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Smith H & Fielding J.P.Department of Aerospace Engineering
School of EngineeringCranfield University UK
Connect Research 2009 12-13 November 2009
OECD Conférence Centre - 2, rue André Pascal, Paris
New Concepts for Environmentally Friendly Aircraft
New Models of Innovation for Economic Growth and Sustainability
• Introduction
• Aircraft Designed to reduce noise
• Aircraft Designed to reduce global warming potential
• Conclusions
Presentation Overview
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LOW NOISE CONCEPTS
• Cranfield program linked to the Cambridge/MIT Silent
aircraft Initiative
• Baseline conventional design
• Novel concept down-select
• Broad delta concepts
• Aft-Mounted Engine (AME)
• SAX-10 (SAI team)
• Cranfield BWB
• Narrow Delta (ND)
• Broad Delta (BD)
• Joined Wing (JW)
Research into Aviation and the Environment - Configuration options for Silent Aircraft Initiative
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MAIN CONFIGURATIONS STUDIED
TAILLESS BROAD DELTA
V-Tail Broad Delta Aircraft
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Description Symbol Units Baseline BDSF BDFT
Wing Area S [M2] 245.1 509.0 355.7
Wing Span B [M] 44.3 45.9 41.6
Wing Aspect Ratio A - 8 4.13 4.87
Wing Quarter Chord Sweep 1/4 [deg] 33 25.6 30.2
Wing Taper Ratio - 0.207 0.181 0.283
Thickness-to-Chord Ratio t/c - 0.11 0.1013 0.1013
Lift-Drag Ratio (Max) L/D - 17.7 18.4 19.9
Cruise Lift Coefficient (CL)cr - 0.55 0.242 0.338
Operational Empty Mass MOEW [kg] 94,595 77,422 74,061
Mass of Payload MPAY [kg] 23,760 23,760 23,760
Mass of Feul Required Mf [kg] 44,694 37,857 30,912
Total Static Thrust T0 [N] 579,130 428,139 405,952
Total Overall Mass M0 [kg] 160,886 139,039 128,732
Noise at ICAO Point - dB(A) 93.8 73.5 72
LOW NOISE CONCEPTS - PERFORMANCE COMPARISONS (subject to powerplant drag verification)
• Aircraft Designed to be more environmentally
benign
• A-6 Greenliner (conventional configuration)
• BWB
• Box Wing
• MRT-7 in-flight refuelling tanker
CRANFIELD RESEARCH
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Healthier Passenger
Experience
Improved Life Cycle /
Sustainability
Improved Impact on
Local Community
Reduced Global
Atmospheric Impact
% of World Total Fuel burn by country
USA
ChinaJapan
UK
50
40
30
20
10
0
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Vehicle Efficiency• Advanced engines
• Fuel efficient (less CO2)• Reduced NOX• Minimised contrail impact
•Reduced airplane weight
• Improved aerodynamics
• Alternate speed / altitude
A-6 Conceptual Design
Healthier Passenger
Experience
Improved Life Cycle /
Sustainability
Improved Impact on
Local Community
Reduced Global
Atmospheric Impact
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Local Environment• Local air quality• Airport noise
A-6 Conceptual Design
Noise• Low Noise Engines and Nacelles• Quiet Takeoff and Landing Procedures• Reduced Airframe Noise• Quiet Ramp Operation
A-6 Conceptual Design
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Local Air Quality
• Reduced engine & APU NOx emissions
• Reduced particulate engine emissions
• Startup emissions reduction
• Fuel venting control
• single engine or electric taxi
A-6 Conceptual Design
Healthier Passenger
Experience
Improved Life Cycle /
Sustainability
Improved Impact on
Local Community
Reduced Global
Atmospheric Impact
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Cabin Experience• Lower cabin altitude • Better air filtration• Higher humidity• Improved cabin baggage stowage• Improved seats• Quieter cabin
Healthier Passenger
Experience
Improved Life Cycle /
Sustainability
Improved Impact on
Local Community
Reduced Global
Atmospheric Impact
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Sustainability• Material choice for recycling• Non hazardous materials• Low energy / Low waste manufacturing processes
Recycling
Cranfield A-6
MTOW: 209,410kgDesign Range: 7500nmDesign PAX: 375Wing span: 64mLength: 67m
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• Engines• Noise shielding• Potential for increased diameter
• Efficient high aspect ratio wing• Natural laminar flow wing
• Low sweep• Low Mach number
• Large cabin• Diameter• Length
Effects of proximity of engines to tailplane
© Cranfield University 2007
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• Natural Laminar Flow Wing
• Advanced Materials
• “All-electric” aircraft
• Pulse electro-thermal de-icing
• Electro Hydrostatic Actuators
• Advanced alternate engine
• Advanced avionics
Introduction to the A-6 GreenlinerNovel Features &
Technologies
Performance
• Cruise• M = 0.74
• Natural laminar flow
• Increase in flight time?
0,5 0,55 0,6 0,65 0,7 0,75 0,8 0,85 0,9
A-6
B777
A340
Mach
10,5 11,5 12,5 13,5 14,5 15,5 16,5 17,5 18,5
A-6
B777
A340
Duration of a 7500 nm flight (h)
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• Assumption• Climbing cruise• Same Sfc
Assumptions 1990’s
B777/A340
2010’s
B787/A350
2020’s
A-6
Turbulent
2020’s
A-6
Laminar
L/D 19 21 24 29
Weight (kg) 351535 230650 209409.9
Number of
passengers
375 290 375 375
Range (nm) 7000 7000 7000 7000
• Operating costs• Direct Operation Cost (DOC)
US$ 0.09 / nm seat (2006)
Cash Operating Cost (COC)
US$15.27/nm (2006)
1.77 1.63 1.61
4.26
10.879.69
9.11
11.51
10.40
0.49
0.32
0.54
0
5
10
15
20
25
30
1 2 3
Aircraft Type (for 7500nm)
CO
C (
US
$/n
m)
Crew Cost Fuel & Oil Cost Direct Maintenance Cost Landing & Navigation Cost
A-6 VCS A340-600 B777-300ER
US$24.13
(+ 58 %)US$21.82
(+ 42.9 %)
US$15.27
Datum
© Cranfield University 2007
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A-6
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Conceptual Designs –Early Cranfield BWB
Advantages
SYSTEMS
•potential for highly integrated
airframe/powerplant
•ideal config. for application of
laminar flow technology
•significant advantages from
control configured vehicle
AERODYNAMICS
•low wetted area to volume ratio
•form conducive to low interference drag
HUMAN FACTORS
•huge volumetric capacity
•flexible cabin layout
STRUCTURES
•efficient deep sections
•favourable span loadingBENEFITS
•Lower fuel burn /
emissions
•Suitable for high
capacity applications
•significant DOC reductions
should be achievable
Blended Wing-Body
Configuration Benefits
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Advantages
Conventional• Take Off Mass
590 000 kg• Fuel Mass
242 000 kg
BWB• Take Off Mass
480 000 kg• Fuel Mass
205 000 kg
7650 nm Mach 0.85 656 passengers
SYSTEMS
•Design of fully integrated propulsion
•Adapt to novel propulsion systems
•Design & integration of lam. flow system
•Control allocation
OPERATIONS
•Span/Wheel track limits
•airport pax. handling
CONCEPTUAL DESIGN
•Tools
•Methods
FLOW CONTROL
•Laminar flowHUMAN FACTORS
•embarkation time
•pax comfort/appeal
•no windows
•emergency evac.
•pilot workload in
reversion modes
AIRWORTHINESS REQUIREMENTS
•Safety
•Evacuation
•Stability augmentation/reliabilitySTRUCTURES
•unconventional layout
•non-circular pressure cabin
•aeroelastics
•major cut-outs for exits
MANUFACTURE
•Large composite components
•Transport to final assembly
Challenges
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• Centre Wing-Body Concepts
Preliminary Design Studies
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THE KESTREL BLENDED WING BODY AIRCRAFT
Joint Cranfield University-BAE SYSTEMS Flying
Demonstrator
Box Wing
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Military Air to Air Refuelling
Introduction to the MRT7
• 1500 US gal/min (5670L/min)
• One point refuelling for all types of military aircraft
(fighters, bombers, airlifters, tankers)
Air-to-Air RefuellingFlying Boom System
Fuel Flow
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Civilian Refuelling
MRT7-T
MRT7-3R
Fuel Flow
Introduction to the MRT7
Boom Tunnel Dimensions:
Length = 15m, Width = 90cm, Height = 45cm
Forward Facing Boom Location
Fuel Flow
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Air-to-Air RefuellingForward Facing Boom Reliability
Hazardous Risks related to the actuation system
Reliability Block Diagrams Methodology
Failure rate: 47 / 106 flying hours
CS-25 Target for Hazardous Failure: 1 / 107 flying hours
• Two Capstans attached to
the airframe
• Power Requirements: 34 kWSafety Cables
Civilian Refuelling
Using MRT7-3Rs will save
20% of the fuel used when
compared to a similar fleet of
Boeing 787 - 8
Introduction to the MRT7
Operational Capability
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Routes (Refuelling hubs)
Cost competitiveness
1st example: 6335NM flight
Buenos Aires – London
Long Range MRT7-8 Short Range MRT7-3R
FUEL SAVINGRange nm
Fuel
(tonnes)
Range
nm
Fuel (tonnes)
Aircraft +
Tanker
Fuel
comparison 6335 57,6
3805+
2562 49 8,6 T 17%
Direct Operating Cost $ Direct Operating Cost $
Cost
comparison 244 300$ 240 000$ 4300$ 2%
TOM: 161 T (-3R)
207 T (-8)
Arrival in Cape Verde
hub, decrease speed
from M0.85 to M0.61
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Conclusions
• The last 105 years have been exciting, but
conventional configuration subsonic aircraft are
approaching a technological, environmental and
cost plateau.
• Global warming and noise are important issues
which require radical solutions
• Operational efficiency and cost-effectiveness will
continue to be major drivers
• Intermediate configurations, such as the Cranfield A-6 Greenliner, should be able to reduce costs, noise and Global Warming, but at a lower cruise speed.
• Civil flight refuelling offers significant fuel burn and pollution reduction benefits, with little technical risk.
• The broad delta appears to be a promising low-noise solution, which also has fuel-saving benefits.
• The Blended-Wing –Body remains an attractive future option
Conclusions - 2
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Slide No. 51