WO2024141531A1 - Aircraft comprising a device for flight control and/or drag reduction by blowing air - Google Patents

Abstract

Disclosed is an aircraft comprising a device (40) for controlling flight and/or reducing drag by blowing a stream (30) of compressed air in a flow area around at least one wing (20). Also disclosed is a method for modifying the drag and/or lift of at least one wing (20) by means of such a device (40).

Description

Aircraft comprising a flight control and/or drag reduction device by blowing

The invention relates to the field of winged aircraft.

The invention is of particular interest for aircraft without an onboard crew, known under the name "drone" or by the acronyms "RPAS" (from the English " Remotely Piloted Aircraft System "), "UAV" (from the English " Unmanned Aerial Vehicle "), "UAS" (from the English " Unmanned Air System ") or even "RPA" (from the English " Remotely Piloted Aircraft ").

State of the prior art

Conventionally, a winged aircraft includes flight control surfaces to control the movement of the aircraft around different axes, in particular a pitch axis, a roll axis and a yaw axis. Flight control surfaces typically include an elevator forming a horizontal tail, ailerons which equip the wings, as well as a rudder, also called a symmetry control surface.

The electronic steering control system of such an aircraft is particularly complex and expensive.

Furthermore, in addition to the quantity of parts necessary for the operation of conventional flight control surfaces, they tend to increase the drag of the aircraft since they include moving parts involving operating clearances and constituting surface irregularities.

An aim of the invention is to simplify and/or reduce the cost of flight control equipment for an aircraft, in particular for an aircraft without an onboard crew.

Another aim of the invention is to provide a solution making it possible to reduce the drag of an aircraft.

• un réservoir apte à contenir un fluide tel que de l’air comprimé,
• un organe de soufflage configuré pour pouvoir diriger un flux dudit fluide vers une zone d’écoulement d’air autour d’une ou plusieurs desdites ailes afin de modifier la traînée et/ou la portance de cette ou ces ailes.

To this end, the subject of the invention is a winged aircraft, comprising:

• a reservoir capable of containing a fluid such as compressed air,
• a blowing member configured to be able to direct a flow of said fluid towards an air flow zone around one or more of said wings in order to modify the drag and/or the lift of this or these wings.

The blowing member and the tank can thus form a flight control device, which can be combined with conventional flight control surfaces or replace all or part of them.

The invention thus provides an alternative to flight controls known in the prior art.

The control of such a blowing member can be carried out by opening and closing one or more solenoid valves, which makes it possible to simplify the control electronics and reduce its cost.

In a non-limiting manner, the device of the invention can in particular be configured to control the aircraft around the roll axis.

In one embodiment, the aircraft can thus be devoid of conventional roll action control members, of the aileron type connected to the wings.

This makes it possible to simplify flight control while eliminating the aerodynamic disturbances which result from the assembly of such ailerons with the wings.

The device of the invention can also be configured to control the aircraft around the pitch axis and/or the yaw axis, which makes it possible to remove all or part of the elevator and rudder controls and to benefit from advantages similar to those described above relating to the removal of ailerons.

In addition, the blowing member of the invention makes it possible to optimize the aerodynamic forces and in particular to reduce the drag of the wings.

In one embodiment, the blowing member is configured to be able to direct said flow in a blowing direction perpendicular or oblique relative to a plane passing through an extrados of at least one of the wings, in order to be able to direct said flow in a direction substantially perpendicular or oblique to said air flow.

Many ejection configurations can be considered.

According to a first variant, the blowing member is configured to eject said flow upstream of a leading edge of one or more of said wings, relative to a direction of said air flow.

Ejection upstream of the leading edge of a wing makes it possible in particular to attach the blowing member to the wing without it being necessary to house it therein.

According to a second variant, the blowing member is configured to eject said flow downstream of the leading edge of one or more of said wings, relative to said direction of said air flow.

In the context of this second variant, it is preferred that the blowing member is configured to eject said flow upstream of a trailing edge of the wing(s), relative to said direction of said air flow.

In a non-limiting manner, a wing equipped with a blowing member conforming to this second variant may comprise an opening, or slot, through which the flow is ejected.

Blowing the flow downstream of the leading edge of a wing makes it possible in particular to optimize aerodynamic performance, in particular to promote the increase in lift and the reduction of the drag of this wing.

According to a third variant, the blowing member is configured to be able to eject said flow at one end of one or more of said wings.

Ejecting the flow at one end of a wing makes it possible to reduce the ejection flow necessary to produce, for example, a rolling action.

These alternative embodiments are not limiting and can be combined with each other.

For example, the blowing member can be configured to eject the flow downstream of the leading edge of a wing and at the level of the end of this wing.

For another example, the blowing member may comprise one or more ejection elements configured to be able to eject part of the flow upstream of the leading edge of a wing and/or one or more ejection elements configured to be able to eject another part of the flow downstream of the leading edge of this wing and/or one or more ejection elements configured to be able to eject another part of the flow at one end of this wing.

It is preferred, but not required, that the blowing member is configured to be able to eject a flow symmetrically from one wing relative to the other.

Furthermore, for each of the wings, the flow can be directed in different directions and, in particular, to one side or the other of the wing.

In particular, the blowing member can be configured to direct said flow towards a part of the air flow zone delimited by an extrados of at least one of the wings.

Alternatively or additionally, the blowing member can be configured to direct said flow towards a part of the air flow zone delimited by an intrados of at least one of the wings.

By way of example, the blowing member may comprise one or more ejection elements configured to direct the flow towards the part of the air flow zone delimited by the upper surface of a wing and one or more other ejection elements configured so as to direct the flow towards the part of the air flow zone delimited by the lower surface of this wing.

Selective control of ejection elements which are differently configured thus makes it possible to modify the relative lift of each of the wings of the aircraft and to trigger rolling actions or other movement of the aircraft.

In one embodiment, the aircraft comprises a fuselage receiving the tank, or having a part forming the tank.

In one embodiment, the aircraft is configured to be controlled remotely and/or by automatic piloting without a crew on board.

In other words, the aircraft may be of the “drone” type, also known by the acronyms “RPAS”, “UAV”, “UAS” or “RPA”.

According to another aspect, the subject of the invention is a method of modifying the drag and/or the lift of one or more wings of an aircraft as defined above.

The method preferably comprises a blowing step, using said blowing member, so as to direct said flow towards said flow zone around one or more of said wings.

In one mode of implementation, the blowing is carried out so as to move the aircraft in rotation around a roll axis and/or a pitch axis and/or a yaw axis.

This can be achieved by directing said flow towards the flow zone around only one of said wings.

This can also be achieved by directing respective parts of said flow towards the flow zone of each of said wings in different quantities and/or respective directions.

In one embodiment, the blowing is carried out so as to produce a separation of a boundary layer of said air flow around one or more of said wings.

It is thus possible to significantly reduce the drag force.

In one embodiment, the blowing is carried out so that said flow is ejected by the blowing member with a temperature identical or substantially identical to the temperature of said air flow.

Other advantages and characteristics of the invention will appear on reading the detailed, non-limiting description which follows.

• La est une vue schématique de dessus d’un aéronef conforme à l’invention ;
• La est une vue schématique en perspective de l’aéronef de la  ;
• La est une vue schématique en perspective d’une partie d’un ensemble comprenant une aile d’aéronef et un organe de soufflage conforme à un premier mode de réalisation de l’invention ;
• La est une vue schématique en perspective d’une partie d’un ensemble comprenant une aile d’aéronef et un organe de soufflage conforme à un deuxième mode de réalisation de l’invention ;
• La est une vue schématique de côté d’une partie de l’ensemble de la  ;
• La est une vue schématique de côté d’une partie d’un ensemble comprenant une aile d’aéronef et un organe de soufflage conforme à un troisième mode de réalisation de l’invention.

The detailed description which follows refers to the appended drawings in which:

• There is a schematic top view of an aircraft according to the invention;
• There is a schematic perspective view of the aircraft of the ;
• There is a schematic perspective view of a part of an assembly comprising an aircraft wing and a blowing member according to a first embodiment of the invention;
• There is a schematic perspective view of a part of an assembly comprising an aircraft wing and a blowing member according to a second embodiment of the invention;
• There is a schematic side view of part of the entire ;
• There is a schematic side view of a part of an assembly comprising an aircraft wing and a blowing member according to a third embodiment of the invention.

Detailed description of embodiments

Figures 1 and 2 show a remotely controllable aircraft 1 allowing flight missions without an onboard crew to be carried out.

In the present description, the terms “front” and “rear”, as well as “upstream” and “downstream”, are defined relative to a direction S1 of air flow when the aircraft 1 flies, in other words relative to the relative wind.

In this non-limiting example, aircraft 1 comprises a fuselage 2, wings 3 and 4, a horizontal tail 5 and a vertical tail 6 in the shape of a T, as well as propulsion assemblies 7 and 8 mounted at the rear of the fuselage 2.

Fuselage 2 extends along a longitudinal axis A1 defining a roll axis.

Wings 3 and 4 extend symmetrically on either side of fuselage 2, along a pitch axis A2.

Each of the wings 3 and 4 comprises a proximal end 11 by which it is connected to the fuselage 2, a distal end 12, a leading edge 13, a trailing edge 14, an intrados 15 and an extrados 16.

For information purposes only, aircraft 1 of the can have a wingspan of approximately 2.5 m, the wingspan corresponding to the distance X1 between the distal ends 12 of the wings 3 and 4, a length X2 of 3 m and an overall mass of between 80 kg and 90 kg at takeoff , fuel included.

In a manner known per se, the horizontal tail 5 and the vertical tail 6 are intended to stabilize the aircraft 1 respectively around the pitch axis A2 and a yaw axis A3 (see ).

A conventional solution for controlling the position of this type of aircraft 1 in rotation around the roll axis A1 consists of equipping wings 3 and 4 with ailerons (not shown). Simultaneous rotation of the ailerons, in the opposite direction of one wing relative to the other, typically makes it possible to increase the lift of one of the wings and reduce the lift of the other wing, resulting in a displacement of aircraft 1 rotating around roll axis A1.

Figures 3 to 6 show non-limiting examples of flight control devices conforming to the invention which make it possible, in particular, to ensure such a rolling action without it being necessary to control ailerons as described above .

Generally speaking, the device of the invention comprises a blowing member configured to blow a flow of a fluid at one or both wings 3 and 4.

The fluid forming this flow is in this example compressed air which is stored in a tank (not shown) and routed to the blowing member by a distribution circuit (not shown).

In this example, the tank is housed in fuselage 2.

As an indication, the tank can have a capacity of several tens of liters, for example to store 56 m ³ of air at 700 bars.

In flight, aircraft 1 moves in an atmospheric air mass. This mass of air forms a flow, generally in direction S1, around aircraft 1 and in particular around wings 3 and 4, the shape of which is designed to limit the air resistance to the movement of aircraft 1 and so as to optimize aerodynamic lift.

The device of the invention is more precisely configured to be able to direct the flow generated by the blowing member towards a zone extending around the wings 3 and 4 and in which the flow of atmospheric air circulates, this zone being called “flow zone.”

In the numerous blowing modes which can be implemented in accordance with the invention, in particular those described below, the generation of such a flow in the flow zone around one or both wings 3 and 4 makes it possible to modify the resulting aerodynamic force which is exerted on this or these wings, in particular the lift and the drag.

Figures 3 to 6 show part of a wing 20 and a blowing member according to different embodiments. The wing 20 shown in these figures can constitute the wing 3 of the aircraft 1 of Figures 1 and 2, it being understood that the following description applies by analogy to the wing 4 of this aircraft 1, which is symmetrical to wing 3, and more generally to one or more wings of aircraft different from that of Figures 1 and 2.

In the embodiment of the , the blowing member 21 forms an ejection element communicating with a slot 22 made on the upper surface 16 of the wing 20.

In this non-limiting example, the slot 22 has a width X11 of approximately 5 mm and is located at a distance X12 of approximately 6 mm from the leading edge 13 of the wing 20, X11 and X12 being considered along 'a direction parallel to the roll axis A1 of the aircraft.

In this non-limiting example, the slot 22 extends parallel to the leading edge 13 of the wing 20, from its distal end 12, over a length X13 which corresponds approximately to a quarter of the length of this wing 20.

Slot 22 is configured to eject a flow 30 of air in the form of a blade.

In this example, the ejection of flow 30 results from an opening command from a solenoid valve.

In a non-limiting manner, the flow 30 is ejected in a direction forming in this example an angle X14 of 90° relative to a plane passing through the extrados 16 of the wing 20.

As an indication, the ejection speed of the flow 30 can be several hundred meters per second, for example between 200 m/s and 300 m/s, for example equal to 250 m/s.

Tests have demonstrated that such a device makes it possible to both reduce the drag of the wing 20 and significantly improve its lift. In particular, by thus ejecting a flow of air having a temperature of 15°C at a speed of 250 m/s, for a flow of atmospheric air around the wing 20 having a temperature of 15°C and a speed of 450 m/s, it is possible to achieve a reduction in wing drag of 20 close to 100% and an increase in lift close to 35%.

On the one hand, the blowing member 21 makes it possible to remove the boundary layer from the air flow around the wing 20, helping to optimize the aerodynamic performance of the wing 20.

On the other hand, by equipping each of the wings 3 and 4 with an aircraft 1 such as that of the with such a blowing member 21, it is in particular possible to move the aircraft 1 in rotation around the roll axis A1.

For example, in a non-limiting manner, the blowing member 21 can be controlled to eject a flow 30 only via the slot 22 made on the upper surface 16 of the wing 3, causing the aircraft 1 to rotate in one direction. around roll axis A1. To drive the aircraft 1 in rotation in the other direction around the roll axis A1, the blowing member 21 can be controlled to eject a flow 30 only via the slot 22 made on the extrados 16 of the wing 4.

In the embodiment of Figures 4 and 5, the blowing member is distinguished from that of the in that it is configured to eject the flow 30 at the front of the leading edge 13 of the wing 20. This embodiment is described only according to its differences compared to the embodiment of the , the preceding description applying by analogy.

With reference to Figures 4 and 5, the blowing member 40 comprises a T-shaped body which extends at the front of the leading edge 13 of the wing 20.

More precisely, the body of the blowing member 40 comprises a front part 41 defining a convex front surface 42 and housing an ejection element configured to eject the flow 30 through a slot 43 located on the side of the extrados 16 of the wing 20.

The body of the blower 40 also includes an arm 44 connecting the front part 41 of the body to the wing 20.

In this non-limiting example, the slot 43 has a width X21 of approximately 5 mm and the arm 44 has a length X22 of approximately 25 mm corresponding to the distance between the slot 43 and the leading edge 13 of the wing 20, X21 and X22 being considered along a direction parallel to the roll axis A1 of the aircraft. The distance X23 between the arm 44 and the part of the body forming the slot 43 is approximately 10 mm.

The method of carrying out the differs from that of Figures 4 and 5 in that the length X22 is equal to 5 mm. The preceding description applies by analogy to this embodiment.

Tests have demonstrated that such embodiments also make it possible to significantly reduce the drag of the wing 20 and significantly improve its lift. In particular, by thus ejecting a flow of air having a temperature of 15°C at a speed of 250 m/s, for a flow of atmospheric air around the wing 20 having a temperature of 15°C and a speed of 450 m/s, it is possible to obtain a reduction in the drag of the wing 20 close to 32% and 59%, respectively, and an increase in lift close to 16% and 22%, respectively for the mode of production of Figures 4 and 5 and for that of the .

The embodiments described above with reference to Figures 3 to 6 are not limiting and numerous variations can be made within the framework of the invention. For example, in each of these embodiments, the blowing member can be controlled so as to eject a flow with a variable air flow rate and/or in different orientations, whether to reduce drag and/or to modify the lift of one or more wings.

In each of the embodiments described above, the blowing member may have another geometry and/or dimensions different from those indicated above and/or occupy another position relative to the wing to which it is connected. For example, the blowing member can be configured to eject a flow in the form of a straight or curved blade or sheet, single or multiple.

In alternative embodiments, not shown, the blowing member can be configured to eject a flow in a part of the flow zone delimited not by the upper surface but by the lower surface of a wing, or selectively on the one hand in a part of the flow zone delimited by the intrados and, on the other hand, in a part of the flow zone delimited by the extrados of this wing.

Thus, the blowing member can be configured to eject one or more flows onto the wings of an aircraft at variable flow rates and/or orientations, depending on the desired modifications of the aerodynamic forces exerted on the wings.

The invention can thus be implemented not only to reduce drag and/or to produce a rolling action but also, alternatively or complementary, to produce or contribute to the production of a pitching action and/or 'a yaw action.

More generally, the different embodiments described above, as well as their variants, can be combined and implemented in aircraft different from that described above with reference to Figures 1 and 2. In particular, the invention can be implemented in an aircraft located in another category of size and/or mass, for example a mass less than 50 kg or on the contrary greater than 100 kg, and/or intended to fly at a different speed, for example less than 150 km/h, and/or having a different architecture, for example another geometry of wings and/or fuselage and/or empennage, including an architecture of the flying wing type, in which case each of the ends of the flying wing constitutes a wing within the meaning of the invention.

Claims (10)

Aircraft (1) with wings (3, 4, 20), characterized in that it comprises:

• a reservoir capable of containing a fluid such as compressed air,
• a blowing member (21, 40) configured to be able to direct a flow (30) of said fluid towards an air flow zone around one or more of said wings (3, 4, 20) in order to modify the drag and /or the lift of this or these wings (3, 4, 20).

Aircraft (1) according to claim 1, in which the blowing member (21, 40) is configured to direct said flow (30) in a blowing direction perpendicular (X14) or oblique with respect to a plane passing through an extrados (16) of at least one of the wings (3, 4, 20). Aircraft (1) according to claim 1 or 2, in which the blowing member (21, 40) is configured to be able to eject said flow (30) upstream and/or downstream of a leading edge (13). of one or more of said wings (3, 4, 20), relative to one direction (S1) of said air flow, and/or to be able to eject said flow (30) at one end (12) of one or more of said wings. Aircraft (1) according to any one of claims 1 to 3, in which the blowing member (21, 40) is configured to be able to direct said flow towards:

• a part of the flow zone delimited by an extrados (16) of at least one of the wings (3, 4, 20), and/or
• a part of the flow zone delimited by an intrados (15) of at least one of the wings (3, 4, 20).

Aircraft (1) according to any one of claims 1 to 4, comprising a fuselage (2) receiving the tank. Aircraft (1) according to any one of claims 1 to 5, configured to be controlled remotely and/or by automatic piloting without a crew on board. Method for modifying the drag and/or lift of one or more wings (3, 4, 20) of an aircraft (1) according to any one of claims 1 to 6, comprising a blowing step, using said blowing member (21, 40), so as to direct said flow (30) towards said flow zone around one or more of said wings (3, 4, 20). Method according to claim 7, in which the blowing is carried out so as to move the aircraft (1) in rotation around a roll axis (A1) and/or a pitch axis (A2) and/or 'a yaw axis (A3):

• either by directing said flow (30) towards the flow zone around only one of said wings (3, 4),
• either by directing respective parts of said flow (30) towards the flow zone of each of said wings (3, 4) in different quantities and/or respective directions.

Method according to claim 7 or 8, wherein the blowing is carried out so as to produce a separation of a boundary layer of said air flow around one or more of said wings (3, 4). Method according to any one of claims 7 to 9, in which the blowing is carried out so that said flow (30) is ejected by the blowing member (21, 40) with a temperature identical or substantially identical to the temperature of said air flow.