Aircraft propulsion system

Abstract

A hybrid propulsion system for an aircraft may include a propeller assembly having at least one propeller and a power generation system. The power generation system may include a first power assembly, a second power assembly, a first motor, and a second motor. The first power assembly may be drivably coupled to the first motor to generate a first amount of electrical power. The second power assembly may be drivably coupled to the second motor to generate a second amount of electrical power. A controller may be operably coupled to the first power assembly, the first motor, or both and the second power assembly, the second power assembly, or both. The controller may be configured to combine at least a portion of the first amount of power and the second amount of power for electrical transmission to the propeller assembly.

Description

Technical Field

[0001] The present subject matter generally relates to hybrid aircraft propulsion systems and methods for operating various propulsion components of the propulsion systems. Background Art

[0002] Aircraft generally include a propulsion system that provides thrust. The propulsion system may include at least two aircraft engines. Each engine is typically mounted to a corresponding one of the wings of the aircraft or at other feasible locations. Although gas turbine engines are lighter and can produce more thrust than internal combustion engines, internal combustion engines may have better fuel combustion characteristics. Therefore, a propulsion system that can operate with the specific benefits of each type of engine would be useful. Summary of the invention

[0003] Aspects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention.

[0004] In some embodiments of the present disclosure, a hybrid propulsion system for an aircraft is disclosed, which includes a propeller assembly having at least one propeller. A power generation system includes at least a first power assembly, a second power assembly, a first motor, and a second motor. The first power assembly is drivingly coupled to the first motor to generate a first amount of electrical power. The second power assembly is drivingly coupled to the second motor to generate a second amount of electrical power. The second power assembly is configured to generate electrical power more efficiently than the first power assembly. A power bus is coupled to the first motor and the second motor. A controller is operably coupled to the first power assembly, the first motor, or both and is operably coupled to the second power assembly, the second motor, or both. The controller and the power bus are configured to combine at least a portion of the first amount of electrical power and the second amount of electrical power to supply the propeller assembly.

[0005] In some embodiments of the present disclosure, a method for operating a hybrid propulsion system of an aircraft is provided herein. The hybrid propulsion system includes a first power assembly operably connected to a first motor, a second power assembly operably connected to a second motor, and a propeller assembly. The propeller assembly includes at least one propeller and is operably connected to at least one of the first motor and the second motor. The method includes receiving a command to provide a first amount of thrust output for a first operating condition by one or more computing devices. The method also includes providing a first amount of electrical power from the first motor by one or more computing devices to provide the first thrust output from the first power assembly to the propeller assembly. In addition, the method includes receiving a command to provide a second amount of thrust output for a second operating condition by one or more computing devices. The method also includes providing a second amount of electrical power from the second motor by one or more computing devices to provide the second thrust output from the second power assembly to the propeller assembly.

[0006] In some embodiments of the present disclosure, a hybrid propulsion system for an aircraft includes a first power assembly having a turbine coupled to a first motor. The hybrid propulsion system also includes a second power assembly having an internal combustion engine coupled to a second motor. A propeller assembly has a first motor operably coupled to the first propeller. The propeller assembly is selectively powered by first and second motors through a power bus coupled to the first and second motors. A controller is operably coupled to the first power assembly, the first motor, or both and operably coupled to the second power assembly, the second power assembly, or both. If the desired thrust output is within the second power assembly operating range, the second power assembly is activated. If the desired thrust output is greater than the second power assembly operating range, the first power assembly is activated.

[0007] Technical Solution 1. A hybrid power propulsion system for an aircraft, comprising:

[0008] a propeller assembly having at least one propeller;

[0009] a power generation system comprising at least a first power assembly, a second power assembly, a first electric machine, and a second electric machine, the first power assembly drivingly coupled to the first electric machine to generate a first amount of electric power, and the second power assembly drivingly coupled to the second electric machine to generate a second amount of electric power, wherein the second power assembly is configured to generate electric power more efficiently than the first power assembly;

[0010] a power bus coupled to the first electric machine and the second electric machine; and

[0011] A controller operably coupled to the first power assembly, the first motor, or both and operably coupled to the second power assembly, the second motor, or both, the controller and the power bus being configured to combine at least a portion of the first amount of electrical power and the second amount of electrical power to supply the thruster assembly.

[0012] Technical Solution 2. A hybrid propulsion system according to any one of the foregoing technical solutions, wherein the first power component comprises a turbine, and the second power component comprises an internal combustion engine.

[0013] Technical Solution 3. A hybrid propulsion system according to any one of the aforementioned technical solutions, wherein the controller is also configured to provide electrical power from the first motor to the propeller assembly under a first operating condition and to provide electrical power from the second power assembly to the propeller assembly under a second operating condition.

[0014] Technical Solution 4. The hybrid propulsion system according to any one of the above technical solutions further comprises:

[0015] An energy storage unit is operably coupled to each of the first power assembly, the second power assembly, and the thruster assembly.

[0016] Technical Solution 5. A hybrid propulsion system according to any one of the aforementioned technical solutions, wherein each of the first power component, the second power component and the thruster component is configured to utilize the electric power stored in the energy storage unit.

[0017] Technical Solution 6. A hybrid propulsion system according to any one of the aforementioned technical solutions, wherein the second power component is configured to generate less electric power than the first motor.

[0018] Technical Solution 7. A hybrid propulsion system according to any one of the aforementioned technical solutions, wherein the first operating condition is indicated by a command to accelerate or climb the aircraft, and the second operating condition is indicated by a command to operate the aircraft under horizontal flight conditions.

[0019] Technical Solution 8. A hybrid propulsion system according to any one of the foregoing technical solutions, wherein the second power component generates an electric power that is less than half of the electric power of the first motor.

[0020] Technical Solution 9. A hybrid propulsion system according to any one of the aforementioned technical solutions, wherein the controller is also configured to: receive a desired thrust output, and if the desired thrust output is within the operating range of the second power component, activate the second power component, and if the desired thrust output is greater than the operating range of the second power component, activate the first power component.

[0021] Technical Solution 10. A hybrid propulsion system according to any one of the aforementioned technical solutions, wherein the first power component is configured to operate within a first range of revolutions per minute, and the second power component is configured to operate within a second range of revolutions per minute, the revolutions per minute in the second range being at least partially less than or greater than the revolutions per minute in the first range.

[0022] Technical Solution 11. The hybrid propulsion system according to any one of the above technical solutions further comprises:

[0023] One or more power electronic devices are positioned between the first power component and the power bus, between the second power component and the power bus, or both.

[0024] Technical Solution 12. A hybrid propulsion system according to any one of the aforementioned technical solutions, wherein, when operating at a common speed and / or operating parameters, the first power component generates a first noise level and the second power component generates a second noise level, and wherein the first noise level is greater than the second noise level.

[0025] Technical Solution 13. A method for operating a hybrid propulsion system of an aircraft, the hybrid propulsion system comprising a first power assembly operably coupled to a first motor, a second power assembly operably coupled to a second power motor, and a propeller assembly, the propeller assembly comprising at least one propeller and operably coupled to at least one of the first motor and the second motor, the method comprising:

[0026] receiving, by one or more computing devices, a command to provide a first amount of thrust output for a first operating condition;

[0027] providing, by the one or more computing devices, a first amount of electrical power from the first electric machine to provide a first thrust output from the first power assembly to the thruster assembly;

[0028] receiving, by the one or more computing devices, a command to provide a second amount of thrust output for a second operating condition; and

[0029] A second amount of electrical power is provided from the second electric machine by the one or more computing devices to provide a second thrust output from the second power assembly to the thruster assembly.

[0030] Technical Solution 14. A method according to any one of the aforementioned technical solutions, wherein the first power component is configured to operate within a first range of revolutions per minute, and the second power component is configured to operate within a second range of revolutions per minute, the revolutions per minute in the second range being at least partially less than or greater than the revolutions per minute in the first range.

[0031] Technical Solution 15. A method according to any one of the aforementioned technical solutions, wherein the first operating condition is a take-off flight condition or a climb flight condition.

[0032] Technical Solution 16. The method according to any one of the preceding technical solutions, wherein the second power component is configured to generate the second amount of electric power more efficiently than the first power component generates the first amount of electric power.

[0033] Technical Solution 17. A hybrid propulsion system for an aircraft, comprising:

[0034] a first power assembly having a turbine coupled to a first electric machine;

[0035] a second power assembly having an internal combustion engine coupled to a second electric machine;

[0036] a propeller assembly having a first motor operably coupled to a first propeller, wherein the propeller assembly is selectively powered by the first motor and the second motor;

[0037] a power bus coupled to the first electric machine and the second electric machine; and

[0038] A controller operably coupled to the first power assembly, the first motor, or both and operably coupled to the second power assembly, the second power assembly, or both, wherein the second power assembly is activated if a desired thrust output is within a second power assembly operating range, and the first power assembly is activated if the desired thrust output is greater than the second power assembly operating range.

[0039] Technical Solution 18. A hybrid propulsion system according to any one of the foregoing technical solutions, wherein, during a first operating condition, the desired thrust output is greater than the operating range of the second power component, and the first operating condition includes a take-off flight condition or a climb flight condition.

[0040] Technical Solution 19. The hybrid propulsion system according to any one of the above technical solutions further comprises:

[0041] An energy storage unit is operably coupled to each of the first power assembly, the second power assembly, and the thruster assembly.

[0042] Technical Solution 20. A hybrid propulsion system according to any one of the aforementioned technical solutions, wherein the propeller assembly further comprises a second motor operably connected to a second propeller, wherein the first propeller assembly and the second propeller assembly are powered in parallel.

[0043] These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims.The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the present invention and, together with the description, serve to explain the principles of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] A complete and enabling disclosure of the present invention, including the best mode thereof, to one of ordinary skill in the art is set forth in the specification with reference to the accompanying drawings, in which:

[0045] Figure 1 is a schematic diagram of a propulsion system architecture of an aircraft according to various aspects of the present disclosure;

[0046] Figure 2 is installed according to various aspects of the present disclosure Figure 1 A schematic cross-sectional view of a gas turbine engine of an aircraft;

[0047] Figure 3 is installed according to various aspects of the present disclosure Figure 1 A schematic cross-sectional view of an internal combustion engine of an aircraft;

[0048] Figure 4 is installed according to various aspects of the present disclosure Figure 1 A schematic cross-sectional view of a propeller assembly of an aircraft;

[0049] Figure 5 is a block diagram of a hybrid propulsion system according to various aspects of the present disclosure;

[0050] Figure 6 is a block diagram of a hybrid propulsion system according to various aspects of the present disclosure;

[0051] Figure 7 is a flow chart of a method for operating a hybrid propulsion system for an aircraft according to various aspects of the present disclosure; and

[0052] Figure 8A computing system according to various aspects of the present disclosure. DETAILED DESCRIPTION

[0053] Reference will now be made in detail to the present embodiments of the present invention, one or more examples of which are shown in the accompanying drawings. The detailed description uses numerical and letter designations to refer to features in the drawings. The same or similar designations in the drawings and description are used to refer to the same or similar parts of the present invention.

[0054] As used herein, the terms “first,” “second,” and “third” may be used interchangeably to distinguish one component from another, and are not intended to indicate the position or importance of each component.

[0055] The terms "front" and "rear" refer to relative positions within a gas turbine engine or vehicle and refer to the normal operating attitude of the gas turbine engine or vehicle. For example, with respect to a gas turbine engine, front refers to a position closer to the engine inlet and rear refers to a position closer to the engine nozzle or exhaust.

[0056] The terms "upstream" and "downstream" refer to relative directions with respect to the flow of a fluid in a fluid path. For example, "upstream" refers to the direction from which the fluid is flowing, and "downstream" refers to the direction to which the fluid is flowing.

[0057] The terms "coupled," "fixed," "attached to," and the like refer to both direct coupling, fixing, or attachment as well as indirect coupling, fixing, or attachment through one or more intermediate components or features, unless otherwise indicated herein.

[0058] The singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise.

[0059] As used throughout the specification and claims, approximate language is used to modify any quantitative representation that may be varied without causing a change in the basic function to which it is related. Thus, a value modified by one or more terms such as "about," "approximately," "substantially," and "substantially" is not limited to the precise value specified. In at least some cases, approximate language may correspond to the precision of an instrument used to measure a value, or the precision of a method or machine used to construct or manufacture a component and / or system. For example, approximate language may refer to within a 10% margin.

[0060] Here and throughout the specification and claims, range limitations are combined and interchanged, such that ranges are identified and include all sub-ranges contained therein unless context or language indicates otherwise. For example, all ranges disclosed herein include the endpoints, and the endpoints are independently combinable with each other.

[0061] As used herein, when used in a list of two or more items, the term "and / or" means that any one of the listed items may be used alone, or any combination of two or more of the listed items may be used. For example, if a composition or assembly is described as comprising components A, B, and / or C, the composition or assembly may comprise A alone, B alone, C alone, a combination of A and B, a combination of A and C, a combination of B and C, or a combination of A, B, and C.

[0062] In general, the present disclosure provides a hybrid propulsion system for an aircraft, which includes one or more propeller assemblies. For example, the hybrid propulsion system may include a hybrid propulsion system for an aircraft provided herein, which may include a propeller assembly having at least one propeller and a power generation system. The power generation system may include a first power assembly, a second power assembly, a first motor, and a second motor. The first power assembly may be drivably coupled to the first motor to generate a first amount of electrical power. The second power assembly may be drivably coupled to the second motor to generate a second amount of electrical power.

[0063] In some embodiments, the controller can be operably coupled to the first power assembly, the first motor, or both and operably coupled to the second power assembly, the second power assembly, or both. The controller can be configured to combine at least a portion of the first amount of power and the second amount of power for electrical transmission to the thruster assembly. The controller can also be configured to provide electrical power from the first motor to the thruster assembly under a first operating condition and to provide electrical power from the second motor to the thruster assembly under a second operating condition. In some cases, the first operating condition can be indicated by a command to accelerate or climb the aircraft, and the second operating condition can be indicated by a command to operate the aircraft in a level flight condition. Additionally or alternatively, in various embodiments, the controller can be configured to: receive a desired thrust output, and if the desired thrust output is within the second power assembly operating range, activate the second power assembly, and if the desired thrust output is greater than the second power assembly operating range, activate the first power assembly.

[0064] In some cases, the first power assembly may be deactivated when the aircraft is in the second operating condition, and the second power assembly may be deactivated when the aircraft is in the first operating condition. Additionally or alternatively, one of the first and second thruster assemblies may be used to provide a desired amount of thrust for the aircraft, while the other of the first and second power assemblies may be simultaneously used to generate electrical power for one or more power loads of the aircraft.

[0065] In various embodiments, both the first motor and the second motor are configured to generate electrical power stored in the energy storage unit. In some cases, the second motor may be configured to generate less electrical power than the first motor. For example, the second motor may generate less than half the electrical power of the first motor.

[0066] In some embodiments, the energy storage unit may be operably coupled to each of the first power assembly, the second power assembly, and the thruster assembly. Each of the first power assembly, the second power assembly, and the thruster assembly may be configured to utilize electrical power stored in the energy storage unit.

[0067] By operating according to one or more of these aspects, the hybrid propulsion system provided herein can provide a sufficient amount of thrust output to the aircraft under each operating condition (e.g., take-off, cruise, standby, etc.) of the aircraft, while operating in an efficient manner. For example, the hybrid propulsion system provided herein can use a first power component and a second power component, the first power component is combined with a lightweight, high specific power engine (e.g., a constant combustion engine) for take-off and / or dash conditions, and the second power component is combined with an efficient, low specific power engine (e.g., an intermittent combustion engine) for long-term cruise / standby conditions. In addition, the hybrid propulsion system can also be combined with a propeller assembly using a partial or full electric drive train, which can realize a combination of power from different devices to drive one or more propellers. One or more propellers can be positioned in any feasible position around the aircraft. In various embodiments, through one or more computing systems, based on system power requirements, when each of one or more propellers is turned on or off, various configurations of thrust output can occur, and the propeller assembly can compensate the hybrid propulsion system when a power component is accelerated during power conversion.

[0068] In some embodiments, the first power assembly may be configured as a gas turbine that is lighter than the second power assembly based on a ratio of weight to pounds of thrust that can be generated, and may generate more electrical power and / or thrust than the second power assembly. In contrast, the second power assembly may be configured as an internal combustion engine that is heavier than the first power assembly based on a ratio of weight to pounds of thrust that can be generated, but may have better fuel combustion characteristics than the first power assembly. By creating a hybrid propulsion system that utilizes the first power assembly for high-power takeoff or high-speed conditions, but relies (perhaps only) on the second power assembly for cruise or standby conditions, the capability of the aircraft can be increased while improving the sustainability of the entire mission. In some cases, the hybrid propulsion system provided herein can result in a double-digit range improvement for a multi-gas turbine architecture and a doubling of the range for a diesel-gas turbine architecture when compared to a single gas turbine architecture.

[0069] A system architecture that combines multiple engine types and uses each engine for the portion of the mission for which it is most efficient results in increased performance and reduced fuel burn throughout the mission. The amount of benefit from the combined architecture is based on aloft duration, making the disclosed architecture beneficial for extended endurance applications. Any extended capability and reduced fuel burn compared to currently available propulsion systems is both a commercial and military advantage.

[0070] Referring now to the drawings, in which like numerals refer to like elements throughout the several views, Figure 1 Generally, a schematic diagram of an aircraft 10 is provided that may incorporate various features of the present disclosure. Figure 1 As shown, the aircraft 10 defines a longitudinal centerline 12 extending therethrough, a transverse direction L, a front end portion 14, and a rear end portion 16. In addition, the aircraft 10 includes a fuselage 18 and an empennage 20 at the rear end portion of the aircraft 10, the fuselage 18 extending longitudinally from the front end portion 14 of the aircraft 10 to the rear end portion 16 of the aircraft 10.

[0071] The aircraft 10 may also include a wing assembly including a first port-side wing 22 and a second starboard-side wing 24. The first wing 22 and the second wing 24 each extend transversely outward relative to the longitudinal centerline 12. The first wing 22 and a portion of the fuselage 18 together define a first side 26 of the aircraft 10, and the second wing 24 and another portion of the fuselage 18 together define a second side 28 of the aircraft 10. For the depicted embodiment, the first side 26 of the aircraft 10 is configured as the port side of the aircraft 10, and the second side 28 of the aircraft 10 is configured as the starboard side of the aircraft 10.

[0072] Each of the wings 22, 24 of the depicted embodiment includes one or more flaps 30, which may be in the form of leading edge flaps and one or more trailing edge flaps. The aircraft 10 also includes (or more precisely, the tail 20 of the aircraft 10 includes) a vertical stabilizer 34 and a pair of horizontal stabilizers 36, the vertical stabilizer 34 may have a rudder flap for yaw control, and the horizontal stabilizer 36 each has an elevator flap 38 for pitch control. The fuselage 18 additionally includes an outer surface or skin 40. However, it will be understood that in other embodiments of the present disclosure, the aircraft 10 may additionally or alternatively include any other suitable configuration. For example, in other embodiments, the aircraft 10 may include any other configuration of the stabilizer. In addition, it will be understood that in some embodiments, without departing from the scope of the present disclosure, the aircraft 10 may be configured as a vertical take-off and landing (VTOL) aircraft, a helicopter or any other type of air vehicle.

[0073] In some embodiments, the aircraft 10 may be an unmanned aerial vehicle capable of flying without a human pilot on board. For example, the aircraft 10 may be piloted by, for example, a human operator remotely, or alternatively, may be fully or intermittently autonomous and controlled by onboard and / or offboard computers.

[0074] refer to Figures 1 to 4 , Figure 1 The aircraft 10 may include a hybrid propulsion system 50 having a power generation assembly 32 and one or more propeller assemblies 56, the power generation assembly 32 may include a first power assembly 52 and / or a second power assembly 54. As used herein, "hybrid" may indicate any propulsion system that includes more than one type of power source. For example, in various embodiments, the power generation assembly 32 may include a turbine engine (e.g., a continuous combustion or continuous rotary engine), an internal combustion engine (e.g., an intermittent combustion or reciprocating engine), an electric motor, and / or any other type of machine capable of generating electrical power and / or propulsion for the aircraft 10. For example, Figure 2 A schematic cross-sectional view of a first power component 52 is provided, Figure 3 A schematic cross-sectional view of a second power assembly 54 is provided, and Figure 4 A schematic cross-sectional view of a propulsor assembly 56 is provided, which can be operably coupled to the first power assembly 52 and / or the second power assembly 54. In various embodiments, each of the first power assembly 52 and / or the second power assembly 54 can be configured in an underwing mounting configuration and generate electrical power and / or thrust in a varying manner. Additionally and / or alternatively, the first power assembly 52 and / or the second power assembly 54 can be operably coupled to the fuselage of the aircraft 10, or can be arbitrarily coupled to the aircraft 10 in any other manner. Furthermore, the propulsor assembly can also be configured in an underwing mounting configuration (or any other practical configuration) and provide thrust in response to receiving electrical power from the power generation assembly 32 (and / or the energy storage unit 70). In some embodiments, at least one of the first power assembly 52 or the second power assembly 54 can be supported by the wings 22, 24 of the aircraft 10, and at least one of the first power assembly 52 or the second power assembly 54 can be supported by the fuselage 18 of the aircraft 10.

[0075] Generally speaking Figures 1 to 4 In some embodiments, the hybrid propulsion system 50 may be generally configured such that the first power assembly 52 has a turbine (and possibly a prime mover (for Figure 2 embodiment, which together are configured as a gas turbine engine, or more precisely, a turbofan engine 60)), drivingly coupled to a first electric machine 62 of the turbine (for Figure 2The embodiment depicted in FIG. 1 is an electric motor / generator), a second power component 54 (for Figure 3 An embodiment configured as an internal combustion engine 64), a second electric machine 66 drivingly coupled to the internal combustion engine 64 (for Figure 3 The embodiment depicted in FIG. 5 is an electric motor / generator), a propeller assembly 56 (for Figure 4 , which is configured as an electric motor assembly), an electrical energy storage unit 70 (which can be electrically connected to the first motor 62, the second motor 66 and / or the propulsion assembly 56), a controller 72 and a power bus 74. The propulsion assembly 56, the electrical energy storage unit 70, the first motor 62 and the second motor 66 can each be electrically connected to each other via one or more wires 76 of the power bus 74. For example, the power bus 74 may include various switches or other power electronic devices 78 that are movable to selectively electrically connect various components of the hybrid propulsion system 50. In addition, the power bus 74 may also include power electronic devices 78 (such as inverters, converters, rectifiers, etc.) for regulating or converting electrical power within the hybrid propulsion system 50. In some cases, at least one of the first power assembly 52 or the second power assembly 54 is also configured to provide thrust to the aircraft 10 when the at least one of the first power assembly 52 or the second power assembly 54 is in operation.

[0076] As will be appreciated, the controller 72 may be configured to distribute electrical power between various components of the hybrid propulsion system 50. For example, the controller 72 may operate with a power bus 74 (including one or more switches or other power electronics 78) to provide electrical power to or draw electrical power from various components (such as the first electric machine 62, the second electric machine 66, and / or the motor of the propulsion assembly 56) to operate the hybrid propulsion system 50 between various conditions and perform various functions. This is schematically depicted as wires 76 extending through the power bus 74 of the controller 72. In some cases, the controller 72 may be configured to provide a desired thrust output from the propulsion assembly 56. In some cases, in response to receiving a command to operate in a first operating condition (such as accelerating or climbing the aircraft 10), electrical power is provided from the first power assembly 52 to the propulsion assembly 56, and in response to receiving a command to operate in a second condition (such as operating in a level flight condition, an idle condition, or a standby condition), electrical power is provided from the second power assembly 54 to the propulsion assembly 56. In some cases, the first power assembly 52 may be disabled when the aircraft 10 is in the second operating condition, and the second power assembly 54 may be disabled when the aircraft 10 is in the first operating condition. Additionally or alternatively, one of the first and second thruster assemblies may be used to provide a desired amount of thrust to the aircraft 10, while the other of the first and second power assemblies 54 may be used to simultaneously provide a desired amount of thrust to the aircraft 10. Figure 6 ) generates electrical power. Additionally or alternatively, the controller 72 may be configured to receive a desired thrust output and activate the second power assembly 54 if the desired thrust output is within the second power assembly operating range, and activate the first power assembly 52 if the desired thrust output is greater than the second power assembly operating range. In some cases, both the first power assembly 52 and the second power assembly 54 may simultaneously generate electrical power that may be used by the propulsion assembly 56.

[0077] The controller 72 may be a stand-alone controller dedicated to the hybrid propulsion system 50, or alternatively, may be integrated into one or more of the main system controller of the aircraft 10, a separate controller for the turbofan engine 60 (such as a full authority digital engine control system, also known as FADEC, for the turbofan engine 60), a separate controller for the internal combustion engine 64 (such as a FADEC), etc. For example, the controller 72 may be integrated with the main system controller of the aircraft 10, such as the main system controller of the aircraft 10, and the like. Figure 8 The computing system 500 described is configured in substantially the same manner (and may be configured to perform one or more of the functions of the method 300 described below).

[0078] The electrical energy storage unit 70 may be configured as one or more batteries, one or more capacitors, or any other suitable electrical energy storage device. It will be appreciated that for the hybrid propulsion system 50 described herein, the electrical energy storage unit 70 is configured to store a relatively large amount of electrical power. For example, in various embodiments, the electrical energy storage unit may be configured to store at least about fifty kilowatt-hours of electrical power, such as at least about sixty-five kilowatt-hours of electrical power, such as at least about seventy-five kilowatt-hours of electrical power, and up to about one thousand kilowatt-hours of electrical power.

[0079] Reference now Figure 1 and Figure 2 , the first power assembly 52 includes a gas turbofan engine 60 that is mounted or configured to be mounted to the first wing 22 or the second wing of the aircraft 10. In some embodiments (such as Figure 2 In the embodiment shown in the figure, the gas turbine engine includes a turbine 102 and a propeller, which is a fan (refer to Figure 2 is referred to as "fan 104"). Therefore, for Figure 2 In the embodiment of the present invention, the gas turbine engine is configured as a turbofan engine 60 .

[0080] The turbofan engine 60 defines an axial direction A1 (extending parallel to a longitudinal axis 101 provided for reference) and a radial direction R1 . As stated, the turbofan engine 60 includes a fan 104 and a turbine 102 disposed downstream of the fan 104 .

[0081] The depicted turbine 102 generally includes a substantially tubular outer casing 106 defining an annular inlet 108. The outer casing 106 encloses, in series flow relationship: a compressor section including a boost or low pressure (LP) compressor 110 and a high pressure (HP) compressor 112; a combustion section 114; a turbine section including a first high pressure (HP) turbine 116 and a second low pressure (LP) turbine 118; and an ejection exhaust nozzle section 120. The compressor section, combustion section 114, and turbine section together at least partially define an air flow path 121 through the turbine 102.

[0082] The turbine 102 of the turbofan engine 60 further includes one or more shafts that are capable of rotating with at least a portion of the turbine section and (for the depicted embodiment) with at least a portion of the compressor section. More specifically, for the depicted embodiment, the turbofan engine 60 includes a high pressure (HP) shaft or spool 122 that drivingly connects the HP turbine 116 to the HP compressor 112. Additionally, the turbofan engine 60 includes a low pressure (LP) shaft or spool 124 that drivingly connects the LP turbine 118 to the LP compressor 110.

[0083] In addition, the depicted fan 104 is configured as a variable pitch fan having a plurality of fan blades 128 coupled to a disk 130 in a spaced apart manner. The fan blades 128 extend outwardly from the disk 130 generally along a radial direction R1. Since the fan blades 128 are operatively coupled to suitable actuating members 132 configured to jointly change the pitch of the fan blades 128, each fan blade 128 is capable of rotating about a corresponding pitch axis P1 relative to the disk 130. The fan 104 is mechanically coupled to the LP shaft 124 so that the fan 104 is mechanically driven by the second LP turbine 118. More specifically, the fan 104 including the fan blades 128, the disk 130, and the actuating members 132 is mechanically coupled to the LP shaft 124 through a power gearbox 134, and is capable of rotating about the longitudinal axis 101 through the LP shaft 124 across the power gearbox 134. The power gearbox 134 includes a plurality of gears for stepping down the rotational speed of the LP shaft 124 to a more efficient fan rotational speed. Thus, the fan 104 is powered by the LP system of the turbomachine 102 (including the LP turbine 118).

[0084] Still reference Figure 2In an embodiment of the present invention, the disk 130 is covered by a rotatable forward hub 136 that is aerodynamically contoured to facilitate airflow through the plurality of fan blades 128. In addition, the turbofan engine 60 includes an annular fan case or outer nacelle 138 that circumferentially surrounds the fan 104 and / or at least a portion of the turbine 102. Thus, the depicted turbofan engine 60 may be referred to as a "ducted" turbofan engine. In addition, the nacelle 138 is supported relative to the turbine 102 by a plurality of circumferentially spaced outlet guide vanes 140. A downstream section 142 of the nacelle 138 extends over an outer portion of the turbine 102 so as to define a bypass airflow passage 144 therebetween.

[0085] Further references Figure 2 , the hybrid propulsion system 50 additionally includes a first electric machine 62, which, for the depicted embodiment, is configured as an electric motor / generator. For the depicted embodiment, the first electric machine 62 is positioned within the turbine 102 of the turbofan engine 60 inside the air flow path 121, and may be coupled to or in mechanical communication with one of the shafts of the turbofan engine 60. For example, for the depicted embodiment, the electric machine is coupled to the second LP turbine 118 via the LP shaft 124. The first electric machine 62 may be configured to convert the mechanical power of the LP shaft 124 into electrical power (such that the LP shaft 124 drives the first electric machine 62), or alternatively, the first electric machine 62 may be configured to convert the electrical power provided to it into mechanical power for the LP shaft 124 (such that the first electric machine 62 drives or assists in driving the LP shaft 124). Thus, the turbine 102 may be used to generate electrical power that may be utilized by the propulsion assembly 56, thrust for the aircraft 10, or both.

[0086] It will be appreciated that in other embodiments, the first motor 62 may instead be positioned at any other suitable location or elsewhere within the turbine 102. For example, in other embodiments, the first motor 62 may be mounted within the turbine section coaxially with the LP shaft 124, or alternatively may be offset from the LP shaft 124 and driven by a suitable gear train. Additionally or alternatively, in other embodiments, the first motor 62 may instead be powered by the HP system, such as by the HP turbine 116 through, for example, the HP shaft 122, or by both the LP system (e.g., the LP shaft 124) and the HP system (e.g., the HP shaft 122) via a dual drive system. Additionally or yet alternatively, in other embodiments, the first motor 62 may include multiple motors, such as one drivingly connected to the LP system (e.g., the LP shaft 124) and one drivingly connected to the HP system (e.g., the HP shaft 122). Furthermore, although the first motor 62 is described as an electric motor / generator, in other embodiments, the first motor 62 may be configured as a generator only.

[0087] In various embodiments, the first motor 62 may be configured to generate at least about ten kilowatts of electrical power when driven by the turbine 102, such as at least about fifty kilowatts of electrical power, such as at least about sixty-five kilowatts of electrical power, such as at least about seventy-five kilowatts of electrical power, such as at least about one hundred kilowatts of electrical power, such as up to five thousand kilowatts of electrical power, such as up to eight hundred and fifty kilowatts of electrical power, such as up to nine hundred kilowatts of electrical power. Additionally or alternatively, the first motor 62 may be configured to provide or otherwise increase the horsepower (hp) of mechanical power to the turbine 102 when the first motor 62 is provided with electrical power from, for example, the electrical energy storage unit 70 of the second power assembly 54. For example, in various embodiments, the first motor 62 may be configured to provide at least about fifteen (such as at least about fifty) horsepower of mechanical power to the turbine 102, such as at least about seventy-five horsepower, such as at least about one hundred horsepower, such as at least about one hundred and twenty horsepower, such as up to about seven thousand horsepower.

[0088] Still reference Figure 1 and Figure 2 , the turbofan engine 60 also includes a controller 150 such as a FADEC and a plurality of sensors. The controller 150 of the turbofan engine 60 may be configured to control the operation of, for example, the actuating member 132, the fuel delivery system, etc. In addition, again referring to Figure 1 , the controller 150 of the turbofan engine 60 is operably connected to the controller 72 of the hybrid propulsion system 50. In addition, the controller 72 may also be operably connected to one or more of the first power assembly 52 (including the controller 150), the first motor 62, the second power assembly 54, the second motor 66, the propeller assembly 56, and the energy storage unit 70 via a suitable wired or wireless communication system (depicted in phantom).

[0089] In various embodiments, the turbofan engine 60 may also include one or more sensors positioned and configured to sense data indicative of one or more operating parameters of the turbofan engine 60. For example, the turbofan engine 60 may include one or more temperature sensors configured to sense a temperature within the air flow path 121 of the turbine 102. For example, such a sensor may be configured to sense the exhaust temperature at the outlet of the combustion section 114. Additionally or alternatively, the turbofan engine 60 may include one or more pressure sensors to sense data indicative of a pressure within the air flow path 121 of the turbine 102, such as within a combustor within the combustion section 114 of the turbine 102. Furthermore, in still other embodiments, the turbofan engine 60 may also include one or more speed sensors configured to sense data indicative of a rotational speed of one or more components of the turbofan engine 60, such as one or more of the LP spool 124 or the HP spool 122. Additionally, in various embodiments, the turbofan engine 60, the hybrid propulsion system 50 as a whole, and / or the aircraft 10 incorporating the hybrid propulsion system 50 may include one or more environmental condition sensors, such as one or more ambient temperature sensors, positioned outside the air flow path 121 of the turbine 102 for sensing data indicative of an environmental condition, such as ambient temperature. Thus, in at least various embodiments, the hybrid propulsion system 50 may receive information about one or more environmental conditions from the aircraft 10. However, it is noted that in other embodiments, the environmental condition may be sensed within the air flow path 121 of the turbine 102 (e.g., at the inlet 108).

[0090] It should also be understood that in other embodiments, Figure 2 The turbofan engine 60 depicted in FIG. 1 may have any other suitable configuration. For example, in other embodiments, the fan 104 may not be a variable pitch fan, and further, in other embodiments, the LP shaft 124 may be directly mechanically coupled to the fan 104 (e.g., the turbofan engine 60 may not include the gearbox 134). Furthermore, it should be understood that in other embodiments, the turbofan engine 60 may be configured as any other suitable gas turbine engine. For example, in other embodiments, the turbofan engine 60 may instead be configured as a turboprop engine, an unducted turbofan engine, a turbojet engine, a turboshaft engine, etc.

[0091] Reference now Figure 1 and Figure 3 As stated above, the hybrid propulsion system 50 may further include a second power assembly 54 for Figure 1In the embodiment depicted in FIG. 1 , the second power assembly 54 is mounted to the fuselage 18 (directly or indirectly) and / or one or more of the first wing 22 and the second wing 24 of the aircraft 10 . Figure 3 As shown, in some embodiments, the second power assembly 54 may be generally configured as an internal combustion engine 64 and a propeller. The internal combustion engine 64 defines an axial direction A2 (extending parallel to a longitudinal centerline 162 provided for reference) and a radial direction R2.

[0092] In some embodiments, the internal combustion engine 64 includes an engine block 164 that forms the primary structure of the internal combustion engine 64 and contains and / or defines many of the internal features of the internal combustion engine 64. The engine block 164 is constructed and arranged to define a crankcase 166 and a plurality of cylinders 168. In various embodiments, the crankcase 166 is oriented substantially parallel to the longitudinal centerline 162 of the internal combustion engine 64. The crankcase 166 houses a crankshaft 170 disposed along the longitudinal centerline 162.

[0093] Still reference Figure 1 and Figure 3 , the plurality of cylinders 168 may include two to twelve (or more) cylinders, such as four to twelve cylinders, such as four to eight cylinders, and such as six cylinders. The cylinders 168 are arranged so that they extend upward from the crankcase 166. Each cylinder 168 may extend at an angle relative to the radial direction R2 perpendicular to the longitudinal centerline. As the number of cylinders 168 increases, for example, to six cylinders, the cylinders 168 may alternate in a configuration that may be referred to as a "V" configuration on opposite sides of the radial direction R2, thereby forming a "V-type" internal combustion engine 64 with three cylinders on each side of the internal combustion engine 64. It is understood that in order to save space, the two cylinders may be substantially opposite to each other, rather than being arranged in a completely alternating manner.

[0094] In various embodiments, each cylinder 168 is configured to slidably receive a piston 172 that is operatively connected to the crankshaft 170 via a connecting rod 174. Each connecting rod 174 is rotatably connected to one of the pistons 172 at one end portion and is rotatably connected to the crankshaft 170 at an opposite end portion via a pin-type crankshaft journal 176. The piston 172 reciprocates linearly within the cylinder 168. In turn, the connecting rod 174 converts the linear movement of the piston 172 into the rotational movement of the crankshaft 170, and vice versa.

[0095] In some embodiments, crankcase 166 may include at least one crank chamber 178, and in various embodiments, crankcase 166 may include one isolated crank chamber 178 for each pair of substantially opposed cylinders 168. A bore 180 may extend through crankcase 166 and each of crank chambers 178. Crankshaft 170 is received by bore 180. In some examples, a balance shaft 182 may also extend through crankcase 166. Balance shaft 182 is provided to counteract the torque generated by the rotation of crankshaft 170 and piston assembly, which torque produces a first order mass moment imbalance. Balance shaft 182 and crankshaft 170 extend through crankcase 166 in a parallel relationship, as shown in FIG. Figure 3 As shown. Balance shaft 182 is rotatably mounted in an inner bore 184 extending through crankcase 166. Suitable bearing assemblies provide for smooth rotation of balance shaft 182. Balance shaft 182 is operatively connected to crankshaft 170 via gear 186, which may be located in gear box 188 at one end portion of crankcase 166.

[0096] In some embodiments, the intake system 190 may be constructed and arranged to receive air from the environment and deliver the air to the intake passage. A throttle valve 196 may be disposed in the inlet of the intake system 190 and may be controlled by a controller 198. The throttle valve 196 may be mechanically or electrically movable to increase or decrease the amount of air entering the intake system 190, and thus help control the rotational speed of the crankshaft 170. It will be appreciated that in some embodiments, the internal combustion engine 64 may include a turbocharger that may be mounted to the internal combustion engine 64. In such embodiments, the turbocharger may include an internal turbine that in turn drives a compressor for compressing the intake air. Therefore, the turbocharger may be designed to increase the pressure of the intake system 190's introduced air.

[0097] The internal combustion engine 64 described herein may be configured to provide a total engine output of about one hundred and forty to about six hundred horsepower (hp). For example, the total engine output is about one hundred and fifty to about five hundred horsepower, about one hundred and sixty to about four hundred horsepower, about one hundred and seventy to about three hundred and seventy-five horsepower, and / or about one hundred and eighty to about three hundred and fifty horsepower. In various embodiments, the total engine output may be about two hundred and twenty horsepower for a naturally aspirated internal combustion engine 64, and may be about three hundred horsepower for a turbocharged internal combustion engine 64. In some embodiments, the second power assembly 54 (or internal combustion engine 64) may be configured to rotate and generate electrical power.

[0098] In some embodiments, the internal combustion engine 64 may also include a propeller shaft 200 that is operatively connected to the internal combustion engine 64 and is also operatively connected to the propeller 160. For example, the propeller shaft 200 is connected to the propeller 160 at one end portion and is connected to the gearbox 202 at an opposite end portion. In some embodiments, the gearbox 202 is constructed and arranged to rotate the propeller shaft 200, and therefore the propeller 160, at a speed of about one hundred to about three thousand revolutions per minute when the internal combustion engine 64 is operating under normal conditions.

[0099] In addition, in an embodiment including a propeller 160, a variable pitch fan having a plurality of propeller blades 210 can be coupled to a disk 212 in a spaced manner. The propeller blades 210 extend outwardly from the disk 212 generally along a radial direction R2. Since the propeller blades 210 are operatively coupled to a suitable actuating member 214 configured to jointly change the pitch of the propeller blades 210, each propeller blade 210 can rotate relative to the disk 212 around a corresponding pitch axis P2. The propeller 160 is mechanically coupled to the propeller shaft 200 so that the propeller 160 is mechanically driven by the crankshaft. More specifically, the propeller 160 including the propeller blades 210, the disk 212 and the actuating member 214 is mechanically coupled to the crankshaft 170 through a gearbox 202, which may also be referred to as a reduction unit or a propeller reduction unit. Therefore, the propeller 160 can be powered by the crankshaft 170 of the internal combustion engine 64.

[0100] In some embodiments, the second motor 66 may be disposed at one or both end portions of the crankshaft 170. When the crankshaft 170 drives the second motor 66 (either through a connection with the crankshaft 170 or through an additional shaft 216 that rotates with the crankshaft 170), the second motor 66 may be configured to convert the mechanical power of the crankshaft 170 into electrical power. The electrical power is then transmitted from the second motor 66 to the one or more electrical wires 76. Alternatively, the second motor 66 may be configured to convert the electrical power supplied thereto into mechanical power for the crankshaft 170, such that the second motor 66 drives or assists in driving the crankshaft 170 through the one or more electrical wires 76.

[0101] It will be appreciated that in some embodiments, the second electric machine 66 may instead be positioned at any other suitable location within the internal combustion engine 64 or elsewhere. For example, in other embodiments, the second electric machine 66 may be mounted coaxially with the propeller shaft 200 (or coupled to the propeller shaft in place of a propeller), or alternatively may be offset from the crankshaft 170 and / or the propeller shaft 200 and driven by a suitable gear train. Furthermore, while the second electric machine 66 is described as an electric motor / generator, in other embodiments, the second electric machine 66 may be configured solely as a generator.

[0102] Notably, in various embodiments, the second electric machine 66 can be configured to generate at least about ten kilowatts of electric power when driven by the internal combustion engine 64, such as at least about fifty kilowatts of electric power, such as at least about sixty-five kilowatts of electric power, such as at least about seventy-five kilowatts of electric power, such as at least about one hundred kilowatts of electric power, such as up to four hundred kilowatts of electric power.

[0103] Still reference Figure 1 and Figure 3 , the internal combustion engine 64 also includes a controller 198 and a plurality of sensors, and the controller 198 may be a FADEC system. The controller 198 of the internal combustion engine 64 may be configured to monitor and control many operating parameters of the internal combustion engine 64. For example, the controller 198 may monitor and control the air-fuel ("air / fuel") ratio or fuel richness provided to the combustion chamber. This may be achieved by controlling the amount of fuel injected. The controller 198 may additionally or alternatively monitor and control the rotational speed of the crankshaft 170, which may be achieved by controlling the amount of fuel and air provided to the combustion chamber. The controller 198 may also provide propeller pitch control, which allows the internal combustion engine 64 to operate more efficiently. In addition, again referring to Figure 1 , the controller 198 of the internal combustion engine 64 is operably connected to the controller 72 of the hybrid propulsion system 50 .

[0104] Now specifically refer to Figure 1 and Figure 4 As previously stated, the hybrid propulsion system 50 may additionally include a propeller assembly 56 for Figure 1 In the embodiment depicted in FIG. 1 , the propeller assembly 56 is mounted to the first wing 22 and the second wing 24 of the aircraft 10 . Figure 4 As shown, in some embodiments, the propeller assembly 56 may include an electric motor 240 and at least one aerodynamic propeller / fan 242 / 104. The propeller assembly 56 defines an axial direction A3 and a radial direction R3, the axial direction A3 extending along a longitudinal centerline axis 244, and the longitudinal centerline axis 244 extending through the propeller assembly 56 for reference. For the depicted embodiment, the propeller 242 is capable of rotating about the centerline axis 244 by the electric motor 240.

[0105] In some embodiments, at least one aerodynamic propeller 242 may include a plurality of fan blades 246 and a fan shaft 248. A plurality of fan blades 246 are attached to / can rotate with the fan shaft 248 and are generally spaced apart along the circumferential direction of the propeller assembly 56. In various embodiments, a plurality of fan blades 246 may be attached to the fan shaft 248 in a fixed manner, or alternatively, a plurality of fan blades 246 may be rotatable relative to the fan shaft 248, such as in the depicted embodiment. For example, a plurality of fan blades 246 each define a corresponding pitch axis P3, and for the depicted embodiment are attached to the fan shaft 248, so that the pitch of each of the plurality of fan blades 246 can be changed, for example, in unison by a pitch changing mechanism 250. Changing the pitch of a plurality of fan blades 246 may increase the efficiency of the propeller assembly 56 and / or may allow the propeller assembly 56 to obtain a desired thrust distribution. For such an embodiment, the propeller 242 may be referred to as a variable pitch fan.

[0106] Moreover, for the depicted embodiment, the depicted propeller assembly 56 additionally includes a fan housing or outer nacelle 252, which is attached to the core 254 of the propeller assembly 56 by one or more struts or outlet guide vanes 256. For the depicted embodiment, the outer nacelle 252 substantially completely surrounds at least one aerodynamic propeller 242, and in particular, the plurality of fan blades 246. Thus, for the depicted embodiment, the propeller assembly 56 may be referred to as a ducted electric fan. However, in some embodiments, the propeller assembly 56 may be configured as a non-ducted fan, which does not include the outer nacelle 252.

[0107] Still reference Figure 4 , the fan shaft 248 is mechanically coupled to the electric motor 240 within the core 254, such that the electric motor 240 drives the propeller 242 via the fan shaft 248. The fan shaft 248 is supported by one or more bearings 258, such as one or more roller bearings, ball bearings, or any other suitable bearings. In addition, the electric motor 240 may be an inner rotor electric motor (e.g., including a rotor positioned radially inwardly of a stator), or alternatively may be an outer rotor electric motor (e.g., including a stator positioned radially inwardly of a rotor), or yet alternatively may be an axial flux electric motor (e.g., the rotor is neither external nor internal to the stator, but is offset from the stator along the axis of the electric motor).

[0108] As briefly described above, the electric power source (e.g., the first electric machine 62, the second electric machine 66, and / or the electric energy storage unit 70) is electrically connected to the thruster assembly 56 (e.g., the electric motor 240) for providing electric power to the thruster assembly 56. For example, in some embodiments, the electric motor 240 is electrically connected to the first electric machine 62, the second electric machine 66, and / or the electric energy storage unit 70 via the electric power bus 74 (and more specifically, via one or more cables or lines 76 extending therebetween).

[0109] Still reference Figure 1 and Figure 4 The propeller assembly 56 also includes a controller 260 and a plurality of sensors. The controller 260 may be a FADEC system. The controller 260 of the propeller assembly 56 may be configured to monitor and control a number of operating parameters of the electric motor 240. For example, the controller 260 may monitor and control the rotational speed of at least one aerodynamic propeller, the pitch of at least one aerodynamic propeller, etc. In addition, referring again to Figure 1 , the controller 260 of the propulsion assembly 56 is operably connected to the controller 72 of the hybrid propulsion system 50 .

[0110] It should be appreciated that, in various embodiments, the hybrid propulsion system 50 may have any other suitable configuration and, further, may be integrated into the aircraft 10 in any other suitable manner. For example, in other embodiments, the propulsion assembly 56 of the hybrid propulsion system 50 may instead be configured as a plurality of propulsion assemblies 54 that are distributed around the aircraft in any feasible manner while being electrically coupled to the first power assembly 52, the second power assembly 54, the energy storage unit 70, or any combination thereof.

[0111] In various embodiments, the electric thruster assembly(s) 200, the gas turbine engine(s), the first electric machine(s) 62, the internal combustion engine(s) 64, and the second electric machine(s) 66 may be mounted to the aircraft 10 in any other suitable manner, including, for example, a tail-mounted configuration, and at any other suitable location. For example, in various embodiments, the electric thruster assembly may be configured to ingest boundary layer air and re-energize such boundary layer air to provide a propulsive benefit to the aircraft 10 (the propulsive benefit may be thrust, or may simply increase the overall net thrust of the aircraft 10 by reducing drag on the aircraft 10).

[0112] refer to Figure 5 and Figure 6, the hybrid propulsion system 50 includes a first electric machine 62, a second electric machine 66, and an electrical energy storage unit 70 that can be electrically connected to the electric motor 240 of the propulsion assembly 56. It will be understood that the hybrid propulsion system 50 provided herein may include any number of first power assemblies, second power assemblies, and / or propulsion assemblies located on any portion of the aircraft 10.

[0113] The first electric machine 62 is further coupled to the turbine 102. In this manner, the first electric machine 62 can extract power from the turbine 102 and / or provide power to the first turbine 102. The second electric machine 66 is further coupled to the internal combustion engine 64. In this manner, the second electric machine 66 can extract power from the internal combustion engine 64 and / or provide power to the internal combustion engine 64.

[0114] Further references Figure 5 In some embodiments, the first power assembly 52 may be configured as a continuous combustion engine, such as a turbine engine, a turboprop engine, an unducted turbofan engine 60, a turbojet engine, a turboshaft engine, etc. In various embodiments, the first power assembly 52 may be capable of generating up to three thousand horsepower, such as five hundred horsepower to two thousand five hundred horsepower, such as one thousand horsepower to two thousand horsepower, such as one thousand eight hundred horsepower to two thousand five hundred horsepower.

[0115] The first electric machine 62 can be integrated within the first power assembly 52 and configured as a motor / generator. In various embodiments, the first electric machine 62 can be configured to generate a first amount of electrical power that can be up to one megawatt (mW), such as up to nine hundred kilowatts (kW), such as up to eight hundred and fifty kW, during operation of the first power assembly 52 when operating in a generator mode.

[0116] In some embodiments, the second power assembly 54 may be configured as a reciprocating engine and / or a fuel cell assembly coupled to the propulsion assembly 56. For example, the second power assembly 54 may be configured as an internal combustion engine 64, which may be configured as a two-stroke engine (e.g., Clark cycle, diurnal cycle, etc.), a four-stroke engine (e.g., Otto cycle), a six-stroke engine, or any other number of strokes. In addition, the internal combustion engine 64 may be configured as a compression ignition engine and / or a spark ignition engine. In addition, the internal combustion engine 64 may be configured to operate through a mechanical / thermodynamic cycle (e.g., Atkinson cycle, Miller cycle, etc.) and / or a rotary engine (e.g., Wankel engine). In various embodiments, the second power assembly 54 may be configured to generate up to seven hundred and fifty horsepower, such as one hundred to seven hundred horsepower, such as two hundred to five hundred horsepower.

[0117] The second electric machine 66 may be operably coupled to the second power assembly 54 and configured as a motor / generator. In various embodiments, the second electric machine 66 may be configured to generate a second amount of electric power that may be up to eight hundred kW, such as between fifty and five hundred kW, such as between one hundred and four hundred and fifty kW, such as between one hundred and fifty and three hundred and seventy-five kW, or any other feasible range when operating in a generator mode, during operation of the first power assembly 52. ​​In some embodiments, the second electric machine 66 may be configured to generate less electric power than the first electric machine 62. For example, the second electric machine 66 may generate less than half the electric power of the first electric machine 62.

[0118] In some embodiments, the first power assembly 52 is drivingly coupled to the first electric machine 62 to generate a first amount of electric power, and the second power assembly 54 is drivingly coupled to the second electric machine 66 to generate a second amount of electric power. In some cases, the second power assembly 54 can be configured to generate the second amount of electric power more efficiently than the first power assembly 52 generates the first amount of electric power. For example, as provided herein, the first power assembly 52 can be a continuous combustion engine 60 (or any other type of engine) that operates at a first efficiency at idle speed (e.g., 10-60% of maximum output), operates at a second efficiency at a mid-range operating speed (e.g., 50-90% of maximum output), and / or operates at a third efficiency at maximum output (e.g., 90-100% of maximum output). The second power assembly 54 may be an internal combustion engine 64 (or any other type of engine) that operates at a fourth efficiency at idle speed (e.g., 10-60% of maximum output), at a fifth efficiency at mid-range operating speeds (e.g., 50-90% of maximum output), and / or at a sixth efficiency at maximum output (e.g., 90-100% of maximum output). In some cases, each of the first power assembly 52 and the second power assembly 54 may use a combustible fuel so as to operate at a defined efficiency.

[0119] In some cases, when configured as a turbine, the first power assembly 52 is most efficient at maximum power output, so that the third efficiency is greater than the first efficiency. In contrast, when operating at a lower rotational speed, the pressure of the compressed air within the first power assembly 52 drops, and therefore the thermal efficiency and fuel efficiency within the first power assembly 52 drop sharply. Therefore, the efficiency of the first power assembly 52 can steadily decrease as the power output decreases, and can be lower in the low power range. In contrast, the fourth, fifth, and sixth efficiencies can be generally within a predetermined percentage (such as 15%) of each other. In some cases, the fourth, fifth, and sixth efficiencies can be greater than the first efficiency and / or less than the third efficiency. It is to be understood that the efficiencies provided herein are related to the amount of fuel consumed by the propulsion generated by the propeller assembly.

[0120] Additionally or alternatively, in various embodiments, the first power assembly 52 may be configured to operate within a first range of revolutions per minute. The second power assembly 54 may be configured to operate within a second range of revolutions per minute that is at least partially less than or greater than the first range of revolutions per minute. In some cases, due to various engine designs between the first and second power assemblies, the variation in revolutions per minute between the first power assembly 52 and the second power assembly 54 may be considerable.

[0121] Additionally or alternatively, in various embodiments, the first power assembly generates a first noise level when operating at idle or at any other defined speed, and the second power assembly generates a second noise level when operating at idle or at any other defined speed. In various embodiments, the first noise level may be greater than the second noise level when operating at a common operating speed and / or operating parameters.

[0122] In some embodiments, the thruster assembly 56 may include one or more electric motors, and it will be appreciated that Figure 5 In the embodiment depicted in FIG. 1 , the propeller assembly 56 may be configured as a purely electric propeller assembly, wherein the electric motor 240 of the propeller assembly 56 is independently coupled to the propeller 242. Figure 6 In other embodiments of the embodiment depicted in , the propulsion assembly 56 may be configured as part of a hybrid propulsion system, wherein at least one of the first and / or second power assemblies may utilize at least one electric motor 240 of the propulsion assembly 56 to rotate a common propeller 242. In various embodiments, the power load of each electric motor 240 within the propulsion assembly 56 may be up to twenty lbf / hp, such as between one and ten lbf / hp, such as between two and eight lbf / hp. In some embodiments, the propulsion assembly 56 may include more than one motor and / or more than one propeller. Each of the propellers 242 may be ducted and / or unducted in any manner and distributed around the aircraft 10. In various embodiments, the propulsion assembly 56 may include any number of motors that may be operably coupled to any one or more propellers 242. Each of the one or more propellers 242 may be operably coupled in parallel and / or in series.

[0123] In some embodiments, the first power assembly 52 and the second power assembly 54 are provided with power in parallel. Additionally or alternatively, the first power assembly 52 and the second power assembly 54 are provided with power in parallel. Therefore, different first power assemblies 52 and second power assemblies 54 can be connected in series (electrical transmission) and in parallel to transmit power based on the mechanical connection between the first power assembly 52 and the second power assembly 54. For example, the first power assembly 52 can provide power to the power electronic device 78 through the rotation of the first motor 62 and / or through the second motor 66. Similarly, the second power assembly 54 can provide power to the power electronic device 78 through the second motor 66 and / or through the rotation of the first motor 62 operably coupled to the first power assembly 52.

[0124] If still Figure 5 As depicted in , the hybrid propulsion system 50 also includes a controller 72 and a power bus 74. The various components of the first power assembly 52, the second power assembly 54, the propeller assembly 56, and the energy storage unit 70 are each capable of being electrically connected to each other via one or more wires 76 of the power bus 74. For example, the power bus 74 may include various switches or other power electronic devices 78, which are movable to selectively electrically connect the various components of the hybrid propulsion system 50, and optionally convert or regulate the electrical power transmitted therethrough. Thus, in certain operations, the first motor 62 may provide electrical power to the propeller assembly 56, and vice versa. In addition, in certain operations, the first motor 62 may provide electrical power to the second motor 66 and / or the second power assembly 54, and vice versa. Similarly, in certain operations, the second power assembly 54 and / or the second motor 66 may provide electrical power to the propeller assembly 56, and vice versa. Additionally or alternatively, the first electric machine 62 and / or the second electric machine 66 may provide electrical power to the electrical energy storage unit 70, or the electrical energy storage unit 70 may provide electrical power to the first power assembly 52, the second power assembly 54, and / or the thruster assembly 56. In various embodiments, based on the power requirements of the system 50, various configurations of thrust output may occur when each power assembly 52, 54 is turned on or off, and each power assembly 52, 54 may be slowed down while the other power assembly 52, 54 is accelerated during power conversion.

[0125] Reference Figure 6, the hybrid propulsion system 50 may include one or more propellers 242 that are operably coupled to more than one of the first power assembly 52, the second power assembly 54, and / or the propeller assembly 56. For example, in some embodiments, the propeller 242 may be operably coupled to the first power assembly 52 and the propeller assembly 56. In some embodiments, the propeller 242 may additionally be operably coupled to the second power assembly 54. Alternatively, in some embodiments, the propeller 242 may be coupled to the second power assembly 54 and the propeller assembly 56. Additionally or alternatively, the first propeller 242 may be coupled to the first power assembly 52 and the propeller assembly 56, while the second propeller 242 is operably coupled to the second power assembly 54 and the propeller assembly 56.

[0126] One or more variable thrust assemblies 270 may be positioned within the hybrid propulsion system 50 to allow at least one aerodynamic propeller 242 to be selectively coupled to one or more of the power assemblies 52, 54 and the propulsion assembly(ies) 56. For example, in various embodiments, the variable thrust assembly 270 may be configured as a clutch assembly and / or a pitch change mechanism 250 ( Figure 4 ). In some embodiments, the propeller assembly 56 can rotate the propeller 242 via the variable thrust assembly 270 while the first power assembly 52 and / or the second power assembly 54 are disengaged from the fan. When disengaged, the first power assembly 52 and / or the second power assembly 54 can continue to generate electrical power via the corresponding first motor 62 and second motor 66. The generated electrical power can be used by the propeller assembly 56, provided to the energy storage unit 70, and / or used by one or more power loads 272 of the aircraft 10.

[0127] like Figure 6 As depicted, each of the first power assembly 52, the second power assembly 54, and the thruster assembly 56 may be operably coupled to the controller 72 and one or more common power electronics 78. In some cases, the power electronics 78 may be configured, for example, to provide or enable electrical power conversion operations (e.g., AC to DC conversion, DC to AC conversion, first DC power to second DC power, etc.) to selectively enable or disable power delivery to one or more specific thruster assemblies and / or power loads 272, depending on, for example, available power distribution supplies, criticality of electrical load functionality, or aircraft operating modes (such as takeoff, cruise, standby, or ground operations).

[0128] Reference now Figure 7 , a flow chart of a method 300 for operating a hybrid propulsion system 50 of an aircraft 10 is provided. The method 300 may be generally similar to that described above with reference to Figures 1 to 6The hybrid propulsion system 50 may be configured to operate with one or more of the hybrid propulsion systems 50 described herein. For example, the hybrid propulsion system 50 may generally include a first power assembly 52 operably coupled to a first electric machine 62, a second power assembly 54 operably coupled to a second electric machine 66, and a propeller assembly 56 including a propeller 242. In some cases, the propeller assembly 56 may be operably coupled to at least one of the first electric machine 62 and the second electric machine 66.

[0129] As depicted, method 300 includes receiving, at (302), by one or more computing devices, a command to provide a desired thrust output. In some cases, receiving, at (302), by one or more computing devices, a command to provide a desired thrust output includes receiving, at (304), by one or more computing devices, a command to provide a first amount of thrust output for a first operating condition. In various cases, the first operating condition may include a pre-level flight condition, such as a takeoff flight condition or a climb flight condition. In such a case, at (306), the method includes providing, by the one or more computing devices, a first amount of electrical power from first motor 62 to provide a first thrust output from first power assembly 52 to thruster assembly 56.

[0130] In some cases, receiving a command to provide a desired thrust output at (302) by one or more computing devices includes receiving a command to provide a second amount of thrust output for a second operating condition at (308) by the one or more computing devices. In various embodiments, the second operating condition may be indicated by a command to operate the aircraft 10 in a cruise condition, an idle condition, or a standby condition. In such a case, at (310) the method includes providing, by the one or more computing devices, a second amount of electrical power from the second electric machine 66 to provide the second thrust output from the second power assembly 54 to the thruster assembly 56.

[0131] In some cases, if the desired thrust output is within the second power assembly operating range (which may indicate a cruise condition and / or a standby condition), the second power assembly 54 may be activated. For example, in some embodiments, the internal combustion engine 64 of the second power assembly 54 may be operated within a defined range of revolutions per minute (rpm) while operating within the second power assembly operating range. In addition, the second power assembly operating range may alternatively be defined as any operating parameter of the internal combustion engine 64 that can monitor the operation of the internal combustion engine 64 and generally ensure that the internal combustion engine 64 operates in a manner consistent with operating the internal combustion engine 64 within the defined range for the parameter. In addition, in some cases, the first amount of electrical power may be greater than the maximum electrical power output of the second power assembly 54.

[0132] If the desired thrust output is greater than the second power assembly operating range (which may indicate a pre-cruise flight condition, including a takeoff flight condition, a climb flight condition, or any other high speed condition), the first power assembly 52 may be activated. In some embodiments, the first power assembly 52 may be deactivated when the aircraft 10 is in the second operating condition, or when the desired thrust output is within the second power assembly operating range.

[0133] The method 300 may also include receiving data indicating that a parameter is approaching or exceeding an upper threshold at (312) by one or more computing devices. It is noteworthy that, as used herein, the term "approaching or exceeding" refers to a parameter value within a predetermined range of a threshold or above a threshold. In certain aspects, such as the depicted aspects, receiving data indicating that a parameter is approaching or exceeding an upper threshold at (312) by one or more computing devices includes receiving data indicating that a temperature is approaching or exceeding a threshold for the first power component 52 or the second power component 54 at (314) by one or more computing devices. The temperature threshold may be a temperature threshold above which the amount of effective output power that can be generated by the first power component 52 due to the intake of too hot ambient air is limited. However, in other aspects of the present disclosure, the temperature parameter may be any other suitable temperature parameter. For example, the temperature parameter may include an exhaust temperature parameter that approaches or exceeds an exhaust temperature parameter upper threshold.

[0134] In addition, the depicted aspects also include: at (316), in response to receiving a command to operate the aircraft 10 under the first operating condition at (304) and receiving data indicating that the parameter is approaching or exceeding the upper threshold at (312), providing or assisting in providing the first thrust output by one or more computing devices through at least one of the second power component 54 and the energy storage unit 70 to generate the first thrust output.

[0135] By providing electrical power to the propulsion assembly 56 according to one or more aspects of the present disclosure, the hybrid propulsion system 50 may provide a desired thrust output from the first power assembly 52 and / or the second power assembly 54 to the propeller assembly 56 in a more efficient manner.

[0136] By operating according to one or more of these aspects, Figures 1 to 6 The hybrid propulsion system 50 provided in Figure 7The method 300 provided in the invention can provide a sufficient amount of thrust output to the aircraft under each operating mode of the aircraft (e.g., take-off, cruise, standby, etc.) while operating in an efficient manner. For example, the hybrid propulsion system 50 provided herein can use a first power component 52 and a second power component 54, the first power component 52 being combined with a lightweight, high specific power engine (e.g., a constant combustion engine) for take-off and / or rush conditions, and the second power component 54 being combined with an efficient, low specific power engine (e.g., an intermittent combustion engine) for long-term cruise / standby conditions. In addition, the hybrid propulsion system can also be combined with a propeller assembly 56 using a partial or full electric drive train, which allows the power from different devices to be combined to drive one or more propellers. In various embodiments, through one or more computing systems, based on system power requirements, when each propeller assembly is turned on or off, various configurations of thrust output can occur, and each propeller assembly can be slowed down while another propeller assembly is accelerated during power conversion.

[0137] Reference now Figure 8 , depicts an example computing system 500 according to an example embodiment of the present disclosure. The computing system 500 may be used, for example, as a controller 72 in a hybrid propulsion system 50, a controller 150 of a first power assembly 52, a controller 198 of a second power assembly 54, and / or a controller 260 of a thruster assembly 56. The computing system 500 may include one or more computing devices 510. The computing device(s) 510 may include one or more processors 510A and one or more memory devices 510B. The one or more processors 510A may include any suitable processing device, such as a microprocessor, a microcontroller, an integrated circuit, a logic device, and / or other suitable processing device. The one or more memory devices 510B may include one or more computer-readable media, including but not limited to non-transitory computer-readable media, RAM, ROM, a hard drive, a flash drive, and / or other memory devices.

[0138] One or more memory devices 510B may store information that can be accessed by one or more processors 510A, including computer-readable instructions 510C that can be executed by one or more processors 510A. Instructions 510C may be any set of instructions that, when executed by one or more processors 510A, cause one or more processors 510A to perform operations. In some embodiments, instructions 510C may be executed by one or more processors 510A to cause one or more processors 510A to perform operations, such as any operations and functions that the computing system 500 and / or (multiple) computing devices 510 are configured for, operations for operating one or more thruster components as described herein (e.g., method 300), and / or any other operations or functions of one or more computing devices 510. Therefore, method 300 may be a computer-implemented method. Instructions 510C may be software written in any suitable programming language, or may be implemented in hardware. Additionally and / or alternatively, instructions 510C may be executed in logically and / or virtually separated threads on (multiple) processors 510A. The memory device(s) 510B may further store data 510D accessible by the processor(s) 510A. For example, the data 510D may include data indicating power flow, data indicating power requirements of various loads in the hybrid propulsion system, data indicating operating parameters of the hybrid propulsion system (including operating parameters of a propeller assembly of the hybrid propulsion system).

[0139] The computing device(s) 510 may also include a network interface 510E for communicating with other components of the system 500 (e.g., via a network), for example. The network interface 510E may include any suitable components for interfacing with one or more networks, including, for example, a transmitter, a receiver, a port, a controller, an antenna, and / or other suitable components. One or more external display devices (not depicted) may be configured to receive one or more commands from the computing device(s) 510.

[0140] Further aspects of the disclosure may be provided in the following clauses:

[0141] A hybrid propulsion system for an aircraft, comprising: a propeller assembly having at least one aerodynamic propeller; a power generation system comprising at least a first power component, a second power component, a first motor and a second motor, the first power component being drivingly connected to the first motor to generate a first amount of electric power, and the second power component being drivingly connected to the second motor to generate a second amount of electric power, wherein the second power component is configured to generate electric power more efficiently than the first power component; a power bus connected to the first motor and the second motor; and a controller operably connected to the first power component, the first motor, or both and operably connected to the second power component, the second motor, or both, the controller and the power bus being configured to combine at least a portion of the first amount of electric power and the second amount of electric power to supply to the propeller assembly.

[0142] A hybrid propulsion system according to one or more of these clauses, wherein the first power assembly comprises a turbine and the second power assembly comprises an internal combustion engine.

[0143] A hybrid propulsion system according to one or more of these clauses, wherein the controller is further configured to provide electrical power from the first motor to the thruster assembly under a first operating condition and to provide electrical power from the second power assembly to the thruster assembly under a second operating condition.

[0144] The hybrid propulsion system according to one or more of these clauses further comprises: an energy storage unit operably coupled to each of the first power assembly, the second power assembly and the thruster assembly.

[0145] A hybrid propulsion system according to one or more of these clauses, wherein each of the first power assembly, the second power assembly and the thruster assembly is configured to utilize electrical power stored in the energy storage unit.

[0146] A hybrid propulsion system according to one or more of these clauses, wherein the second power assembly is configured to generate less electrical power than the first electric machine.

[0147] A hybrid propulsion system according to one or more of these clauses, wherein the first operating condition is indicated by a command to cause the aircraft to accelerate or climb, and the second operating condition is indicated by a command to cause the aircraft to operate in a level flight condition.

[0148] A hybrid propulsion system according to one or more of these clauses, wherein the second power assembly generates less than half the electrical power of the first electric machine.

[0149] A hybrid propulsion system according to one or more of these clauses, wherein the controller is further configured to: receive a desired thrust output and activate the second power component if the desired thrust output is within the second power component operating range, and activate the first power component if the desired thrust output is greater than the second power component operating range.

[0150] A hybrid propulsion system according to one or more of these clauses, wherein the first operating condition is indicated by a command to cause the aircraft to accelerate or climb, and the second operating condition is indicated by a command to cause the aircraft to operate in a level flight condition.

[0151] The hybrid propulsion system of one or more of these clauses further comprises: one or more power electronic devices positioned between the first power assembly and the power bus, between the second power assembly and the power bus, or both.

[0152] A hybrid propulsion system according to one or more of these clauses, wherein, when operating at common speed and / or operating parameters, the first power component generates a first noise level and the second power component generates a second noise level, and wherein the first noise level is greater than the second noise level.

[0153] A method for operating a hybrid propulsion system for an aircraft, the hybrid propulsion system comprising a first power assembly operably coupled to a first motor, a second power assembly operably coupled to a second motor, and a thruster assembly, the thruster assembly comprising at least one aerodynamic thruster and operably coupled to at least one of the first motor and the second motor, the method comprising: receiving, by one or more computing devices, a command to provide a first amount of thrust output for a first operating condition; providing, by one or more computing devices, a first amount of electrical power from the first motor to provide the first thrust output from the first power assembly to the thruster assembly; receiving, by one or more computing devices, a command to provide a second amount of thrust output for a second operating condition; and providing, by one or more computing devices, a second amount of electrical power from the second motor to provide a second thrust output from the second power assembly to the thruster assembly.

[0154] A method according to one or more of these clauses, wherein the first power component is configured to operate within a first range of revolutions per minute and the second power component is configured to operate within a second range of revolutions per minute, the revolutions per minute in the second range being at least partially less than or greater than the revolutions per minute in the first range.

[0155] A method according to one or more of these clauses, wherein the first operating condition is a take-off flight condition or a climb flight condition.

[0156] A method as described in one or more of these clauses, wherein the second power assembly is configured to generate the second amount of electrical power more efficiently than the first power assembly generates the first amount of electrical power.

[0157] A hybrid propulsion system for an aircraft, comprising: a first power assembly having a turbine coupled to a first electric motor; a second power assembly having an internal combustion engine coupled to a second electric motor; a propeller assembly having a first motor operably coupled to the first propeller, wherein the propeller assembly is selectively powered by the first and second electric motors; a power bus coupled to the first and second electric motors; and a controller operably coupled to the first power assembly, the first electric motor, or both and operably coupled to the second power assembly, the second power assembly, or both, wherein the second power assembly is activated if a desired thrust output is within an operating range of the second power assembly, and the first power assembly is activated if the desired thrust output is greater than the operating range of the second power assembly.

[0158] A hybrid propulsion system according to one or more of these clauses, wherein during a first operating condition, the desired thrust output is greater than the second power assembly operating range, the first operating condition comprising a takeoff flight condition or a climb flight condition.

[0159] The hybrid propulsion system according to one or more of these clauses further comprises: an energy storage unit operably coupled to each of the first power assembly, the second power assembly and the thruster assembly.

[0160] A hybrid propulsion system according to one or more of these clauses, wherein the propeller assembly further comprises a second motor operably coupled to the second propeller, wherein the first and second propeller assemblies are powered in parallel.

[0161] The techniques discussed herein refer to computer-based systems and actions taken by computer-based systems and information sent to and from computer-based systems. It will be appreciated by those of ordinary skill in the art that the inherent flexibility of computer-based systems allows for various possible configurations, combinations, and divisions of tasks and functions between and among components. For example, the processes discussed herein may be implemented using a single computing device or multiple computing devices working in combination. Databases, memories, instructions, and applications may be implemented on a single system or distributed across multiple systems. Distributed components may operate sequentially or in parallel.

[0162] Although specific features of various embodiments may be shown in some drawings but not in other drawings, this is only for convenience. According to the principles of the present disclosure, any feature of the drawings may be combined with any feature of any other drawings and cited and / or claimed.

[0163] This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims and may include other examples that occur to one skilled in the art. These other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements that have insubstantial differences from the literal language of the claims.

Claims

1. A hybrid propulsion system for an aircraft, comprising: a propeller assembly having at least one propeller; a power generation system comprising at least a first power assembly, a second power assembly, a first electric machine, and a second electric machine, the first power assembly drivingly coupled to the first electric machine to generate a first amount of electric power, and the second power assembly drivingly coupled to the second electric machine to generate a second amount of electric power, wherein the second power assembly is configured to generate electric power more efficiently than the first power assembly; a power bus coupled to the first electric machine and the second electric machine; and a controller operably coupled to the first power assembly, the first motor, or both and operably coupled to the second power assembly, the second motor, or both, the controller and the power bus configured to combine at least a portion of the first amount of electrical power and the second amount of electrical power to supply the thruster assembly, Wherein, the first power assembly includes a turbine and the second power assembly includes an internal combustion engine.

2. The hybrid propulsion system according to claim 1, wherein: The controller is also configured to provide electrical power to the thruster assembly from the first motor under a first operating condition and to provide electrical power to the thruster assembly from the second motor under a second operating condition.

3. The hybrid propulsion system according to claim 2, further comprising: An energy storage unit is operably coupled to each of the first power assembly, the second power assembly, and the thruster assembly.

4. The hybrid propulsion system according to claim 3, wherein: Each of the first power assembly, the second power assembly, and the thruster assembly is configured to utilize electrical power stored in the energy storage unit.

5. The hybrid propulsion system according to claim 1, wherein: The second power assembly is configured to generate less electrical power than the first electric machine.

6. The hybrid propulsion system according to claim 2, wherein: The first operating condition is indicated by a command to cause the aircraft to accelerate or climb, and the second operating condition is indicated by a command to cause the aircraft to operate in a level flight condition.

7. The hybrid propulsion system according to claim 1, wherein: The second power assembly generates electric power that is less than half of the electric power of the first electric machine.

8. The hybrid propulsion system according to claim 1, wherein: The controller is further configured to receive a desired thrust output and activate the second power assembly if the desired thrust output is within a second power assembly operating range and activate the first power assembly if the desired thrust output is greater than the second power assembly operating range.

9. The hybrid propulsion system according to claim 1, wherein: The first power assembly is configured to operate within a first range of revolutions per minute, and the second power assembly is configured to operate within a second range of revolutions per minute, the second range of revolutions per minute being at least partially less than or greater than the first range of revolutions per minute.

10. The hybrid propulsion system of claim 1 , further comprising: One or more power electronic devices are positioned between the first power component and the power bus, between the second power component and the power bus, or both.

11. The hybrid propulsion system according to claim 1, wherein: The first power assembly generates a first noise level and the second power assembly generates a second noise level when operating at a common speed and / or operating parameters, and wherein the first noise level is greater than the second noise level.

12. A method for operating a hybrid propulsion system for an aircraft, the hybrid propulsion system comprising a first power assembly operably coupled to a first electric machine, a second power assembly operably coupled to a second electric machine, and a propeller assembly, the propeller assembly comprising at least one propeller and operably coupled to at least one of the first electric machine and the second electric machine, the method comprising: receiving, by one or more computing devices, a command to provide a first amount of thrust output for a first operating condition; providing, by the one or more computing devices, a first amount of electrical power from the first electric machine to provide a first thrust output from the first power assembly to the thruster assembly; receiving, by the one or more computing devices, a command to provide a second amount of thrust output for a second operating condition; as well as providing, by the one or more computing devices, a second amount of electrical power from the second electric machine to provide a second thrust output from the second power assembly to the thruster assembly, Wherein, the first power assembly includes a turbine and the second power assembly includes an internal combustion engine.

13. The method according to claim 12, wherein: The first power assembly is configured to operate within a first range of revolutions per minute, and the second power assembly is configured to operate within a second range of revolutions per minute, the second range of revolutions per minute being at least partially less than or greater than the first range of revolutions per minute.

14. The method according to claim 12, wherein: The first operating condition is a take-off flight condition or a climb flight condition.

15. The method according to claim 12, wherein: The second power assembly is configured to generate the second amount of electrical power more efficiently than the first power assembly generates the first amount of electrical power.

16. A hybrid propulsion system for an aircraft, comprising: a first power assembly having a turbine coupled to a first electric machine; a second power assembly having an internal combustion engine coupled to a second electric machine; a propeller assembly having a first motor operably coupled to a first propeller, wherein the propeller assembly is selectively powered by the first motor and the second motor; a power bus coupled to the first electric machine and the second electric machine; and A controller operably coupled to the first power assembly, the first motor, or both and operably coupled to the second power assembly, the second power assembly, or both, wherein the second power assembly is activated if a desired thrust output is within a second power assembly operating range, and the first power assembly is activated if the desired thrust output is greater than the second power assembly operating range.

17. The hybrid propulsion system of claim 16, wherein: The desired thrust output is greater than the second power assembly operating range during a first operating condition, the first operating condition comprising a takeoff flight condition or a climb flight condition.

18. The hybrid propulsion system of claim 16, further comprising: An energy storage unit is operably coupled to each of the first power assembly, the second power assembly, and the thruster assembly.

19. The hybrid propulsion system of claim 16, wherein: The thruster assembly also includes a second motor operably coupled to a second thruster, wherein the first thruster and the second thruster are powered in parallel.

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