Blended wing body
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.
- Significant payload advantages in strategic airlift, air freight, and aerial refueling roles
- Increased fuel efficiency – 10.9% better than a conventional widebody
- Lower noise – NASA audio simulations show a 15dB reduction of Boeing 777-class aircraft, while other studies show 22–42 dB reduction below Stage 4 level, depending on configuration.
- Evacuating a BWB in an emergency could be a challenge. Because of the aircraft's shape, the seating layout would be theatre-style instead of tubular. This imposes inherent limits on the number of exit doors.
- Passengers may be unwilling to sit in windowless environments.
- Passengers sitting at the edges of the cabin may feel uncomfortable during wing roll.
- The centre wingbox needs to be tall to be used as a passenger cabin, requiring a larger wing span to balance out.
- A BWB has more empty weight for a given payload, and may not be economical for short missions of around four or fewer hours.
- A larger wing span may be incompatible with some airport infrastructure, and affect the quick loading of cargo, requiring a change in infrastructure.
- It is more expensive to modify the design to create differently-sized variants compared to a conventional fuselage and wing which can be stretched or shrunk easily.
List of blended wing body aircraft
|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.|
In popular culture
Popular Science concept art
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.
- Russell H. Thomas, Casey L. Burley and Erik D. Olson (2010). "Hybrid Wing Body Aircraft System Noise Assessment With Propulsion Airframe Aeroacoustic Experiments" (PDF). Retrieved 26 January 2013. Presentation Archived 2013-05-16 at the Wayback Machine
- Crane, Dale. Dictionary of Aeronautical Terms, third edition. Newcastle, Washington: Aviation Supplies & Academics, 1997. ISBN 1-56027-287-2. p. 224.
- Liebeck, R.H. (January–February 2004). "Design of the Blended Wing Body Subsonic Transport". Journal of Aircraft. 41 (1): 10–25. doi:10.2514/1.9084.
- "A flight toward the future." Archived December 4, 2012, at the Wayback Machine Boeing, August 7, 2012 Retrieved: November 23, 2012.
- Reim, Garrett (11 February 2020). "Airbus studies blended-wing airliner designs to slash fuel burn". Flight Global.
- Michael Braukus / Kathy Barnstorff (Jan 7, 2013). "NASA's Green Aviation Research Throttles Up Into Second Gear". NASA. Retrieved Jan 26, 2013.
- Bullis, Kevin (January 24, 2013). "NASA has demonstrated a manufacturing breakthrough that will allow hybrid wing aircraft to be scaled up". MIT Technology Review.
- Graham Warwick (Aug 22, 2016). "Finding Ultra-Efficient Designs For Smaller Airliners". Aviation Week & Space Technology.
- Warwick, Graham. "Boeing works with airlines on commercial blended wing body freighter." Flight International, May 21, 2007.
- Warwick, Graham (Jan 12, 2013). "Hear This - The BWB is Quiet!". Aviation Week.
- E. R. Galea; L. Filippidis; Z. Wang; P. J. Lawrence; J. Ewer (2011). "Evacuation Analysis of 1000+ Seat Blended Wing Body Aircraft Configurations: Computer Simulations and Full-scale Evacuation Experiment". Pedestrian and Evacuation Dynamics. pp. 151–61. doi:10.1007/978-1-4419-9725-8_14. ISBN 978-1-4419-9724-1.
- Galea, Ed. "Evacuation analysis of 1000+ seat Blended Wing Body aircraft configurations". evacmod.net (video). Retrieved August 25, 2015.
- "Boeing not convinced by blended wing aircraft design". Institution of Mechanical Engineers. June 16, 2015.
- "Don't look for commercial BWB airplane any time soon, says Boeing's future airplanes head". Leeham News. April 3, 2018.
- "Airbus reveals its blended wing aircraft demonstrator", Airbus, 11 February 2020. (Retrieved 18 February 2020)
- Caroline Delbert; "Will We One Day Fly in This 'Blended Wing' Airplane? Airbus Built a Prototype To Find Out", Popular Mechanics, 13 February 2020. (Retrieved 18 February 2020)
- "Future of Flight." Popular Science, November 2003.
- "Future Flight: A Gallery of the Next Century in Aviation." PopSci.com, October 15, 2003. Retrieved: November 22, 2012.
- "New Boeing 797 Giant "Blended Wing" Passenger Airliner-Fiction!". TruthOrFiction.com. March 17, 2015.
- Christensen, Brett M. "Boeing 797 Hoax" Hoax-Slayer, April 19, 2012. Retrieved: November 22, 2012.
- Baseler, Randy. "Air mail." Boeing blogs: Randy's Journal, November 1, 2006. Retrieved: November 22, 2012.
- Al Bowers (Sep 16, 2000). "Blended-wing-body: Design challenges for the 21st century". The Wing is The Thing.
- V. Mukhopadhyay, NASA Langley (April 2005). "Blended-Wing-Body (BWB) Fuselage Structural Design for Weight Reduction" (PDF). AIAA conference.
- "'Blended wing' craft passes wind-tunnel tests". New Scientist. 14 November 2005.
- "'Silent aircraft': How it works". BBC. 6 November 2006.
- R. Vos, F.J.J.M.M. Geuskens, M.F.M. Hoogreef, TU Delft (April 2012). "A New Structural Design Concept for Blended Wing Body Cabins". AIAA conference.CS1 maint: uses authors parameter (link)
- Cranfield University (May 4, 2012). "A Blended Wing Body Concept" – via youtube.
- "X-48 Highlights". NASA. Apr 18, 2013.
- Jörg Fuchte, Till Pfeiffer, Pier Davide Ciampa, Björn Nagel, Volker Gollnick, DLR (Sep 2014). "Optimization of revenue space of a blended wing body" (PDF). Congress of the International Council of the Aeronautical Sciences.CS1 maint: uses authors parameter (link)