A blended wing body (BWB), also known as blended body or hybrid wing body (HWB), is a fixed-wing aircraft having no clear dividing line between the wings and the main body of the craft. The aircraft has distinct wing and body structures, which are smoothly blended together with no clear dividing line. This contrasts with a flying wing, which has no distinct fuselage, and a lifting body, which has no distinct wings. A BWB design may or may not be tailless.
The main advantage of the BWB is to reduce wetted area and the accompanying form drag associated with a conventional wing-body junction. It may also be given a wide airfoil-shaped body, allowing the entire craft to generate lift and thus reducing the size and drag of the wings.
In the early 1920s Nicolas Woyevodsky developed a theory of the BWB and, following wind tunnel tests the Westland Dreadnought was built. It stalled on its first flight in 1924, severely injuring the pilot, and the project was cancelled. The idea was proposed again in the early 1940s for a Miles M.26 airliner project and the Miles M.30 "X Minor" research prototype was built to investigate it. The McDonnell XP-67 prototype interceptor also flew in 1944 but did not meet expectations.
NASA returned to the concept in the 1990s with an artificially stabilized 17-foot (5.2 m) model (6% scale) called BWB-17, built by Stanford University, which was flown in 1997 and showed good handling qualities.:16 From 2000 NASA went on to develop a remotely controlled research model with a 21-foot (6.4 m) wingspan.
NASA has also jointly explored BWB designs for the Boeing X-48 unmanned aerial vehicle. Studies suggested that a BWB airliner carrying from 450 to 800 passengers could achieve fuel savings of over 20 percent.:21
Airbus is studying a BWB design as a possible replacement for the A320neo family. A sub-scale model flew for the first time in June 2019 as part of the MAVERIC (Model Aircraft for Validation and Experimentation of Robust Innovative Controls) programme, which Airbus hopes will help it reduce CO2 emissions by up to 50% relative to 2005 levels.
The BWB form minimises the total wetted area - the surface area of the aircraft skin, thus reducing skin drag to a minimum. It also creates a thickening of the wing root area, allowing a more efficient structure and reduced weight compared to a conventional craft. NASA also plans to integrate Ultra High Bypass (UHB) ratio jet engines with the hybrid wing body.
The wide interior spaces created by the blending pose novel structural challenges. NASA has been studying foam-clad stitched-fabric carbon fiber composite skinning to create uninterrupted cabin space.
A conventional tubular fuselage carries 12-13% of the total lift compared to 31-43% carried by the centerbody in a BWB, where an intermediate lifting-fuselage configuration better suited to narrowbody sized airliners would carry 25-32% for a 6.1% - 8.2% increase in fuel efficiency.
|Lockheed A-12, M-21 and YF-12||US||Jet||Reconnaissance||1962||production||18||YF-12 was a prototype interceptor|
|Lockheed SR-71 Blackbird||US||Jet||Reconnaissance||1964||production||32|
|McDonnell XP-67||USA||Propeller||Fighter||1944||Prototype||1||Aerofoil profile maintained throughout.|
|Rockwell B-1 Lancer||USA||Jet||Bomber||1974||Production||104||Variable-sweep wing|
|Tupolev Tu-160||USSR||Jet||Bomber||1981||Production||36||Variable-sweep wing|
|Tupolev Tu-404||Russia||Propeller||Airliner||1991||Project||0||One of two alternatives studied|
|Westland Dreadnought||UK||Propeller||Transport||1924||Prototype||1||Mail plane. Aerofoil profile maintained throughout.|
A concept photo of a blended wing body commercial aircraft appeared in the November 2003 issue of Popular Science magazine. Artists Neill Blomkamp and Simon van de Lagemaat from The Embassy Visual Effects created the photo for the magazine using computer graphics software to depict the future of aviation and air travel. In 2006 the image was used in an email hoax claiming that Boeing had developed a 1000-passenger jetliner (the "Boeing 797") with a "radical Blended Wing design" and Boeing refuted the claim.