Abstract:
A rotatable leading edge for the fuselage and wings of an aircraft is disclosed. The leading edge may be rotated from an undeflected or retracted position adjacent to the fuselage and wings to a deflected or extended position. In the extended position, the leading edge increases lift of the aircraft at low speeds. In the retracted position, gaps associated with the leading edge are avoided.

Description:
FIELD OF THE INVENTION 
     The present invention relates to aircraft with a rotatable leading edge, and more particularly relates to a combined fuselage and wing leading edge which can be rotated from an undeflected or retracted position against the fuselage and wings to a deflected or extended position which provides increased lift for the aircraft at low speeds. 
     BACKGROUND INFORMATION 
     Aircraft often utilize devices on leading wing edges in order to increase lift at low speeds. For example, aircraft with high leading edge wing sweep may use devices on the leading edges of the wings to increase lift during takeoff and landing and thus reduce runway length. Such leading edge devices typically have gaps that are visible from the front when the devices are stowed. However, some aircraft have survivability requirements that do not allow leading edge gaps when the devices are stowed. It would be desirable to provide a leading edge device which avoids such problems. 
     SUMMARY OF THE INVENTION 
     The present invention provides a rotatable leading edge for the fuselage and wings of an aircraft. The leading edge is a continuous, unbroken piece transversing the entire span of the aircraft. The leading edge may be rotated from an undeflected or retracted position adjacent to the fuselage and wings to a deflected or extended position away from the fuselage and wings which increases lift of the aircraft, particularly during takeoff, landing and other low speed operations. When the leading edge is retracted to its undeflected position during flight, unwanted gaps are avoided. 
     An aspect of the present invention is to provide an aircraft comprising a fuselage, wings connected to the fuselage, and a leading edge rotatable from a retracted position against the fuselage and wings to an extended position from the fuselage and wings. 
     This and other aspects of the present invention will be more apparent from the following description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a partially schematic top view of an aircraft including a rotatable leading edge adjacent to the fuselage and wings of the aircraft in accordance with an embodiment of the present invention. 
         FIG. 2  is a partially schematic cross sectional view taken through section  2 — 2  of  FIG. 1 , illustrating a wing of the aircraft and a portion of the leading edge in an undeflected or retracted position in accordance with an embodiment of the present invention. 
         FIG. 3  is a partially schematic top view of the aircraft of  FIG. 1 , with the rotatable leading edge in a deflected or extended position. 
         FIG. 4  is a partially schematic cross sectional view taken through section  4 — 4  of  FIG. 3 , illustrating the extended position of the leading edge with respect to the wing. 
         FIG. 5  is a partially schematic side view of an aircraft including a rotatable leading edge of the fuselage and wings in a retracted position in accordance with an embodiment of the present invention. 
         FIG. 6  is a partially schematic side view of the aircraft of  FIG. 5 , with the rotatable leading edge in an extended position. 
         FIG. 7  is a partially schematic front view of an aircraft including a rotatable leading edge of the fuselage and wings in a retracted position in accordance with an embodiment of the present invention. 
         FIG. 8  is a partially schematic front view of the aircraft of  FIG. 7 , with the rotatable leading edge in an extended position. 
         FIG. 9  is a partially schematic side view of an aircraft including a rotatable leading edge of the fuselage and wing similar to the embodiment shown in  FIGS. 1–8 , except the axis of rotation of the leading edge has been moved aft on the aircraft, and the portion of the leading edge in front of the rotational axis deflects downwardly while the portion of the leading edge behind the rotational axis deflects upwardly. 
         FIG. 10  is a partially schematic cross sectional view of a portion of an aircraft wing and a leading edge of the wing portion, illustrating downward deflection of the leading edge when the leading edge is in an extended position in accordance with an embodiment of the present invention. 
         FIG. 11  is a partially schematic longitudinal sectional view of an aircraft fuselage and a leading edge of the fuselage, illustrating downward deflection of the leading edge when the leading edge is in an extended position in accordance with an embodiment of the present invention. 
         FIG. 12  is a partially schematic cross sectional view of a rotatable leading edge having a concave rear contact surface in accordance with an embodiment of the present invention. 
         FIG. 13  is a partially schematic cross sectional view of a rotatable leading edge having a angled rear contact surface in accordance with an embodiment of the present invention. 
         FIG. 14  is a partially schematic cross sectional view of a rotatable leading edge having a flat rear contact surface in accordance with an embodiment of the present invention. 
         FIGS. 15–17  are partially schematic cross sectional views of an aircraft wing including a Krueger flap and a rotatable leading edge in accordance with an embodiment of the present invention. In  FIG. 15 , the Krueger flap is stowed and the leading edge is retracted. In  FIG. 16 , the Krueger flap remains stowed, but the leading edge is in an extended position. In  FIG. 17 , the Krueger flap is deployed and the leading edge is in the extended position. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  is a partially schematic top view of an aircraft  10  including a fuselage  12  and wings  14 . The aircraft  10  has a nose section  16  and a tail section  18 . As used herein, the term “fuselage” includes the body of an aircraft as well as any structural features integrally formed with the body, such as strakes, leading edge extensions and the like, which have leading edges. 
     As shown in  FIG. 1 , a rotatable leading edge in accordance with an embodiment of the present invention includes a portion  20   a  adjacent to the fuselage  12 , and portions  20   b  adjacent to the wings  14 . The leading edge  20   a ,  20   b  is rotatable around an axis A that is substantially parallel with a transverse direction of the aircraft. In this embodiment, the axis of rotation A of the leading edge  20   a ,  20   b  is located adjacent to the nose  16  of the fuselage  12 . However, the axis of rotation A may be located at any other suitable location along the longitudinal direction of the aircraft. For example, the axis of rotation A may be moved farther aft. 
       FIG. 2  is a cross sectional view of the wing  14  and leading edge  20   b , taken through section  2 — 2  of  FIG. 1 . In  FIGS. 1 and 2 , the leading edge  20   a ,  20   b  is in a retracted position. In the retracted position, a portion of the leading edge  20   b  is seated against and contacts the wing  14 . 
       FIGS. 3 and 4  are similar views as shown in  FIGS. 1 and 2 , respectively, except the leading edge  20   a ,  20   b  has been rotated around the axis A through an arc R to an extended position. The extended position of the leading edge  20   b  is most clearly shown in  FIG. 4 , which is a cross sectional view of the wing  14  taken through line  4 — 4  of  FIG. 3 . As shown in  FIG. 4 , the leading edge  20   b  is in an extended position away from the wing  14 . In the extended position, the leading edge  20   b  is elevated above the wing  14  a distance D W . Since the leading edge  20   a ,  20   b  rotates around the axis A through an arc R, the elevated distance D W  between the leading edge  20   b  and the wing  14  will vary depending upon the particular location along the wing  14 . 
     Although not shown in  FIG. 3  or  4 , at least a portion of the leading edge  20   a  adjacent to the fuselage  12  is also elevated away from the fuselage  12  when the leading edge is in the extended position. If the axis of rotation A is moved farther aft from the location shown in  FIGS. 1 and 3 , the portion of the leading edge  20   a  behind the axis A may deflect upward while the portion of the leading edge in front of the axis A may deflect downward. 
     As can be seen most clearly in  FIGS. 1 and 3 , the wings  14  of the aircraft  10  have a sweep angle S W  measured from a transverse direction of the aircraft. As can also be seen in  FIGS. 1 and 3 , the fuselage  12 , including strakes and other structures having leading edges, may also have a sweep angle S F measured from the transverse direction of the aircraft  10 . In the embodiment illustrated in  FIGS. 1 and 3 , the wing sweep angle S W  is different from the fuselage sweep angle S F , i.e., the wing sweep angle S W  is less than the fuselage sweep angle S F . 
     In the embodiments shown in  FIGS. 1 and 3 , the wing sweep angle S W  remains constant along the wing  14 , and the fuselage sweep angle S F  remains constant along the fuselage  12 . However, the wing sweep angle S W  and/or the fuselage sweep angle S F  may vary. Accordingly, although constant wing and fuselage sweep angles S W  and S F  are shown in the present figures, any other desired wing and fuselage configuration may be used in accordance with the present invention. 
       FIGS. 5 and 6  are partially schematic side views of an aircraft similar to that shown in  FIGS. 1 and 3 . In  FIG. 5 , the leading edge  20   a ,  20   b  is in the retracted position. In  FIG. 6 , the leading edge  20   a ,  20   b  is in the extended position, illustrating rotation of the leading edge  20   a ,  20   b  around an axis near the nose  16  of the aircraft. The leading edge may traverse an arc R, for example from about 0 to about 10 degrees, when rotated around the axis from the retracted to the extended position. 
       FIGS. 7 and 8  are partially schematic front views of an aircraft similar to that shown in  FIGS. 1 and 3 . In  FIG. 7 , the leading edge  20   a ,  20   b  is in the retracted position. In  FIG. 8 , the leading edge  20   a ,  20   b  is in the extended position. 
     The leading edge  20   a ,  20   b  is a continuous single piece from left wing tip to right wing tip and may be made of any suitable material. For example, the leading edge may comprise a substantially rigid material such as aluminum or conventional composite materials. The material will have no gaps extending to the physical leading edge or may show no gaps detectable in the electromagnetic spectrum. 
     The mechanism used to extend and retract the leading edge  20   a ,  20   b  may be any suitable linkage  28 , such as a conventional double pivoted screwjack and four bar linkages. Any suitable controller for actuating the mechanism may be used, such as conventional manually operated controls or automatic controls for extending and retracting the leading edge based on airspeed. 
       FIG. 9  is a partially schematic side view of an aircraft including a rotatable leading edge of the fuselage and wing similar to the embodiment shown in  FIGS. 1–8 , except the axis of rotation of the leading edge has been moved aft on the aircraft, and the portion of the leading edge in front of the rotational axis deflects downwardly while the portion of the leading edge behind the rotational axis deflects upwardly. 
       FIG. 10  is a partially schematic cross sectional view of a portion of an aircraft wing and a leading edge of the wing portion, illustrating downward deflection of the leading edge when the leading edge is in an extended position in accordance with an embodiment of the present invention. 
       FIG. 11  is a partially schematic longitudinal sectional view of an aircraft fuselage and a leading edge of the fuselage, illustrating downward deflection of the leading edge when the leading edge is in an extended position in accordance with an embodiment of the present invention. 
       FIG. 12  is a partially schematic cross sectional view of the leading edge  20   b , which includes a front edge  21  and a rear contact surface  22 . In the embodiment shown in  FIG. 12 , the rear contact surface  22  has a concave shape which conforms with the front edge  15  of the wing  14 . Thus, the rear contact surface  22  and the front edge  15  are tightly seated against each other when the leading edge  20   b  is in the retracted position. This conforming arrangement of the rear contact surface  22  of the leading edge  20   b  and front edge  15  of the wing  14  can be seen in  FIGS. 2 and 4 . 
     As shown in  FIGS. 2 ,  4  and  12 , the front edge  21  of the leading edge  20   b  may have a relatively pointed shape, while the rear contact surface  22  and front edge  15  of the wing  14  may have a relatively rounded shape. Thus, the front edge  21  of the leading edge  20   b  has a smaller radius of curvature than the front edge  15  of the wing  14 . This may be desirable in some aircraft because the rounder front edge  15  of the wing  14  may delay wing stall. The leading edge  20   a  or  20   b  forward of the rotation point A will have a rear contact shape to allow the leading edges to be deflected below its stowed position. 
       FIGS. 13 and 14  illustrate alternative rear contact surface shapes of leading edges in accordance with embodiments of the present invention. In  FIG. 13 , the leading edge  23  has an angled contact surface  24 . In  FIG. 14 , the leading edge  25  has a generally flat contact surface  26 . 
       FIGS. 15–17  illustrate an embodiment of the present invention in which a conventional Krueger flap  30  is rotatably mounted on the wing  14 . In  FIG. 15 , the leading edge  20   b  is in the retracted position, and the Krueger flap  30  is in the stowed position. In  FIG. 16 , the leading edge  20   b  is extended from the wing, while the Krueger flap  30  remains stowed. In  FIG. 17 , the leading edge  20   b  is extended and the Krueger flap  30  is rotated into a deployed position. Any known Krueger flap design and deployment mechanism may be used in accordance with this embodiment of the invention. 
     Whereas particular embodiments of this invention have been described above for purposes of illustration, it will be evident to those skilled in the art that numerous variations of the details of the present invention may be made without departing from the invention as defined in the appended claims.