Airplane with unswept slotted cruise wing airfoil

An aircraft system, comprising:

• at least one wing having an upper surface shaped to include at least one transonic region during cruise flight;
• and
• a flap assembly that includes a forward airfoil element having an upper surface portion and a lower surface portion, and an aft airfoil element coupled to the forward airfoil element, the aft airfoil element having an upper surface portion and a lower surface portion, at least a part of the aft airfoil element being spaced apart from a part of the forward airfoil element by a fixed first slot, the first slot being configured to be open during cruise flight to divert some of the air flowing along the lower surface portion of the wing to flow over the upper surface portion of the aft airfoil element, the first slot having an aft-facing exit opening at an offset between the upper surface of the wing and the upper surface portion of the aft airfoil element, the offset being in the thickness direction, and wherein the forward airfoil element and the aft airfoil element are movable as a unit relative to the at least one wing to open a second slot between the forward airfoil element and the at least one wing, the forward and aft airfoil elements having a fixed angular relationship with each other when the second slot is open and when the second slot is closed.

An aircraft system, comprising:

• at least one wing having a leading edge, an upper surface, and a lower surface, the upper surface being shaped to include at least one transonic region during cruise flight;
• and
• a trailing edge device carried by the at least one wing, the trailing edge device having an upper surface and a lower surface, the upper surface of the trailing edge device being recessed away from an aft-extended contour of the at least one wing upper surface in a thickness direction along its entire length when in a neutral, undeflected position, at least one of the at least one wing and the trailing edge device having a spanwise slot, the slot having an aft-facing exit opening at an offset between the upper surfaces of the at least one wing and the trailing edge device, the offset being in the thickness direction, the slot being configured to be open during cruise flight to divert some of the air flowing along the lower surface of the at least one wing to flow over the upper surface of the trailing edge device, the slot being positioned to increase a Mach number at which the at least one wing undergoes transonic drag rise by about 0.03 compared with a wing having generally similar shape without the slot, the Mach number corresponding to a component of flow travelling generally normal to the leading edge of the at least one wing.

A method for manufacturing an aircraft system, comprising coupling a trailing edge device to an aircraft wing, with the aircraft wing overlapping the trailing edge device by a distance at least approximately equal to three percent of a combined chord length of the aircraft wing and the trailing edge device, and with a spanwise slot positioned between at least part of the aircraft wing and at least part of the trailing edge device, the slot being configured to be open during cruise flight to divert some of the air flowing along a lower surface of the aircraft wing to flow over an upper surface of the trailing edge device, the upper surface of the trailing edge device being recessed away from an aft-extended contour of the aircraft wing upper surface in a thickness direction along its entire length when in a neutral, undeflected, undeployed position, the slot having an aft-facing exit opening at an offset between an upper surface of the aircraft wing and the upper surface of the trailing edge device, the offset being in the thickness direction.

A method for manufacturing an aircraft system, comprising:

• coupling a trailing edge device to an aircraft wing;
• and
• positioning a slot between at least part of the aircraft wing and at least part of the trailing edge device to increase a Mach number at which the aircraft wing undergoes transonic drag rise by about 0.03 compared with an aircraft wing having a generally similar shape without the slot, the Mach number corresponding to a component of flow travelling generally normal to the leading edge of the aircraft wing, the slot being configured to be open during cruise flight to divert some of the air flowing along a lower surface of the aircraft wing to flow over an upper surface of the trailing edge device.