Blade pitch linked to propulsion system tilt

Abstract

An embodiment provides a mechanism for coupling rotor blade pitch to a propulsion system tilt angle in an aircraft, more particularly in an electric aircraft. The system can include a tiltable propulsion system configured to move between a first tilt angle and a second tilt angle, the tiltable propulsion system including a plurality of rotor blades each configured to move between a first pitch position and a second pitch position, a tilt mechanism coupled to the tiltable propulsion system and configured to move the tiltable propulsion system between the first tilt angle and the second tilt angle, a pitch mechanism coupled to one or more of the plurality of rotor blades and configured to move the one or more of the plurality of rotor blades between the first pitch position and the second pitch position, and an actuator configured to simultaneously actuate both the tilt mechanism and the pitch mechanism.

Description

[Technical Field]

[0001] Cross-reference to other applications This application claims the benefit under 35 U.S.C. §119(e) of U.S. Provisional Patent Application No. 63 / 440,054, entitled "Blade Pitch Linked to Tilt," filed January 19, 2023, the entire disclosure of which is incorporated herein by reference for all purposes.

[0002] The described embodiments relate generally to aircraft with vertical takeoff and landing capabilities. In particular, the embodiments provide an electric aircraft with one or more tiling propulsion systems. [Background technology]

[0003] Aircraft with tiltable propulsion systems typically include a tilting mechanism for tilting the propulsion system between different tilt angles. Some aircraft may include additional mechanisms dedicated to changing the pitch of the rotor blades connected to the tiltable propulsion system. While these mechanisms provide useful functionality, each utilized mechanism adds extra actuators and control functions, thereby increasing the components, weight, and complexity of the aircraft.

[0004] The embodiments address these and other issues individually and collectively. Summary of the Invention

[0005] The techniques disclosed herein generally relate to aircraft including tiltable propulsion systems. More specifically, the techniques disclosed herein provide a mechanism for linking the pitch position of the rotor blades of a propulsion system to the tilt angle of the propulsion system. According to various embodiments, an electric aircraft may include an electric vertical take-off and landing (VTOL) aircraft having multiple propulsion systems. One or more of the propulsion systems may be tiltable to provide thrust in various directions, such as horizontally for forward flight and vertically for vertical flight. Some embodiments provide a mechanism for automatically changing the pitch of the rotor blades in response to changes in the tilt angle of the propulsion system. The pitch position and tilt angle may be linked in any suitable manner, and in some embodiments, a single actuator may be used to control both pitch and tilt. Various embodiments of the present invention, including methods, processes, systems, devices, and the like, are described herein.

[0006] An embodiment provides a system including a tiltable propulsion system configured to move between a first tilt angle and a second tilt angle, the tiltable propulsion system including: a plurality of rotor blades each configured to move between a first pitch position and a second pitch position; a tilt mechanism coupled to the tiltable propulsion system and configured to move the tiltable propulsion system between the first tilt angle and the second tilt angle; a pitch mechanism coupled to one or more of the plurality of rotor blades and configured to move the one or more of the plurality of rotor blades between the first pitch position and the second pitch position; and an actuator configured to simultaneously actuate both the tilt mechanism and the pitch mechanism.

[0007] According to a further embodiment, the system further includes a linkage between the pitch mechanism and the tilt mechanism such that movement of the tiltable propulsion system by the tilt mechanism causes corresponding movement of one or more of the plurality of rotor blades by the pitch mechanism.

[0008] According to a further embodiment, the coupling between the pitch mechanism and the tilt mechanism is configured such that each tilt angle of the tiltable propulsion system results in a pitch position for one or more of the plurality of rotor blades.

[0009] According to a further embodiment, a first tilt angle results in a first pitch position and a second tilt angle results in a second pitch position.

[0010] According to a further embodiment, the pitching mechanism moves one or more of the plurality of rotor blades between a first pitch position and a second pitch position when the tilting mechanism moves the tiltable propulsion system between the first and second tilt angles.

[0011] According to a further embodiment, the coupling between the pitch mechanism and the tilt mechanism is configured to provide a non-linear relationship between the tilt angle of the tiltable propulsion system and the pitch position of one or more of the plurality of rotor blades.

[0012] According to a further embodiment, when the tiltable propulsion system is set at a first tilt angle, the nonlinear relationship causes a relatively small change in the pitch position of one or more of the plurality of rotor blades in response to changes in the tilt angle, and when the tiltable propulsion system is set at a second tilt angle, the nonlinear relationship causes a relatively large change in the pitch position of one or more of the plurality of rotor blades in response to changes in the tilt angle.

[0013] According to a further embodiment, the system further includes a coupling mechanism configured to provide a coupling between the pitching mechanism and the tilting mechanism, the coupling mechanism configured to convert a tilting motion caused by the tilting mechanism into a linear motion in the pitching mechanism, and the pitching mechanism configured to convert the linear motion in one or more of the plurality of rotor blades into a rotational motion.

[0014] According to a further embodiment, the system further includes a support structure, the tiltable propulsion system is coupled to the support structure, and the linkage is connected to the support structure and the tiltable propulsion system.

[0015] According to a further embodiment, the linkage mechanism is not directly connected to the tilting mechanism.

[0016] According to a further embodiment, the linkage mechanism includes a first pivot point offset from a second pivot point of the tilting mechanism.

[0017] According to a further embodiment, the linkage mechanism includes a four-bar crank slider and the pitching mechanism includes a slider connected to the four-bar crank slider.

[0018] According to a further embodiment, the actuator is a component of the tilt mechanism and the pitch mechanism is coupled to the tilt mechanism.

[0019] According to a further embodiment, the pitching mechanism does not include a separate dedicated actuator.

[0020] According to a further embodiment, the first tilt angle corresponds to a vertical flight configuration and the second tilt angle corresponds to a forward flight configuration.

[0021] According to a further embodiment, the system further includes an aircraft including a fuselage, a pair of wings coupled to opposite sides of the fuselage, and a tiltable propulsion system, the tiltable propulsion system coupled to a first wing of the pair of wings.

[0022] According to a further embodiment, the system further includes a control system configured to control the tilt mechanism and the pitch mechanism via the actuators, and configured to: actuate the tilt mechanism to gradually move the tiltable propulsion system from a first tilt angle through a set of intermediate tilt angles to a third tilt angle; actuate the tilt mechanism to suspend movement of the tiltable propulsion system upon reaching the third tilt angle; and actuate the tilt mechanism to move the tiltable propulsion system from the third tilt angle to the second tilt angle after the aircraft reaches a predetermined speed or a predetermined altitude.

[0023] According to a further embodiment, the first tilt angle corresponds to a vertical flight configuration, the second tilt angle corresponds to a forward flight configuration, and the third tilt angle is within 10 degrees of the second tilt angle.

[0024] According to a further embodiment, the system further includes a linkage between the pitching mechanism and the tilting mechanism configured such that each tilt angle of the tiltable propulsion system results in a corresponding pitch position for one or more of the plurality of rotor blades, wherein a first tilt angle results in a first pitch position, a second tilt angle results in a second pitch position, and a third tilt angle results in a third pitch position, the third pitch position being at least 3 degrees less than the second pitch position.

[0025] According to a further embodiment, the first pitch position corresponds to an acceleration pitch and the second pitch position corresponds to an efficiency pitch.

[0026] Further details regarding embodiments of the invention are provided in the detailed description and drawings.

[0027] Various embodiments of the present invention are disclosed in the following detailed description and the accompanying drawings, in which similar components or features may have the same reference label. Furthermore, various components of the same or similar type may be distinguished by following the reference label with a dash and a second label that distinguishes between the similar components. [Brief explanation of the drawings]

[0028] [Figure 1A] FIG. 1 is a plan view of an exemplary aircraft having a tilting fan in a forward configuration, according to an embodiment. [Figure 1B] FIG. 1 is a plan view illustrating an exemplary aircraft having a tilting fan in a vertical configuration, according to an embodiment. [Figure 2A] FIG. 1 is a diagram of an example of a propulsion system having a pitching mechanism coupled to a tilting mechanism, according to an embodiment. [Figure 2B]FIG. 1 is a diagram of an example of a propulsion system having a pitching mechanism coupled to a tilting mechanism, according to an embodiment. [Figure 3A] 1 is an illustration of two different rotor blade pitch positions, according to various embodiments. [Figure 3B] 1 is an illustration of two different rotor blade pitch positions, according to various embodiments. [Figure 4A] 10A-10C are diagrams illustrating an example of the motion of a pitching mechanism, according to various embodiments. [Figure 4B] 10A-10C are diagrams illustrating an example of the motion of a pitching mechanism, according to various embodiments. [Figure 4C] 10A-10C are diagrams illustrating an example of the motion of a pitching mechanism, according to various embodiments. [Figure 4D] 10A-10C are diagrams illustrating an example of the motion of a pitching mechanism, according to various embodiments. [Figure 5A] 10A-10C are diagrams illustrating an example of the movement of a linkage mechanism, according to various embodiments. [Figure 5B] 10A-10C are diagrams illustrating an example of the movement of a linkage mechanism, according to various embodiments. [Figure 5C] 10A-10C are diagrams illustrating an example of the movement of a linkage mechanism, according to various embodiments. [Figure 5D] 10A-10C are diagrams illustrating an example of the movement of a linkage mechanism, according to various embodiments. [Figure 6] 10 is a chart illustrating an example of a non-linear relationship between tilt angle and pitch position, according to an embodiment. [Figure 7A] FIG. 10 is a diagram of an example of an offset pivot mechanism, according to an embodiment. [Figure 7B] FIG. 10 is a diagram of an example of an offset pivot mechanism, according to an embodiment. [Figure 7C] FIG. 10 is a diagram of an example of an offset pivot mechanism, according to an embodiment. [Figure 8A] 1 illustrates an example of a linkage mechanism in the form of an exemplary four-bar crank-slider mechanism, according to various embodiments. [Figure 8B] 1 illustrates an example of a linkage mechanism in the form of an exemplary four-bar crank-slider mechanism, according to various embodiments. [Figure 9A]10A-10C illustrate various embodiments of a roller cam mechanism on a centerline. [Figure 9B] 10A-10C illustrate various embodiments of a roller cam mechanism on a centerline. [Figure 9C] 10A-10C illustrate various embodiments of a roller cam mechanism on a centerline. [Figure 9D] 10A-10C illustrate various embodiments of a roller cam mechanism on a centerline. DETAILED DESCRIPTION OF THE INVENTION

[0029] The techniques disclosed herein generally relate to aircraft including tiltable propulsion systems. More specifically, the techniques disclosed herein provide mechanisms for linking the pitch position of the rotor blades of a propulsion system to the tilt angle of the propulsion system. According to various embodiments, an electric aircraft may include an electric vertical take-off and landing (VTOL) aircraft having multiple propulsion systems. One or more of the propulsion systems may be tiltable to provide thrust in various directions, such as horizontally for forward flight and vertically for vertical flight. Some embodiments provide mechanisms for automatically changing the pitch of the rotor blades in response to changes in the tilt angle of the propulsion system. The pitch position and tilt angle may be linked in any suitable manner, and in some embodiments, a single actuator may be used to control both pitch and tilt. Various embodiments of the present invention, including methods, processes, systems, devices, and the like, are described herein.

[0030] Some illustrative embodiments will now be described with reference to the accompanying drawings, which form a part of this specification. The following description provides examples only and is not intended to limit the scope, applicability, or configuration of the present disclosure. Instead, the following description of the embodiments will provide one of ordinary skill in the art with a possible description for implementing one or more embodiments. It should be understood that various changes may be made in the function and arrangement of elements without departing from the spirit and scope of the present disclosure. In the following description, for purposes of explanation, specific details are set forth in order to provide a thorough understanding of particular inventive embodiments. However, it will be apparent that various embodiments may be practiced without these specific details. The drawings and descriptions are not intended to be limiting. In this specification, the words "example" or "exemplary" are used to mean "serving as an example, instance, or illustration." Any embodiment or design described herein as "exemplary" or "illustrative" is not necessarily to be construed as preferred or advantageous over other embodiments or designs.

[0031] 1A and 1B depict a plan view of an exemplary aircraft 100, according to an embodiment. Aircraft 100 may be any suitable type of air vehicle, such as an airplane, a helicopter, a drone, or a hybrid type air vehicle. In some embodiments, aircraft 100 may be capable of vertical take-off and landing (VTOL). Aircraft 100 may be configured for human piloted, remotely piloted, and / or autonomous flight.

[0032] In the illustrated example, the aircraft 100 includes a fuselage 104 that may include a cabin portion (e.g., nose-facing) for carrying passengers and / or cargo. A pair of wings, including a first wing 102 and a second wing 103, may be mounted to the fuselage 104 or may be otherwise attached. The pair of wings may be coupled to opposite sides of the fuselage and may have any suitable shape and configuration. For example, the pair of wings may be rectangular straight wings, tapered straight wings, rounded or elliptical straight wings, swept wings, delta wings, or any other suitable type of wing. In some embodiments, the first wing 102 and the second wing 103 may be coupled to the fuselage 104 in a high-wing configuration. That is, as shown in FIGS. 1A-1B , the first wing 102 and the second wing 103 may be mounted on top of the fuselage 104.

[0033] The aircraft 100 may also include support structures 106(A)-(F), which may be coupled to the wings 102, 103. As shown in FIGS. 1A-1B, each of the support structures 106(A)-(F) may take the form of a boom, although embodiments include any other suitable structures. Six support structures 106(A)-(F) are shown in FIGS. 1A-1B, with three support structures 106(A)-(F) provided below each of the pair of wings 102, 103. The support structures 106(A)-(F) may be coupled to the underside of the pair of wings and may include a forward portion extending forward of the wings and an aft portion extending aft of the wings.

[0034] In some embodiments, each of the support structures 106(A)-(F) is identical, and thus the support structures 106(A)-(F) may be interchangeable between positions on the wing. For example, a first support structure 106(A) closer to the fuselage may be interchangeable with an adjacent second support structure 106(B) (e.g., a central boom on the wing) or with an additional third support structure 106(C) (e.g., a boom furthest from the fuselage).

[0035] propulsion system The aircraft 100 may also include propulsion systems 101(A)-(L). While twelve propulsion systems 101(A)-(L) are shown in FIGS. 1A-1B, any suitable number of propulsion systems 101(A)-(L) may be included. The propulsion systems 101(A)-(L) may be coupled to a pair of wings 102, 103 or may be evenly divided between the wings. In some embodiments, as shown in FIGS. 1A-1B, one or more of the propulsion systems 101(A)-(L) may be mounted on a support structure 106(A)-(F). For example, a pair of propulsion systems 101(A)-(L) may be mounted at opposite ends of each support structure 106(A)-(F), with one propulsion system mounted forward of the wing and the other propulsion system mounted aft of the wing. In other embodiments, one or more of the propulsion systems 101(A)-(L) may be directly coupled to the wing. The number of booms and / or propulsion systems may vary depending on the flight needs and requirements of the aircraft 100.

[0036] In various embodiments, each of the propulsion systems 101(A)-(L) may be configured to provide thrust to the aircraft 100. The thrust from one or more of the propulsion systems 101(A)-(L) may be used to move, control, and / or stabilize the aircraft 100. The propulsion systems 101(A)-(L) may take the form of any suitable mechanism for providing thrust. In one example, the propulsion systems may include rotors (e.g., fans). The propulsion systems may also include drive mechanisms for the rotors, such as dedicated electric motors (e.g., in the case of electric vehicles).

[0037] The rotor may include any suitable number of rotor blades (e.g., 2, 3, 4, 5, 6, 7, or 8 blades). The rotor blades may have a predetermined pitch or a predetermined angle of attack. In some embodiments, all of the rotor blades may have the same pitch or angle of attack. In other embodiments, at least two of the rotor blades may have a different pitch or angle of attack from one another. The rotor blades may be evenly spaced or unevenly spaced. The rotor may further include a hub. The rotor blades may be attached to the hub. In some embodiments, the rotor blades and the integral hub may be manufactured as a single piece. The hub provides a central structure to which the rotor blades connect and, in some embodiments, is shaped to encase the motor.

[0038] In some embodiments, the motor components are low profile so that the entire motor fits within the rotor hub, providing low resistance to airflow during forward flight. The rotor can be attached to the rotating components of the motor. The stationary components of the motor can be attached to a support structure. In some embodiments, the motor can be a permanent magnet motor and can be controlled by an electronic motor controller. The electronic motor controller can send current to the motor in a precise sequence to enable the rotor to rotate at a desired speed or with a desired torque.

[0039] Propulsion system orientation - vertical According to various embodiments, one or more of the propulsion systems 101(A)-(L) may be positioned, oriented, and / or otherwise configured to provide thrust and / or motion to the aircraft 100 in a predefined direction. For example, one or more of the propulsion systems 101(A)-(L) may be configured to provide vertically upward thrust. As shown in FIG. 1A , these may include propulsion systems 101(D), 101(E), 101(F), 101(J), 101(K), and / or 101(L). Propulsion systems configured to provide thrust in a vertical direction may also be referred to as vertical fans or lift fans, or as propulsion systems with a lift orientation or a hover orientation. The vertical fans may be used to generate vertical thrust (e.g., lift) for takeoff, landing, hovering, stabilization, and / or control of the aircraft 100.

[0040] The vertical direction may be defined relative to the body of the aircraft 100. For example, the vertical direction may be the aircraft's vertical axis or z-axis (e.g., the plumb line that intersects the zenith and is perpendicular to the ground when the aircraft 100 is stationary on the ground or hovering directly above the ground). In some examples, the vertical direction may be perpendicular to the ground when the aircraft 100 is stationary on the ground and / or in a stable hover directly above the ground in a flat orientation. When the aircraft 100 is tilted, the aircraft's z-axis (and vertical direction) may no longer be perpendicular to the ground. Vertical thrust may be thrust in a vertical direction (e.g., up or down).

[0041] Vertical thrust can be achieved by mounting the vertical fans and / or their corresponding support structures 106(A)-(F) such that the vertical fans' respective axes of rotation are parallel to the vertical direction and / or perpendicular to the direction of forward flight. In other words, the vertical fans can be oriented such that their rotor blades rotate in a horizontal plane (e.g., a plane parallel to the fuselage or a plane defined by the x- and y-axes of the aircraft 100) and about a vertical axis (e.g., the z-axis of the aircraft 100). In some embodiments, the vertical fans can be configured such that each set of rotor blades rotates in the same plane. In other embodiments, the vertical fans can be configured such that one or more of the sets of rotor blades rotate in different planes (e.g., parallel planes).

[0042] In other embodiments, some or all of the vertical fans, at individual levels, are oriented at an angle such that one or more vertical fans have rotor blades that do not rotate in a horizontal plane and instead provide thrust in a direction angled relative to the vertical. However, in combination, a set of angled vertical fans can together provide a net thrust in the vertical direction. For example, a non-vertical thrust component provided by an angled vertical fan on a first wing 102 can be countered by an equal and opposite non-vertical thrust component provided by an oppositely angled vertical fan on a second wing 103.

[0043] In some embodiments, two adjacent vertical fans may have their rotor blades mounted at opposite angles of attack such that their rotor blades spin in opposite directions. Adjacent vertical fans may refer to two vertical fans coupled to opposite ends of the same support structure 106(A) (e.g., 101A and 101D), or two vertical fans on different support structures (e.g., 101A and 101B), or two vertical fans on different wings (e.g., 101A and 101G).

[0044] According to various embodiments, a first subset of the vertical fans may spin in a first direction, and a second subset of the vertical fans (e.g., the remaining vertical fans) may spin in a second direction opposite the first direction. Configuring the vertical fans so that some spin in a first direction and others spin in an opposite second direction can advantageously cancel any angular momentum created by the spinning blades, thereby allowing the air vehicle 100 to hover in a stable manner without rolling.

[0045] Furthermore, rotational movement (e.g., yaw) of the aircraft 100 about a vertical axis can be achieved when desired by temporarily decreasing the spin rotational speed of some or all of a first subset of the vertical fans spinning in a first direction and / or temporarily increasing the spin rotational speed of a second subset of the vertical fans spinning in a second direction such that the total angular momentum created by the spinning blades does not cancel. Thus, the aircraft 100 can rotate using the vertical fans without requiring a thrust source in another direction.

[0046] Propulsion system orientation - horizontal According to various embodiments, one or more of the propulsion systems 101(A)-(L) may be configured to provide horizontal, forward thrust. As shown in FIG. 1A, these may include propulsion systems 101(A), 101(B), 101(C), 101(G), 101(H), and / or 101(I). Propulsion systems configured to provide thrust in a horizontal direction may also be referred to as horizontal fans or propellers, or as propulsion systems oriented for forward flight. A horizontal fan may be used to provide horizontal thrust for forward flight, climb, descent, and / or cruise. As shown in FIGS. 1A-1B, two propulsion systems of the same type (e.g., two vertical fans) or different types (e.g., one vertical fan and one horizontal fan) may be installed on each of the support structures 106(A)-(F).

[0047] The horizontal direction may be defined relative to the body of the aircraft 100. For example, the horizontal direction may be the forward axis or x-axis of the aircraft. In some embodiments, the horizontal direction may be parallel to the ground when the aircraft 100 is stationary on the ground, in a stable hover just above the ground in a flat orientation, and / or in forward flight. When the aircraft 100 is banked, the aircraft's x-axis (and horizontal direction) may no longer be parallel to the ground. Horizontal thrust may be thrust in a horizontal direction (e.g., forward or aft).

[0048] Horizontal thrust (e.g., forward thrust) can be achieved by mounting the horizontal fans and / or their corresponding support structures 106(A)-(F) such that the horizontal fans' respective axes of rotation are parallel to the horizontal direction and / or parallel to the direction of forward flight. In other words, the horizontal fans can be oriented such that their rotor blades rotate in a vertical plane (e.g., a plane defined by the z-axis and y-axis of the aircraft 100) and about a forward axis (e.g., the x-axis of the aircraft 100). In some embodiments, the horizontal fans can be configured such that each set of rotor blades rotates in the same plane. In other embodiments, the horizontal fans can be configured such that one or more of the sets of rotor blades rotate in different parallel planes.

[0049] In some embodiments, the horizontal fan may be configured with the ability to spin in either direction. As a result, the horizontal fan can provide reverse thrust. Reverse thrust may be useful for moving the aircraft 100 in a rearward direction (e.g., backing out of a hangar area from a hover position). In addition, reverse thrust may be used to reduce forward flight speed. For example, reverse thrust from the horizontal fan may be used instead of or in addition to flaps to slow the aircraft 100 and / or to bring the aircraft 100 into a stationary hover.

[0050] In some embodiments, the horizontal and vertical directions may be orthogonal to one another. Thus, the vertical and horizontal fans may provide thrust in substantially orthogonal directions. In other embodiments, the vertical and horizontal fans may provide thrust that is approximately orthogonal or close to orthogonal, but not exactly orthogonal. Separating the directional thrust into two distinct types of components is beneficial for simplifying the control and design of the aircraft 100. In some embodiments, the horizontal and vertical fans may be actuated, powered, and otherwise controlled independently of one another, thereby allowing thrust to be applied independently in orthogonal directions (e.g., thrust may be applied in different directions simultaneously and at different times).

[0051] The combination of the horizontal fan and the wings 102, 103 can achieve both forward motion and lift. In some embodiments, it may be more efficient to utilize the horizontal fan and the wings 102, 103 instead of the vertical fan to achieve vertical lift. Once the aircraft 100 reaches a sufficient speed (e.g., a predetermined amount of speed or cruising speed) such that the wings provide sufficient lift to the aircraft 100, the vertical fan is no longer needed to provide lift and may temporarily cease operation. For example, the vertical fan may initially be active and generate vertical thrust to lift the aircraft 100. Once the aircraft 100 leaves the ground and / or reaches a certain height, the horizontal fan may activate and / or increase horizontal thrust so that the aircraft 100 gains horizontal speed. Because the wings 102, 103 cannot provide sufficient vertical lift until a predetermined speed (e.g., cruising speed) is achieved, the vertical fan may continue to provide vertical lift while the horizontal speed increases. The vertical fans may eventually (or gradually) reduce their vertical thrust contribution as the wings 102, 103 gradually provide more (e.g., increasing amounts) of vertical lift during the increase in horizontal speed, and then the vertical fans may reactivate and / or increase vertical thrust as the aircraft 100 slows or returns to a hover position.

[0052] Propulsion system orientation - fixed According to various embodiments, one or more of the propulsion systems 101(A)-(L) may have a fixed orientation. For example, one or more of the propulsion systems 101(A)-(L) may be installed with a fixed orientation relative to the respective wing 102 or 103, the respective support structure 106(A)-(F), and / or the aircraft 100. While the rotor blades of a fixed propulsion system may rotate when activated, the orientation of the propulsion system housing and structure may not be rotatable with respect to the aircraft 100. As a result, a fixed propulsion system may be configured to provide thrust in a constant direction relative to the aircraft 100. The thrust direction and orientation of a propulsion system that is fixed relative to the aircraft 100 (e.g., the fuselage, the wings, and / or the support structure) may remain constant or immovable, according to embodiments, regardless of the current aircraft 100 activity and / or direction of movement (e.g., both forward and vertical flight).

[0053] In some embodiments, one or more vertical fans may have a fixed orientation. For example, one or more of propulsion systems 101(D), 101(E), 101(F), 101(J), 101(K), and / or 101(L) may have a fixed vertical orientation. These may also be referred to as fixed vertical fans.

[0054] Additionally, according to some embodiments, one or more of the horizontal fans may have a fixed orientation. For example, propulsion systems 101(A), 101(B), 101(C), 101(G), 101(H), and / or 101(I) may have a fixed horizontal orientation. These may also be referred to as fixed horizontal fans.

[0055] In some embodiments, all of the propulsion systems 101(A)-(L) may have a fixed orientation, such that the vertical and horizontal fans may be permanently configured to provide thrust in orthogonal (or substantially orthogonal) directions.

[0056] Propulsion system orientation - tiltable In other embodiments, one or more of the propulsion systems 101(A)-(L) may be configured to change direction. For example, one or more of the propulsion systems 101(A)-(L) may be configured and / or installed in such a manner that the angle and orientation is tiltable relative to the respective wing 102 or 103, the respective support structure 106(A)-(F), and / or the aircraft 100. As a result, a tilting propulsion system, which may also be referred to as a tiltable propulsion system or tilting fan, may be configured to provide thrust to the aircraft 100 in multiple directions.

[0057] The tilting fans may be coupled to the respective support structures 106(A)-(F) via one or more tilting mechanisms, including, for example, a motor and linkage. The tilting mechanisms may include one or more components coupled to the tilting fans and the respective support structures 106(A)-(F), thereby enabling changes in the relative position and angle between the tilting fans and the respective support structures 106(A)-(F). The tilting mechanisms may be controllable and / or configured to change or move the orientation and thrust direction of the tilting fans relative to the aircraft 100 (e.g., fuselage, wings, and / or support structures) based on the current aircraft 100 activity, need, and / or direction of movement (e.g., forward flight, vertical flight), according to some embodiments. The entire tilting fan assembly, including the spinner and set of rotor blades, may all tilt together.

[0058] As described above, propulsion systems 101(A), 101(B), 101(C), 101(G), 101(H), and / or 101(I) may take the form of fixed horizontal fans. However, in other embodiments, one or more of propulsion systems 101(A), 101(B), 101(C), 101(G), 101(H), and / or 101(I) may instead take the form of tilting fans. Such tilting fans may be configured to switch (e.g., rotate or tilt) between a horizontal and a vertical orientation. The horizontal orientation may also be referred to as a horizontal direction, a forward flight configuration, a second tilt configuration, and / or a second tilt angle. The vertical orientation may also be referred to as a vertical direction, a vertical flight configuration, a first tilt configuration, and / or a first tilt angle. Figure 1A shows the tilting fan currently set in a forward flight configuration (also referred to as a second tilt configuration or second tilt angle), and Figure 1B shows the tilting fan currently set in a vertical flight configuration (also referred to as a first tilt configuration or first tilt angle).

[0059] As shown in FIG. 1B , all of the propulsion systems 101(A)-(L) can have a vertical orientation. Some of these can be vertical fans with a fixed vertical orientation (e.g., propulsion systems in the rear locations at 101(D), 101(E), 101(F), 101(J), 101(K), and / or 101(L)), while others can be tilting fans (e.g., propulsion systems in the front locations at 101(A), 101(B), 101(C), 101(G), 101(H), and / or 101(I)) that are currently and temporarily set to have a vertical orientation or in a vertical flight configuration. The tilting fans can have the same orientation as the vertical fans or a similar orientation. FIG. 1A shows the tilting fan in a forward flight configuration (e.g., propulsion system in the forward location at 101(A), 101(B), 101(C), 101(G), 101(H) and / or 101(I)).

[0060] 2A-2B show detailed views of propulsion system 101 configured to tilt. Propulsion system 101 (also referred to as a tilting fan) can be configured to tilt through a predefined range of tilt configurations, which may include a vertical flight configuration 211 as shown in FIG. 2A, a forward flight configuration 212 as shown in FIG. 2B, and / or any other suitable number of intermediate tilt angles between vertical flight configuration 211 (e.g., at or about 90 degrees) and forward flight configuration 212 (e.g., at or about 0 degrees).

[0061] The propulsion system 101 can be controlled to switch between inclination configurations to provide additional thrust in any appropriate direction depending on the current maneuver needs of the aircraft. For example, during takeoff, landing, and / or hovering, the propulsion system 101 may be set to vertical flight configuration 211 to provide additional vertical thrust. During forward cruise flight, the propulsion system 101 may be set to forward flight configuration 212 to provide horizontal thrust. During forward acceleration, deceleration, altitude gain, and / or altitude descent phases, the propulsion system 101 may be set to intermediate inclination angles and configurations to provide both horizontal and vertical thrust components.

[0062] According to an embodiment, propulsion system 101 may be tilted gradually, repeatedly, or otherwise through multiple different intermediate tilt angles based on the flight phase and / or needs of the aircraft. For example, during the forward acceleration and / or altitude gain phase of flight, propulsion system 101 may be tilted gradually (e.g., 0.5 degrees at a time, 1 degree at a time, etc.) from vertical toward horizontal as speed and / or altitude is gained.

[0063] In some embodiments, vertical flight configuration 211 may be at the maximum inclination and forward flight configuration 212 may be at the minimum inclination of propulsion system 101. In other embodiments, propulsion system 101 may be capable of inclination angles and configurations greater than vertical flight configuration 211 (e.g., angled above vertical so that there is an opposite horizontal component) and / or lower inclination angles and configurations than forward flight configuration 212 (e.g., angled below horizontal so that there is a downward component).

[0064] 1 , embodiments enable the aircraft 100 to include any suitable combination and number of tilting fans, fixed horizontal fans, and / or fixed vertical fans. Additionally, each type of fan may be positioned at any suitable location along the wings 102, 103 and / or any suitable support structure 106(A)-(F). The type of propulsion system at each location may be selected to enhance any number of flight characteristics, including forward thrust, vertical thrust, maneuverability, drag, and / or suitable flight characteristics.

[0065] While tilting fans can provide the ability to increase thrust in a particular direction as desired, it may be beneficial to incorporate one or more propulsion systems in a fixed orientation to reduce weight, reduce moving parts, reduce possible points of failure, and / or reduce maintenance concerns.

[0066] Propeller Blade Pitch The rotor blades (also called propeller blades) of the propulsion system 101 can be configured to have a constant blade pitch. The blade pitch of a rotor blade refers to the angle between the blade chord line and one of the planes of rotation of the propulsion system's spinner, aircraft body, or propeller. Blade pitch can be described as the rate of forward distance per revolution, assuming no slip. Generally, a low pitch (also called fine pitch) gives the aircraft good low-speed acceleration and rate of climb, while a high pitch (also called course pitch) optimizes high-speed performance and fuel economy.

[0067] According to an embodiment, one or more rotor blades of the propulsion system 101 may have an adjustable pitch setting (also referred to as a variable pitch position). Such a propulsion system may be referred to as a variable pitch propeller. In a variable pitch propeller, the blade pitch of one or more rotor blades may be adjusted during flight. Thus, the blade pitch may be adjusted to optimize thrust and / or efficiency based on the phase of flight, such as takeoff, climb, or cruise. For example, a fine pitch setting, which may provide greater thrust, may be used during takeoff, acceleration, altitude gain, and / or landing. A course pitch, which may provide better efficiency, may be used for high-speed cruise flight. An example of a low pitch during takeoff is approximately 15 degrees. An example of a high pitch used during cruise flight is approximately 40 degrees.

[0068] The amount of thrust produced by a rotor blade depends on its speed and angle of attack. The rotor blade's effective angle of attack can decrease as airspeed increases. To maintain a constant or otherwise optimal effective angle of attack, blade pitch may be increased.

[0069] Suitable mechanisms may be included to enable pitch adjustment. For example, the rotor blades may be coupled to their respective spinners via one or more pitching mechanisms, including, for example, motors and linkages. The pitching mechanisms may be controllable and / or configured to change or move the pitch position of the rotor blades relative to the spinners (or other components of the propulsion system) based on the current activity, needs, and / or direction of movement (e.g., forward flight, vertical flight) of the aircraft 100, according to some embodiments. As discussed in more detail below, in some embodiments, the pitching mechanism may be coupled to and / or combined with a tilting mechanism.

[0070] 3A-3B illustrate a propulsion system 101 having rotor blades 250 with variable pitch positions. The rotor blades 250 may be configured to rotate through a predefined range of pitch positions, which may include a first pitch position 380 as illustrated in FIG. 3A and a second pitch position 390 as illustrated in FIG. 3B.

[0071] The first pitch position 380 may be used during the first phase of flight (e.g., when the aircraft is in a vertical flight configuration), such as vertical takeoff, landing, hovering, forward acceleration, or altitude gain. The first pitch position 380 may be referred to as a hover pitch or an acceleration pitch. The first pitch position 380 may be any pitch suitable for hover flight, takeoff, and / or acceleration. Illustratively, the first pitch position 380 may be any suitable pitch between approximately 5 degrees and approximately 25 degrees (e.g., 5 degrees, 10 degrees, 15 degrees, 18 degrees, 20 degrees, 23 degrees, 25 degrees).

[0072] A second pitch position 390 (e.g., 40 degrees) may be used during a second phase of flight, such as cruise flight (e.g., when the aircraft is in a forward flight configuration). This second pitch position 390 may be referred to as a cruise pitch or an efficiency pitch. The second pitch position 390 may be any pitch suitable for cruise for forward flight (e.g., suitable for efficient flight at cruise conditions). Illustratively, the second pitch position 390 may be any suitable pitch between approximately 30 degrees and approximately 50 degrees (e.g., 30 degrees, 35 degrees, 40 degrees, 45 degrees, 50 degrees).

[0073] In some embodiments, first pitch position 380 may be a minimum pitch and second pitch position 390 may be a maximum pitch for example rotor blade 250, with other pitch positions existing between first pitch position 380 and second pitch position 390. In other embodiments, rotor blade 250 may achieve a pitch lower than first pitch position 380 and a pitch higher than second pitch position 390.

[0074] Referring back to FIG. 1 , as described above, one or more of the propulsion systems 101(A)-(L) may be tilting fans that can be tilted between a forward flight configuration and a vertical flight configuration. Thus, in some embodiments, both the blade pitch of the rotor blades and the tilt angle of the tilting fans may be adjustable. Both the blade pitch and tilt angle may be adjusted based on the needs of the current flight phase or other movements of the aircraft. For example, during takeoff, one or more tilting fans may be set to have a vertical flight configuration to provide vertical lift, and one or more sets of rotor blades may be set to have a low pitch. During cruise flight, one or more tilting fans may be set to have a forward flight configuration to provide horizontal thrust, and one or more sets of rotor blades may be set to have a high pitch. There may be times when these settings are paired differently. For example, before reaching cruising speed, one or more tilting fans may be set to have a forward flight configuration or a configuration for providing intermediate tilt angle and horizontal thrust, and one or more sets of rotor blades may be set to have a low pitch for optimal acceleration. Once a predetermined speed and / or altitude is reached, the low pitch can be changed to a high pitch.

[0075] Rotor blade pitch to propulsion system tilt coupling According to various embodiments, the pitch mechanism can be coupled to and / or combined with the tilt mechanism, and the pitch mechanism can be configured such that a movement or change in the tilt of the propulsion system automatically causes a corresponding movement or change in the pitch of one or more rotor blades of the propulsion system.

[0076] Embodiments may couple the pitch mechanism to the tilt mechanism in any suitable manner. For example, a single actuator (e.g., a motor) may control both the tilt mechanism and the pitch mechanism. In some embodiments, the actuator for the tilt mechanism may be coupled to the pitch mechanism, eliminating a separate, dedicated actuator for the pitch mechanism and thereby reducing the number of actuators on the aircraft. The actuator may be directly linked to the pitch mechanism, or the actuator may be indirectly coupled to the pitch mechanism via one or more other components, such as a component of the tilt mechanism.

[0077] 2A-2B illustrate an example propulsion system 101 having a pitching mechanism 230 coupled to a tilting mechanism 220, according to an embodiment. The propulsion system 101 may include a linkage mechanism 240 that may be configured to couple (e.g., directly or indirectly) the tilting mechanism 220 to the pitching mechanism 230. The tilting mechanism 220 may be referred to as a first mechanism, the pitching mechanism 230 may be referred to as a second mechanism, and the linkage mechanism 240 may be referred to as a third mechanism.

[0078] Angular motion caused by tilt mechanism 220 can be converted into linear motion in linkage mechanism 240 via the connection between tilt mechanism 220 and linkage mechanism 240. Furthermore, linear motion in linkage mechanism 240 can be converted into torsional motion in pitch mechanism 230 via the connection between pitch mechanism 230 and linkage mechanism 240. As a result, motion caused by tilt mechanism 220 can be converted into torsional motion in pitch mechanism 230 via linkage mechanism 240. Actuator 221 of tilt mechanism 220 can thereby actuate and / or control both tilt mechanism 220 and pitch mechanism 230 simultaneously in a linked manner.

[0079] 2A-2B . In addition, the linkage mechanism 240 can include one or more components that are indirectly coupled to the tilt mechanism 220. For example, similar to the tilt mechanism 220, the linkage mechanism 240 can include one or more components that are coupled to the support structure 106 and the propulsion system 101. As a result, even though the linkage mechanism 240 is not in direct contact with the tilt mechanism 220, a change in the relative position and / or angle between the support structure 106 and the propulsion system 101 (e.g., caused by the tilt mechanism 220) can cause movement of one or more components of the linkage mechanism 240. In other examples, the linkage mechanism 240 can be directly coupled to one or more components of the tilt mechanism 220.

[0080] tilting mechanism 2A-2B, in some embodiments, tilt mechanism 220 may include actuator 221, a load path including rod 223, and connection point 225. Actuator 221 may illustratively include a motor (e.g., an electric motor) or a hydraulic system. Embodiments allow for actuator 221 to include a local power source (e.g., a battery) and / or be connected to a separate aircraft power source (e.g., a battery). Additionally, actuator 221 may be in communication with and controlled by the aircraft's central control system.

[0081] A load path including rod 223 may connect to support structure 106 and to propulsion system 101 at connection point 225. Connection point 225 may be a rotatable connection point, such as a ball screw, pin, or other suitable form of connection. Rod 223 may be extendable (e.g., a "slider" configured for flexible extension and retraction), thereby providing an extendable or otherwise dynamic, adjustable connection between propulsion system 101 and support structure 106. As rod 223 extends and retracts, the tilt position of propulsion system 101 can be changed. Rod 223 may be coupled to and / or controllably extend and retract by actuator 221. As a result, the tilt configuration of propulsion system 101 can be controlled by actuator 221 via rod 223. Actuator 221 and rod 223 together may be referred to as a linear actuator. The tilt mechanism 220 shown in Figures 2A-2B is for illustrative purposes only, and embodiments allow for any other suitable tilt mechanism components and configurations.

[0082] Pitching Mechanism Pitching mechanism 230 may include a transfer rod 231, a hub 232, one or more blade rods 233, and one or more rotatable base components 234. Transfer rod 231 (sometimes referred to as a slider) may be positioned along the centerline of propulsion system 101. Transfer rod 231 may be coupled to linkage 240 at one end and to hub 232 (e.g., a central portion of the hub) at the other end. Movement of linkage 240 (which may be caused, for example, by movement of tilting mechanism 220) may cause transfer rod 231 to move linearly (e.g., a sliding piston motion) forward and backward along the centerline of propulsion system 101, which may cause hub 232 to move linearly as well. During the forward flight configuration 212, the centerline of the propulsion system 101 can be aligned with the x-axis (as shown in FIG. 2B) or can be aligned near the x-axis (e.g., angled upward or downward within a few degrees of the x-axis). During the vertical flight configuration 211, the centerline of the propulsion system 101 can be aligned with the z-axis (as shown in FIG. 2A) or can be aligned near the z-axis (e.g., angled forward or backward within a few degrees of the z-axis). The hub 232 (also referred to as a collective) can be coupled to one or more blade rods 233 (also referred to as pitch links and / or push rods), which can be located at or near points along the circumference of the hub 232. Movement of the hub 232 can cause similar forward and backward movement of each of the one or more blade rods 233. Each of the blade rods 233 can be coupled to and / or coupled with a corresponding rotatable base component 234, which can also be referred to as a blade cuff. The blade rod 233 and corresponding rotatable base component 234 may be configured such that forward and rearward movement of the blade rod 233 causes rotation of the rotatable base component 234 .For example, the rotatable base component 234 may be circular, and the blade rods 233 may be connected to the outer surface of the circular shape such that lateral movement of the blade rods 233 may be translated into rotation in the rotatable base component 234. Corresponding rotor blades 250 may be coupled to the rotatable base component 234, such that rotation of the rotatable base component 234 causes the rotor blades 250 to change pitch. According to an embodiment, each rotor blade 250 may be grouped with and coupled to a corresponding rotatable base component 234 and blade rod 233.

[0083] As shown, pitch mechanism 230 may be located entirely within propulsion system 101 and / or may be considered part of propulsion system 101. Additionally or alternatively, actuator 221 and other suitable components of linkage mechanism 240 and tilt mechanism 220 may also participate in generating pitching motion, according to some embodiments, and thus may be considered part of pitch mechanism 230. Pitch mechanism 230 shown in Figures 2A-2B is for illustrative purposes, and embodiments allow for any other suitable pitch mechanism components and configurations.

[0084] Another example of pitching mechanism 230 is illustrated alone in FIGS. 4A-4D. The figures illustrate snapshots of pitching mechanism 230 as propulsion system 101 is tilted or moved from a vertical flight configuration (e.g., in FIG. 4A) to a forward flight configuration (e.g., in FIG. 4D) as pitching mechanism 230 moves from a first pitch position (e.g., in FIG. 4A) through an intermediate pitch position (e.g., in FIGS. 4B-4C) to a second pitch position (e.g., in FIG. 4D). Each one of FIGS. 4A-4D includes a first cross-sectional image revealing components of pitching mechanism 230 within propulsion system 101 and a second image showing the exterior of propulsion system 101 with rotor blades 250. The progression of FIGS. 4A-4D shows how pitching mechanism 230 is actuated and, as a result, how rotor blades 250 are rotated or twisted through different pitch positions.

[0085] A further example of a pitching mechanism 930 is illustrated substantially in isolation (e.g., without the context of a propulsion system) in Figures 9A-9D. The pitching mechanism 930 in Figures 9A-9D is coupled to an alternative linkage mechanism 906, but the components of the pitching mechanism 930 are otherwise similar. Figures 9A-9D illustrate snapshots of the pitching mechanism 930 as it moves from a first pitch position (e.g., in Figure 9A), through an intermediate pitch position (e.g., in Figures 9B-9C), to a second pitch position (e.g., in Figure 9D). Figures 9A-9D are described in more detail below.

[0086] connection mechanism 2A-2B , linkage 240 may include any suitable components and structures for connecting tilt mechanism 220 to pitch mechanism 230. An example of linkage 240 shown through different snapshots of motion is shown in FIGS. 5A-5D . As shown, linkage 240 may include multiple rigid structures 242, 244, and 247, which may include rods, bars, angular connectors, and / or any other structure suitable for translational motion. First rigid structure 247 may be a pitch link, second rigid structure 244 may be a rocker link, and third rigid structure 242 may be a push rod link. Additionally, linkage 240 may include connection points 241, 243, 245, 246, and 248, which may take the form of pins or any other suitable rotary connection points. Connection point 248 may connect linkage 240 to a support structure (e.g., a boom) of the aircraft. Connection point 241 can connect linkage 240 to transfer rod 231 of pitch mechanism 230 on propulsion system 101. The remaining connection points 243, 245, and 246 can connect rigid structures 242, 244, and 247 to form one or more prismatic joints. The components can be sized and positioned such that tilting of the tilt propulsion system (e.g., caused by actuator 221 of tilt mechanism 220) (e.g., by changing the shape or position of a component) puts linkage 240 into relative motion, and that motion puts transfer rod 231 of pitch mechanism 230 into motion. For example, tilt of tilt propulsion system 101 can be about a first pivot point (or center of rotation), while linkage 240 can have a second pivot point offset from the first pivot point. The offset between the two pivot points causes relative movement and therefore movement of the transfer rod 231.

[0087] 5A-5D illustrate an example of the movement of linkage mechanism 240 as propulsion system 101 tilts from a vertical flight configuration to a forward flight configuration, caused by the actuators of tilt mechanism 220. FIG. 5A can represent a vertical flight configuration, FIG. 5D can represent a forward flight configuration, and FIGS. 5B-5C can represent intermediate tilt angles and configurations. From the aircraft's frame of reference, propulsion system 101 tilts from vertical to horizontal, while connection point 248 (as well as the aircraft and supporting structure, not shown) remains fixed. However, to illustrate the movement of linkage mechanism 240, the images in FIGS. 5A-5D are in the propulsion system's frame of reference. As a result, propulsion system 101 is depicted unchanged across snapshots, making the movement of linkage mechanism 240 easier to see. As shown, within this frame of reference, the components of linkage mechanism 240 are generally shifted toward the left, rigid structure 247 is shifted downward and rotated from an angled position to approximately horizontal, and rigid structure 242 is shifted upward. As rigid structure 242 shifts upward, transfer rod 231 of pitching mechanism 230 also shifts upward, causing a pitch change in the rotor blades. Thus, active tilting of propulsion system 101 can cause responsive (or passive) movement in linkage 240, which in turn can cause responsive (or passive) movement in pitching mechanism 230. All of these movements can be caused and controlled by a single actuator, such as actuator 221 of tilting mechanism 220 as shown in FIG. 2A.

[0088] Nonlinear slope-pitch relationship 2A-2B, the coupling of tilt mechanism 220 to pitch mechanism 230 may be configured such that a change in tilt angle can be translated into any suitable change in pitch position. In some embodiments, a change in tilt angle can have a linear relationship with a responsive change in pitch. For example, a 1-degree change in tilt angle can cause any suitable corresponding change in pitch (e.g., 0.1 degrees, 0.3 degrees, 0.5 degrees, 0.8 degrees, 1 degree, 2 degrees, etc.), regardless of the current pitch position and / or tilt angle.

[0089] In other embodiments, the change in tilt angle can have a non-linear relationship with a responsive change in pitch position, and the amount of pitch change can depend on the current tilt angle and / or pitch position in addition to the amount of tilt angle change.

[0090] The connection between the tilt mechanism and the pitch mechanism can be configured to provide such a non-linear relationship between the tilt angle and the pitch position. For example, according to an embodiment, linkage mechanism 240 may be configured to provide a non-linear relationship between the tilt angle and the pitch position. For example, referring back to FIGS. 5A-5D , any suitable non-linear relationship between the tilt angle and the pitch position can be achieved by correspondingly configuring (e.g., shaping, sizing, and / or positioning) one or more of rigid structures 242, 244, and / or 247 and / or one or more of connection points 241, 243, 245, 246, and / or 248. The configuration of rigid structures 242, 244, 247 and / or linkage points 241, 243, 245, 246, 248 can be arranged such that rigid structures 242, 244, 247 and / or linkage points 241, 243, 245, 246, 248 can collectively affect the linear motion generated by linkage mechanism 240 at transfer rod 231 as the tilt angle changes, and thus a particular blade pitch position can be achieved at a corresponding predefined tilt angle as desired.

[0091] An example of the nonlinear relationship between cant angle and pitch position is shown in chart 600 of Figure 6. In chart 600, the x-axis represents propulsion system cant angle 620, with cant angle increasing to the right, and the y-axis represents pitch position 630 of one or more rotor blades of the propulsion system, with pitch position increasing as the y value increases.

[0092] Chart 600 includes a set of plotted points illustrating examples of pitch positions that may be linked to and / or caused by corresponding tilt angles due to the configuration of the linkage between the tilt and pitch mechanisms. As shown, pitch positions generally increase with decreasing tilt angles.

[0093] Point 680 can represent a pitch angle associated with a vertical flight configuration (e.g., about 90 degrees), as well as a first pitch position used during the vertical flight configuration. The first pitch position can be any pitch appropriate for vertical flight, such as a pitch position between about 5 degrees and about 25 degrees (e.g., 5 degrees, 10 degrees, 15 degrees, 18 degrees, 20 degrees, 23 degrees, 25 degrees).

[0094] Point 690 may represent a pitch angle associated with a forward flight configuration (e.g., approximately 0 degrees) as well as a second pitch position used during the forward flight configuration. The second pitch position may be any pitch appropriate for forward cruise flight, such as a pitch position between approximately 30 degrees and approximately 50 degrees (e.g., 30 degrees, 35 degrees, 40 degrees, 45 degrees, 50 degrees).

[0095] Chart 600 illustrates the nonlinear change in pitch position 630 as the tilt angle 620 changes. It is noteworthy that at higher tilt angles (e.g., near point 680), the change (e.g., amount of fluctuation) in pitch position is relatively small. At lower tilt angles (e.g., near point 690), the change (e.g., amount of fluctuation) in pitch position is relatively large.

[0096] This type of nonlinear relationship may be beneficial because it allows a low pitch position 630 to be utilized over a wider range of pitch angles 620 compared to a linear relationship. A low pitch position may provide greater thrust and therefore may be desirable for multiple flight phases utilizing intermediate pitch angles 620. For example, during forward acceleration and altitude gain, the propulsion system may be tilted throughout a range of intermediate pitch angles to provide both forward acceleration and vertical lift components. During such flight phases, greater thrust output may be desired, and therefore it may be beneficial to maintain a low pitch position as the propulsion system continues to tilt.

[0097] Later, as the aircraft gains altitude and speed and enters forward cruise flight, the propulsion system tilt angle can approach horizontal. At this point, it can be advantageous to change pitch position more rapidly to reach a higher pitch position, which can produce the desired efficiency during forward cruise flight.

[0098] Chart 600 includes point 685 marking an intermediate pitch angle near horizontal (or near horizontal) in the forward flight configuration. This intermediate pitch angle may also be referred to as the third pitch angle. The third pitch angle at point 685 may be slightly above horizontal (e.g., 3 degrees, 5 degrees, 8 degrees, 10 degrees, 15 degrees, or any other suitable angle). As shown, the pitch position at point 685, referred to as the third pitch position, is also lower by a meaningful amount than the second pitch position at point 690 due to the sharp curve in this region 600 of the chart. The third pitch position may be 3 degrees lower, 5 degrees lower, 7 degrees lower, 10 degrees lower, 15 degrees lower, 20 degrees lower, or any other suitable amount lower than the second pitch position.

[0099] In some embodiments, during the acceleration and altitude-gain phases of flight, the propulsion system may be continuously or systematically tilted from a vertical flight configuration toward a forward flight configuration. However, the tilt may be paused for any suitable length of time at the third pitch angle at point 685. This allows the propulsion system to provide primarily horizontal thrust (e.g., similar to a forward flight configuration) while maintaining a third pitch position lower than the second pitch position, thereby providing greater thrust output. Once sufficient speed and altitude are achieved, a final tilt from point 685 to point 690 can be performed to reach the forward cruise flight configuration. While this final small tilt may not result in a significant adjustment to thrust direction, it can now functionally modify the rotor blade pitch position so that efficiency is prioritized over maximum thrust output for forward cruise flight.

[0100] In other words, the non-linear relationship shown in chart 600, even though the tilt angle is coupled to the pitch position, can effectively allow for the pitch position to be controlled and modified in a relatively independent manner when the current tilt angle is near point 690, without requiring a significant change in the tilt angle. Similarly, the non-linear relationship shown in chart 600, even though the tilt angle is coupled to the pitch position, can effectively allow for the pitch position to be controlled and modified in a relatively independent manner when the current tilt angle is near point 680, without requiring a significant change in the pitch position.

[0101] Hydraulic lines Embodiments provide various mechanisms integrated with the tilt mechanism of the tilting lift fan for scheduling the tilt angle of the tilting lift fan and the blade pitch angle of the rotor blades, thus reducing complexity and eliminating the need for additional actuators for pitch control.

[0102] In some examples, instead of coupling the pitch mechanism to the actuator via a linkage and / or tilt mechanism (e.g., in series), the pitch mechanism can be coupled directly to the actuator (e.g., in parallel with the tilt mechanism).

[0103] For example, an exemplary mechanism can include a hydraulic system having a first line to a tilt mechanism and a second line to a pitch mechanism. The hydraulic system can include a primary cylinder connected to the tilt mechanism and a secondary cylinder connected to the pitch mechanism. A hydraulic line can connect the secondary cylinder to a line connecting a pump to the first cylinder. When the pump moves the primary cylinder, the hydraulic line from the primary cylinder to the secondary cylinder also drives the secondary cylinder. Thus, a single pump drives two cylinders through a hydraulic linkage, thereby functioning as a single actuator to drive the tilt of the tiltable lift fan and the blade pitch of the tiltable lift fan blades.

[0104] Additional actuator for fine pitch control According to some embodiments, an additional actuator may be included for fine adjustment of the pitch mechanism. The pitch mechanism may still be coupled to the tilt mechanism, but this second actuator may provide smaller adjustments to the overall pitch position. For example, the second actuator may adjust the pitch position by 0.5 degrees, 1 degree, 1.5 degrees, 2 degrees, 5 degrees, or other suitable amount relative to the overall pitch position provided by the coupling to the tilt mechanism. The second actuator may be located entirely on the propulsion system, or some or all of the second actuator may be located on the support structure or elsewhere on the aircraft.

[0105] Position Sensor According to some embodiments, as shown in Figures 2A-2B, position sensor 290 may be included as part of pitching mechanism 230 or otherwise in propulsion system 101. Position sensor 290 may be located on and / or coupled to any suitable component of pitching mechanism 230 and / or one or more rotor blades 250.

[0106] Position sensor 290 may be configured to monitor the current pitch position of one or more rotor blades. Position sensor 290 may also be configured to communicate with a control system to provide information regarding the current pitch position. Due to the coupling between tilt mechanism 220 and pitch mechanism 230, the control system may indirectly control pitch mechanism 230 (e.g., via tilt mechanism 220) and may not be able to determine, via tilt mechanism 220 or actuator 221, whether pitch mechanism 230 is functioning according to predefined conditions or positioned as intended. Thus, position sensor 290 can provide pitch position information that might otherwise be lost due to the coupled arrangement.

[0107] Offset Swivel Mechanism According to various embodiments, an example coupling mechanism can include an offset swivel mechanism. Figures 7A-7C show an example propulsion system having a pitching mechanism coupled to a tilting mechanism through an offset swivel mechanism, according to some embodiments. The offset swivel mechanism 750 is coupled to the tiltable lift fan 701, according to various embodiments. The offset swivel mechanism 750 can include a first mechanism, a second mechanism, and a third mechanism.

[0108] The first mechanism may include a linear actuator 723 coupled to a ball screw 727. The first mechanism may pivot the entire tiltable lift fan 701 between a vertical flight configuration, as shown in Figure 7A, and a forward flight configuration, as shown in Figure 7C.

[0109] The third mechanism can include a first element 738 (e.g., a link) and a second element 731 (e.g., a slider) that extends through the centerline of a motor (e.g., the motor of tiltable lift fan 701). The third mechanism can convert tilting motion into piston-like motion of the second element 731. In the forward flight configuration shown in FIG. 7C, the second element 731 is pulled to the left from the motor. In the vertical flight configuration shown in FIG. 7A, the second element 731 is pushed to the right into the motor. The second element 731 has a linear motion, which can prevent twisting when moving in and out of the motor.

[0110] A second mechanism converts the linear motion of second element 731 into torsional motion of one or more rotor blades (e.g., via a torsion cuff coupled to the rotor blades). As a result, the pitch position of the rotor blades can change as tiltable lift fan 701 pivots between different tilt configurations.

[0111] According to an embodiment, first element 738 can have a second pivot point that is offset or otherwise positioned differently relative to the first pivot of tiltable lift fan 701. The different center of rotation results in linear movement (or change in length) of second element 731. Movement of second element 731 results in a change in blade pitch.

[0112] According to various embodiments, one or more of the joints in offset pivot mechanism 750 may be revolute joints that provide surface contact between all moving elements. In some embodiments, offset pivot mechanism 750 may include roller bearing or bushing-like surface contact on the joints.

[0113] According to various embodiments, the offset swivel mechanism 750 can provide a rotor blade pitch change of approximately 40 to 70 degrees.

[0114] Four-section crank slider According to various embodiments, an exemplary linkage mechanism can include a four-bar crank-slider mechanism. Figures 8A-8B show another example of a linkage mechanism in the form of an exemplary four-bar crank-slider mechanism 800, according to various embodiments. The four-bar crank-slider mechanism 800 includes a first bar 804, a second bar 810, a third bar 812, and a fourth bar 814. An inner bar 816 slides (e.g., freely retracts) in and out of the fourth bar 814 to form a slider.

[0115] The four-bar crank slider 800 includes a first element 802 that slides linearly along a first bar 804, a second element 808 (e.g., a first joint) that is rigidly connected to a second bar 810, and a third element 806 (e.g., a second joint) that connects the second element 808 and the first element 802, forming a four-bar crank slider. The second element 808 is a prismatic joint between the first element 802 and the first bar 804. The third element 806 is connected to the second element 808 rather than to a base.

[0116] According to various embodiments, the four-bar crank-slider mechanism 800 may be coupled to a tiltable lift fan. The first element 802 may be coupled to a pitching mechanism of the lift fan that can vary the pitch of the lift fan's rotor blades. The first bar 804 may be coupled to a lift fan motor with a propeller attached.

[0117] Figure 8A shows the arrangement (e.g., four-bar crank-slider mechanism 800 coupled to a tiltable lift fan) in a forward flight configuration, while Figure 8B shows the arrangement in a vertical flight configuration.

[0118] In response to the lift fan tilting from a forward flight configuration to a vertical flight configuration, the first element 802 can slide upward, providing linear motion. The linear motion is then converted to rotational motion of the first bar 804 via the second element 808 and the third element 806. As the tiltable lift fan moves from the vertical flight configuration back to the forward flight configuration, the first element 802 slides relative to the first bar 804 because the axial sliding activates the blade pitch mechanism, thereby providing axial piston motion.

[0119] The first element 802, second element 808, and third element 806 allow sliding movement of the inner bar 816 in and out of the fourth bar 814. Relative movement of the first bar 804 with either the third bar 812 or the second bar 810 actuates a blade pitching mechanism. Thus, the blade pitch mechanism, according to the embodiment, may not require an additional actuator dedicated to changing the blade pitch.

[0120] Centerline roller cam Embodiments allow for the linkage mechanism to take other suitable forms. As another example, the linkage mechanism can take the form of a roller cam coupled to a structure having a curved slot. The roller cam can be coupled to a transfer rod of the pitching mechanism, and the structure having the curved slot can be mounted to a support structure (e.g., not on the propulsion system). As a result, tilting of the propulsion system can cause the roller cam to roll within the curved slot. As the roller cam rolls, the curvature of the slot and / or the tilting motion can push the roller cam inward and / or pull it outward relative to the pitching mechanism (e.g., depending on the direction of tilt), thereby moving the transfer rod of the pitching mechanism forward and backward.

[0121] 9A-9D illustrate a centerline roller cam mechanism 900 according to various embodiments. The centerline roller cam mechanism 900 includes a stationary portion 906 (e.g., a structure having a curved slot) and a pivoting portion 950, which can include a pitching mechanism 930 and a roller cam 904.

[0122] 9A-9D, stationary portion 906 (which may be, for example, a linkage mechanism) corresponds to first element 738 shown in FIGS. 7A-7D, and slider 931 corresponds to second element 731 in FIGS. 7A-7D. Pivoting portion 950 is coupled to stationary portion 906 and pivots along a predetermined path 908 relative to stationary portion 906. One end of pivoting portion 950 is coupled to stationary portion 906, while the opposite end includes cuffs 902 for each blade of the tiltable lift fan that may be coupled to centerline roller-cam mechanism 900.

[0123] When the pivoting part 950 pivots relative to the stationary part 906 (e.g., due to propulsion system tilt), the cuff 902 connected to the blade twists. Figures 9A-9D show the twisting of the cuff 902 in a left-handed twisting motion while the pivoting part 950 pivots in a counterclockwise motion relative to the stationary part 906. The centerline roller-cam mechanism 900 converts the tilt angle of the pivoting part 950 into a piston-like motion of the slider 931, which twists the cuff 902 connected to the blade, thereby changing the blade pitch.

[0124] The pitching mechanism 930 converts the linear motion of the slider 931 into a twisting motion of the blade (e.g., by twisting a cuff connected to the blade). For example, the pitching mechanism 930 can include a coupler 920 disposed around the distal end of the slider 931. The coupler 920 can have a star shape as shown in FIG. 9. The coupler 920 can move linearly with the slider 931.

[0125] The coupler 920 may be attached to multiple blades via attachment means 922 (e.g., cuffs). For example, the coupler 920 may be connected to the attachment means 922 via one or more links 924 that extend parallel to the slider 931. Linear movement of the slider 931 and coupler 230 causes linear movement of the links 924, which in turn rotates the attachment means 922 and, in turn, rotates the blades.

[0126] According to various embodiments, the shape of the curved slot 908 in the stationary portion 906 may be modified (e.g., linear, parabolic, etc.) to change the scheduling of the blade pitch. For example, a sharper curve in a first particular region along the curved slot 908 (e.g., corresponding to a first range of tilt angles) may produce a faster pitch change, while a sharper curve in a second particular region along the curved slot 908 (e.g., corresponding to a second range of tilt angles) may produce a slower pitch change. The curved slot 908 may be a sealed opening that is sealed against foreign debris.

[0127] Control system 1A-1B , according to various embodiments, the aircraft 100 may be an electric aircraft or a hybrid-electric aircraft. One or more battery units may be included in the aircraft 100 (e.g., within the fuselage 104) and configured to power various aircraft components, such as one or more electric motors and / or onboard computer systems. The propulsion systems 101(A)-(L) may be driven by electric motors powered by a power system including one or more battery units. In some embodiments, each of the propulsion systems 101(A)-(L) may be coupled to a dedicated battery unit. Alternatively, there may be a one-to-many relationship between one or more battery units and the propulsion systems 101(A)-(L). In some cases, one or more battery units may be the sole power source for the aircraft 100. Each battery unit may include one or more battery cells.

[0128] According to various embodiments, aircraft 100 may include a control system 107, such as a flight control system, configured to control aircraft 100. Control system 107 may be configurable to control aircraft 100 automatically and / or remotely (e.g., via control signals received from a remote entity, such as a remote controller, a remote pilot, or a remote control tower). In various embodiments, control system 107 may include one or more computers having one or more non-transitory computer-readable media that store instructions and one or more processors configured to execute the instructions to perform the processing and control functions described herein.

[0129] For example, control system 107 may control when propulsion systems 101(A)-(L) should be activated and / or the amount of power provided to propulsion systems 101(A)-(L). Control system 107 may be configurable to control propulsion systems 101(A)-(L) independently of one another. According to various embodiments, control system 107 may control propulsion systems 101(A)-(L) based on inputs received from a remote controller (e.g., a remote pilot), inputs received from an autopilot, sensor data and / or flight data received from sensors (e.g., sensors measuring air temperature, electric motor temperature, aircraft airspeed, etc.), computers, and other input / output devices coupled to the aircraft.

[0130] The flight control system 107 can also control one or more tilt mechanisms to switch the position of one or more tilting fans from a forward flight configuration to a vertical flight configuration, from a vertical flight configuration to a forward flight configuration, to one or more intermediate tilt angles, and / or continuously change the position through a range of tilt angles as needed or required by the flight plan. According to various embodiments, the control system (e.g., the flight control system) can control the angle of the tilting fans based on sensor data and / or flight data received from sensors (e.g., sensors measuring air temperature, electric motor temperature, aircraft airspeed, etc.) coupled to the aircraft, computers, and other input / output devices.

[0131] The flight control system 107 may further control one or more pitching mechanisms to switch the position of one or more rotor blades between two or more pitch positions. According to various embodiments, the control system 107 may control the pitch position of the rotor blades based on sensor data and / or flight data received from sensors (e.g., sensors measuring air temperature, electric motor temperature, aircraft airspeed, etc.), computers, and other input / output devices coupled to the aircraft. The pitch of the rotor blades may be set based on the current flight phase and / or flight needs. For example, a first pitch, which may be a low pitch, may be selected when the aircraft is accelerating (e.g., forward or upward), hovering, taking off, and / or landing. A second pitch, which may be a high pitch, may be selected when the aircraft reaches cruise flight (e.g., reaches a preset forward speed).

[0132] As discussed above, in some embodiments, the pitch mechanism can be coupled to the tilt mechanism. In this case, the flight control system 107 can further control the tilt mechanism and pitch mechanism together using one or more shared actuators and according to a predefined relationship between the tilt angle and the pitch position. The flight control system 107 can determine and adjust the tilt angle of the tilt fan and the pitch position of the rotor blades based on the current flight phase and / or flight needs. The flight control system 107 can prioritize the tilt angles by selecting the most appropriate tilt angle, allowing the pitch mechanism to be passively adjusted. The relationship between the tilt angle and the pitch position can be preset so that the corresponding pitch position is typical or always appropriate for a given tilt angle. In some embodiments, the flight control system 107 can prioritize the pitch position when the tilt angle is close to horizontal. For example, the flight control system 107 may be configured to select a third pitch angle slightly higher than horizontal to allow for a pitch position (e.g., the third pitch position discussed above) that is lower than the predefined pitch position (e.g., the second pitch position discussed above) that is paired with the horizontal pitch angle.

[0133] Thus, control system 107 may be configured to convert pilot or other operator inputs and / or corrections calculated by the onboard computer into forces and moments, and / or further convert such forces and moments into a set of actuators (e.g., control surfaces such as rotors, propellers, ailerons, etc.) and / or associated parameters (e.g., lift, fan power, tilt angle, rotor blade pitch, speed, or torque) to provide the desired forces and moments. For example, pilot or other operator input may indicate a desired change in the speed, direction, and / or orientation of the aircraft, and / or wind or other forces may act on the aircraft, requiring the propulsion system and / or other actuators to be used to maintain a desired aircraft attitude (roll / pitch / yaw), speed, and / or altitude.

[0134] According to various embodiments, control systems 107 may be configurable to receive flight commands, such as takeoff, hover, cruise, or landing commands. Control systems 107 may then determine the current location and / or velocity of aircraft 100 and control the operation of propulsion systems 101(A)-(L) based on the flight commands. During operation of aircraft 100, control systems 107 may be configurable to continuously monitor the operating status of propulsion systems 101(A)-(L) in light of the flight commands.

[0135] Aircraft 100 may further include landing gear 130. Landing gear 130 may include any suitable combination of one or more skids, wheels, skis, pontoons, shock absorbers, struts, and / or any other suitable components for supporting aircraft 100 during and / or landing on the ground. In some examples, landing gear 130 may be retractable within a compartment within fuselage 104.

[0136] The aircraft 100 may include other suitable control structures and control surfaces. Any suitable number of ailerons, rudders, elevators, slats, flaps, spoilers, and / or stabilizers may be included. For example, the horizontal stabilizer 140 (e.g., a tail) may be coupled to the aft end or tail section of the fuselage 104. The horizontal stabilizer may have any suitable shape or configuration. For example, as shown in FIGS. 1A-1B, the horizontal stabilizer 140 may include two stabilizer surfaces projecting horizontally from the tail. In some embodiments, each of the stabilizer surfaces may further include a hinged control surface at its trailing edge. In addition, as shown in FIGS. 1A-1B, an additional (e.g., a third) vertical stabilizer surface extending vertically upward and / or downward may be installed on the tail. The horizontal stabilizer 140 may provide additional stability and control of the aircraft 100. This is particularly useful during times when the vertical fan is disabled or otherwise not utilized or relied upon for control and stability (eg, during cruise flight).

[0137] Flight Process According to various embodiments, a control system may control the flight of an aircraft configured for vertical takeoff and landing.

[0138] An aircraft may be in a stationary position on the ground. For example, the aircraft may be parked at a charging station to charge its batteries. Or, the aircraft may be parked at a location awaiting the arrival of cargo or passengers. The aircraft's flight control system may receive a flight plan (e.g., from an autopilot, a pilot, or a remote controller pilot) to reach a predetermined destination. The flight plan may include instructions for takeoff from the ground. The flight control system may control and activate one or more of the propulsion systems. For example, the aircraft's thrust-producing components may be deactivated or in standby mode. The flight control system may power up the propulsion systems from a deactivated mode so that the propulsion systems are ready to generate vertical lift.

[0139] The control system can operate a first set of one or more propulsion systems coupled to the aircraft, each of which can have two or more rotor blades and a fixed vertical orientation or a tiltable orientation that is currently set to a vertical flight configuration.

[0140] For example, the flight control system may initiate a takeoff sequence to lift the aircraft off the ground. The flight control system may activate a first set of one or more propulsion systems to provide vertical thrust so that the aircraft leaves the ground. The flight control system may continue to activate the first set of one or more propulsion systems in this manner until a certain amount of time has elapsed or a certain height (e.g., a safe distance from the landing pad) has been reached. The control system may continue to activate the first set of one or more propulsion systems to provide vertical thrust during liftoff, hovering, landing, or any other suitable flight phase.

[0141] The control system may at some point control one or more of the first set of one or more propulsion systems, such as fixed vertical fans, to deactivate during other flight phases, such as forward cruise flight, during which vertical lift may additionally and / or alternatively be provided by the aircraft's wings. For example, after a certain amount of time has elapsed and / or after altitude has been gained, the flight control system may receive a command to transition to forward flight. Before switching to forward flight mode, the control system may check one or more of the aircraft's altitude, speed, and heading to ensure that the parameters are within predetermined desired ranges. In some embodiments, the control system may communicate the parameters to a remote entity (e.g., a remote control tower or a remote pilot).

[0142] The control system can actuate a second set of one or more propulsion systems. Each of the second set of one or more propulsion systems has a fixed horizontal orientation or a tiltable orientation set in a forward flight configuration. Each of the second set of one or more propulsion systems can have two or more rotor blades. In some embodiments, one or more propulsion systems, such as tilting fans, can be included in both the first set of one or more propulsion systems and the second set of one or more propulsion systems.

[0143] For example, upon receiving a flight command to transition to forward flight, the control system may activate a second set of one or more propulsion systems to generate forward thrust for the aircraft. The flight control system may control forward acceleration in any suitable manner, such as by gradually increasing power supplied to the second set of one or more propulsion systems so that the aircraft gradually gains forward speed.

[0144] In some embodiments, the second set of one or more propulsion systems can activate and begin to provide forward thrust while the aircraft is still in the process of gaining altitude from the vertical lift fans. As a result, forward progress and vertical lift can overlap. Additionally, the flight control system can adjust the power of the first set of one or more propulsion systems as needed to maintain stability and altitude while the second set of one or more propulsion systems increases forward airspeed.

[0145] In some embodiments, one or more of the first set of propulsion systems and / or one or more of the second set of propulsion systems may be actuated to tilt between a forward flight configuration and a vertical flight configuration, and such tilting propulsion systems may be actuated in both one or more steps to provide vertical thrust and one or more steps to provide horizontal thrust.

[0146] In some embodiments, one or more tilt propulsion systems may be actuated to gradually, repeatedly, and / or continuously tilt from a vertical flight configuration to a forward flight configuration. When the tilt propulsion systems are set at one or more intermediate tilt angles, thrust may be provided at an angle having a partial vertical component and a partial horizontal component. As the tilt propulsion systems tilt through one or more intermediate tilt angles, the horizontal thrust component increases and the vertical thrust component decreases. In some embodiments, one or more tilt propulsion systems may be actuated to suspend movement and tilt at a predefined intermediate tilt angle (referred to as a third tilt angle, critical tilt angle, or threshold tilt angle) that is near but may exceed horizontal, while the propulsion systems continue to operate and provide thrust. Once a predefined speed and / or altitude is achieved, the one or more tilt propulsion systems may be actuated to resume the tilt progression until the forward flight configuration is reached.

[0147] The control system may set and / or modify the pitch position setting of one or more rotor blades of one or more propulsion systems (e.g., from the first set and / or the second set). In some embodiments, the one or more rotor blades may be initially set to a first pitch position. The first pitch position may be maintained during one or more phases of flight, such as takeoff and / or forward acceleration. The control system may later adjust the one or more rotor blades to have a second pitch position. For example, once cruise flight is reached (e.g., after reaching a certain forward speed), the pitch setting may be changed to the second pitch position. In some embodiments, the pitch setting may be gradually and / or repeatedly changed from the first pitch position to the second pitch position as forward speed increases, and gradually changed from the second position to the first position as forward speed decreases.

[0148] In some embodiments, the pitching mechanism of one or more rotor blades of the tilt propulsion system can be coupled to the tilt mechanism of the propulsion system. When the tilt angle changes (e.g., decreases), the pitching mechanism is configured to automatically change (e.g., increase) in response. In some embodiments, the control system can actuate the propulsion system to suspend the tilting movement at a predetermined intermediate tilt angle (referred to as a third tilt angle) that is near but may be above horizontal, such that the aircraft can maintain a constant predefined pitch position (referred to as a third pitch position) coupled to the third tilt angle while continuing to gain speed and / or altitude. Once the predefined speed and / or predefined altitude are attained, the one or more tilt propulsion systems can be actuated to resume the tilting progression until a forward flight configuration is reached, whereby the pitch position can be correspondingly changed to a predefined pitch position (referred to as a second pitch position) coupled to the forward flight tilt configuration.

[0149] The control system may continue to activate the second set of one or more propulsion systems during forward cruise flight, forward acceleration, deceleration, or any other suitable flight phase to provide horizontal thrust. The control system may at some point control the first set of one or more propulsion systems to be deactivated during other flight phases, such as liftoff, hovering, and / or landing. At some point, the control system may activate both the first set of one or more propulsion systems and the second set of one or more propulsion systems simultaneously.

[0150] The flight control system may then deactivate one or more of the first set of one or more propulsion systems or reduce the power supplied to the first set of one or more propulsion systems. For example, once the second set of one or more propulsion systems is generating a predetermined speed and the wings are providing enough lift to maintain altitude, the first set of one or more propulsion systems may no longer be needed for vertical lift. Thus, one or more of the first set of one or more propulsion systems may be powered down, deactivated, placed in a standby mode, or operated at a reduced power level during forward flight of the aircraft.

[0151] The control system may continue to alternate between activating one or more of the first set of one or more propulsion systems and / or the second set of one or more propulsion systems, continue to tilt the one or more tilting propulsion systems, and / or continue to adjust the pitch position of the one or more rotor blades (e.g., by adjusting the coupled tilt angle of the propulsion systems).

[0152] In the foregoing specification, embodiments of the present disclosure have been described with reference to numerous specific details that may vary from implementation to implementation. Accordingly, the specification and drawings are to be regarded in an illustrative rather than a restrictive sense. The sole and exclusive indication of the scope of the present disclosure, and what is intended by the applicant to be the scope of the present disclosure, is the literal and equivalent scope of the claims issuing from this application, including any subsequent amendments, in the specific form in which such claims arise. Specific details of particular embodiments may be combined in any suitable manner without departing from the spirit and scope of the embodiments of the present disclosure.

[0153] Additionally, spatially relative terms such as "bottom" or "top" may be used to describe the relationship of an element and / or feature to another element and / or feature, for example, as shown in the drawings. It should be understood that spatially relative terms are intended to encompass different orientations of the device in use and / or operation in addition to the orientation depicted in the drawings. For example, if the device in the drawings is inverted, an element described as having a "bottom" surface may then face "above" the other element or feature. The device may be oriented otherwise (e.g., rotated 90 degrees or at another orientation) and the spatially relative descriptors used herein interpreted accordingly.

[0154] The methods, systems, and devices discussed herein are illustrative. Various embodiments may omit, substitute, or add various procedures or components as appropriate. For example, features described with respect to a particular embodiment may be combined in various other embodiments. Different aspects and elements of the embodiments may be combined in a similar manner. Also, because technology evolves, many of the elements are illustrative, and they do not limit the scope of the disclosure to these specific examples.

[0155] The terms “and,” “or,” and “and / or,” as used herein, can include a variety of meanings, and it is expected that this meaning will also depend, at least in part, on the context in which such terms are used. Generally, when “or” is used to connect a list, such as A, B, or C, it is intended to refer to A, B, and C, which are used herein in an inclusive sense, as well as A, B, or C, which are used herein in an exclusive sense. Additionally, as used herein, the term “one or more” may be used to describe any feature, structure, or characteristic in the singular or may be used to describe any combination of features, structures, or characteristics. However, it should be noted that this is merely an illustrative example, and claimed subject matter is not limited to this example. Furthermore, the term “at least one of,” when used to connect a list, such as A, B, or C, can be interpreted to mean any combination of A, B, and / or C, such as A, B, C, AB, AC, BC, AA, AAB, ABC, AABBCCC, etc.

[0156] Throughout this specification, references to "one example," "example," "particular example," or "exemplary implementation" mean that a particular feature, structure, or characteristic described in connection with the feature and / or example may be included in at least one feature and / or example of the claimed subject matter. Thus, appearances of the phrases "in one example," "example," "particular example," "in a particular implementation," or other similar phrases in various places throughout this specification do not necessarily all refer to the same features, examples, and / or limitations. Furthermore, particular features, structures, or characteristics may be combined in one or more examples and / or characteristics.

[0157] In the foregoing detailed description, numerous specific details have been set forth to provide a thorough understanding of the claimed subject matter. However, those skilled in the art will understand that the claimed subject matter may be practiced without such specific details. In other instances, methods and apparatuses that would be known to those skilled in the art have not been described in detail so as not to obscure the claimed subject matter. Therefore, it is intended that the claimed subject matter not be limited to the particular examples disclosed, but that such claimed subject matter also include all aspects falling within the scope of the appended claims, and equivalents thereof.

Claims

1. a system including a tiltable propulsion system configured to move between a first tilt angle and a second tilt angle, the tiltable propulsion system including a plurality of rotor blades each configured to move between a first pitch position and a second pitch position; a tilt mechanism coupled to the tiltable propulsion system and configured to move the tiltable propulsion system between the first tilt angle and the second tilt angle; a pitching mechanism coupled to one or more of the plurality of rotor blades and configured to move the one or more of the plurality of rotor blades between the first pitch position and the second pitch position; an actuator configured to simultaneously actuate the tilt mechanism and the pitch mechanism; Including, the system.

2. a coupling between the pitch mechanism and the tilt mechanism such that movement of the tiltable propulsion system by the tilt mechanism causes corresponding movement of one or more of the plurality of rotor blades by the pitch mechanism. The system of claim 1 further comprising:

3. 3. The system of claim 2, wherein the connection between the pitch mechanism and the tilt mechanism is configured such that each tilt angle of the tiltable propulsion system results in a pitch position for one or more of the plurality of rotor blades.

4. The system of claim 3 , wherein the first tilt angle produces the first pitch position and the second tilt angle produces the second pitch position.

5. 2. The system of claim 1, wherein the pitch mechanism moves one or more of the plurality of rotor blades between the first pitch position and the second pitch position when the tilt mechanism moves the tiltable propulsion train between the first tilt angle and the second tilt angle.

6. 3. The system of claim 2, wherein the coupling between the pitch mechanism and the tilt mechanism is configured to provide a non-linear relationship between a tilt angle of the tiltable propulsion system and a pitch position of one or more of the plurality of rotor blades.

7. 7. The system of claim 6, wherein the nonlinear relationship causes a first change in the pitch position of one or more of the plurality of rotor blades in response to a change in the tilt angle when the tiltable propulsion system is set at the first tilt angle, and wherein the nonlinear relationship causes a second change in the pitch position of one or more of the plurality of rotor blades in response to a change in the tilt angle when the tiltable propulsion system is set at the second tilt angle, the second change being greater than the first change.

8. a linkage connecting the pitch mechanism and the tilt mechanism, the linkage configured to convert a tilting motion caused by the tilt mechanism into a linear motion in the pitch mechanism, and the pitch mechanism configured to convert the linear motion in one or more of the plurality of rotor blades into a rotational motion. The system of claim 1 further comprising:

9. a support structure, the tiltable propulsion system being coupled to the support structure, the coupling mechanism being connected to the support structure and the tiltable propulsion system; The system of claim 8 further comprising:

10. The system of claim 9 , wherein the linkage mechanism is indirectly coupled to the tilting mechanism.

11. The system of claim 8 , wherein the linkage mechanism includes a first pivot point offset from a second pivot point of the tilt mechanism.

12. 9. The system of claim 8, wherein the linkage mechanism includes a four-bar crank slider, and the pitching mechanism includes a slider connected to the four-bar crank slider.

13. 2. The system of claim 1, wherein the actuator is a component of the tilt mechanism, the pitch mechanism is coupled to the tilt mechanism, the pitch mechanism operates without a separate dedicated actuator, and the first tilt angle corresponds to a vertical flight configuration and the second tilt angle corresponds to a forward flight configuration.

14. An aircraft, The torso and a pair of wings connected to both sides of the fuselage; one or more booms coupled to respective ones of the pair of wings; the tiltable propulsion system, wherein the tiltable propulsion system is coupled to a first boom of the one or more booms; and Including aircraft The system of claim 1 further comprising:

15. a control system configured to simultaneously control the tilt mechanism and the pitch mechanism via the actuator, the control system comprising: actuating the tilt mechanism to gradually move the tiltable propulsion system from the first tilt angle through a set of intermediate tilt angles to a third tilt angle; activating the tilt mechanism to suspend movement of the tiltable propulsion system when the third tilt angle is reached; and activating the tilt mechanism to move the tiltable propulsion system from the third tilt angle to the second tilt angle after the aircraft reaches a predetermined speed or a predetermined altitude. a control system configured to The system of claim 14 further comprising:

16. 16. The system of claim 15, wherein the first tilt angle corresponds to a vertical flight configuration, the second tilt angle corresponds to a forward flight configuration, and the third tilt angle is within 10 degrees of the second tilt angle.

17. a coupling between the pitching mechanism and the tilting mechanism configured such that each tilt angle of the tiltable propulsion system produces a corresponding pitch position for one or more of the plurality of rotor blades, the first tilt angle producing the first pitch position, the second tilt angle producing the second pitch position, and the third tilt angle producing a third pitch position, the third pitch position being at least 3 degrees less than the second pitch position; The system of claim 15 further comprising:

18. The control system activating the pitching mechanism to move one or more of the plurality of rotor blades from the third pitch position to the second pitch position; The system of claim 17 further configured to:

19. 20. The system of claim 18, wherein actuating the pitch mechanism to move one or more of the plurality of rotor blades from the third pitch position to the second pitch position is accomplished indirectly by actuating the tilt mechanism to move the tiltable propulsion train from the third tilt angle to the second tilt angle.

20. The system of claim 1 , wherein the first pitch position corresponds to an acceleration pitch and the second pitch position corresponds to an efficiency pitch.

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