Gallery: Three Decades of Blended Wing Body Development

In response to a 1988 NASA call for revolutionary advances in air transport designs, McDonnell Douglas engineer Robert Liebeck sketched out this early blended wing body concept. The proposed design, which held the promise of raising transport lift-to-drag ratios from 17 to near 28, led to further refinement work with Liebeck’s colleagues Mark Page and Blaine Rawdon. The result was the eventual birth of the subscale Boeing/NASA X-48 demonstrator.

NASA and McDonnell Douglas interest in the BWB led to flight tests of the BWB-17, a dynamically scaled 17-ft.-span radio-controlled model developed at Stanford University. Built principally by Ben Tigner, now CEO of eVTOL developer Overair, along with other students under the direction of Stanford professor Ilan Kroo, the vehicle was tested at NASA Ames in June 1997. The BWB-17 was the largest of a series of small-scale development tests, which began with an unpowered glider variant in 1995.
 

By 1998, following the merger of McDonnell Douglas and Boeing, the focus for BWB studies shifted from earlier work on an 800-seat concept to a lower-capacity 450-seat design designated the BWB-450. Initial comparisons with the Airbus A380 indicated 32% lower fuel burn per seat for the concept. 

Initial NASA/Boeing efforts to develop a low-speed BWB subscale demonstrator designated the X-48A were canceled in 2001 amid budget issues and complications related to the development of the flight control system. At the time of the cancellation, in-house construction of the X-48A had been underway at NASA Langley for a year with first flight of the vehicle targeted for 2004.

Continuing military interest in the BWB led to the U.S. Air Force in 2005 assigning the designation X-48B to a small-scale remotely piloted blended wing research vehicle. Formerly launched the following year with a Boeing and Air Force Research Laboratory agreement, the 2%-scale model—dubbed the BWB-450-1L—was subsequently tested in 2007 in the Arnold Engineering Development Center’s 16-ft. Transonic Wind Tunnel in Tullahoma, Tennessee.
 

In 2006, a Massachusetts Institute of Technology-Cambridge University team explored the low-noise potential of the blended wing with a deep, lifting fuselage concept dubbed the Silent Aircraft eXperimental SAX-40 BWB. Produced under the Silent Aircraft Initiative, the 200-seat design incorporated three engines with semi-recessed inlets and was predicted to generate noise levels of 63 dBA outside airport perimeters, or around 25 dB quieter than other comparable aircraft at the time.

NASA and Boeing flight-tested the 8.5% scale X-48B at NASA Dryden—now Armstrong Flight Research Center— between 2007 and 2010. The 20.4-ft.-span, three-engine aircraft was built by UK-based Cranfield Aerospace for the test program, which was designed to investigate the BWB’s stability and control characteristics. Tests, including wind tunnel evaluation of a second low-speed vehicle, were concluded after 80 flights. 
 

Boeing revived the X-48 in 2010 for more flight tests under NASA’s Environmentally Responsible Aviation (ERA) program. Redesignated the X-48C, the original B version was modified to evaluate the low-speed stability and control of a low-noise version of a notional, future hybrid wing body (HWB) aircraft design. For noise shielding, the winglets were repositioned from the wingtips to inboard next to the engines, turning them into twin tails. The aft deck of the aircraft was extended 2 ft., and the X-48B's three 50-lb.-thrust jet engines were replaced with two 89-lb.-thrust engines. Thirty flights were flown between 2012 and 2013.

Further testing of the refined Boeing HWB concept with ultra-high-bypass engines and leading edge devices continued under ERA through 2015 and showed fuel savings of up to 53% over conventional 300-seat widebody airliners and a noise reduction of more than a cumulative 40 dB below the Stage 4 limit. 

Following encouraging results from ERA, NASA was eager to explore further advances with an ambitious series of large-scale X-plane concepts under its New Aviation Horizons initiative. In 2016, as an initial step toward competing for the first X-plane, NASA awarded six-month contracts to four companies—three of which proposed various forms of BWBs. In addition to blended designs from Boeing and Lockheed Martin, startup Dzyne Technologies proposed a scalable regional/business jet BWB in which the landing gear and cargo were moved out from under the cabin to enable a single-deck center body with thin wings. The concept, which at the time included the use of Boeing-developed Prseus stitched composite technology for the structure, would later prove the basis for much of the 2023 JetZero BWB design.
 

One of the 2016 X-plane study awards went to Lockheed Martin, which proposed a different form of hybrid wing body combining a blended wing and forebody for aerodynamic and structural efficiency with a conventional aft fuselage and tail compatible with existing cargo-handling equipment. Targeted at a future airlifter, wind tunnel tests showed the HWB had the potential to burn 45% less fuel than the Boeing C-17 while carrying outsize cargo of the kind transported by the Lockheed C-5. The Air Force Research Laboratory and NASA also funded studies of a dual-use demonstrator for a commercial freighter and military airlifter.

International interest in the BWB concept has also grown outside the U.S. In 2020, Airbus revealed it had been seriously studying blended wings since 2017 and in 2019 had begun flight tests of a subscale technology demonstrator under the Maveric (Model Aircraft for Validation and Experimentation of Robust Innovative Controls) program. Airbus said tests of the 7-ft.-span, 10-ft.-long vehicle indicated a full-scale version would offer potential fuel-burn savings of up to 20% compared to current single-aisle aircraft. In 2022, as part of its ZEROe zero-emission aircraft initiative, Airbus also revealed that a version of the Maveric concept (center) is a longer-term candidate for a hydrogen-powered airliner because of the large internal volume provided by a BWB design. 

Bombardier is flight-testing a series of subscale hybrid wing body designs under its EcoJet business aircraft study. Optimized through a long-running Canadian research program, the Green Aviation Research and Development Network (GARDN), the hybrid BWB incorporates a slender lifting fuselage, a U-shape tail and distinct high-aspect-ratio wings. Although the GARDN project, which ran from 2009 to 2021, was aimed at a 100-seater regional airliner, the EcoJet design has scaled this down to business jet size with rear-mounted turbofans shielded by the tail. Design options remain under study for the fuselage and noncircular cabin, which Bombardier has constrained to a usable volume equivalent to that of its Global 6500 long-range business jet. Additional design options include a tailless variant.

Other potential small-scale applications of the BWB concept are also under development, including a remotely piloted regional cargo feeder aircraft designed by San Diego, California-based Natilus. The company’s first model, the Kona, is designed to carry more than 9,000 lb. of freight over a range of up to 900 nm at speeds up to 220 kt. from runways as short as 2,600 ft. The aircraft will be offered with the option of twin Pratt & Whitney PT6A-67D turboprops driving pusher propellers or ZeroAvia ZA600 hydrogen-electric engines.
 

The high-density seating capability of the BWB concept has also attracted interest in China, where Northwestern Polytechnical University revealed in 2023 it had flown the BWB-300, a 10.3%-scale model of a 300-330-seat blended wing vehicle. Based on long-running studies since the late 1990s, the BWB-300 was designed in collaboration with commercial aircraft manufacturer Comac, the subscale model was flown autonomously from the UAV flight-test center at Jingbian in Shaanxi Province. Future plans include focusing on structural design and noise reduction and development of concepts for electric- and hydrogen-powered BWBs with distributed propulsion. 

In April 2023, California startup JetZero revealed it was bidding for the U.S. Defense Department’s plan for a BWB demonstrator that is to be evaluated as a tanker and airlifter. The focus for its bid is the Z-5, which is optimized for a range of at least 5,000 nm and up to 250 passengers as a passenger aircraft. As a tanker, the all-composite aircraft is designed to carry up to twice the fuel of the Boeing KC-46 tanker on a maximum-range mission. JetZero also plans to flight-test a 23-ft.-wingspan, 12.5%-scale demonstrator vehicle funded under an earlier NASA contract. The aircraft will be used to evaluate key Z-series design features including the novel pivoting nose landing gear devised by Mark Page’s Dzyne company, a forerunner of JetZero.