System for lift, propulsion and control of an aircraft

Abstract

A system for providing lift, propulsion, and control for an aircraft vehicle is described to facilitate vertical takeoff and landing / short takeoff and landing operations. The system is configured to provide a wing having a leading edge and a trailing edge, a crossflow fan partially embedded in the wing and mounted adjacent the trailing edge of the wing, and an outlet passage for the crossflow fan that provides a distributed flow along the trailing edge of the system to achieve high propulsion efficiency in forward flight and to achieve a substantially vertical jet for vertical takeoff and landing.

Description

Technical Field

[0001] This invention relates to systems and methods for lift, propulsion, and control of aircraft. More specifically, it relates to the control of system elements to achieve the desired lift, propulsion, and control of an aircraft during vertical, horizontal, and transitional flight operations. Background Technology

[0002] Current advancements in aircraft technology have facilitated more efficient propulsion systems. Furthermore, the introduction of stronger and lighter materials, additive manufacturing processes, computer control systems, and the further development of electric power sources and other alternative energy sources have enabled the development of vertical takeoff and landing (VTOL) / short takeoff and landing (STOL) vehicles not only for military purposes but also for commercial applications.

[0003] Today, most of these VTOL and STOL systems employ thrust vectoring mechanisms to provide vertical flight capability. This is achieved by designing the propulsion system in various ways. However, these propulsion systems typically require rotating or tilting the entire vehicle and / or engine and / or thrusters, necessitating complex structures and mechanisms.

[0004] Developed by Mortier in 1893, the crossflow fan (CFF), or tangential fan, is widely used in the heating, ventilation, and air conditioning (HVAC) industry. The fan is typically long relative to its diameter, so the airflow remains roughly two-dimensional (2D) along its length. The CFF uses an impeller with forward-curved blades housed in a casing consisting of a rear wall and vortex walls. Unlike radial machines, the mainstream travels laterally through the impeller, passing the blades twice.

[0005] Figure 1 The diagram illustrates a prior art system, showing a cross-sectional view of a common HVAC configuration. For an aircraft to fly effectively forward, the thruster must absorb and exhaust airflow at a small angle to the direction of forward flight. Conventional HVAC-type CFF housings, characterized by an approximately 90-degree turn from inlet to outlet, are not well-suited for this application.

[0006] The popularity of cross-flow fans (CFFs) stems from their ability to handle flow distortion and provide high pressure coefficients. Essentially rectangular fans, their diameters are easily scaled to fit available space, and their lengths are adjustable to meet the flow rate requirements of specific applications. Because the airflow enters and exits the impeller radially, cross-flow fans are well-suited for aircraft applications, particularly where a spanwise trailing-edge air jet is desired for distributed propulsion. Due to the 2D nature of the airflow, fans can be easily integrated into wings for both thrust generation and vectoring with boundary layer control.

[0007] In addition to improved propulsion efficiency, embedded propulsion also offers reduced noise and enhanced safety, as the thrusters are now embedded within the aircraft's structure (e.g., no exposed thrusters). Furthermore, by eliminating engine pylon / nacelle support structures, parasitic drag on the aircraft can be reduced by up to 18% to 20%, thus improving cruise efficiency and range.

[0008] Attempts to incorporate crossflow fans within aircraft wings have largely been unsuccessful. For example, some system designs use crossflow fans embedded within the middle of conventional aircraft wings. Other designs distribute fully embedded crossflow fans near the trailing edge of conventional transport aircraft, with shafts and connectors linking them to gas turbines mounted at the wingtips and roots. Air enters the fan through channels from both wing surfaces and exits at the trailing edge. However, these system designs limit fan size and channel capacity. Furthermore, CFFs may not be a viable option for high-speed applications due to compressibility effects (i.e., blockage). These configurations fail to achieve their intended performance due to poor fan placement and housing design. These shortcomings result in low fan performance, reduced cycle control, and low thrust.

[0009] Some attempts have also been made to modify the geometry of the CFF exit region to vectorize the exit flow at relatively small angles for applications such as high angle-of-attack flight and / or pitch control during forward flight in STOL flight. However, efficient VTOL flight using the same fan and exit channel has not been considered due to the difficulty in achieving aerodynamically efficient geometries for both applications.

[0010] In particular, in the prior art, Kummer and Dang et al. disclosed various modifications to the surfaces of flaps mounted at the rear of crossflow fans to aid in short takeoff and landing (STOL) and stall characteristics at high angles of attack. Specifically, U.S. Patent Publication No. 2012 / 0111994 (Kummer), published on May 10, 2012, discloses an inlet surface that rotates about its leading edge, and also discloses a lower flap surface that twists about its leading edge and a fan back that alters the clearance with the rotor.

[0011] Note that this can be applied to VTOL operations. However, this form of VTOL is generally considered unacceptable, where aircraft passengers must face the sky during takeoff and landing with the ground behind them only partially visible. Subsequently, U.S. Patent No. 9,783,291B2 (Kummer), published on October 10, 2017, disclosed adding an axial fan to an aircraft with a cross-flow fan to avoid this problem and provide further downward thrust for efficient VTOL operations, although this increases complexity and weight.

[0012] Therefore, many VTOL aircraft used for transporting personnel are arranged so that the fuselage remains roughly horizontal, and the thrust used for propulsion and VTOL is vectored, for example, by rotating the propulsion elements on the wings or rotors and motor pods. Another popular alternative is to provide separate rotors for vertical and horizontal flight (Aurora et al.). A further advantage of this design is that the thrust required for VTOL is many times greater than that required for horizontal flight, and this can significantly improve both propulsion and lift efficiency for forward flight. However, this increases the cost and complexity of the system.

[0013] Therefore, an improved and advanced propulsion system with a thrust vectoring mechanism is needed. Furthermore, a modularly designed propulsion system with a thrust vectoring mechanism is required to endow vehicles with VTOL / STOL capabilities with better efficiency and reduced complexity. Summary of the Invention

[0014] In an embodiment, the present invention provides a lift, propulsion, and control system for an aircraft vehicle to facilitate vertical takeoff and landing (VTOL) / short takeoff and landing (STOL) operations, the system comprising:

[0015] a. At least one wing extending from the leading edge to the trailing edge.

[0016] b. A rotor, which is a crossflow fan rotor at least partially embedded in the wing and substantially the same length as the wing and mounted adjacent to the trailing edge of the wing; and

[0017] c. An outlet channel for the crossflow fan, configured to provide a distributed flow along the trailing edge of the system to achieve high propulsion efficiency in forward flight and to provide a substantially vertical jet for vertical takeoff and landing.

[0018] The system is also provided with a flap that can rotate about the rotor axis, wherein the flap has an upper and a lower surface, and wherein the flap includes a flexible lip having an upper surface (16) that forms an outlet passage.

[0019] In one embodiment, the system may be provided with flaps that are connected to the wing and rotatable about the rotor axis, and the wing includes a flexible lip.

[0020] The system also includes an exit channel, which further includes:

[0021] a. Below the flap on one side; and above the flexible lip on the other side.

[0022] The outlet channel is also configured to combine with a predetermined fan speed of the crossflow fan and the positions of the flexible lip and flaps to eject the longitudinal air jet required to generate vertical lift. In the example, the predetermined speed could be an appropriate fan speed to generate the longitudinal air jet required for the aircraft's vertical lift.

[0023] In one embodiment, the system may also include several elements configured at multiple locations within the aircraft fuselage, including a thick wing, an embedded crossflow fan, and an exit channel. Furthermore, the exit channel generates a distributed flow along the trailing edge of the system for achieving high propulsion efficiency during forward flight, and the exit channel can be reconfigured to generate a substantially vertical jet for vertical takeoff and landing (VTOL).

[0024] In an embodiment, the present invention provides a lift, propulsion, and control element for an aircraft, which can be configured at multiple locations within the aircraft fuselage. The system further includes a wing extending from the leading edge to the trailing edge and a crossflow fan rotor, the crossflow fan rotor being at least partially embedded in the wing and substantially the same length as the wing and mounted adjacent to the trailing edge of the wing, and the fan's outlet passage having two surfaces, the two surfaces including…

[0025] i. The flap below, which is connected to the wing and can rotate about the rotor axis, also has an upper part, the inner edge of which controls the inlet flow area to the rotor.

[0026] ii. The upper part of the flexible lip moves in coordination with and substantially parallel to the lower part of the flap to guide airflow from the fan, thereby creating a substantially uniformly distributed thrust along the length of the element.

[0027] In one embodiment, the system provides an exit channel as described, wherein flaps and a flexible lip are mechanically connected and movable to generate thrust, which can be vectorized from a substantially horizontal direction to a substantially vertical direction.

[0028] In one embodiment, the flap and flexible lip are connected and moved through an angle such that thrust can be vectorized through an angle greater than 70 degrees.

[0029] In an embodiment, the invention provides an outlet channel as described, wherein flaps and flexible lips are connected such that each moves simultaneously but at different angular rates to transmit the desired variation in both the angle of the vector thrust and the mass flow.

[0030] In an embodiment, the present invention provides an exit channel as described, wherein the flaps and flexible lip are connected and actuated or moved through an angle such that thrust can be vectorized through an angle greater than 70 degrees.

[0031] In an embodiment, the present invention provides an exit channel as described, wherein changes in the actuation angles of the flaps and the lip produce changes in the magnitude and / or direction of thrust, which are used to control the attitude of the aircraft.

[0032] In an embodiment, the invention provides an outlet channel as described, wherein the upper inner edge of the flap is rotated accordingly to increase the inlet flow area to the rotor, such that when combined with an increased rotor speed, the increased mass flow can be obtained from the fan when the flap is rotated to a position that generates vertical thrust for VTOL operation.

[0033] In one embodiment, the present invention provides a wing with a distributed flow, an embedded crossflow fan, and an outlet channel element, the distributed flow having low parasitic drag during forward flight.

[0034] In an embodiment, the present invention provides an airfoil with distributed flow, an embedded crossflow fan, and an outlet channel element, wherein the airfoil has a thickness chord ratio greater than 30%, and any flow separation is limited by boundary layer inhalation in the crossflow fan.

[0035] In one embodiment, the present invention provides a wing, an embedded crossflow fan, and an outlet channel element, wherein the rotor speed of the crossflow fan is independent of any other fan on the aircraft, and the speed varies relative to other fans to help control the attitude and flight direction of the aircraft.

[0036] In an embodiment, the present invention provides a wing, an embedded crossflow fan, and an outlet channel element, wherein the rotor diameter of the crossflow fan is between 10% and 30% of the wing's chord, and more specifically in the range of 15% to 25%.

[0037] In an embodiment, the present invention provides a wing, an embedded crossflow fan, and an outlet channel element, wherein the upper surface radius of the wing is between 50% and 60%. In an example, this range can be configured to be 55% and 58% of the chord, and extends over one-third of the upper surface on a substantially flat lower surface, and over one-third of the lower surface and on the rear surface forming the rear wall of the embedded crossflow fan.

[0038] In one embodiment, the present invention provides a wing, an embedded crossflow fan, and an exit channel element that facilitates the reduction of parasitic drag during forward flight, which decreases with increasing angle of attack until it reaches a maximum value between 5 and 15 degrees. In another embodiment, the angle of attack can vary outside the range of 5 to 15 degrees.

[0039] In one embodiment, the invention provides a wing, an embedded crossflow fan, and an outlet channel element, wherein the crossflow fan draws in the boundary layer of the wing, thereby facilitating stall-free operation at angles of attack between 5 and 20 degrees. In another embodiment, the angle of attack can vary outside the range of 5 to 20 degrees.

[0040] In an embodiment, the present invention provides an airfoil, an embedded crossflow fan, and an outlet channel element, wherein the outlet channel can be configured to deflect the jet from the trailing edge of the element through an angle between 50 and 90 degrees with respect to the jet direction for optimal forward flight.

[0041] In the foregoing embodiments, the ranges of angle of attack, wing surface radius, exit channel elements, etc., can also be configured to vary outside the ranges defined herein. The above embodiments discuss exemplary implementations and are not limited thereto. Attached Figure Description

[0042] The accompanying drawings are provided to facilitate understanding of the invention. The drawings illustrate embodiments of the invention and are not intended to limit the scope of the invention. The drawings will now be described by way of example only, in which:

[0043] Figure 1 A crossflow fan of the prior art is shown.

[0044] Figure 2 This is a schematic diagram of a baseline inline housing according to an embodiment of the present invention.

[0045] Figure 3 The illustration shows the lift, propulsion, and control system, illustrating the exit channel geometry of the flaps and flexible lip when configured for forward flight.

[0046] Figure 4 This is a schematic diagram of the lift, propulsion, and control system, showing the exit channel geometry of the flaps and flexible lip when configured for VTOL operation.

[0047] Figure 5 A cross-section of the wing, embedded crossflow fan, and outlet channel geometry according to the invention is shown, illustrating the range of motion of the flaps and flexible lip.

[0048] Figure 6 This is an illustration showing the airflow around and through the wing and crossflow fan elements when the invention is configured for VTOL.

[0049] Figure 7 This is an illustration of the airflow surrounding and passing through the wing and cross-flow fan elements when the invention is configured for horizontal forward flight. Detailed Implementation

[0050] In the detailed embodiments, different alternatives will be discussed in more detail with reference to the accompanying drawings. However, it should be understood that the drawings are not intended to limit the scope of the invention to the subjects depicted in the drawings. The scope of the invention is defined in the appended claims.

[0051] In exemplary embodiments, various features and details are illustrated in combination. The fact that several features are described with reference to specific examples should not be construed as implying that those essential features must be included together in all embodiments of the invention. Rather, features described with reference to different embodiments should not be construed as mutually exclusive. As will be readily understood by those skilled in the art, the inventors have contemplated embodiments that combine any subset of the features described herein and are not explicitly interdependent, and such embodiments are part of the intended disclosure. However, a detailed description of all such embodiments would not aid in understanding the principles of the invention, and therefore some arrangements have been omitted for simplicity.

[0052] In the embodiments, some terms, such as "aircraft and aircraft," are used interchangeably throughout the description and are not intended to limit the scope of the invention.

[0053] Figure 1 A prior art crossflow fan is shown. The CFF has an inlet and outlet, a filling zone, a rear wall, and a vortex wall. The first and second stages are used to manage the flow through the CFF. As previously indicated, Figure 1 This diagram shows a cross-sectional view of a cross-flow fan's heating, ventilation, and air conditioning (HVAC) configuration. For an aircraft to fly effectively forward, the propeller must draw in and expel air at a small angle to the direction of forward flight. Conventional HVAC-type CFF housings, characterized by an approximately 90-degree turn from inlet to outlet, are not well-suited for this application.

[0054] Figure 2 This is a schematic diagram of a baseline inline housing according to an embodiment of the present invention. The crossflow fan (CFF) assembly 10 consists of a rotor 14, a rear wall 11, and a vortex wall 12. The achieved flow path is shown as indicated by reference numeral 16.

[0055] Figure 3 A diagram of the lift, propulsion, and control system is shown, illustrating the exit channel geometry of the flaps and flexible lip when configured for forward flight. Figure 3 As shown, see wing 20, flexible lip 24 attached to and forming part of wing 20, crossflow fan rotor 14, flap 26 rotatable about the axis of rotor 14 and mounted thereon, and outlet channel 15 originating from crossflow fan rotor 14 and formed by the lower part 17 of flap 26 and the upper part 16 of flexible lip 24. The positions of flexible lip 24 and flap 26 are as follows: Figure 3As shown. With the flexible lip 24 and flap 26 configured in this position and at an appropriate fan speed, a longitudinal air jet from channel 15 is ejected along the length of the lift, propulsion, and control system to achieve distributed propulsion and, desirably, gain the benefit of forward flight propulsion efficiency. Collaboratively, the edge 18 of the face 19 of flap 26 limits the inlet area to the crossflow fan, thereby providing the optimal flow velocity through the fan for achieving optimal propulsion efficiency.

[0056] Figure 4 This is a schematic diagram of the lift, propulsion, and control system, showing the exit channel geometry of the flaps and flexible lip when configured for VTOL operation. (The last sentence appears to be incomplete and possibly refers to a different topic.) Figure 4 In the VTOL configuration shown, with Figure 3 In contrast, the flexible lip 24 and flap 26 are moved to different positions. The diagram shows a wing 20, a flexible lip 24 attached to and forming part of the wing 20, a crossflow fan rotor 14, a flap 26 rotatable about the axis of the rotor 14 and mounted thereon, and an outlet passage 15 originating from the crossflow fan rotor 14 and formed by the lower part 17 of the flap 26 and the upper part 16 of the flexible lip 24. With the flexible lip 24 and flap 26 configured in this position, i.e., with the flexible lip and flap relative to... Figure 3 With rotation and at an appropriate fan speed, a longitudinal air jet from channel 15 is ejected from the length of the lift, propulsion, and control system to achieve a substantially vertical jet, thereby generating upward thrust or vertical lift for VTOL operation. Collaboratively, the edge 18 of surface 19 moves to generate a much larger inlet area to the crossflow fan, thus providing optimal flow velocity through the fan for vertical thrust.

[0057] Figure 5 A cross-section of the wing, embedded crossflow fan, and outlet channel geometry according to the invention is shown, illustrating the range of motion of the flaps and flexible lip. Now refer to Figure 5 The image shows a wing 20 with an upper surface radius 21 and an angle of attack 22 relative to the airflow direction 23, a crossflow fan assembly consisting of a rotor 14, a rear wall 11, and a vortex wall 12, a rear flexible lip 24 rotatable through an angle 25 and having an upper surface 16, a flap 26 rotating about a rotor axis 27 (rotatable through an angle 28 and having a lower surface 17), and an outlet passage 15 formed by the upper surface 16 of the flexible lip and the lower surface 17 of the flap. In an embodiment, angle 28 can be configured to be different from angle 25. In an embodiment, according to the invention, angle 22 is set in conjunction with the exit angle of the channel jet to achieve a maximum lift-to-drag ratio. Furthermore, the area ratio of the fan inlet area to the fan outlet area can be configured to be optimized by the movement of the flap 26 to achieve both high propulsion efficiency in the upper position and high vertical thrust in the lower position.

[0058] Furthermore, despite its relatively low fan efficiency, this invention is competitive with conventional propulsion technologies. The raised inlet formed by the flaps 26 eliminates the fan size limitations that would arise if the fan were fully embedded within the wing 20. Moreover, the crossflow fan performance is very insensitive to even large wake intakes, making it well-suited for this configuration. The fan of this invention can penetrate the boundary layer, regardless of its thickness.

[0059] refer to Figure 3 , Figure 4 and Figure 5 The thick wing 20 seen in the diagram can produce a considerable wake even at small angles of attack 22, resulting in significant pressure drag. This makes a very thick wing section impractical for most aircraft applications, as the drag loss outweighs any gains in lift or internal volume. Even at small angles of attack, airflow separation occurs without the suction effect of the rear-mounted cross-flow fan rotor 14. The embedded cross-flow fan near the trailing edge eliminates this separation by drawing airflow back towards the surface and into the fan duct, resulting in a very high lift coefficient. This, in turn, leads to low in-flight aircraft stall speeds without the need for additional high-lift devices such as slotted flaps and leading-edge slats, but more importantly, it benefits small, short, high-lift wings that can be easily configured as lift elements for compact aircraft as described herein.

[0060] During forward flight, the distributed propulsion generated by the spanwise air jet from channel 15 produces a phenomenon known as distributed propulsion, which can be used to generate very high propulsive efficiency during forward flight. This, along with the lower drag resulting from the absence of engine nacelles, pylons, and interference drag, offsets any low fan efficiency.

[0061] By using coordinated control of flaps 26 and flexible lip 24 to vectorize thrust, thereby opening the inlet to the crossflow fan and increasing the fan speed, it is possible to achieve additional lift for VTOL. This configuration in Figure 4 , Figure 5 and Figure 7 The diagram shows the broad range of permissions for the flexible lip and flaps.

[0062] In this embodiment, the more ideal lift, propulsion, and control elements of the VTOL aircraft with a crossflow fan are determined to vectorize the airflow from a substantially horizontal to a substantially vertical direction, but will also provide an effective increase in thrust during VTOL, since the thrust required for VTOL operation is significantly greater than the thrust required for forward propulsion. This additional thrust can be achieved by increasing the rotor speed, but this reduces lift efficiency or power load. To offset this efficiency loss, the fan area is increased.

[0063] Figure 3 and Figure 4 The embodiment described implements a system in which flaps rotate about the rotor axis such that the ratio of the fan's inlet and outlet areas changes in coordination with the redirection of the air jet in the outlet passage. In a first position, a curved or deformed lip coordinates with the flaps to provide both the desired outlet flow vector and the desired area ratio across the fan for forward flight propulsion efficiency. The flaps and lip, then moved to a second position, provide sufficient variation in the area ratio across the fan and redirection of the outlet flow vector to provide effective VTOL operation. Effective VTOL operation allows wing elements and attached fuselage, as well as passengers, to remain substantially level during takeoff, landing, and transition to cruise flight.

[0064] Figure 6 This is an illustration showing the airflow around and through the wing and crossflow fan elements when the present invention is configured for VTOL. The positional changes of the flaps and flexible lip can be observed to achieve the desired VTOL.

[0065] Figure 7 This is an illustration of the airflow surrounding and passing through the wing and crossflow fan elements when the invention is configured for horizontal forward flight. Figure 7 It was observed that, in order to achieve the required thrust for horizontal forward flight, the positional changes of the flaps and flexible lip were similar to those observed previously. Figure 6 different.

[0066] The system of the present invention enables two configurations with flaps and flexible lips that vary in position, thereby altering the air passage and facilitating the propulsion required for both forward flight motion and vertical takeoff and landing of the aircraft.

Claims

1. A system for providing lift, propulsion, and control for vertical takeoff and landing / short takeoff and landing operations of an aircraft vehicle, the system comprising: a. At least one wing extending from the leading edge to the trailing edge (20); b. The rotor (14) of the crossflow fan is at least partially embedded in the wing (20) and has a length substantially the same as the wing and is mounted adjacent to the trailing edge of the wing; as well as c. The outlet channel (15) for the crossflow fan is configured to provide a distributed flow along the trailing edge of the system. The system also includes: d. A flap (26) arranged to rotate about the rotor axis (27) of the crossflow fan, wherein the flap has an upper (9) and a lower (17) and wherein the wing (20) includes a flexible lip (24) having an upper (16) forming the outlet channel (15), wherein the flap (26) and the flexible lip (24) of the outlet channel (15) are configured to generate thrust and vectorize the thrust, wherein the flap (26) and the flexible lip (24) of the outlet channel (15) are also configured to move simultaneously but at different angular rates to transmit the desired variation in both the angle and mass flow of the vectorized thrust.

2. The system according to claim 1, wherein the outlet channel (15) comprises: b. Below (17) of the flap (26) on one side; and c. Above (16) the flexible lip (24) on the other side.

3. The system of claim 1, wherein the outlet channel (15) is further configured to combine with a predetermined fan speed of the crossflow fan (14) and the positions of the flexible lip (24) and the flap (26) to eject a longitudinal air jet required to generate vertical lift.

4. The system of claim 1, wherein the lower part (17) of the flap (26) is configured to move cooperatively with and substantially parallel to the upper part (16) of the flexible lip.

5. The system of claim 1, wherein the flap (26) and the flexible lip (24) of the outlet channel (15) are mechanically connected and configured to generate thrust, capable of vectorizing the thrust from a substantially horizontal direction to a substantially vertical direction.

6. The system of claim 1, wherein the flap (26) and the flexible lip (24) are configured to move through an angle to obtain thrust, and the thrust can be vectorized through an angle to produce a change in both the magnitude and direction of the thrust.

7. The system of claim 1, wherein the flap (26) and the flexible lip (24) are connected and moved through an angle greater than 70 degrees, such that thrust can be vectorized through the angle.

8. The system of claim 1, wherein the wing (20) has a thickness chord ratio greater than 30%, and flow separation is limited by boundary layer inhalation into the crossflow fan.

9. The system of claim 1, wherein the wing (20) is curved, the upper surface radius of the wing is between 50% and 60% of the chord, and wherein the curved portion extends on at least one-third of the upper surface, on a substantially flat lower surface, and on at least one-third of the lower surface and on the rear surface forming the rear wall of the embedded crossflow fan.

10. The system according to claim 1, wherein the rotor diameter of the crossflow fan (14) is configured between 10% and 30% of the chord of the wing (20).

11. The system of claim 1, wherein the system is configured to also provide a distributed flow along the crossflow fan, the crossflow fan having low parasitic drag in forward flight and drag decreasing with increasing angle of attack (22) until the angle of attack (22) reaches a maximum value between 5 degrees and 15 degrees.

12. The system of claim 1, wherein the crossflow fan (14) is configured to draw in the boundary layer of the wing to facilitate stall-free operation at angles of attack (22) between 5 and 20 degrees.

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