主题：大飞机从707到340没有多大变化，未来是音速巡航？ -- intools

（1）传统的管身加翼,

（2）blended wing-body,

（3）hybrid flying wing,

（4）flying wing.

Note that the progression does not represent either a chronological or technical progression; the YB-49, representing a true flying wing, actually predates all other depicted aircraft, while the "conventional" Boeing 757 is a relatively new and technologically advanced aircraft.

Blended wing body

Blended Wing Body, or BWB, designates an alternative airframe design which incorporates design features from both a traditional tube and wing design into a hybrid flying wing configuration. The claimed advantages (see Potential Advantages below) of the BWB approach are efficient high-lift wings and a wide airfoil-shaped body. This enables the entire craft to contribute to lift generation with the result of potentially increased fuel economy.

Overview

Flying wing designs are defined as having no separate body, only a single wing, though there may be structures protruding from the wing. Blended wing/body aircraft have a flattened and airfoil shaped body, which produces most of the lift to keep itself aloft, and distinct and separate wing structures, though the wings are smoothly blended in with the body.

An early aircraft exhibiting BWB design principles was the Junkers G.38, which flew in 1929. This "super jumbo" airliner of its day, seated thirty-four passengers, six in each of its two meter thick wings, and the balance in the central fuselage. In comparison, a contemporary passenger aircraft, the Ford Trimotor, carried a total of nine passengers in its more traditional wing and box fuselage design.

In some ways, the B-2 Spirit stealth bomber is a design which falls between classic flying wing concepts and the BWB concept. It is usually classified as a flying wing, however, as the protruding body sections are not much larger than the underlying wing shape structure.

Currently, both NASA and Boeing are exploring BWB designs under the designation X-48[1]. Studies suggest that BWB aircraft, configured for passenger flight, could carry from 450 to 800 passengers and achieve fuel savings of over 20 percent. NASA has been developing, since 2000, a remotely controlled model with a 35 foot (11 m) wingspan. This research is focused on establishing the base data concerning the lift, stall and spin characteristics inherent in a Blended Wing Body design.

Progression of aircraft design concepts from conventional airliner (1), blended wing-body (2), hybrid flying wing (3), flying wing (4). Note that the progression does not represent either a chronological or technical progression; the YB-49, representing a true flying wing, actually predates all other depicted aircraft, while the "conventional" Boeing 757 is a relatively new and technologically advanced aircraft.

Potential advantages

Improved fuel economy

Reduced noise impact (if the engines are placed above the wings)

Enormous payload advantages in strategic airlift/air freight[2] and aerial refueling roles

Improved structural weight

Potential disadvantages

Inherent instability (though possible to counter with fly by wire controls)

Layout tends to place cargo and passengers farther from aircraft centerline, exaggerating vertical motions experienced during rolls

No possibility of side windows for passenger compartments

Circular cross sections (as seen in conventional fuselages) are structurally superior shapes for use as pressure vessels in comparison to the rectangular or oval cross section of a blended wing body.