircraft. Includes design, jig & tools, testing, prototypes.
Price is not the same as Cost
EDXCW/PR/PB/20808A
Cost Estimation - Price Prediction
• The Price is what airlines are willing to pay for the aircraft
Price
is market driven and is dependent on the aircraft’s capabilities:
– Primary effects:
Range, Payload (passenger & freight)
– Secondary effects: Speed, Comfort, Operating Cost
– Tertiary effects:
Fleet commonality, cross-crew qualification, etc.
Airframe
price can be estimated by statistical assessment of a/c list
prices against combinations of their capabilities, i.e.
Airframe price = fn(payload, range, speed, ...)
© AIRBUS S.A.S. All rights reserved. Confidential and proprietary document.
Engine
price can be estimated in a similar way, assessed against
relevant engine parameters:
Engine price = fn(thrust, efficiency, ...)
Airlines
rarely pay full price (... see next slide)
Aircraft price is determined by the market place
EDXCW/PR/PB/20808A
Price - List vs. Discounted
© AIRBUS S.A.S. All rights reserved. Confidential and proprietary document.
Boeing jet prices glimpsed in deal
How much does Ryanair Chief Executive Michael O'Leary pay for his Boeing jets?
His bare-bones, low-cost airline is one of Boeing's most important customers. But Boeing's prices
are one of its best-kept secrets — Airbus would certainly like to know.
Ryanair gave a glimpse of the answer yesterday in an unusual regulatory filing connected to its
February order for 70 jets. The papers offer details of Boeing's commercial jet pricing that are not
normally revealed.
O'Leary's starting point for price negotiations is way below Boeing's public list price — and he gets
deep concessions from there, according to the proxy document provided to shareholders.
In addition, the deal retroactively applies the newest, biggest discounts to 89 previously ordered
jets that Boeing hasn't yet delivered to Ryanair.
Ryanair, one of the fastest-growing airlines in the world, has a fleet of 89 Renton-built Boeing 737s
in service, with another 145 of the jets on firm order and options to buy a further 193. The order
placed earlier this year needs shareholder approval in a May 12 vote — hence the proxy filing.
Yesterday's filing said $51 million is a "basic price" for the 70 Boeing 737-800 airplanes ordered in
February, including the engines and some optional features. Ryanair will also pay around
$900,000 per aircraft for equipment from third parties that Boeing will install.
That basic price is already discounted between 17 and 27 percent from the public list price of
$61.5 million to $69.5 million given on Boeing's Web site.
However, the filing adds that Boeing granted Ryanair "certain price concessions" in the form of
credit and allowances that "will reduce the effective price of each aircraft to Ryanair significantly
below the basic price."
Boeing will also provide a range of support services, and will install fuel-conserving winglets at no
extra cost.
The document gives one further clue to Ryanair's price tag: It states that 454 million euros (or
$593 million) will be required to fund the 29 jets to be delivered between now and March 2006, or
about $20 million per aircraft.
And elsewhere it says 30 percent of the price is required in advance of delivery, suggesting the
$593 million will pay the remaining 70 percent.
That works out to a bargain price tag on Ryanair's jets of about $29 million.
For a hard-driving negotiator like O'Leary, $29 million for a 737-800 — less than half the public list
price — is "not out of the realm of imagination," said industry analyst Byron Callan of Merrill Lynch.
Callan said he'd heard of such prices being offered in the recent Iberia sales campaign that Boeing
lost to Airbus.
"Even at these price levels, I still have to believe Boeing is making money," Callan said.
To persuade shareholders to approve the purchase, the filing gives the rationale for picking the
737 over Airbus' A320: Boeing offered the best price; its jet has lower per-seat operating costs;
and the airline already operates an all-Boeing fleet.
Source: Seattle Times, 23 April 2005
... $51 million is a "basic price"...
... already discounted between 17 and
27 percent from the public list price of
$61.5 million to $69.5 million...
... Boeing granted Ryanair "certain
price concessions" ... that "will reduce
the effective price of each aircraft ...
Boeing will also provide a range of
support services, and will install fuelconserving winglets at no extra cost.
... a bargain price tag on Ryanair's
jets of about $29 million ...
In addition, the deal retroactively
applies the newest, biggest discounts
to 89 previously ordered jets that
Boeing hasn't yet delivered
"Even at these price levels, I still have
to believe Boeing is making money"
http://seattletimes.nwsource.com/html/boeingaerospace/2002250601_ryanair23.html
Discounts are unpredictable – Always use list price
EDXCW/PR/PB/20808A
Cost Estimation - RC Prediction
• The Recurring Cost [RC] is the cost of making one aircraft
 Materials,
man-hours, transportation, bought items, energy, etc.
 Cost prediction can be harder than price prediction.
• There are two main methods:
© AIRBUS S.A.S. All rights reserved. Confidential and proprietary document.
 Top
Down
– Airframe cost = fn(Airframe Weight)
– Method predicts light, high-tech structures are cheap (... rarely the case)
– Fairly simple, good at OAD level, historical data driven - not particularly
accurate – predicts yesterday’s cost tomorrow ?
 Bottom up (Manufacturing process based)
– Airframe cost = S(component costs)
– Component cost = Material cost + Process Cost
(Process cost includes man-hours, machining, energy, transportation)
– Method correctly predicts heavy, simply machined components are cheap
– More complicated, far more accurate, component & sub-component
... See note on next page
Aircraft cost is determined by the aircraft design
EDXCW/PR/PB/20808A
Cost Estimation - NRC Prediction
• Non-Recurring Cost [NRC] is the cost of design and set up
for manufacture of a new aircraft
• Consists of ...
Main stream engineering will typically take ~5 years
Tests: Wind tunnel test program, Materials & structures tests
Jig and tooling costs
Static & fatigue test airframes
Flight test aircraft - Typically costs about 30% more than a normal
production aircraft
© AIRBUS S.A.S. All rights reserved. Confidential and proprietary document.
Engineering:
Note:
RCs and NRCs, and hence aircraft cost, may already be a deliverable for
the project Business Case chapter.
– If so, use these values in the operating cost calculations
– If not, a suggested NRC and RC estimation method can be found in:
“Airplane Design, Part VIII: Airplane Cost Estimation” by Dr. J. Roskam
... and maybe use the updated factors from the “AAA” method
EDXCW/PR/PB/20808A
Results - Example COC & DOC Input Data
© AIRBUS S.A.S. All rights reserved. Confidential and proprietary document.
Airframe Price
Engine Price (per engine)
Fuel Price
Labour rate
$M
$M
$/USGal
$/hr
SPP Passengers
Stage Length (Study Mission)
Block Fuel
Block Time
nm
lbs
hrs
MTOW
MWE
Engine Weight
T
T
T
Number of Engines
Sea Level Static Thrust
Take-Off Shaft horsepower
BPR
Propeller Diameter
Propeller blades
Compressor Stages
OPR
EDXCW/PR/PB/20808A
klb
SHP×10-3
m
Example
Design
Project
48.0
6.0
variable
66
?
?
variable
66
150
500
7189
1.602
?
?
?
?
75.5
38.0
3.5
?
?
?
2
26500
n/a
4.75
n/a
n/a
14
27.4
?
?
?
?
?
?
?
?
Results - Example COC & DOC Results
Fuel Price
$/USgal
1.0
2.5
4.0
$/trip
$/trip
$/trip
2567.44
1797.21
189.18
2567.44
1797.21
189.18
2567.44
1797.21
189.18
$/trip
$/trip
1046.58
421.36
1046.58
421.36
1046.58
421.36
$/trip
$/trip
$/trip
$/trip
$/trip
608.76
480.60
568.94
453.00
1072.99
608.76
480.60
568.94
453.00
2686.46
608.76
480.60
568.94
453.00
4291.94
Total COC Sector Cost
Total COC Seat-Mile Costs
$/trip
cent/seat-nm
4652.23
6.20
6261.71
8.35
7871.19
10.49
Total DOC Sector Cost
Total DOC Seat-Mile Cost
$/trip
cent/seat-nm
9206.07
12.27
10815.54
14.42
12425.02
16.57
© AIRBUS S.A.S. All rights reserved. Confidential and proprietary document.
Financial Costs
Depreciation
Interest
Insurance
Maintenance Costs
Airframe Maintenance
Engine Maintenance
Flight Costs
Cockpit Crew
Cabin Crew
Navigation Charges
Landing Fees
Fuel
Use these results to validate your method
EDXCW/PR/PB/20808A
Results - Example COC & DOC Pie charts
Historic
Current
The Future?
Fuel = 1.00 $/USgal
Fuel = 2.50 $/USgal
Fuel = 4.00 $/USgal
Airframe maintenance
13%
Airframe maintenance
17%
Airframe maintenance
22%
Fuel
24%
Engine maintenance
5%
Engine maintenance
7%
Fuel
42%
COC
Cockpit crew
8%
Engine maintenance
9%
Landing fees
10%
Cockpit crew
10%
Cockpit crew
13%
Navigation charges
12%
Cabin crew
6%
Cabin crew
8%
Cabin crew
10%
Landing fees
7%
Fuel
12%
Fuel
24%
Depreciation
27%
Landing fees
5%
Fuel
55%
Navigation charges
7%
Navigation charges
9%
Landing fees
6%
Depreciation
21%
Depreciation
24%
Fuel
34%
© AIRBUS S.A.S. All rights reserved. Confidential and proprietary document.
Navigation charges
6%
DOC
Cabin crew
5%
Landing fees
4%
Cockpit crew
7%
Navigation charges
5%
Engine maintenance
5%
Airframe maintenance
11%
Interest
14%
Interest
20%
Insurance
2%
Cabin crew
4%
Cockpit crew
6%
Engine maintenance
4%
Interest
17%
Landing fees
4%
Insurance
2%
Airframe maintenance
10%
Insurance
2%
Navigation charges
5%
Airframe maintenance
8%
Cabin crew
4%
Engine maintenance
3%
Cockpit crew
5%
Blue = Financial Costs
Green = Maintenance Costs
Airline analysis: Use COC
EDXCW/PR/PB/20808A
Red = Flight Costs
Design studies: Use DOC
Sensitivity Analysis - Trade Studies
• Price Variability Studies
Both
fuel price and MSP are fixed by market forces, not the
manufacturer, so investigate their effect on COC
• Technical Trade Studies
As
part of your sizing loops, investigate the effect of aircraft
configuration change on DOC
– Geometric parameters, i.e. Wing area, Wing span
– Use of technology, i.e. CFRP vs. Metallic
technical trade studies it is important to use a Cost + Profit
method (i.e. price variant), rather than assumed aircraft price.
© AIRBUS S.A.S. All rights reserved. Confidential and proprietary document.
For
EDXCW/PR/PB/20808A
This document and all information contained herein is the sole
property of AIRBUS UK LTD. No intellectual property rights
are granted by the delivery of this document or the disclosure
of its content. This document shall not be reproduced or
disclosed to a third party without the express written consent
of AIRBUS UK LTD. This document and its content shall not
be used for any purpose other than that for which it is
supplied.
© AIRBUS S.A.S. All rights reserved. Confidential and proprietary document.
The statements made herein do not constitute an offer. They
are based on the mentioned assumptions and are expressed
in good faith. Where the supporting grounds for these
statements are not shown, AIRBUS UK LTD will be pleased to
explain the basis thereof.
EDXCW/PR/PB/20808A
All-New Aircraft Design
• Moving directly from the idea to the product has caused
problems
e.g.
aircraft designed for too narrow a market…
AZ 8 L
Vickers VC10
© AIRBUS S.A.S. All rights reserved. Confidential and proprietary document.
Convair CV990
• Only permanent questioning of concepts ensures that no
better concept has been left aside
EDXCW/PR/PB/20808A
© AIRBUS S.A.S. All rights reserved. Confidential and proprietary document.
Carpet Plots
EDXCW/PR/PB/20808A
A bluffer’s guide to drawing carpet plots (1/3)
A couple of thoughts:
- A 3×3 carpet plot is only six curves on the same axes
L
- The X-axis of a carpet plot is an arbitrary scale
Variable
roughly sketch what you
want your carpet plot to
look like – it doesn’t have
to be accurate
2) Arbitrarily label each
© AIRBUS S.A.S. All rights reserved. Confidential and proprietary document.
3) Map your sketch to your
P
F
B
E
A
I
H
D
table of results:
Variable
- The highest and lowest
A
P
corners (C & G) are the
highest and lowest values,
- from which the their
B
curves (R & N, P & L) can
A
be determined
R
D
- The rest of the curves
Q
and loci should now be Variable
P
fairly easy to map
A
EDXCW/PR/PB/20808A
N
2.9 3.7 4.5
Variable A
C
R
R
Variable
B
Variable
A
locus on the carpet plot
(i.e. A to I)
Q
0.9 1.7 2.5
M 1.9 2.7 3.5
B
1) On a piece of paper,
Variable A
P
G
N
Variable
B
L
Variable
B
L
0.9
M
N
1.7
2.5
1.9
2.7
3.5
2.9
3.7
4.5
P
F
E
I
H
L
G
R
C
Variable A
C
G
Q
M
Variable
B
Variable
B
R
0.9
G
1.7 D
2.5 A
M 1.9
H
2.7 E
3.5 B
N
I
3.7 F
4.5
L
N
Q
2.9
C
A bluffer’s guide to drawing carpet plots (2/3)
C
B
4) In Excel, tabulate the co-ordinates of
the first curve you wish to plot, with
an arbitrary X-scale proportional to
the spacing between the 2nd variables
(L, M & N are assumed to be linearly
spaced in this example).
R
A
Q
Variable
A
F
Variable A
E
I
H
D
P
G
L
P
N
M
Variable
B
L
Tip: It’s simplest to start with a curve
on the left-hand side of the carpet
5
4.5
4
3.5
© AIRBUS S.A.S. All rights reserved. Confidential and proprietary document.
5) The second curve in this set will be
“slipped” along the X-axis by a
constant delta. Tabulate the coordinates for this curve and plot it as
a new data series on the same chart
6) The third curve in the set is slipped
again by a delta proportional to the
spacing between the 1st variables (R,
Q & P are assumed to be linearly
spaced in this example).
EDXCW/PR/PB/20808A
2.5
Variable A = R
2
1.5
1
0.5
0
0
1
2
3
4
5
4.5
4
3.5
3
Variable A = R
2.5
Variable A = Q
2
1.5
1
0.5
0
0
1
2
3
4
5
5
4.5
4
3.5
3
Variable A = R
2.5
Variable A = Q
Variable A = P
2
1.5
1
0.5
0
0
1
2
3
4
5
R
Variable M 1.9 2.7 3.5
B
N 2.9 3.7 4.5
3
Plot these in an “XY Scatter” chart
Q
0.9 1.7 2.5
6
A bluffer’s guide to drawing carpet plots (3/3)
C
B
7) The first curve of the
second set of data is
plotted in a similar way,
but you need to determine
where each curve
intersects with the first set
of curves and use the
same X-ordinates
First co-ord.
of curve “P”
R
A
Q
Variable
A
First co-ord.
of curve “Q”
F
Variable A
E
I
H
D
P
G
L
P
N
M
Variable
B
L
5
4
3.5
3
Variable A = R
Variable A = Q
2.5
Variable A = P
Variable B = L
2
1.5
1
0.5
0
0
1
2
3
4
5
6
8) The remaining curves can be
tabulated and plotted in the same
way
5
4.5
4
3.5
Variable A = R
3
Variable A = Q
Variable A = P
2.5
Variable B = L
Variable B = M
2
Variable B = N
1.5
1
0.5
1
2
3
4
5
6
9) Format the chart as required.
- You will need to manually add
labels to identify the curves
- Remove X-axis values as these
are meaningless
Trade Study showing the effect of
varying "A" and "B"
5
Dependent Variable
© AIRBUS S.A.S. All rights reserved. Confidential and proprietary document.
0
0
4
3
N
R
2
1
Variable
"A"
M
Q
P
0
EDXCW/PR/PB/20808A
L
Variable
"B"
R
Variable M 1.9 2.7 3.5
B
N 2.9 3.7 4.5
4.5
First co-ord.
of curve “R”
Q
0.9 1.7 2.5
Process & Performance
• Use shared & common assumptions – discuss & agree.
•Set up spreadsheets to facilitate quick turnaround of data – get the
process right, otherwise you’ll waste time later in the multi iterations.
•OAD Integration – Component level sizing loops are key: Excellent wing
concept on a poor overall aircraft won’t work !
•Focus on generating data that assists decision making - sensitivities
© AIRBUS S.A.S. All rights reserved. Confidential and proprietary document.
Initial ‘guesstimates’ on design weights (MTOW/ OWE/ Fuel/ PL).
Performance evaluation at key points in flight envelope to meet required P-R;
–TOFL & BFL
–First segment & second segment ROC requirements
–ICA – Top of climb thrust available to give 300 fpm ROC margin
–Fuel volume calcs for ‘assumed’ aero efficiency & weights
•Don’t complicate the solution unless absolutely certain its needed.
EDXCW/PR/PB/20808A
Sensitivity Analysis - Fuel & A/C Price Study
Example Carpet Plot showing Relative Seat-Mile COC & DOC sensitivity
140
COC
© AIRBUS S.A.S. All rights reserved. Confidential and proprietary document.
Relative Seat-Mile Cost (%)
130
DOC
4.0
120
110
4.0
100
2.5
90
Fuel Price
($/USgal)
80
70
60
2.5
1.0
50
60
70
Fuel Price
($/USgal) 1.0
50
70
60
Aircraft Price
($M)
Aircraft Price ($M)
Notes: 1) A constant aircraft configuration is used for fuel & price sensitivity studies
2) A constant aircraft configuration has a constant cost.
Reducing price to meet a DOC target directly affects profits
EDXCW/PR/PB/20808A
© AIRBUS S.A.S. All rights reserved. Confidential and proprietary document.
Sensitivity Analysis - Wg Area vs Span Trades
Varying
Cost

Fixed
Price

Note: Importance of using cost in technical trade studies, not fixed price
Configuration changes can have significant DOC effects
EDXCW/PR/PB/20808A