MVJ College department of Aeronautics

Seminar on Blended Wing Body Aircraft

(BWB)

Presented by: NAGARJUN B S 1MJ08AE032

Contents

Introduction * BWB Definition * Blended Wing Body Concept * History Of BWB * Square-Cube-Law

Boeing BWB 450 * Basic configuration and nomenclature * BWB-450 SpecificationsWhat Does the Future Hold for the BWB? Projects * BWB ProjectsPreliminary sizing Aero disciplines * Aerodynamics * Flight Mechanics * StructuresBWB advantages compared to today's advanced aircraft

Introduction to BWB aircraft configuration

1) Conventional Configuration: "Tube and Wing" or "Tail Aft" 2) Blended Wing Body Aircraft (BWB)3) Hybrid Flying Wing4) Flying Wing

BWB DefinitionThe Blended Wing Body aircraft is a blend ofthe tail aft and the flying wing configurations:A wide lift producing centre body housing the payloadblends into conventional outer wings.

What is a Blended wing body concept ?

Blended Wing Body, or BWB, designates an alternative airframe design which incorporates design features from both a futuristic fuselage and flying wing design. The purported advantages of the BWB approach are efficient high-lift wings and a wide airfoil-shaped body. This enables the entire craft to contribute to lift generation with the result of potentially increased fuel economy.

The airplane concept blends the fuselage, wing, and the engines into a single lifting surface, allowing the aerodynamic efficiency to be maximized

How is it different from flying wing Aircraft

Flying wing Aircraft are defined as having two separate bodies and only a single wing, though there may be structures protruding from the wing.

Blended wing/body aircraft have a flattened and airfoil shaped body, which produces most of the lift, the wings contributing the balance.

History of BWB Early aircraft - circa 1926 - exhibiting BWB design principles was the Stout Batwing. The

designer William Bushnell Stout, toured the US promoting his aircraft of the future which did not have a traditional fuselage

Successful applications of this configuration are the H-09 and latter H-0229 developed by the Horton brothers for Nazi’s during 1942.

Latter Northrop started NIM in 1942 then latter XB-35 bomber that flew first in 1946.

the B-2 Spirit stealth bomber is a design which falls between classic flying wing and the BWB concept, First flight in 1989.

STOUT BATWING XB-35 BOMBER B-2 BOMBER

1946 XB-35 bomber

YB-49 1949

B-2 bomber 1989 X-47A (UCAV) 2003 X-48 B 2007

H09 1939STOUT BATWING 1926

Square-Cube-Law

When a physical object maintains the same density and is scaled up, its mass is increased by the cube of the multiplier while its surface area only increases by the square of said multiplier. This would mean that when the larger version of the object is accelerated at the same rate as the original, more pressure would be exerted on the surface of the larger object.

Basic configuration and nomenclature of Boeing BWB 450

BWB-450 specifications

Seating capacity 478 passengers in three class interior arrangement Design Range 7750 nautical milesNo: of engines The BWB-450 uses three upper surface pylon mounted

turbofan engines, located at the trailing edge of the wing, for propulsion

Type of engines 3 UEET direct drive turbofan engines (Ultra-Efficient Engine Technology)

Cruise mach no: A recent Boeing optimization study1 indicated that a cruise Mach number of 0.90 is optimal for a range of 7,750 nm.

Maximum gross weight

823,000 lb

Cruise speed 0.85 mach (560 mph)

What Does the Future Hold for the BWB?

Cont…..

BWB shows a significant advantage over a conventional aircraft in terms of performance and weight It is mainly used in military applications. Boeing and the US military are designing the BWB to be used as an advanced tactical transport and as an air refuel tanker . The BWB has a large fuselage and can carry massive amounts of fuel. Also, it can provide two permanent refueling boom stations, rather than one as in the KC-135, KC-10 or KC-767.

A Boeing BWB tanker with pylon-mounted engines

Other BWB projects 5th Framework Program of the European Commission: VELA and MOB

VELA 1 VELA 2

Very Efficient Large Aircraft (VELA) from 1999 to 2002

6th Framework Program of the European Commission: NACRE with PDA (VELA follow on)

Vela 3 (2003-2006)

Preliminary sizing VELA 3

Assumptions:OEW / MTOW = 0,5 LOFTIN: 0,52 (T/W!) A380: 0,49 BWB structural benefits?SFC = 1.6 mg/(Ns) normal technology level assumedapproach speed = 165 ktReserves: 200 NM to alternate, 30 min. holding, 5% trip fuel allowance

Given:

range: 7650 NMMTOW: 700000 kgWing Area: 2052 m²Wing Loading: 341 kg/m² (very low for pass. transp. due to low lift coeff.)mass of pax and luggage: 95.0 kg per paxpayload: 71250 kg

Preliminary sizing VELA 3

Preliminary sizing VELA 3

Sizing Results:lift coefficient landing: 0.86 (higher than HAW wind tunnel results)L/D during 2. segment: 15.2 (higher than conv. due to small lift coefficient and small drag)L/D during missed approach: 11.0 (normal, because landing gear drag dominates, FAR!)L/Dmax : 20.9 (lower than BWB estimate)V / Vmd = 1.0 => L/D = L/Dmax (normal: V / Vmd = 1.0 ... 1.316)lift coefficient cruise: 0.31trust to weight ratio: 0.28 (value is slightly high for 4-engined A/C, reason: TOFL and CL)Initial Cruise Altitude (ICA): 37800 ft (= 11.7 km)MLW: 469000 kgOEW: 350000 kgFuel: 279000 kg (VELA 3: 282800 kg)Thrust: 481 kN (for each of the four engines)

Aero disciplines: AerodynamicsAC20.30: CFD with FLUENT

VELA 3

lift coefficient

angle of attack, α

Aero disciplines: AerodynamicsAC20.30: CFD with FLUENT

VELA 3Stalls can easily be handledUsable lift up to AOA of 12°At 22° AOA: wings are stalled body continues to produce lift but control surfaces do not deliver control power

path lines

Aero disciplines: Aerodynamics

AC20.30: CFD with FLUENTVELA 3

Aero disciplines: Aerodynamics

AC20.30: CFD with FLUENTVELA 3

lift to drag ratio, L/D

angle of attack, α

Aero disciplines: FlightMechanics

Aero disciplines: FlightMechanics

Static Longitudinal Stability for VELA Configurations

Aero disciplines: Structures

Aero disciplines: Structures VELA 2 - Basic Structural Layout

BWB advantages compared to today's advanced aircraft

better L/D 10 to 15% better

reduction in emissions yes

reduction in noise only with engines on top (reduction in noise to 42db below stage 4)

increase of airport capacity yes, more than 750 pax per A/C(probably no problems with wake turbulence)

Fuel burnt when compared to conventional aircraft

reduction in fuel consumption

20% less

yes, due to L/D

Team members studying the Blended-Wing-Body (BWB) design

McDonnell Douglas, Stanford University, The University of Southern California, Clark Atlanta University, The University of Florida, NASA Langley and Lewis Research Centers. Boeing Phantom Works Air Force Research Laboratory NASA's Dryden Flight Research Center Institute of Aircraft Design and Lightweight Structures, TU Braunschweig

THANK YOU