Aircraft comprising a flight control and / or drag reduction device using a blower

Abstract

Aircraft comprising a flight control and / or drag reduction device (40) for blowing a stream (30) of compressed air into a flow zone around at least one wing (20). Method for modifying the drag and / or lift of at least one wing (20) using such a device (40). Figure for the abstract: Fig. 5

Description

Title of the invention: Aircraft comprising a flight control and / or wind reduction device by blowing. Technical field

[0001] The invention relates to the field of winged aircraft.

[0002] The invention is of particular interest for unmanned aircraft, known as "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 "RPA" (from the English "Remotely Piloted Aircraft"). Prior art

[0003] Typically, a winged aircraft includes flight control surfaces to control the aircraft's movement 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 stabilizer, ailerons that equip the wings, and a rudder, also called a swashplate.

[0004] The electronic steering control system of such an aircraft is particularly complex and expensive.

[0005] In addition, besides the quantity of parts required for the operation of conventional flight controls, these tend to increase the drag of the aircraft since they include moving parts involving operating clearances and constituting surface irregularities. Description of the invention

[0006] One object of the invention is to simplify and / or reduce the cost of flight control equipment of an aircraft, in particular of an unmanned aircraft.

[0007] Another object of the invention is to provide a solution for reducing the drag of an aircraft.

[0008] For this purpose, the invention relates to a winged aircraft, comprising: • a tank capable of containing a fluid such as compressed air, • a blowing device configured to be able to direct a flow of said fluid towards an airflow zone around one or more of said wings in order to modify the drag and / or lift of this or these wings.

[0009] The blower and the reservoir can thus form a flight control device, which can be combined with conventional flight controls or replace all or part of them.

[0010] The invention thus provides an alternative to flight controls known in the state of the previous technique.

[0011] The control of such a blowing device can be achieved by opening and closing one or more solenoid valves, which simplifies the control electronics and reduces its cost.

[0012] By way of non-limitation, the device of the invention can in particular be configured to control the aircraft around the roll axis.

[0013] In one embodiment, the aircraft can thus be devoid of conventional roll action control devices, of the type with ailerons connected to the wings.

[0014] This simplifies flight control while eliminating aerodynamic disturbances resulting from the assembly of such ailerons with wings.

[0015] 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 elevators and rudder and to benefit from advantages similar to those described above relating to the removal of the ailerons.

[0016] In addition, the blowing device of the invention makes it possible to optimize aerodynamic forces and in particular to reduce wing drag.

[0017] In one embodiment, the blowing member is configured to be able to direct said flow in a blowing direction perpendicular or oblique to a plane passing through an extrados of at least one of the wings, so as to be able to direct said flow in a substantially perpendicular or oblique direction to said airflow.

[0018] Many ejection configurations can be envisaged.

[0019] According to a first variant, the blowing device is configured to eject said flow upstream of a leading edge of one or more of said wings, relative to a direction of said airflow.

[0020] An ejection upstream of the leading edge of a wing makes it possible in particular to bring the blowing element back onto the wing without it being necessary to house it in the wing.

[0021] According to a second variant, the blowing device is configured to eject said flow downstream of the leading edge of one or more of said wings, relative to said direction of said airflow.

[0022] In the context of this second variant, it is preferred that the blowing element be configured to eject said flow upstream of a trailing edge of the wing or wings, relative to said direction of said airflow.

[0023] By way of non-limitation, a wing equipped with a blowing device conforming to this second variant may include an opening, or slot, through which the flow is ejected.

[0024] Blowing the airflow downstream of the leading edge of a wing makes it possible, in particular, to optimize aerodynamic performance, especially by promoting the increase in lift and the reduction in drag of this wing.

[0025] 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.

[0026] Ejecting the flow at the end of a wing makes it possible to reduce the ejection flow rate needed to produce, for example, a roll action.

[0027] These embodiment variants are not limiting and can be combined with each other.

[0028] For example, the blowing device can be configured to eject the flow downstream of the leading edge of a wing and at the tip of that wing.

[0029] For another example, the blowing device may include one or more ejection elements configured to be able to eject a 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.

[0030] It is preferred, but not required, that the blowing device be configured to be able to eject a flow symmetrically from one wing to the other.

[0031] Moreover, 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.

[0032] In particular, the blowing device can be configured to direct said flow towards a part of the airflow area delimited by an extrados of at least one of the wings.

[0033] Alternatively or complementarily, the blowing device can be configured to direct said flow towards a part of the airflow area delimited by an intrados of at least one of the wings.

[0034] By way of example, the blowing device may include one or more ejection elements configured to direct the flow towards the part of the airflow 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 airflow zone delimited by the lower surface of this wing.

[0035] A selective control of ejection elements which are differently configured thus makes it possible to modify the relative lift of each of the aircraft's wings and to trigger roll actions or other movement of the aircraft.

[0036] In one embodiment, the aircraft includes a fuselage receiving the tank, or having a part forming the tank.

[0037] In one embodiment, the aircraft is configured to be remotely controlled and / or by autopilot without a crew on board.

[0038] In other words, the aircraft may be of the "drone" type, also known as the acronyms “RPAS”, “UAV”, “UAS” or “RPA”.

[0039] According to another aspect, the invention relates to a method for modifying the drag and / or lift of one or more wings of an aircraft as defined above.

[0040] The method preferably includes a blowing step, using said blowing device, so as to direct said flow towards said flow zone around one or more of said wings.

[0041] In one embodiment, 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.

[0042] This can be achieved by directing said flow towards the flow area around only one of said wings.

[0043] 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.

[0044] In one embodiment, the blowing is carried out in such a way as to produce a separation of a boundary layer of said airflow around one or more of said wings.

[0045] It is thus possible to significantly reduce the drag force.

[0046] 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 airflow.

[0047] Other advantages and features of the invention will become apparent from the following detailed, non-limiting description. Brief description of the drawings

[0048] The following detailed description refers to the attached drawings on which: • Fig. 1 is a schematic top view of an aircraft according to the invention; • Fig. 2 is a schematic perspective view of the aircraft in Fig. 1; • Figure 3 is a schematic perspective view of part of a set comprising an aircraft wing and a blowing device according to a first embodiment of the invention; • The [Fig.4] is a schematic perspective view of part of an assembly comprising an aircraft wing and a blowing device according to a second embodiment of the invention; • The [Fig.5] is a schematic side view of part of the whole of the [Fig.4]; • Fig. 6 is a schematic side view of part of an assembly comprising an aircraft wing and a blowing device according to a third embodiment of the invention. Detailed description of implementation methods

[0049] Figures 1 and 2 show a remotely controlled aircraft 1 capable of carrying out flight missions without an onboard crew.

[0050] In this description, the terms "front" and "rear", as well as "upstream" and "downstream", are defined relative to an SI direction of airflow when the aircraft 1 is flying, that is, with respect to the relative wind.

[0051] In this non-limiting example, the aircraft 1 comprises a fuselage 2, wings 3 and 4, a horizontal tail 5 and a T-shaped vertical tail 6, as well as propulsion assemblies 7 and 8 mounted at the rear of the fuselage 2.

[0052] The fuselage 2 extends along a longitudinal axis Al defining a roll axis.

[0053] The wings 3 and 4 extend symmetrically on either side of the fuselage 2, along a pitch axis A2.

[0054] 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.

[0055] For the sake of indication, aircraft 1 of [Fig. 1] may have a wingspan of approximately 2.5 m, the wingspan corresponding to the distance XI between the distal ends 12 of the wings 3 and 4, a length X2 of 3 m and an overall mass between 80 kg and 90 kg at takeoff, including fuel.

[0056] 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 [Fig.2]).

[0057] A conventional solution for controlling the position of this type of aircraft 1 rotating about the roll axis A1 consists of equipping the wings 3 and 4 with ailerons (not shown). Simultaneous rotation of the ailerons, in opposite directions on one wing relative to the other, typically increases the lift of one wing and reduces the lift of the other wing, resulting in a displacement of the aircraft 1 in rotation about the roll axis A1

[0058] Figures 3 to 6 show non-limiting examples of flight control devices according to the invention which make it possible, in particular, to ensure such a roll action without it being necessary to control ailerons as described above.

[0059] In general, the device of the invention includes a blowing element configured to blow a flow of a fluid at the level of one or both of the wings 3 and 4.

[0060] The fluid forming this flow is, in this example, compressed air which is stored in a reservoir (not shown) and conveyed to the blower by a circuit of distribution (not shown).

[0061] In this example, the tank is housed in the fuselage 2.

[0062] As an indication, the tank can have a capacity of several tens of litres, for example to store 56 m3 of air at 700 bars.

[0063] In flight, aircraft 1 moves within an atmospheric air mass. This air mass forms a flow, generally in the SI direction, around aircraft 1 and in particular around wings 3 and 4 whose shape is designed to limit air resistance to the movement of aircraft 1 and thus optimize aerodynamic lift.

[0064] The device of the invention is more precisely configured to be able to direct the flow generated by the blowing element towards an area extending around the wings 3 and 4 and in which the flow of atmospheric air circulates, this area being called the "flow area".

[0065] In the many blowing modes that can be implemented according to the invention, in particular those described below, the generation of such a flow in the flow zone around one or both of the wings 3 and 4 makes it possible to modify the resulting aerodynamic force exerted on this or these wings, in particular the lift and the drag.

[0066] Figures 3 to 6 show part of a wing 20 and a blowing element 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 the wing 3, and more generally to one or more wings of aircraft different from that of Figures 1 and 2.

[0067] In the embodiment of [Fig.3], the blowing member 21 forms an ejection element communicating with a slot 22 made on the extrados 16 of the wing 20.

[0068] In this non-limiting example, the slot 22 has a width XI1 of about 5 mm and is located at a distance X12 of about 6 mm from the leading edge 13 of the wing 20, XI1 and X12 being considered along a direction parallel to the roll axis Al of the aircraft.

[0069] 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 one quarter of the length of this wing 20.

[0070] The slot 22 is configured to eject a flow 30 of air in the form of a blade.

[0071] In this example, the ejection of the flow 30 results from an opening command of a solenoid valve.

[0072] By way of non-limitation, the flow 30 is ejected in a direction forming in this example an angle X14 of 90° with respect to a plane passing through the extrados 16 of the wing 20.

[0073] As an indication, the ejection velocity 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.

[0074] Tests have demonstrated that such a device makes it possible to both reduce the drag of wing 20 and significantly improve its lift. In particular, by ejecting an airflow with a temperature of 15°C at a speed of 250 m / s, for an atmospheric airflow around wing 20 with a temperature of 15°C and a speed of 450 m / s, it is possible to obtain a reduction in the drag of wing 20 of nearly 100% and an increase in lift of nearly 35%.

[0075] On the one hand, the blowing element 21 makes it possible to separate the boundary layer of the airflow around the wing 20, contributing to optimizing the aerodynamic performance of the wing 20.

[0076] On the other hand, by equipping each of the wings 3 and 4 of an aircraft 1 such as that of [Fig.1] with such a blowing device 21, it is in particular possible to move the aircraft 1 in rotation around the roll axis Al.

[0077] For example, but not limited to, the blower 21 can be controlled to eject a flow 30 only through the slot 22 made on the upper surface 16 of the wing 3, causing the aircraft 1 to rotate in one direction about the roll axis Al. To cause the aircraft 1 to rotate in the other direction about the roll axis Al, the blower 21 can be controlled to eject a flow 30 only through the slot 22 made on the upper surface 16 of the wing 4.

[0078] In the embodiment of Figures 4 and 5, the blowing element differs from that of [Fig.3] in that it is configured to eject the flow 30 to the front of the leading edge 13 of the wing 20. This embodiment is described only according to its differences with respect to the embodiment of [Fig.3], the preceding description applying by analogy.

[0079] With reference to figures 4 and 5, the blowing member 40 comprises a T-shaped body which extends forward of the leading edge 13 of the wing 20.

[0080] More specifically, the body of the blowing organ 40 includes 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 upper surface 16 of the wing 20.

[0081] The body of the blowing element 40 also includes an arm 44 connecting the front part 41 of the body to the wing 20.

[0082] 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, with X21 and X22 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.

[0083] The embodiment of [Fig. 6] 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.

[0084] 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 ejecting an airflow with a temperature of 15°C at a speed of 250 m / s, for an atmospheric airflow around the wing 20 with 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 of approximately 32% and 59%, respectively, and an increase in lift of approximately 16% and 22%, respectively, for the embodiment shown in Figures 4 and 5 and for that of [Fig. 6].

[0085] The embodiments described above with reference to Figures 3 to 6 are not limiting, and numerous variations can be made within the scope of the invention. For example, in each of these embodiments, the blower can be controlled to eject a flow with a variable air flow rate and / or in different directions, whether to reduce drag and / or to modify the lift of one or more wings.

[0086] In each of the embodiments described above, the blowing element may have a different geometry and / or dimensions than those indicated above and / or occupy a different position relative to the wing to which it is connected. For example, the blowing element may be configured to eject a flow in the form of a straight or curved blade or sheet, single or multiple.

[0087] In alternative embodiments, not shown, the blowing device can be configured to eject a flow into a part of the flow zone delimited not by the extrados but by the intrados of a wing, or selectively on the one hand into a part of the flow zone delimited by the intrados and, on the other hand, into a part of the flow zone delimited by the extrados of this wing.

[0088] Thus, the blowing device can be configured to eject one or more flows onto the wings of an aircraft according to variable flow rates and / or directions, depending on the desired modifications of the aerodynamic forces exerted on the wings.

[0089] The invention can thus be implemented not only to reduce drag and / or to produce a roll action but also, alternatively or complementaryly, to produce or contribute to the production of a pitch action and / or a yaw action.

[0090] More generally, the various embodiments described above, as well as their variants, can be combined and implemented in aircraft other than that described above with reference to Figures 1 and 2. In particular, the invention can be implemented in an aircraft of a different size and / or mass category, for example, a mass of less than 50 kg or, conversely, 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 wing and / or fuselage and / or tail geometry, including a flying wing type architecture, in which case each of the ends of the flying wing constitutes a wing within the meaning of the invention.

Claims

Demands

1. Aircraft (1) with wings (3, 4, 20), characterized in that it comprises: • a tank capable of containing a fluid such as compressed air, • a blower (21, 40) configured to be able to direct a flow (30) of said fluid towards an airflow zone around one or more of said wings (3, 4, 20) in order to modify the drag and / or lift of said wing or wings (3, 4, 20), the blower (40) comprising a body extending forward of a leading edge (13) of one or more of said wings (3, 4, 20) in order to be able to eject said flow (30) upstream of said leading edge (13), relative to a direction (SI) of said airflow.

2. Aircraft (1) according to claim 1, wherein the blowing member (21, 40) is configured to direct said flow (30) in a blowing direction perpendicular (XI4) or oblique to a plane passing through an extrados (16) of at least one of the wings (3, 4, 20).

3. Aircraft (1) according to claim 1 or 2, wherein the blowing member (21, 40) is configured to be able to eject said flow (30) downstream of the leading edge (13) of one or more of said wings (3, 4, 20), relative to said direction (SI) of said airflow, and / or to be able to eject said flow (30) at one end (12) of one or more of said wings.

4. Aircraft (1) according to any one of claims 1 to 3, wherein the blowing element (21, 40) is configured to be able to direct said flow to: • a part of the flow area delimited by an upper surface (16) of at least one of the wings (3, 4, 20), and / or • a part of the flow area delimited by an lower surface (15) of at least one of the wings (3, 4, 20).

5. Aircraft (1) according to any one of claims 1 to 4, comprising a fuselage (2) receiving the tank.

6. Aircraft (1) according to any one of claims 1 to 5, configured to be remotely controlled and / or by autopilot without crew on board.

7. Method of 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 device (21, 40), so as to direct said flow (30) towards said flow zone around one or more of said wings (3, 4, 20).

8. A method according to claim 7, wherein the blowing is carried out so as to move the aircraft (1) in rotation about 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), • or by directing respective parts of said flow (30) towards the flow zone of each of said wings (3, 4) in different quantities and / or directions.

9. 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 airflow around one or more of said wings (3, 4).

10. A method according to any one of claims 7 to 9, wherein 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 airflow.

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