Case Study - very large transport airplane Airplane Design: Past, Present and Future –

An Early 21st Century Perspective

John H. McMastersTechnical Fellow

The Boeing Companyjohn.h.mcmasters@boeing.com

and

Affiliate Professor

Department of Aeronautics and Astronautics

University of Washington

Seattle, WA

April 2007

Ed Wells Partnership Short Course

Based on: American Institute of Aeronautics and Astronautics (AIAA) & Sigma Xi Distinguished Lectures &

Von Kármán Institute for Fluid Dynamics Lecture Series: “Innovative Configurations for Future Civil Transports”, Brussels, Belgium June 6-10, 2005

Notation and Symbols Used

A Area (ft.2, m2)a Speed of sound (ft./sec., m/s)AR Aspect ratio, b/č = b2/Sb Wing span (ft., m)č Average wing chord (ft.,m)CF Force coefficients (lift, drag, etc.) = F/qSCℓ Section (2D) lift coefficientCM Moment coefficient = M/qSĉCp Pressure coefficient = Δp/qD Drag force (lb., N)E Energy (Ft.-lbs., N-m)e “Oswald efficency factor”ew Wing span efficiency factor (= 1/kw )F Force (lift, drag, etc.) (lbs., N)H Total head (reservoir pressure)I Moment of inertiakw Wing span efficiency factor (= 1/ew)L Lift force (lb., N)ℓ Length (ft., m)M Mach number (V/a)M Mass (kg)M Moment (ft. lbs., N m)P Power (ft.-lbs./sec., N-m/sec.)p Static pressure (lbs./ft.2)

q Dynamic pressure (lbs./ft.2) = ½ρV2

R Range (mi., km)Rn Reynolds number (ρVℓ / μ)S Wing area (ft.2, m2)T Thrust (lb., N)T Temperature (oF)u Local x-direction velocity componentV Velocity, Speed (ft./sec., m/s, mph, km/h)v Local y-direction velocity componentw Downwash velocity (ft./sec., m/s)ż Sink rate (vertical velocity) (ft./sec., m/s)

Greek:α Angle of attack (deg.)Γ Circulationγ Climb or glide angle (deg., rad.)γ Ratio of specific heats in a fluidε Wing twist angle (deg.)θ Downwash angle (deg.)φ Velocity potentialΛ Wing sweep angle (deg.)μ Dynamic viscosityν Kinematic viscosity (μ/ρ)ρ Fluid mass density (kg/m3)

• Case StudiesII. “Very large” transport airplanes (A380s, flying wings and C-wings)

Presentation Overview

Case II. The “Big Airplane” Problem

Antonov An 225 “Mriya”

Wing Span: 290 ft. (88.4 m)

MTOW: 1,322,750 lb. (600,000 kg)

Six 51,590 lb. ST (23,400 kgp) Lotarev D-18T turbofans

Boeing Product Development Opportunities(circa 1990)

In Production Development or Study

Seats

Range (nmi.)

7J7

777

NLA

Typical Marketing “Range-Payload” Diagram (Market Niches –Product Development Opportunities – circa 1985-90)

Air Traffic Growth and Aircraft Arrival/Departure Data for Kennedy International Airport (to circa 1995)

1960 1970 1980 1990 2000

Year

PassengersPer Year(millions)

15

10

5

0

AircraftPer Year

(thousands)

85

70

55

40

Advent of Wide-Body Transports (B 747, DC-10, L 1011, etc.)

Aircraft

Passengers

Heavy (H) Airplanes over 300,00 lb. max. certified take-off weight (MCTOW)(e.g. B777, B767, B747, MD 11)

Medium (M) Airplanes with MCTOW between 15,400 and 300,000 lbs.

Light (L) Airplanes with MCTOW less than 15,400 lbs.

Wake Vortex Separation Standards

Radar Separation: Time Separation: Heavy behind Heavy 4 n. mi. Medium behind Heavy 2 min. Medium behind Heavy 5 n. mi. Light behind Heavy 3 min. Light behind A380 10 n. mi. Light behind Heavy 6 n. mi. Light behind Medium 5 n. mi.

Passengers Passengers

Win

g S

pa

n (

ft.)

Dir

ec

t O

pe

rati

ng

Co

st

(ce

nts

/sea

t-m

i.)

“Square-Cube Law” Trends in Size & DOC(Conventional “Tube and Wing” Configurations)

~ 600

Thanks to Ilan kroo

Classic Configuration Evolution

707-120

747-400

Super 747 (NLA)

7?7 (NLA)

~140 passengers

~ 425 passengers

600+ passengers

Too long to fit in terminal gates, so..

Outboard engines at wing tip stations of a 747

Airbus A380 Jumbo Jumbo-Jet

Goodyear

Jumbo 600 Passenger Subsonic Transport (circa 1992)

Configuration Issues:

• Runway limits• Taxiway limits• Terminal gate limits• Emergency evacuation• Community noise• Wake vortices• Wing skin size limits• Ditching/flotation• Passenger comfort

Must fit within a 80 m box

Airbus A380 in a Cross Wind

Northrop B-49 bomber (circa 1948-49)

Northrop Grumman B-2

Early Attempts to Solve the “Large [600+ Passenger]Transport Airplane Problem”

An Early Version of the Liebeck Blended Wing-Body Subsonic Transport

From the desk of J. H. McMasters, 1992

McMasters/BoeingConceptual “747 XXL”

circa 1992

Griffith airfoil

Wing Spans b ≈ 300 ft.

The Griffith Airfoil (circa 1944)

Suction slot

Conventional airfoil (chord ć )

Griffith airfoil (chord c )

CP

-

+

Pressure recovery(turbulent flow)

Favorable gradient for laminar flow

Transonic Griffith airfoil

t

c

ć0

1

A Suite of Drag Reducing Wing Tip Devices

A Flawed (and Clumsy) Attempt to Emulate Nature

http://www.winggrid.ch/index.htm

A Family of Non-Planar Wing ConfigurationsConstant wing span (b), area (S) and height-to-span ratio [ h/b=0.2 ]

Biplane kw = 0.74

X-wing kw = 0.75

Branched tips kw = 0.76(“pfeathers”)

Tip plates kw = 0.72

Box biplane kw = 0.68

Joined wing kw = 0.95

C-Wing kw = 0.69

Tip plated winglets kw = 0.83

Winglets kw = 0.71

Dihedral kw = 0.97

Treffetz plane analyses due to Prof. Ilan Kroo, Stanford University (circa 1992).

Note: For an optimally loaded planar wing of the same span and area kw = 1.0

Total Drag (D) = Dviscous + Dinduced [+ Dcompressibility ] Dviscous ~ SwetV2f(CL)

Induced Drag (drag due to lift) = Di ~ kw [Lift (L)/span (b)]2x speed (V)-2 ~ kw [W/b] 2

kw = theoretical wing span efficiency factor = 1/ew In steady, level flight,

Lift (L) = Weight (W)

b

h

Aspect ratio = b2 S

Non-Planar Wing Span Loads

L/2

L/2

L/2

L1

L2

L1

b/2 b/2

h

h

L/2

L/2

L/2 + L2

L1

L1

L2

Planar Wing

Winglets

C-Wing

Winglet-let

A Possible [Slightly Grotesque] C-Wing Large Transport Airplane Configuration

From the desk of J.H. McMasters, 1994

Baseline Configuration

Baseline

600+ Passenger C-Wing Transport Configuration(Semi-Span Loader, Quasi-Three-Surface Airplanes)

McMasters, J.H. and Kroo, I. M., “Advanced Configurations for Very Large Subsonic Transport Airplanes”, NASA CR 198351, Oct. 1996; also Aircraft Design, Vol. 1, No. 4, 1998, pp. 217-242.

Boeing configuration patent granted 1996.

Layout of Passenger Accommodations (LOPA) for a Single Deck, 3-Class, 600 Passenger C-Wing Transport

Size Comparison for a Conventional and C-Wing 600 Passenger Transport Airplane

“Winged Watermelon” (“Flying Spud”)

“Transonic Seagull”

“Klingon Battle Cruiser”

A “Smart” C-Wing BWB ?2 or more “small” airplanes In formation ?

Some Configuration Options For Very Large Commercial Transport Airplanes

Smart Wings

Inputs from nervesdistributed throughout the living tissue of the

wing membrane

Control output to muscles

throughout wing

membrane

Brain highly modified to process sensory data and provide needed

control output

Ultra light weight

structure (strong but

highly flexible)

Analogies

Pterosaur Airplane

• Brain Computer• Nerves Fiber optic strain gages, pressure sensors• Bone and tissue Composite materials• Variable geometry Electro-mechanical control via large control of large and small muscles and small aerodynamic

devices distributed over wing trailing edge

Potential Benefits

• Reduced wing weight for a given wing span• Increased span (reduced drag) for wing of given weight• May enable the use of highly non-planar wing configurations (e.g. C-wings)

Kroo MITEs(digitized, segmentedGurney flaps)