Flap arrangement for varying the aerodynamic lift generated...

Details Flap arrangement for varying the aerodynamic lift generated... Flap arrangement for varying the aerodynamic lift generated...

2002-09-25

2003-11-04

Eldred, J. Woodrow (Department: 3644)

Aeronautics and astronautics

Aircraft sustentation

Sustaining airfoils

C244S204000, C244S206000, C244S212000, C244S215000

Reexamination Certificate

active

06641089

ABSTRACT:

PRIORITY CLAIM
This application is based on and claims the priority under 35 U.S.C. §119 of German Patent Application 101 47 827.5, filed on Sep. 27, 2001, the entire disclosure of which is incorporated herein by reference.
FIELD OF THE INVENTION
The invention relates to a flap arrangement that can be selectively extended to protrude into an airflow boundary layer of an aerodynamic element, such as a wing, an aileron, a rudder, an elevator, a stabilizer surface, or a flap, preferably having a planar trailing edge, so as to selectively vary the aerodynamic lift generated by this aerodynamic element.
BACKGROUND INFORMATION
A great variety of different flap arrangements for varying the aerodynamic lift generated by an aerodynamic element of an aircraft are generally known. For example, there are many known configurations of high lift flaps arranged along the trailing edge of a main lifting wing of an aircraft. Such conventionally known flap arrangements are generally rather complicated, i.e. having a complex geometry and construction, and require a complex support and drive mechanism for selectively extending and retracting the flap arrangement. Such flap arrangements typically and generally aim to selectively smoothly increase or reduce the chord length, the curvature, and/or the angle of attack of the sectional aerodynamic profile of the respective aerodynamic element.
As an alternative, it is also generally known to rigidly fix a sheet metal plate or the like on the trailing edge of an aerodynamic lift-generating element so as to form a perpendicular wall protruding substantially perpendicularly into the transverse plane airflow. This will alter the pressure distribution over the aerodynamic element, and therewith alter the magnitude of the lift and the resistance generated by this aerodynamic element. Although this has been known as a theoretical and experimental concept, it has never been further developed into a practically useful arrangement for varying the aerodynamic lift generated by an aerodynamic element of an aircraft.
SUMMARY OF THE INVENTION
In view of the above, it is an object of the invention to provide a flap arrangement that enables a rapid adjustment or variation of the aerodynamic lift generated by an aerodynamic element of an aircraft, so as to enable a controlled load variation and lift distribution of the aerodynamic element of the aircraft within projected effective or working ranges. It is another object of the invention to provide a flap arrangement that is extremely simple in design, construction, and operation. It is a further object of the invention to provide such a flap arrangement that can selectively either increase or decrease the aerodynamic lift generated by an aerodynamic element, in comparison to the clean configuration of the aerodynamic element. The invention further aims to avoid or overcome the disadvantages of the prior art, and to achieve additional advantages, as apparent from the present specification. The attainment of these objects is, however, not a required limitation of the present invention.
The above objects have been achieved according to the invention in a flap arrangement provided on a trailing edge of an aerodynamic lift-generating element of an aircraft. The aerodynamic lift-generating element will also simply be called an aerodynamic element herein, and may particularly be a main lifting wing, an auxiliary or secondary wing, a flap, an aileron, a rudder, an elevator, a stabilizer element such as the horizontal and vertical stabilizers or tail plane and fin of an aircraft tail unit, or the like. Throughout this specification, the terms “lift” and “aerodynamic lift” refer to the component of the aerodynamic force generated by the aerodynamic element in a direction perpendicular to the apparent air flow direction relative to the aerodynamic element. Thus, the general term “lift” is not limited to a vertically upward lift, but rather could also refer to a horizontally directed lateral aerodynamic lift, e.g. in the case of a rudder or the like.
According to the invention, a relatively small movable and controllable auxiliary flap is movably arranged at the trailing edge of an aerodynamic element in such a manner so that the auxiliary flap is selectively movable to any selected one of at least three positions. In a first end position, which is an upper end position in the case of a wing or the like as the aerodynamic element, the auxiliary flap protrudes into a first boundary layer of the airflow over a first surface of the aerodynamic element (i.e. into the upper boundary layer of the airflow along the upper surface of the wing). In a second end position (e.g. the lower end position in the case of a wing), the auxiliary flap protrudes into the second boundary layer of the airflow along the second surface of the aerodynamic element (e.g. the lower boundary layer of the airflow along the lower surface of the wing as the aerodynamic element). In a third neutral position, between the first and second end positions, the auxiliary flap does not protrude into and does not influence either of the two boundary layers.
The trailing edge of the aerodynamic element is preferably a flat planar trailing edge, rather than tapering to a single line edge at an intersection-of the two opposite aerodynamic surfaces of the aerodynamic element. Preferably further, the auxiliary flap has a configuration of a flat planar rectangular plate, i.e. without any aerodynamic airfoil shape, curvature, or thickness variation. Also, preferably, in at least the first and second positions, the auxiliary flap extends parallel to the flat planar trailing edge, and substantially perpendicular (e.g. 90°+10°) relative to a central chord line intersecting the trailing edge and extending between the first and second aerodynamic surfaces of the aerodynamic element. That also approximately corresponds to a substantially perpendicular protrusion of the auxiliary flap into the respective boundary layer in the respective end positions. In the third position, the auxiliary flap may remain parallel to the plane of the trailing edge, or may extend substantially parallel to or along (e.g. ±10°) the central chord line.
More specifically, in a first embodiment of the invention, the auxiliary flap is rotatably connected to the aerodynamic element, e.g. by rotational means, so that the auxiliary flap can be selectively rotated through approximately 180° to rotatably move the auxiliary flap among the above described first, second and third positions. The term “rotatable” does not require complete freedom to rotate through 360°, but rather also encompasses partial rotation or pivoting. In the first position, the auxiliary flap extends substantially perpendicularly to the chord line of the aerodynamic element, while in the second position the auxiliary flap extends substantially 180° opposite from the first position, and in the third position, the auxiliary flap extends substantially parallel to the chord line of the aerodynamic element, i.e. respectively 90° between the first and second positions. To achieve this, one of the longitudinally extending edges of the auxiliary flap is secured to a shaft that is rotatably supported and extends parallel to the trailing edge of the aerodynamic element in the direction of the span (e.g. the wing span) of the aerodynamic element. This shaft has a relatively small diameter, e.g. a diameter corresponding substantially to the thickness of the auxiliary flap.
Alternatively, instead of a shaft, a cylindrical drum or roll having a larger diameter can be rotatably supported and arranged along the trailing edge of the aerodynamic element. In this embodiment, the circular cross-section of the cylindrical drum is preferably at least partially received in a semi-cylindrical recess along the trailing edge of the aerodynamic element. The cross-sectional diameter of the drum is substantially greater than (e.g. 2, 3 or even 4 or more times) the cross-sectional thickness of the auxiliary flap, and may correspond to a dimension in the range of

Affiliated with

Also associated with

Rating

Flap arrangement for varying the aerodynamic lift generated... does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Flap arrangement for varying the aerodynamic lift generated..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Flap arrangement for varying the aerodynamic lift generated... will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3173221