Patent Publication Number: US-2020277062-A1

Title: Aircraft having hybrid-electric propulsion system with electric storage located in wings

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of and priority to U.S. Provisional Patent Application No. 62/812,777, filed Mar. 1, 2019, the disclosure of which is hereby incorporated by reference in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present disclosure relates to an aircraft having a hybrid-electric propulsion system, and more particularly, to an aircraft having a hybrid-electric propulsion system with batteries that are located in the wings of the aircraft. 
     2. Description of Related Art 
     Aircraft engines vary in efficiency and function over a plurality of parameters, such as thrust requirements, air temperature, air speed, altitude, and the like. Aircraft require the most thrust at take-off, wherein the demand for engine power is the heaviest. However, during the remainder of the mission, the aircraft engines often do not require as much thrust as during take-off. The size and weight of the engines allows them to produce the power needed for take-off, however after take-off the engines are in effect over-sized for the relatively low power required to produce thrust for cruising in level flight. 
     The conventional techniques have been considered satisfactory for their intended purpose. However, there is an ever present need for improved aircraft engines. This disclosure provides a solution for this need. 
     SUMMARY 
     An aircraft includes a fuselage defining a longitudinal axis between a forward end and an aft end. At least one airfoil is laterally extending from the fuselage defining an airfoil axis. An electrical system has an electric storage. The electric storage is positioned within the airfoil. 
     In accordance with some embodiments, the aircraft includes a hybrid-electric propulsion system. The electrical system can be part of the hybrid-electric propulsion system. The hybrid-electric propulsion system can include a heat engine, and/or an electric-motor. The electrical system and electric storage can be operatively connected to the electric-motor for receiving power therefrom or for supplying power thereto. The electrical system can be electrically coupled to the electric-motor by way of a 1000-volt power bus. The electrical system can be electrically coupled to the electric-motor by way of a high voltage power bus. The aircraft can include a nacelle mounted to the airfoil. The electric storage can be positioned inboard of and/or outboard of the nacelle. The heat engine and the electric-motor can be positioned within the nacelle. 
     In some embodiments, the aircraft includes a liquid fuel tank. The liquid fuel tank can be positioned inboard of and/or outboard of the nacelle. The airfoil can include vent openings between an area outside of the airfoil and an electrical compartment in which the electric storage is positioned. 
     The electrical system can include an electric-motor controller. The airfoil can include an electrical compartment in which the electric-motor controller and electric storage are positioned. The airfoil can include an electrical compartment in which the electric storage is positioned. The electrical compartment can be made from a material that is fire proof and/or fire resistant, and/or can include a lining that is fire proof and/or fire resistant. In some embodiments, the electric storage includes at least one battery. In some embodiments, at least one battery includes a plurality of batteries. The airfoil can include an electrical compartment in which the plurality of batteries are stored. The electrical compartment can include sections configured and adapted to contain a respective portion of the plurality of batteries. Each section can be divided from adjacent sections by a wall that is fire proof and/or fire resistant. 
     In accordance with some embodiments, the at least one airfoil includes two airfoils extending from opposite sides of the fuselage. In some embodiments, each of the two airfoils includes a plurality of batteries and a liquid fuel tank. In some embodiments, a first of the two airfoils can include a plurality of batteries and a liquid fuel tank and a second of the airfoils can include two liquid fuel tanks. The aircraft can include a 28V aircraft power system connected to the hybrid-electric propulsion system for generating 28V of aircraft power supply for aircraft systems. 
     These and other features of the systems and methods of the subject disclosure will become more readily apparent to those skilled in the art from the following detailed description of the embodiments taken in conjunction with the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       So that those skilled in the art to which the subject disclosure appertains will readily understand how to make and use the devices and methods of the subject disclosure without undue experimentation, embodiments thereof will be described in detail herein below with reference to certain figures, wherein: 
         FIG. 1  is a schematic depiction of a top plan view of an embodiment of an aircraft constructed in accordance with the present disclosure, showing batteries positioned within both of the airfoils extending from the aircraft; 
         FIG. 2  is a schematic depiction of a perspective view of a portion of the aircraft of  FIG. 1 , showing batteries positioned inboard of respective nacelles; 
         FIG. 3  is a schematic depiction of an embodiment of a hybrid-electric propulsion system constructed in accordance with the present invention, showing the batteries operatively connected to the electric-motor controller and electric-motor; 
         FIG. 4  is a schematic depiction of a bottom plan view of a portion of the aircraft of  FIG. 1 , showing a heat vent on an underside surface of an airfoil; 
         FIG. 5  is a schematic depiction of a perspective view of the electrical compartment of the aircraft of  FIG. 1 , showing batteries positioned within the compartment  120 ; 
         FIG. 6  is a schematic depiction of a top plan view of another embodiment of an aircraft constructed in accordance with the present disclosure, showing batteries positioned within both of the airfoils extending from the aircraft; 
         FIG. 7  is a schematic depiction of a perspective view of a portion of the aircraft of  FIG. 6 , showing batteries positioned outboard of respective nacelles; 
         FIG. 8  is a schematic depiction of a bottom plan view of a portion of the aircraft of  FIG. 6 , showing a heat vent on an underside surface of an airfoil; 
         FIG. 9  is a schematic depiction of a top plan view of an embodiment of an aircraft constructed in accordance with the present disclosure, showing batteries positioned within one of the airfoils extending from the aircraft; 
         FIG. 10  is a schematic depiction of a perspective view of a portion of the aircraft of  FIG. 9 , showing batteries positioned outboard of one of the nacelles; 
         FIG. 11  is a schematic depiction of a bottom plan view of a portion of the aircraft of  FIG. 9 , showing air scoops and a heat vent on an underside surface of one of the airfoils; and 
         FIG. 12  is a schematic depiction of a top plan view of another embodiment of an aircraft constructed in accordance with the present disclosure, showing batteries positioned inboard of the nacelle. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Reference will now be made to the drawings wherein like reference numerals identify similar structural features or aspects of the subject disclosure. For purposes of explanation and illustration, and not limitation, a partial view of an exemplary embodiment of an aircraft constructed in accordance with the present disclosure is shown in  FIG. 1  and is designated generally by reference character  10 . Other embodiments of aircraft  10  in accordance with the disclosure, or aspects thereof, are provided in  FIGS. 2-12 , as will be described. The systems and methods described herein can be used to provide hybrid propulsion, e.g., for improving fuel efficiency in aircraft. Moreover, embodiments described herein can readily apply to all-electric aircraft, or the like. 
     As shown in  FIGS. 1-3 , an aircraft  10  includes a fuselage  20  defining a longitudinal axis A between a forward end  30  and an aft end  40 . Airfoils  50   a  and  50   b  laterally extend from the fuselage  20  and each define a respective airfoil axis B. Each airfoil  50   a  and  50   b  includes a respective nacelle  122   a  and  122   b  mounted to thereto. The aircraft  10  includes hybrid-electric propulsion systems  100 , portions of which are disposed in each nacelle  122   a  and  122   b.  An electrical system  101  is part of each hybrid-electric propulsion system  100 . Each hybrid-electric propulsion system  100  includes a heat engine  104 , e.g. a thermal engine, and an electric-motor  106 , which on their own or together drive an air mover  105 , e.g. a propeller, fan or the like, by way of a reduction gear box  107  and shaft  111 . Each nacelle  122   a  and  122   b  includes a respective heat engine  104  and an electric-motor  106 . Air movers  105  are not shown in  FIG. 1 , but it is contemplated that each nacelle  122   a  and  122   b  would include a respective air mover  105  mounted on their forward facing hubs  131 . Each reduction gear box  107  has an input  109   a  for heat engine  104  and an input  109   b  for electric-motor  106 . Those skilled in the art will also readily appreciate that a clutch can be disposed between each reduction gear box  107  and its respective heat engine  104  and another clutch can be disposed between each electric-motor  106  and its respective reduction gear box  107 . 
     It is contemplated that heat engine  104  (and heat engines  204  and  304 , described below) could be a heat engine of any type, e.g., a gas turbine, spark ignited, diesel, rotary or reciprocating engine of any fuel type and with any configuration of turbomachiney elements, either turbocharger, turbosupercharger, supercharger and exhaust recovery turbo compounding, either mechanically, electrically, hydraulically or pneumatically driven. 
     With continued reference to  FIGS. 1-3 , each electrical system  101  includes an electric storage  103  that includes a battery bank, or the like. In the embodiment of  FIGS. 1-3 , each storage  103  is made up of a plurality of batteries  102 . Batteries  102  can be rechargeable batteries. Sets of batteries  102  are positioned on both airfoil  50   a  and airfoil  50   b  inboard of respective nacelles  122   a  and  122   b.  Each airfoil  50   a  and  50   b  also includes a liquid fuel tank  124 . The positioning of the respective sets of batteries  102  and the fuel tanks  124  in each of the two airfoils  50   a  and  50   b  is symmetrical across the longitudinal axis A. Each liquid fuel tank  124  is operatively connected to one or more of heat engines  104  to provide fuel thereto. A fuel control system, e.g. fuel system  133 , is disposed between one or more liquid fuel tanks  124  and heat engines  104  to control fuel distribution from one or more fuel tanks  124  to heat engines  104  (regardless of position of the tank  124  on airfoil  50   a  or  50   b ). Each liquid fuel tank  124  is positioned outboard from their respective nacelles  122   a  and  122   b.  Each hybrid-electric propulsion system  100  is operatively connected to a 28V aircraft power system  135  to supply 28V power for aircraft systems, e.g. computer systems and the like. Aircraft power system  135  can include one more rectifiers, batteries, and/or distribution systems contained therein. Those skilled in the art will readily appreciate that aircraft power system  135  can provide power to a variety of aircraft electronics systems that run on standard aircraft voltage, e.g. 28V, via output  139 . 
     As shown in  FIGS. 2-3 , the storage  103  (and the associated batteries  102 ) are operatively connected to a respective electric-motor  106  for receiving power therefrom or for supplying power thereto by way of an electric-motor controller  121 . It is contemplated that an electrical distribution system or battery management system can be positioned within the storage  103 , or between storage  103  and the electric-motor controller  121 . The electrical distribution system and/or battery management system is configured for managing the electrical power from the power storage  103 , e.g. the batteries  102 , to the electric-motor  106 . Each electric-motor controller  121  is positioned within a respective one of nacelles  122   a  and  122   b.    
     In some embodiments, it is contemplated that the electric-motor controllers  121  can be positioned within the fuselage  20  or an electrical compartment  120 , as described below, or any suitable location within aircraft  10 . As shown in  FIGS. 2-3 , each electrical system, e.g. the electric-motor controller  121  and the storage  103 , is electrically coupled to a given electric-motor  106  by way of a high voltage power bus  123 . High voltage power bus  123  can be for 500 V or greater, e.g. a range from 890-1000 V, or higher. The high voltage power bus  123  is bi-directional, meaning power can go to electric-motor  106  from electric-motor controller  121  and from electric-motor  106  to electric-motor controller  121 . Each power storage  103 , e.g. each group of batteries  102 , is operatively connected to its respective electric-motor controller  121  by a respective conductor  125 . 
     With continued reference to  FIGS. 2-3 , those skilled in the art will also readily appreciate that hybrid-electric propulsion system  100  can include a motor drive positioned in between the electric-motor controller  121  and the electric-motor  106 . The motor drive is configured for controlling, for instance, a rotational speed of the electric-motor  106 . It is also contemplated that each set of batteries  102 , e.g. the set on airfoil  50   a  and the set on airfoil  50   b,  is connected to one or more inverter/rectifier components (for example, positioned between each storage  103  and its respective electric-motor  106 ) for supplying power from each storage  103  to drive the respective electric-motor  106 , or, in an energy recovery mode, to store into each storage  103  energy generated by driving each electric-motor  106  in a generator mode. 
     As shown in  FIG. 5 , it is also contemplated that compartment  120  can include a liquid cooling circuit  129  (schematically shown by broken-lined arrows in  FIG. 5 ) to assist in on-ground cooling, for example. Liquid cooling circuit  129  includes an input  141  and an output  151 . The liquid cooling circuit can be connected to a ground cart that includes the remaining portions of the cooling system (e.g. pump, coolant, etc.) or it can be contained within aircraft  10 . If contained in aircraft  10 , various coolant system components, such as a radiator, heat exchanger or the like, may be included. 
     With reference now to  FIGS. 3-4 , each airfoil  50   a  and  50   b  includes vent openings  128 , e.g. heat vent outlets  128 , that are in fluid communication with openings  115  and/or  127  of respective compartments  120  between the area  118  outside of the airfoil and the electrical compartment  120  in which the batteries  102  are positioned. While  FIG. 11  shows vent openings  128  both inboard and outboard of nacelle  122   b,  it is contemplated that vent openings  128  can be included either inboard or outboard, depending on the position of batteries  102 . Moreover, while not shown, it is contemplated that airfoil  50   a  also includes vent openings similar to those shown on airfoil  50   b  to allow venting from electrical compartment  120  positioned thereon. Vent openings  128  allow heat, fumes, or the like to be dissipated from the electrical storage  103 , e.g. the group of batteries  102 , in compartment  120 . Vent openings  128  (and/or corresponding openings  115  and/or  127 , described below) can include fire detection and/or extinguishing methods and systems. It is also contemplated that heat dissipated from electrical storage  103  can be used for anti-ice or de-icing of airfoils  50   a  and  50   b,  or other components, or general heating of the aircraft  10  and its components (e.g. cabin, etc.). The heat can be directed to a given area for anti-ice/de-ice or heating as needed, directly, by way of heat exchanger, or the like (this readily applies to heat from electrical storages  203  and  303 , described below). 
     As shown in  FIG. 5 , each electrical compartment  120  is configured to hold electrical storage  103 . Each electrical compartment  120  includes a fire proof and/or resistant lining  125 . It is also contemplated that in lieu of or in addition to the lining  125 , each compartment  120  can be made from a fire proof and/or fire resistant material, or be constructed in another suitable fire resistant and/or proof configuration. In the embodiment of  FIG. 5 , electrical storage  103  is a plurality of batteries  102 . For sake of clarity, only some of batteries  102  are shown. In some embodiments, a given electric-motor controller  121  can be positioned within a respective electrical compartment  120 . Each electrical compartment  120  includes sections  130  configured and adapted to contain a respective portion of the plurality of batteries  102 . Each section is divided from adjacent sections  130  by a fire proof and/or resistant wall  132 . Electrical compartment  120  includes openings  115  and/or  127  for venting. 
     As shown in  FIGS. 6-7 , an aircraft  10  includes a fuselage  20  defining a longitudinal axis A between a forward end  30  and an aft end  40 . Airfoils  50   a  and  50   b  laterally extend from the fuselage  20  and each define a respective airfoil axis B. Each airfoil  50   a  and  50   b  includes a respective nacelle  222   a  and  222   b  mounted to thereto. The aircraft  10  includes hybrid-electric propulsion systems  200 , portions of which are disposed in each nacelle  222   a  and  222   b.  An electrical system, not shown, is very similar to electrical system  101 , and is part of each hybrid-electric propulsion system  200 . The description of electrical system  101  readily applies to the electrical system of electric propulsion system  200 . Hybrid-electric propulsion system  200  and the operation thereof is very similar to system  100  described above except for the position of batteries  202  with respect to the nacelles  222   a  and  222   b.  As such, the description provided above for system  100  readily applies to system  200 . Each hybrid-electric propulsion system  200  includes a heat engine  204 , e.g. a thermal engine, and an electric-motor  206 , which on their own or together drive an air mover, e.g. a air mover  105 , by way of a reduction gear box, e.g. reduction gearbox  107 , and a shaft, e.g. shaft  111 . Each nacelle  222   a  and  222   b  includes a respective heat engine  204  and an electric-motor  206 . It is contemplated that each nacelle  222   a  and  222   b  would include a respective air mover, similar to air mover  105  described above, mounted on their forward facing nacelle hubs  231 . Each reduction gear box has inputs similar to inputs  109   a  and  109   b,  described above. Those skilled in the art will also readily appreciate that hybrid-electric propulsion system  200  includes one or more clutches, similar to those describe above relative to system  100 . 
     With continued reference to  FIGS. 6-8 , each electrical system includes an electric storage  203  that includes a battery bank, or the like. In the embodiment of  FIGS. 6-8 , the storage  203  is made up of a plurality of batteries  202 , similar to batteries  102  and storage  103  described above. The electrical system of  FIGS. 6-8  is the same as electrical system  101  except that batteries  202  are positioned on both airfoil  50   a  and airfoil  50   b  outboard of respective nacelles  222   a  and  222   b.  Each airfoil  50   a  and  50   b  also includes a liquid fuel tank  224 . Each liquid fuel tank  224  is operatively connected to one or more of heat engines  204  to provide fuel thereto. A fuel control system, e.g. fuel system  133 , is disposed between one or more liquid fuel tanks  224  and heat engines  204  to control fuel distribution from one or more fuel tanks  224  to heat engines  204  (regardless of position of the tank  224  on airfoil  50   a  or  50   b ). Each liquid fuel tank  224  is positioned inboard from a respective nacelle  222   a  or  222   b.  Each hybrid-electric propulsion system  200  is similar to system  100  in that they are both operatively connected to a 28V aircraft power system, e.g. power system  135 , to supply 28V power. The aircraft power system connected to system  200 , and the function thereof, is similar to aircraft power system  135  described above such that the description thereof readily applies to system  200 . 
     As shown in  FIGS. 7-8 , the storage  203 , e.g. batteries  202 , are operatively connected to a respective electric-motor  206  for receiving power therefrom or for supplying power thereto by way of an electric-motor controller  221 , similar to electric-motor  106  and batteries  102 , described above. Each electric-motor controller  221  is positioned within a respective one of nacelles  222   a  and  222   b.  In some embodiments, it is contemplated that the electric-motor controllers  221  can be positioned within the fuselage  20  or a respective electrical compartment  220 , as described above with respect to electric-motor controllers  121 . Each electrical compartment  220  is the same as that of  120  as shown in  FIG. 5 , except its position relative to the nacelles, e.g. nacelles  222   a  and  222   b  is different. The electrical system, e.g. the electric-motor controller  221  and the storage  203 , is electrically coupled to each electric-motor  206  by way of a high voltage power bus  223 . High voltage power bus  223  can be for 500 V or greater, e.g. a range from 890-1000 V, or higher. It is also contemplated that each set of batteries  202 , e.g. the set on airfoil  50   a  and the set on airfoil  50   b,  is connected to one or more inverter/rectifier components, similar to those described above relative to each storage  103  and their respective electric-motor  106 . The power storage  203  is operatively connected to the electric-motor controller  221  by conductors  225 . It is also contemplated that compartment  220  can include a liquid cooling circuit to assist in on-ground cooling, for example. The liquid cooling circuit in compartment  220  is similar to the liquid cooling circuit  129  described above relative to compartment  120 . 
     With reference now to  FIG. 8 , each airfoil  50   a  and  50   b  includes vent openings  228 , e.g. heat vent outlets  228 , that are in fluid communication with openings, similar to openings  115  and  127 , of respective compartments  220  between the area  218  outside of the airfoil and the electrical compartment  220  in which the batteries  202  are positioned. While  FIG. 8  shows vent openings  228  both inboard and outboard of nacelle  222   b,  it is contemplated that vent openings  228  can also be included either inboard or outboard, depending on the position of batteries  202 . Moreover, while not shown, it is contemplated that airfoil  50   a  also includes vent openings  228  similar to those shown on airfoil  50   b  to allow venting from electrical compartment  220  positioned thereon. Vent openings  228  function similarly to vent openings  128 , as described above. Each electrical compartment  220  includes openings, e.g. openings  115  and  127 , and fire proof and/or resistant features, e.g. a lining and walls, similar to those of compartment  120 . Vent openings  228  and/or corresponding compartment  120  openings can include fire detection and/or extinguishing methods and systems. 
     As shown in  FIGS. 9-10 , an aircraft  10  includes a fuselage  20  defining a longitudinal axis A between a forward end  30  and an aft end  40 . Airfoils  50   a  and  50   b  laterally extend from the fuselage  20  and are similar to airfoils  50   a  and  50   b  of  FIG. 1 . Each airfoil  50   a  and  50   b  includes a respective nacelle  322   a  and  322   b  mounted to thereto. The aircraft  10  includes a hybrid-electric propulsion system  300 , very similar to hybrid-electric propulsion system  100 , portions of which are disposed in first nacelle  322   a.  An electrical system, similar to electrical system  101 , is part of the hybrid-electric propulsion system  300 . The description above relative to electrical system  101  readily applies to the electrical system of hybrid-electric propulsion system  300 . The hybrid-electric propulsion system  300  is the same as hybrid-electric propulsion system  100  except that batteries  302  of system  300  are located outboard of a respective nacelle  322   a.  Air movers are not shown in  FIGS. 9-10 , but it is contemplated that each nacelle  322   a  and  322   b  would include a respective air mover, similar to air mover  105 , mounted on their forward facing hubs  331 . Hybrid-electric propulsion system  300  includes a reduction gear box, similar to reduction gear box  107 , having similar inputs as reduction gearbox  107 . Hybrid-electric propulsion system  300  includes at least one clutch similar to those described above with respect to system  100 . 
     With continued reference to  FIGS. 9-10 , the electrical system, similar to system  101 , includes an electric storage  303  that includes a battery bank, or the like. In the embodiment of  FIGS. 9-11  the storage  303  is made up of a plurality of batteries  302 , similar to batteries  102  described above. Batteries  302  are positioned on airfoil  50   a  and airfoil  50   a  also includes a liquid fuel tank  324 . One or more liquid fuel tanks  324  are operatively connected to heat engine  104  to provide fuel thereto. A fuel control system, similar to fuel system  133  described above, is disposed between one or more liquid fuel tanks  324  and heat engine  304  to control fuel distribution from one or more fuel tanks  324  to heat engine  304  (regardless of position of the tank  124  on airfoil  50   a  or  50   b ). Unlike the embodiments of  FIGS. 1-8 , instead of having batteries  302  on the other airfoil  50   b,  only liquid fuel tanks  324  are included on airfoil  50   b.  Moreover, it is also contemplated that nacelle  322   b  includes a turbine engine, instead of a hybrid-electric propulsion system  300 . However, those skilled in the art will readily appreciate that another hybrid-electric propulsion system, like that of system  100 , can be used on airfoil  50   b  and nacelle  122   b.  Hybrid-electric propulsion system  300  is operatively connected to a 28V aircraft power system, similar to system  135  described above. 
     With reference now to  FIGS. 10-11 , the heat engine  304  and the electric-motor  306  are positioned within the nacelle  322   a.  The batteries  302  are shown positioned outboard of the nacelle  322   a.  However, it is also contemplated that in some embodiments, the batteries are positioned inboard of the nacelle  322   a  (e.g. as shown in  FIG. 12 ). The liquid fuel tank  324  on airfoil  50   a  is positioned inboard of the nacelle  322   a.  However, it is also contemplated that in some embodiments the liquid fuel tank  324  can be positioned outboard of nacelle  322   a,  for example, when batteries  302  are positioned inboard of nacelle  322   a  (as shown in  FIG. 12 ). 
     As shown in  FIGS. 10-11 , the batteries  302  are operatively connected to the electric-motor  306  for receiving power therefrom or for supplying power thereto by way of an electric-motor controller  321 . The electrical system  301 , e.g. the electric-motor controller  321  and the storage  303 , is electrically coupled to the electric-motor  306  by way of a high voltage power bus  323 . High voltage power bus  323  can be for 500 V or greater, e.g. a range from 890-1000 V, or higher. It is also contemplated that batteries  302  are connected to one or more inverter/rectifier components, similar to those described above for batteries  102  and  202 . 
     As shown in  FIG. 11 , the airfoil  50   a  includes vent openings  328 , similar to vent openings  128  and/or  228 , which can be in fluid communication with openings of compartment  320  between the area  318  outside of the airfoil and the electrical compartment  320  in which the batteries  302  are positioned. While  FIG. 11  shows vent openings  328  both inboard and outboard of nacelle  322   a,  it is contemplated that vent openings  328  can also be included either inboard or outboard, depending on the position of batteries  302 . Vent openings  328  and/or corresponding openings in compartment  320  can include fire detection and/or extinguishing methods and systems. Vent openings  228  function similarly to vent openings  128 , as described above. It is also contemplated that compartment  320  can include a liquid cooling circuit to assist in on-ground cooling, for example. The liquid cooling circuit in compartment  320  is similar to the liquid cooling circuit  129  described above relative to compartment  120 . 
     With continued reference to  FIGS. 9-11 , the electrical compartment  320  includes openings, e.g. openings  115  and  127 , and fire proof and/or resistant features/configurations, e.g. materials, a lining and/or walls, similar to those of compartment  120 . While electric-motor controller  321  is shown positioned in electrical compartment  320 , those skilled in the art will readily appreciate that electric-motor controller  321  can be positioned within the fuselage  20  or within the nacelle  322   a,  as described above in  FIGS. 1-9 . 
     As shown in  FIG. 12 , an alternative embodiment of aircraft  10  is shown. Aircraft  10  of  FIG. 12  is the same as aircraft  10  of  FIG. 9 , except that the batteries  302  are positioned inboard of the nacelle  322   a  and the liquid fuel tank  324  on airfoil  50   a  is positioned outboard of nacelle  322   a.  Airfoil  50   b  includes liquid fuel tanks  324  without any electric storage  103  and nacelle  322   b  of airfoil  50   b  can include a gas turbine engine, for example. Similar to the embodiment of  FIG. 9 , those skilled in the art will readily appreciate that while the combination of batteries  302  and fuel tank  324  are only shown on airfoil  50   a,  a similar hybrid-electric propulsion system  300 , and the associated batteries  302  and fuel tank  324  could be used on airfoil  50   b  such that both propulsion systems on the aircraft  10  are hybrid-electric. 
     The methods and systems of the present disclosure, as described above and shown in the drawings provide for hybrid-electric and/or electric propulsion systems with superior properties including improved energy storage and use of hybrid heat engine and electric-motor power. While the apparatus and methods of the subject disclosure have been shown and described with reference to certain embodiments, those skilled in the art will readily appreciate that change and/or modifications may be made thereto without departing from the scope of the subject disclosure.