Like it or not, the blended wing-body airliner will not go away. Those that like the BWB point to its aerodynamic and structural efficiency, its ample volume for passengers, cargo and fuel. Those that don't point to its lack of windows. non-circular pressure vessel and edge-of-the-envelope flying qualities. But if the world starts to take the environment seriously, and demands that aviation dramatically cuts its fuel consumption, emissions and noise, where else can airlines go? Solar-powered passenger-carrying airships?
Here is NASA's vision of one possible future:
There is an interesting chart from a recent NASA presentation that illustrates the BWB's fundamental attraction - for the same volume it has a third less surface area than a conventional tube-and-wing airliner. And less surface area means less friction drag. The same presentation also charts the evolution of BWB designs, from the 800-passenger, 7,000nm-range monster conceived by McDonnell Douglas in the early 1990s to Boeing's X-48B subscale demonstrator.
The X-48B is the culmination of research begun in the late 1990s and using a 450-seat BWB as the reference design for a series of small-scale windtunnel models to investigate the configuration's challenging flight dynamics. There was to be a 14%-scale, 35ft-span low-speed flight demonstrator, the X-48B, but it was cancelled by NASA when aeronautics fell out of favour. Instead, Boeing and Cranfield built the 8.5% X-48B, which first flew in July 2007 (watch the video here).
Where next? Well NASA has funded Boeing to investigate the noise benefits of a BWB. It is also funding Boeing, MTI and UCI to mature the blended wing-body design concept produced by the UK/US Silent Aircraft Initiative ... Cal Poly, meanwhile, will refine its concept for a 100-seat hybrid wing-body STOL airliner under NASA grant.
The Silent Aircraft Initiative was a three-year effort by the Cambridge-MIT Institute to develop a credible concept for a 2025-timeframe airliner that would be inaudible outside the airport boundaries (see Flight's story and a video here). Cal Poly's concept is a 2020s-timeframe, low-noise, powered-lift airliner designed ease airport congestion by using shorter runways. And, guess what, neither is a tube with wings.