Conventional aircraft typically include a fuselage, a wing attached to a mid portion of the fuselage, and a tail-group, or “empennage,” attached to an aft portion of the fuselage behind the wing. The empennage typically includes a vertical stabilizer with a movable stabilizer (i.e., a “rudder”) for controlling yaw of the aircraft, and a horizontal stabilizer with another movable stabilizer (i.e., an “elevator”) for controlling pitch of the aircraft. One configuration that may offer certain aerodynamic advantages over the conventional aircraft configuration is the aft-mounted main wing configuration. This configuration can include a fuselage, a main wing attached to an aft portion of the fuselage, and a smaller wing, or canard, attached to a forward portion of the fuselage in front of the main wing.
One problem with the aft-mounted main wing configuration is how to adequately balance the aircraft. For example, aircraft having aft-mounted main wings typically carry most of their passengers and/or cargo in the fuselage forward of the center of gravity (“CG”). Consequently, to balance the aircraft about the CG, such configurations typically carry as much fuel as possible in the main wing aft of the CG. This region of the main wing, however, typically houses the main landing gear assemblies, thus limiting the amount of fuel that can be carried there. As a result, the aft-mounted main wing configuration is typically nose-heavy and often requires an aerodynamic trim force to balance about the CG. This aerodynamic trim force has the disadvantage of increasing aerodynamic drag and, accordingly, fuel consumption.
Another problem with the aft-mounted main wing configuration is the difficulty associated with increasing passenger capacity with derivative configurations. For example, a well-known method for increasing passenger capacity of conventional aircraft configurations is to add a fuselage section both fore and aft of the main wing to increase fuselage length without moving the CG. On aircraft configurations having aft-mounted main wings, however, the fuselage typically extends only forward of the main wing. As a result, the only way to increase fuselage length without undertaking a major redesign is to add a fuselage section forward of the main wing. This has the disadvantage of moving the CG forward and, accordingly, increasing the aerodynamic trim force necessary to balance the aircraft.
USPTO Backgrounds
USPTO Backgrounds