Aeronautics and astronautics – Aircraft sustentation – Sustaining airfoils
Reexamination Certificate
2001-01-25
2003-02-04
Carone, Michael J. (Department: 3641)
Aeronautics and astronautics
Aircraft sustentation
Sustaining airfoils
C244S201000, C244S215000
Reexamination Certificate
active
06513761
ABSTRACT:
PRIORITY CLAIM
This application is based on and claims the priority under 35 U.S.C. §119 of German Patent Application 100 18 389.1, filed on Apr. 13, 2000, the entire disclosure of which is incorporated herein by reference.
FIELD OF THE INVENTION
The invention relates to an apparatus and to a method for reducing so-called trailing vortices that are generated by the high performance lift producing systems of the aircraft wings particularly the landing flaps.
BACKGROUND INFORMATION
Conventionally, the wings of aircraft, particular large subsonic transport aircraft are equipped with high performance lift producing systems such as landing flaps and their drives for generating the required lift, particularly during slow speed flight, for example during landing. Speeds above ground of about 200 miles per hour or less are referred to as slow speeds, that may vary depending on the type of aircraft. As a rule, such high performance lift producing systems comprise slats, landing flaps and their drives. When a wing produces lift, harmful vortices are generated in the wake of the wings, particularly downstream of the landing flaps. Such harmful vortices are referred to herein as trailing vortices. More specifically, a trailing vortex is formed at the outer end of the respective landing flaps away from the central longitudinal axis of the aircraft. Further vortices are generated in the area of the wing tips. These tip vortices are also referred to as trailing vortices. All trailing vortices form a vortex system in which each individual vortex rotates about its own axis while additionally rotating within the vortex system, whereby the entire vortex system follows a spiral motion that is entrained into the air flow along the aircraft.
The trailing vortices produced in the wake of large aircraft pose a danger for any following aircraft, particularly in the dense flight patterns prevailing in landing approach paths. Regulation safety spacings between two consecutive aircraft preparing for landing reduce the danger, but have the drawback of limiting the capacity of a landing strip. This capacity, expressed as a number of aircraft that can land on the same landing strip in a specified time, is reduced even more for large and heavier aircraft which require ever larger safety spacings. The heavier or larger an aircraft gets the larger is the safety spacing required for maintaining the regulation flight safety, particularly since the vortex intensity of the trailing vortices depends on the weight of the aircraft. The ever increasing use of large capacity aircraft, for example the A3XX and the ever growing air traffic, however, require a reduction in the so far generously allocated safety spacings between two landing aircraft. Thus, efforts have been made in the design of such large capacity aircraft to provide aircraft features which are capable of reducing the intensity of the trailing vortices and which preferably cause their rapid dissipation.
International Publication WO 99/00297 (Croucii et al.) shows that for some time now efforts have been made to reduce the trailing vortices or their harmful effects. For this purpose, the aileron (68) and spoiler flaps (70) are continuously operated to swing back and forth. The aileron motions and the flap motions are computer controlled in response to a plurality of criteria for exciting the trailing vortices to perform cross vibrations which are intended to rapidly dissipate the trailing vortices. However, the just described conventional features do not avoid the formation of large scale vortices downstream of the aircraft, yet do require an involved computer control program and system.
Another approach is disclosed in British Patent GB 2,051,706 A1 in which vortex reducing vanes (9) are secured to the end of the lift increasing landing flaps (2) or to the fixed wing structure adjacent the flap ends or to booms (10) which in turn are secured to the flap ends for reducing the formation of trailing vortices to thereby also reduce aircraft drag. However, this conventional device due to its position and shape is not capable of producing a controlled interference or counter vortex for dissipating a respective trailing vortex.
OBJECTS OF THE INVENTION
In view of the above it is the aim of the invention to achieve the following objects singly or in combination:
to provide a method and apparatus for reducing trailing vortices in the wake of an aircraft, particularly in the wing wake of an aircraft during slow flight for example during landing;
to provide a method and apparatus which assures a rapid dissipation of trailing vortices so that the formation of large scale vortices downstream of the aircraft is also reduced or even avoided;
to provide aircraft features that permit reducing the safety spacings between two aircraft in a landing approach while maintaining the required safety; and
to reduce the trailing vortices by generating counteracting or interfering vortices in the critical locations where the trailing vortices are unavoidably generated at the wing especially by the landing flaps.
SUMMARY OF THE INVENTION
According to the invention an apparatus for reducing trailing vortices generated in an aircraft by wing components including lift producing trailing edge landing flaps of the aircraft, is characterized by at least one controllable vortex generator secured to a mounting area of each wing at an outer end of an extended trailing edge landing flap for generating a controlled counteracting vortex for a respective trailing vortex downstream of each wing. Preferably, the at least one controllable vortex generator is so positioned that the counteracting vortex causes a respective trailing vortex to vibrate, thereby dissipating the respective trailing vortex at least partially. The vibrations of the trailing vortex preferably extend perpendicularly to a central longitudinal aircraft axis. At least one controllable vortex generator is provided for each trailing edge landing flap.
The above mentioned mounting area on the fixed wing of the aircraft is bounded in the flight direction by a line or point positioned downstream of the wing leading edge at 60% of the respective clean wing section which is the wing section when flaps and slats are retracted or not extended. The wing section is measured in the flight direction at the location of the present controllable vortex generator. The mounting area is further bounded in the direction opposite to the flight direction by a line or point positioned at 80% of the wing chord. In the spanwise wing direction the mounting area has a length, that is centered for example on an outer edge of a respective landing flap and corresponds to 10% of one half of the aircraft's span in either direction away from said outer edge.
The controllable vortex generators in the form of auxiliary flaps are secured with their forward edge to the fixed wing portion in the above defined mounting area and are operated, for example by conventional spoiler drives for extending and retracting the auxiliary vortex generator flap.
By rapidly dissipating the trailing vortices, the invention reduces or even avoids the formation of dangerous vortices downstream of the aircraft during slow flight especially during landing approach flight, whereby air traffic safety is generally increased. A further advantage of the invention is seen in that the regulation safety spacings between two landing aircraft can be reduced, whereby the capacity of a landing strip is increased, thereby accommodating the growing requirements of modern air traffic. The teachings of the invention are particularly suitable for use in large aircraft in which conventionally the formation of trailing vortices has posed a serious problem for air traffic. Moreover the present teachings provide a simple yet very efficient solution of the stated problems.
In a preferred embodiment the present vortex generator is a simple, small auxiliary flap which is recessed into the wing when it is not used. It has been found that the most efficient position of the auxiliary flap is next to an outer
Airbus Deutschland GmbH
Carone Michael J.
Fasse W. F.
Fasse W. G.
Sukman Gabriel S
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