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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