The concept of blended wing body (BWB) aircraft has been around for almost as long as the self-propelled flight itself and consists of a fixed-wing aircraft with no clear divide between the wings and the main body (the fuselage). The design was first proposed in the early 1920s when the Westland Dreadnought was built to test the aerodynamic effects of such a design. While this first prototype quickly proved unfeasible – it stalled on its first flight in 1924, injuring the pilot and ending the project– the Dreadnought paved the way for subsequent BWB concepts. The first BWB aircraft to be put into production was the Lockheed A-12/M-21 (1962) – this was later developed into the SR-71 Blackbird (1964) – of which 50 were manufactured. In this case, a BWB approach was selected primarily for its ability to deflect incoming radar waves, which, along with other features, made the aircraft nearly undetectable. The Rockwell B-1 Lancer (1974) bomber aircraft was produced in larger numbers (104) and used a variable-sweep blended wing body for a similar reason, as well as to improve aerodynamics at supersonic speeds. Despite the moderate success of BWB aircraft in the second half of the 20th century, the design has seen only prototypical use in the 60 years since. This, however, is not for a lack of attempts by major aerospace manufacturers, such as Airbus, Boeing (and McDonnell Douglas), Nasa, and Northrop Grumman, each of whom developed several prototypes over the last 20 years trying to take advantage of another benefit of blended wings: aerodynamic efficiency. This is thanks to the reduced wetted area (surface area in contact with the air) and associated drag compared with conventional wing-body junctions. This can result in range, fuel economy, and reliability improvements.
Boeing, in particular, has been leading in the development of BWB unmanned aerial aircraft (UAVs) with the X-45 (2002) and X-48 (B-2007, C-2013), as well as earlier prototypes by McDonnell Douglas, which was acquired by Boeing in 1997. In the early 2000s, their plan was to develop a flying wing – similar to a blended wing but with no defined fuselage at all, meaning it is the body itself, which generates the lift–passenger aircraft, colloquially labelled the “797”. It would have had room for at least 1,000 seats due to the significant payload improvements which are possible with a BWB design and would likely have been a modern successor to the 747 and competitor to the new Airbus A380 but with a greater than 10% fuel efficiency improvement compared with either. However, the “797” never even reached the prototype stage, likely due to technical and logistical (the aircraft would be significantly heavier and wider than current large airliners, necessitating infrastructure redesign) complexities. The concept was not popular in consultations, where the theatre-style seating configuration and reduced emergency exits were unpopular. Boeing did however continue to explore the BWB concept for military applications, such as strategic airlifting and aerial refueling. Airbus has also recently explored similar options for BWB passenger aircraft, which they say would reduce fuel consumption by up to 20%. An experimental UAV demonstrator, the MAVERIC, first flew in June 2019. With a wingspan of just 3.2 metres, the MAVERIC was only a scaled-down model of the theoretical production aircraft, a 200-passenger hydrogen turbofan aircraft announced in 2020, which would form part of Airbus’ ZEROe range of emission-free aircraft.
Despite these forays into BWB passenger aircraft, the largest use of flying wing designs especially has been in the military bomber and reconnaissance sectors. Northrop Grumman is a particularly important player in this sector as the manufacturer of the B-2 Spirit (1987) bomber, the first production aircraft to use a flying wing design, aiding its aerodynamic efficiency, payload, and, most importantly, its observability. Based on previous discontinued Northrop projects – the YB-35 and YB-49 – from the early 1950s, the B-2 was truly revolutionary in the field of strategic stealth bombing, and all but one (destroyed in a 2008 crash) are still in service today, due to be replaced in 2032 with the new B-21 Raider. Also designed by Northrop Grumman for the US Air Force (USAF) as part of the Long-Range Strike Bomber (LRS-B) program, it will serve a similar purpose to the B-2, with the capability to deliver both conventional and thermonuclear weapons. The B-21 will also replace the nearly 50-year-old B-1 Lancer and will be the first of the new Sixth-Generation Aircraft family. It will introduce a range of new designs, materials, and weapons technologies to a flying wing design very similar to that of the B-2.
To conclude, the concept of a BWB aircraft has been around for a century but has so far only had limited use, with its primary application being high-altitude, long-range military reconnaissance and bomber aircraft such as the SR-71 Blackbird, B-1 Lancer, and B-2 Spirit. This will also remain a future use case of flying wing designs, with the soon-to-be-delivered sixth-generation B-21 Raider being just one example. However, BWB aircraft also possess significant potential in other areas, namely the civil aviation and strategic military airlifting and refuelling segments, with both Airbus and Boeing showing significant interest as the two largest filers of patents in this area over the last decade. It is therefore likely that blended and flying wings will play some role in the future of both civil and military aviation.
