Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Aeronautical vehicle
Reexamination Certificate
1999-04-20
2001-07-10
Cuchlinski, Jr., William A (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Aeronautical vehicle
C701S004000, C701S014000, C701S016000, C342S033000, C244S075100, C244S07600R, C244S175000
Reexamination Certificate
active
06259975
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a flight control system for an aircraft, particularly for a helicopter.
Said flight control system is intended more particularly, although not exclusively, for facilitating ground approaches, for the purpose of landing, with a strong crosswind, in particular steep approaches in poor visibility.
2. Description of the Related Art
Usually, when a helicopter makes a so-called “instrument” approach, following a guidance direction (or approach path), for example a guidance beam emitted by a ground marker, it corrects the lateral deviations, for example the drift caused by a crosswind, by a course modification in the appropriate direction. It thus produces a lateral speed with respect to the ground, which allows it to return to the approach path if it deviates therefrom.
This usual mode of approach, by course modification, although widely used does have several drawbacks, especially in the case of aircraft, such as a helicopter or a tilt-rotor aircraft, which are capable of making steep approaches at low speed.
This is because, at low speed, which is necessary in the case of a steep approach, controlling the course by the roll become difficult since the slightest inclination generates a large yaw rotation.
In addition, compensation for a strong crosswind or correction of a drift generated especially by a strong crosswind relative to the approach path generally requires a very large course deviation with respect to the alignment with said approach path.
In practice, this course deviation sometimes amounts to values greater than 30°, something which is hardly acceptable, especially for safety reasons.
The object of the present invention, which relates to a suitable flight control system, is to remedy these drawbacks.
SUMMARY OF THE INVENTION
For this purpose, according to the invention, said flight control system for an aircraft, particularly for a helicopter, of the type receiving a number of items of information, especially the positions of flight control members of said aircraft, and sending, depending on these items of information, control inputs to control of the aircraft, is noteworthy in that it comprises:
at least one sensor which measures actual values of at least one parameter representative of the flight of said aircraft; and
computing means which generate, at least from said measured actual values and from positions of flight control members, corrected control inputs which are intended to be sent to said controls and which make it possible to control, without external visual references, the lateral speed of said aircraft with respect to the ground, without varying the course of said aircraft.
Thus, by virtue of the invention, it is possible to control the lateral speed of the aircraft with respect to the ground, i.e. to compensate for or correct the effect of a crosswind, without correspondingly varying the course, it being possible, for example, for the latter to remain aligned with respect to a guidance direction during a ground approach.
This allows optimum use of the sideways flight capability of said aircraft, for example a helicopter, and thus makes it easier to fly it, especially during approaches.
It should be noted that, in the context of the present invention:
the term “ground” should not be limited to a fixed terrestrial surface, such as a landing pad of a heliport for example, but relates to any surface, even a moving surface, such as the platform of a ship capable of acting as a landing area for said aircraft; and
the system according to the invention may be applied both to an aircraft provided with a fly-by-wire or fly-by-light device and to an aircraft provided with mechanical flight controls or with an autopilot.
Moreover, said computing means advantageously generate corrected control inputs in order to keep the direction of the speed (and therefore the path) of said aircraft with respect to the ground constant during a modification of the course and/or a modification of the longitudinal speed of the latter.
This embodiment is, in particular, especially advantageous and useful during an approach phase, in particular when the path of the aircraft is aligned with respect to a guidance direction.
This is because, in this situation, a course rotation control, an acceleration and/or a deceleration of the aircraft have/has no influence on the path which, by virtue of the invention, remains aligned with respect to the guidance direction, which thus makes landing very much easier.
Furthermore, said computing means are advantageously actuable. They may therefore be actuated and de-actuated, either manually by the pilot or automatically, for example depending on the flight phases, to be used only when the control assistance that they provide is necessary or useful, i.e. especially during a landing.
In a preferred embodiment, said system is noteworthy in that said computing means comprise:
a first computing unit which computes at least one reference value, for example a lateral speed, a longitudinal speed and/or a longitudinal acceleration, specified below, from said measured actual values; and
a second computing unit which generates said corrected control inputs from at least said reference value and from positions of flight control members.
Furthermore, in order to make flying or decision-taking by the pilot(s) easier, the system according to the invention advantageously includes, in addition:
a value indicator capable of indicating, to a pilot of the aircraft, the value of the lateral speed of the aircraft with respect to the ground; and
a position indicator which is coupled to said value indicator and which is capable of indicating, to a pilot of the aircraft, the position of the latter with respect to a defined path.
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Mezan Serge Joseph
Rollet Philippe Alain Jean
Cuchlinski, Jr. William A
Eurocopter
Hernandez Olga
Stevens Davis Miller & Mosher LLP
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