Blended wing body

Blended Wing Body, or BWB, designates an alternative airframe design which incorporates design features from both a traditional tube and wing design into a hybrid flying wing configuration. The claimed advantages (see Potential advantages below) 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.

Overview

Flying wing designs are defined as having no separate body, 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 to keep itself aloft, and distinct and separate wing structures, though the wings are smoothly blended in with the body.

An early aircraft exhibiting BWB design principles was the Junkers G.38, which flew in 1929. This "super jumbo" airliner of its day, seated thirty-four passengers, six in each of its two meter thick wings, and the balance in the central fuselage. In comparison, a contemporary passenger aircraft, the Ford Trimotor, carried a total of nine passengers in its more traditional wing and box fuselage design.

In some ways, the B-2 Spirit stealth bomber is a design which falls between classic flying wing concepts and the BWB concept. It is usually classified as a flying wing, however, as the protruding body sections are not much larger than the underlying wing shape structure.

Currently, both NASA and Boeing are exploring BWB designs under the designation X-48. [cite news | title = Boeing Phantom Works to Lead Research on X-48B Blended Wing Body Concept | publisher = Boeing | date = 4 May 2006 | url = http://www.boeing.com/phantom/news/2006/q2/060504b_nr.html] Studies suggest that BWB aircraft, configured for passenger flight, could carry from 450 to 800 passengers and achieve fuel savings of over 20 percent. NASA has been developing, since 2000, a remotely controlled model with a 21 ft (6.4 m) wingspan. This research is focused on establishing the base data concerning the lift, stall and spin characteristics inherent in a Blended Wing Body design.

Potential advantages

* Improved fuel economy
* Reduced noise impact (if the engines are placed above the wings)
* Enormous payload advantages in strategic airlift/air freight [cite news | last = Warwick | first = Graham | title = Boeing works with airlines on commercial blended wing body freighter | publisher = Flight International | date = 21 May 2007 | url = http://www.flightglobal.com/articles/2007/05/21/213997/boeing-works-with-airlines-on-commercial-blended-wing-body.html] and aerial refueling roles
* Improved structural weight

Potential disadvantages

* Layout tends to place cargo and passengers farther from aircraft centerline, exaggerating vertical motions experienced during rolls
* No possibility of side windows for passenger compartments
* Circular cross sections (as seen in conventional fuselages) are structurally superior shapes for use as pressure vessels in comparison to the rectangular or oval cross section of a blended wing body.

References

ee also

* List of flying wings
* Northrop YB-49
* Northrop B-2 Spirit
* Underwater glider

External links

* [http://oea.larc.nasa.gov/PAIS/pdf/FS-1997-07-24-LaRC.pdf "The Blended-Wing-Body", NASA Facts]
* [http://www.newscientist.com/channel/mech-tech/dn8310.html ‘Blended wing’ craft passes wind-tunnel tests] "NewScientist.com news service", 14 November 2005
* [http://news.bbc.co.uk/2/hi/technology/6120132.stm How design of SAX-40 aircraft reduces noise and improve efficiency]
* [http://www.wingco.com/progress.htm Progress on the Wingco Atlantica small BWB plane]
* [http://www.airliners.net/open.file/0623950/L/ Airliners.net photo of the Atlantica prototype aircraft, July 2004]
* [http://www.truthorfiction.com/rumors/b/b797.htm "Truth Or Fiction" on the rumour of the Boeing 797 blended wing passenger liner]
* [http://www.ac2030.de/ Blended Wing Body, HAW Hamburg]