A jet quieter than your washer, with greater fuel efficiency per capita than a Toyota Prius? Sounds like science fiction. But don't tell Boeing, who—with some help from the Air Force and NASA's Fundamental Aeronautics Program—is developing the ultra-streamlined blended-wing-body aircraft that are set to revolutionize aviation in the decades to come. Though a scaled-down model dubbed the X-48B was flight-tested by Boeing last July, and BWBs may be flying military missions by 2020, for us civilians it might be 30 years before takeoff. "We're still years away from a full-scale aircraft," says Norm Princen, chief engineer of the X-48B, "but blended-wing-body technology has enormous green potential—a low-noise, low-fuel-burn, and low-carbon-emissions aircraft all rolled into one."

1. GOOD IDEAS: Dozens of airlines have retrofitted fleets with "winglets," similar to the vertical wingtips seen here. These small airfoils reduce drag—and can increase fuel efficiency by 2 to 5 percent. And the Airbus A380, flying commercially since last October, and Boeing's 787 Dreamliner, scheduled to begin service this November, feature lighter frames, smaller, quieter engines, and more aerodynamic designs.

2. BIG AMBITIONS: Even the largest BWBs, with 240-foot wingspans, will be up to 50 percent more efficient than some of today's commercial aircraft and seat up to 800 passengers in the middle of the fuselage. And the sleek form and built-in engines will damp and block noise, meaning a plane more than ten times quieter than today's least obnoxious commercial jet.

3. SHARP SHAPE: With no flaps or tail and a low-profile undercarriage, the integrated fuselage and wings will significantly cut air resistance and, possibly, weight, which might allow for smaller engines and make for a greatly improved lift-to-drag ratio. Eventually, BWBs may be able to reduce fuel burn and emissions by 50 percent.