Abstract:
One embodiment of the present invention is a unique augmented gas turbine engine propulsion system. Another embodiment is a gas turbine engine power augmentation system. Yet another embodiment is a system for augmenting power in an engine powered air vehicle. Other embodiments include apparatuses, systems, devices, hardware, methods, and combinations for fluid driven actuation systems. Further embodiments, forms, features, aspects, benefits, and advantages of the present application shall become apparent from the description and figures provided herewith.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application claims the benefit of U.S. Provisional Patent Application 61/291,534, filed Dec. 31, 2009, and is incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to air vehicle systems, and more particularly, to a power augmentation system for an engine powered air vehicle. 
       BACKGROUND 
       [0003]    Air vehicle power systems remain an area of interest. Some existing systems have various shortcomings, drawbacks, and disadvantages relative to certain applications. Accordingly, there remains a need for further contributions in this area of technology. 
       SUMMARY 
       [0004]    One embodiment of the present invention is a unique augmented gas turbine engine propulsion system. Another embodiment is a gas turbine engine power augmentation system. Yet another embodiment is a system for augmenting power in an engine powered air vehicle. Other embodiments include apparatuses, systems, devices, hardware, methods, and combinations for power augmentation system. Further embodiments, forms, features, aspects, benefits, and advantages of the present application shall become apparent from the description and figures provided herewith. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]    The description herein makes reference to the accompanying drawings wherein like reference numerals refer to like parts throughout the several views, and wherein: 
           [0006]      FIG. 1  schematically illustrates an augmented gas turbine propulsion system for an air vehicle in accordance with an embodiment of the present invention. 
           [0007]      FIG. 2  schematically illustrates an augmented gas turbine propulsion system for an air vehicle in accordance with another embodiment of the present invention. 
           [0008]      FIG. 3  schematically illustrates an augmented gas turbine propulsion system for an air vehicle in accordance with yet another embodiment of the present invention. 
           [0009]      FIG. 4  schematically illustrates a twin engine augmented gas turbine propulsion system for an air vehicle in accordance with an embodiment of the present invention. 
           [0010]      FIG. 5  schematically illustrates a twin engine augmented gas turbine propulsion system for an air vehicle in accordance with another embodiment of the present invention. 
           [0011]      FIG. 6  schematically illustrates a twin engine augmented gas turbine propulsion system for an air vehicle in accordance with yet another embodiment of the present invention. 
           [0012]      FIG. 7  schematically illustrates an embodiment whereby power may be transmitted to or from inertial storage in accordance with an embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0013]    For purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings, and specific language will be used to describe the same. It will nonetheless be understood that no limitation of the scope of the invention is intended by the illustration and description of certain embodiments of the invention. In addition, any alterations and/or modifications of the illustrated and/or described embodiment(s) are contemplated as being within the scope of the present invention. Further, any other applications of the principles of the invention, as illustrated and/or described herein, as would normally occur to one skilled in the art to which the invention pertains, are contemplated as being within the scope of the present invention. 
         [0014]    Referring now to the drawings, and in particular  FIG. 1 , a non-limiting example of an augmented gas turbine engine propulsion system  10  for an air vehicle  12  in accordance with an embodiment of the present invention is schematically depicted. Propulsion system  10  includes a gas turbine engine  14 . Gas turbine engine  14  is operative to drive a thrust rotor  16  via a shaft  18  that rotates at the output speed of engine  14 . In one form, shaft  18  is an engine  14  spool main shaft, in particular, the output shaft of engine  14 . In one form, engine  14  is a turboshaft engine for powering an air vehicle  12  in the form of a rotary wing aircraft, wherein thrust rotor  16  is in the form of a helicopter rotor or a tiltrotor aircraft main rotor. As a rotary-wing aircraft, air vehicle  12  includes a transmission  20 . Shaft  18 , e.g., an output shaft of engine  14 , is coupled to transmission  20  and provides the output from engine  14  to thrust rotor  16  via transmission  20 . In some forms, e.g., in helicopter and tiltrotor applications, shaft  18  may alternatively be considered as a transmission input shaft coupled to the output shaft of engine  14  via an overrunning clutch, which allows shaft  18  to rotate when the engine  14  output spool, e.g., the low pressure (LP) spool, is not rotating. Transmission  20  is a step-down transmission that reduces the output speed of engine  14 . 
         [0015]    In one form, engine  14  is a two-spool engine having an LP spool for driving shaft  18 , and a high pressure (HP) spool, e.g., a gas producer or gas generator spool. In some embodiments, the LP spool may include a compressor, whereas in other embodiments, the LP spool may not include a compressor. In other embodiments, engine  14  may be a 3-spool engine having an LP spool, an intermediate pressure spool and an HP spool. In yet other embodiments, engine  14  may be a single-spool engine. 
         [0016]    Although described herein with respect to a turboshaft engine for a helicopter, other embodiments may include other air vehicle and gas turbine engine forms. For example, in other embodiments, air vehicle  12  may be in the form of a turboprop fixed-wing aircraft, and engine  14  may be in the form of a turboprop engine with transmission  20  in the form of a turboprop reduction gearbox for driving a thrust rotor  16  in the form of one or more propellers. 
         [0017]    In still other embodiments, air vehicle  12  may be in the form of a fixed-wing aircraft, and engine  14  may be in the form of a turbofan engine with thrust rotor  16  in the form of a fan rotor. In one such embodiment, engine  14  may be a geared turbofan engine with transmission  20  in the form of a step-up and/or reduction gearbox. In another such embodiment, engine  14  may be a turbofan engine without a transmission  20 , e.g., a direct fan drive, wherein shaft  18  is in the form of a fan driveshaft. It will be understood that various other embodiments may take other forms, including single and multi-engine aircraft having one or more thrust rotors, each being powered by a single or multiple engines  14 . 
         [0018]    Propulsion system  10  includes a power augmentation system  22 . In one form, power augmentation system  22  includes a high speed motor generator  24 , a high speed motor generator  26 , a flywheel  28  and a controller  30 . Power augmentation system  22  is operative to receive and store power from output shaft  18 , e.g., during periods of low power demand, such as engine  14  idle or cruise conditions, and to transmit the previously stored power back to output shaft  18 . In some embodiments, power augmentation system  22  may also be energized by an external source, e.g., via electrical power supplied by a ground cart or another source of electrical power. In such embodiments, the energy stored in power augmentation system  22  may subsequently be used to power output shaft  18 . 
         [0019]    High speed motor generator  24  operates at the rotational speed of output shaft  18  of gas turbine engine  14 , and is operative to generate electrical power based on the rotation of output shaft  18 . In the context of the present application, a motor generator is a “high speed” motor generator if it is configured to operate at rotational speeds substantially greater than 3600 rpm. In one form, a high speed motor generator is a motor generator configured to operate at or greater than the rotational speed of a gas turbine engine spool in an engine with which the motor generator is associated. For example, a motor generator operating at or greater than the speed of the output shaft of a turboshaft engine, the fan drive shaft of a conventional and/or geared turbofan engine, an HP or gas producer spool of a multi-spool engine, and an intermediate pressure spool of a three-spool engine. 
         [0020]    Because motor generator  24  is a “high speed” motor generator, a reduction gearbox may not be required in some embodiments, which may prevent the weight penalty associated with such a reduction gearbox. Further, because motor generator  24  is a “high speed” motor generator, the size and weight of motor generator  24  may be smaller than those of a conventional motor generator. In one form, motor generator  24  is coupled directly to output shaft  18 , i.e., without an intervening speed/torque conversion mechanism such as a gearbox. Motor generator  24  is operative to rotate at the same rotational speed as output shaft  18 . In one form, motor generator  24  includes a motor generator rotor  32  mounted on output shaft  18 . In another form, motor generator rotor  32  is integral with output shaft  18 . In other embodiments, motor generator rotor  32  may be directly coupled to output shaft  18  without being mounted thereon or integral therewith. 
         [0021]    Motor generator  26 , like motor generator  24 , is a high speed motor generator. Motor generator  26  is electrically coupled to motor generator  24  via an electrical link  34 , such as a power cable. Electrical link  34  is operative to transmit electrical power between motor generator  24  and motor generator  26 . Motor generator  26  is mechanically coupled to flywheel  28 . Flywheel  28  is operative to store inertial energy. Although the term, “flywheel” is used herein, it will be understood that flywheel  28  is not limited to any particular shape, but rather, the term, “flywheel,” is used to refer to a rotating inertial storage rotor, and may be shaped as a wheel, a cylinder, or any other suitable shape. In one form, motor generator  26  is coupled directly to flywheel  28 , whereby flywheel  28  and motor generator  26  operate at the same rotational speed. In other embodiments, flywheel  28  and motor generator  26  may operate at some non-unitary fixed or variable speed ratio relative to each other. 
         [0022]    Controller  30  is communicatively coupled to motor generator  24  and motor generator  26  via communications links  36  and  38 , respectively. In one form, communications links  36  and  38  are wired digital links. In other embodiments, other types of communications links may be employed, e.g., analog links, wireless links, and/or optical links. In still other embodiments, controller  30  may be coupled to motor generator  24  and motor generator  26  via electrical link  34  in addition to or in place of communications links  36  and  38 . 
         [0023]    Controller  30  is configured to execute program instructions to selectively direct power augmentation system  22  to transmit power from output shaft  18  to flywheel  28 , and to transmit power from flywheel  28  to output shaft  18 . In one form, controller  30  is microprocessor based and the program instructions are in the form of software stored in a memory (not shown). However, it is alternatively contemplated that the controller and program instructions may be in the form of any combination of software, firmware and hardware, including state machines, and may reflect the output of discreet devices and/or integrated circuits, which may be co-located at a particular location or distributed across more than one location, including any digital and/or analog devices configured to achieve the same or similar results as a processor-based controller executing software or firmware based instructions. For example, in one form, controller  30  may be part of a full authority digital engine controller (FADEC) of engine  14 . As another non-limiting example, controller  30  may be integral with one or both of motor generator  24  and motor generator  26 . As yet another example, controller  30  may be in the form of switches or switching circuitry. 
         [0024]    Power augmentation system  22  is operative to receive and store power from output shaft  18  and to transmit the stored power back to output shaft  18  in order to augment the output of engine  14 . For example, in one form, output shaft  18  is rotated, e.g., under the power of engine  14  or via windmilling of thrust rotor  16 . Under the control supervision of controller  30 , the mechanical power is absorbed by motor generator  24 , which converts the mechanical power into electrical power. The electrical power is then transmitted to motor generator  26  via electrical link  34 . Under the direction of controller  30 , motor generator  26  converts the electrical power back into mechanical power, which is absorbed by flywheel  28  in the form of rotating inertial energy. Upon receiving a command to augment power to thrust rotor  16 , motor generator  26  absorbs mechanical power from flywheel  28  and converts the mechanical power to electrical power under the direction of controller  30 . The electrical power is then transmitted to motor generator  24  via electrical link  34 . Motor generator  24  then converts the electrical power into mechanical power under the direction of controller  30 , which is transmitted to output shaft  18  by motor generator rotor  32 . 
         [0025]    Referring now to  FIG. 2 , another embodiment of engine  14  with power augmentation system  22  is described. In the embodiment of  FIG. 2 , engine  14  is a multi-spool engine in which output shaft  18  is part of the LP spool. Engine  14  includes an HP spool as a gas producer, which includes a main shaft, such as a gas producer shaft  40 . In addition to motor generator  24  and motor generator  26 , power augmentation system  22  also includes a high speed motor generator  42  mechanically coupled to gas producer shaft  40 . Motor generator  42  is electrically coupled to motor generator  26  via an electrical link  44 , such as a power cable, and communicatively coupled to controller  30  via a communications link  46 , similar to that described above with respect to the embodiment of  FIG. 1 . 
         [0026]    In one form, high speed motor generator  42  is directly coupled to gas producer shaft  40 , i.e., without an intervening speed/torque conversion mechanism such as a gearbox. Motor generator  42  is operative to rotate at the same rotational speed as gas producer shaft  40 . In one form, motor generator  42  includes a motor generator rotor  48  mounted on gas producer shaft  40 . In another form, motor generator rotor  48  is integral with gas producer shaft  40 . In other embodiments, motor generator rotor  48  may be directly coupled to gas producer shaft  40  without being mounted thereon or integral therewith. In still other forms, motor generator rotor  48  may be coupled to gas producer shaft  40  via a speed increasing or speed reducing gear train, such as an accessory drive system (not shown). 
         [0027]    With the embodiment of  FIG. 2 , controller  30  is configured to execute program instructions to selectively direct power augmentation system  22  to transmit power from motor generator  42  to motor generator  26 . Power may thus be extracted from gas producer shaft  40  and stored in flywheel  28  for subsequent use at output shaft  18 . Extracting power from the gas producer requires engine  14  to operate at lower flows and higher temperatures, which may in some embodiments increase part power efficiency of engine  14 . Such part power efficiency improvements may be more pronounced in an engine  14  having a heat recovery system, such as a recuperator. 
         [0028]    As an example of transferring power from gas producer shaft  40  to flywheel  28 , engine  14  is operated to rotate gas producer shaft  40 . Under the direction of controller  30 , mechanical power from gas producer shaft  40  is absorbed by motor generator  42 , which converts the mechanical power into electrical power. The electrical power is then transmitted to motor generator  26  via electrical link  44 . Under the direction of controller  30 , motor generator  26  converts the electrical power back into mechanical power, which is absorbed by flywheel  28  in the form of rotating inertial energy. Upon receiving a command to augment power to thrust rotor  16 , motor generator  26  absorbs mechanical power from flywheel  28  and converts the mechanical power to electrical power under the direction of controller  30 . The electrical power is then transmitted to motor generator  24  via electrical link  34 . Motor generator  24  then converts the electrical power into mechanical power under the direction of controller  30 , which is transmitted to output shaft  18  by motor generator rotor  32 . 
         [0029]    Referring now to  FIG. 3 , another embodiment of engine  14  with power augmentation system  22  is described.  FIG. 3  is similar to the embodiment of  FIG. 2 , except that motor generator  42  is electrically coupled to motor generator  24  via an electrical link  50 , such as a power cable, instead of being coupled to motor generator  26  via electrical link  44 . It will be understood that in other embodiments, motor generator  42  may be electrically coupled to both motor generator  24  and motor generator  26 . In the embodiment of  FIG. 3 , controller  30  is configured to execute program instructions to selectively direct power augmentation system  22  to transmit power from motor generator  42  to motor generator  24 . The embodiment of  FIG. 3  allows the transfer of power from gas producer shaft  40  directly to output shaft  18 , which may increase the part power efficiency of engine  14 , as set forth above with respect to the embodiment of  FIG. 2 . 
         [0030]    As an example of transferring power from gas producer shaft  40  to output shaft  18 , engine  14  may be operated to rotate gas producer shaft  40 . Under the direction of controller  30 , mechanical power from gas producer shaft  40  is absorbed by motor generator  42 , which converts the mechanical power into electrical power. Under the direction of controller  30 , the electrical power is transmitted to motor generator  24  via electrical link  50 . Motor generator  26  converts the electrical power back into mechanical power, which is transmitted to output shaft  18  by motor generator rotor  32 . 
         [0031]    Referring now to  FIGS. 4 ,  5  and  6 , some many possible additional embodiments are illustrated. In the embodiments of  FIGS. 4-6 , each transmission  20  is powered by two engines  14 . The embodiment of  FIG. 4  may be considered a twin-engine version of the embodiment of  FIG. 1 . In the embodiment of  FIGS. 4-6 , a single motor generator  26  and flywheel  28  are employed. In the embodiment of  FIG. 4 , each motor generator  24  is electrically coupled to the common motor generator  26 . In the embodiment of  FIG. 5 , each motor generator  24  and each motor generator  42  are electrically coupled to the common motor generator  26 . In the embodiment of  FIG. 6 , each motor generator  24  is electrically coupled to the common motor generator  26 , and each motor generator  42  is electrically coupled to the motor generator  24  corresponding to the same engine  14 . 
         [0032]    Power augmentation system  22  may store energy in flywheel  28  for subsequent use to provide power to thrust rotor  16 . In some embodiments, power augmentation system  22  energizes flywheel  28  by extracting mechanical power from the operation of engine  14 . For example, during part power engine  14  operation, e.g., ground idle, flight idle, ascent, descent or cruise power settings, energy may be stored in flywheel  28 , e.g., by converting mechanical power to electrical power using motor generator  24  and/or motor generator  42 , depending upon the embodiment. The electrical power is then converted to mechanical power by motor generator  26  and stored in flywheel  28  as inertial energy. 
         [0033]    In other embodiments, power from a helicopter or tiltrotor main rotor (thrust rotor  16 ) is used to rotate output shaft  18  and provide mechanical power, e.g., during the descent phase of an autorotation landing. The mechanical power is received by power augmentation system  22  and stored in flywheel  28 . Power augmentation system  22  may then be used to transmit the power back to output shaft  18  in order to provide power to the main rotor during the landing flare, e.g., which may aid flight safety and the landing of the air vehicle. 
         [0034]    In still other embodiments, all or part of power augmentation system  22  may aid in performing a ground or in-flight startup of an engine  14 . For example, in one form, energy stored in flywheel  28  may be used to rotate the output shaft of a single shaft engine  14  via motor generator  24 , which in some embodiments may be performed on the ground and/or during flight operations. In another form, energy stored in flywheel  28  may be used to rotate the gas producer shaft of a multi-spool engine  14  via motor generator  42 , which in some embodiments may be performed on the ground and/or during flight operations. In yet another form, electrical power may be generated via motor generator  24  during windmilling, e.g., of a fan rotor, a helicopter rotor or a propeller, which may be supplied to the gas producer of a multi-spool engine via motor generator  42  and/or motor generator  26 , which may be used to start or aid in starting engine  14 . 
         [0035]    In yet still other embodiments flywheel  28  may be energized by another source of electrical power, e.g., a ground cart, and in some embodiments, the energy stored in flywheel  28  may be used to provide power to other devices in addition to or in place of output shaft  18 . For example, referring now to  FIG. 7 , in some embodiments, motor generator  26  may electrically coupled to a system  52  via an electrical link  54 , such as a power cable. System  52  may take various forms in different embodiments. For example, in one form, system  52  may be a static power source, such as a land-based power system, a land-based electrical grid and/or a ground cart, which may be used to energize flywheel  28  by providing electrical power to motor generator  26 . 
         [0036]    The power delivered by power augmentation system  22  may be utilized for many other purposes. For example, in one exemplary form, a sizing feature for a twin-engine helicopter includes a one engine inoperative (OEI) rating, which may be two minutes, with a higher emergency rating of 30 seconds. Energy stored in flywheel  28  may be employed to increase the OEI capability of the engine by providing additional power. 
         [0037]    As another example, electronic weapons such as lasers or other high energy weapons often require bursts of transient power. For example, referring again to  FIG. 7 , in one form, system  52  may be an electronic or other weapon system that requires bursts of transient power. In some embodiments, an aircraft fitted with power augmentation system  22  may use the energy stored in flywheel  28  to power the weapon, by converting the mechanical energy stored in flywheel  28  to electrical energy with motor generator for use by the weapon system. 
         [0038]    As yet another example, helicopters and tiltrotor aircraft require substantial amounts of power to hover prior to gaining forward velocity and translational lift. By energizing flywheel  28  prior to takeoff, the energy stored in flywheel  28  may be subsequently extracted by power augmentation system  22  during takeoff. 
         [0039]    As still another example, gas turbine engine  14  thermodynamic output may be reduced during critical operations and augmented by power augmentation system  22 , which may reduce engine noise and heat signature, e.g., during stealth operations. 
         [0040]    As yet still another example, peak power demands and transient power demands are typically the parameters used to size a gas turbine engine core, e.g., to determine the maximum power rating for the engine. However, the air vehicle typically operates at a fraction of the maximum available power. Fuel efficiency at part power is typically much less than when operating at the maximum power design point. By sizing the gas turbine engine to account for the power that may be provided by power augmentation system  22 , the peak power demands from the gas turbine engine are reduced. This may allow for the use of a smaller gas turbine engine core that, under normal operating conditions such as cruise conditions, operates closer to design point. In some embodiments, this may potentially yield increased efficiency relative to propulsions systems that do not include a power augmentation system such as power augmentation system  22 . 
         [0041]    As a further example, power augmentation system  22  may be used to transfer power from gas producer shaft  40  to output shaft  18  as set forth above with respect to  FIG. 2 . 
         [0042]    As a yet further example, power augmentation system  22  may be energized by an aircraft prior to leaving the gate (e.g., at an airport), and then subsequently used to power electric drive motors in the aircraft wheels. This may allow an aircraft to taxi to the runway without idling the main engine, which may reduce noise, fuel usage, exhaust emissions and noise. 
         [0043]    Embodiments of the present invention include an augmented gas turbine engine propulsion system for an air vehicle, comprising: a gas turbine engine having an output shaft operative to drive a thrust rotor for the air vehicle; and a power augmentation system coupled to the output shaft and operative to receive and store power from the output shaft and to transmit power to the output shaft, the power augmentation system including: a first high speed motor generator coupled directly to the output shaft and operative to rotate at a same rotational speed as the output shaft; a flywheel operative to store inertial energy; and a second high speed motor generator electrically coupled to the first high speed motor generator and mechanically coupled to the flywheel. 
         [0044]    In a refinement, the augmented gas turbine engine propulsion system further includes a controller communicatively coupled to the first high speed motor generator and the second high speed motor generator, wherein the controller is configured to execute program instructions to selectively direct the power augmentation system to transmit power from the output shaft to the flywheel and to transmit power from the flywheel to the output shaft. 
         [0045]    In another refinement, the first high speed motor generator includes a motor generator rotor mounted on the output shaft. 
         [0046]    In yet another refinement, the first high speed motor generator includes a motor generator rotor integral with the output shaft. 
         [0047]    In still another refinement, the air vehicle is a rotary wing aircraft, and wherein the thrust rotor is a helicopter main rotor. 
         [0048]    In yet still another refinement, the air vehicle is a fixed wing aircraft, and wherein the thrust rotor is a propeller. 
         [0049]    In a further refinement, the output shaft is a fan drive shaft, and the augmented gas turbine engine propulsion system further includes a fan rotor, wherein the air vehicle is a fixed wing aircraft, and wherein the thrust rotor is the fan rotor. 
         [0050]    In a yet further refinement, the gas turbine engine is a multi-spool engine, and wherein the output shaft is a main shaft of a first spool of the gas turbine engine, further comprising a third high speed motor generator mechanically coupled to a second spool of the gas turbine engine and electrically coupled to the second high speed motor generator. 
         [0051]    Embodiments also include a gas turbine engine power augmentation system, comprising: a first high speed motor generator coupled directly to an output shaft of the gas turbine engine and operative to rotate at a same rotational speed as the output shaft; a flywheel operative to store inertial energy; and a second high speed motor generator electrically coupled to the first high speed motor generator and mechanically coupled to the flywheel, wherein the power augmentation system is operative to receive and store power from the output shaft and to transmit power to the output shaft. 
         [0052]    In a refinement, the gas turbine engine power augmentation system further includes a controller communicatively coupled to the first high speed motor generator and the second high speed motor generator, wherein the controller is configured to execute program instructions to selectively direct the power augmentation system to transmit power from the output shaft to the flywheel and to transmit power from the flywheel to the output shaft. 
         [0053]    In another refinement, the gas turbine engine is a multi-spool engine, and the output shaft is a main shaft of a first spool of the gas turbine engine, wherein the gas turbine engine power augmentation system further includes a third high speed motor generator mechanically coupled to a main shaft of a second spool of the gas turbine engine. 
         [0054]    In yet another refinement, the third high speed motor generator is electrically coupled the first high speed motor generator. 
         [0055]    In still another refinement, the gas turbine engine power augmentation system further includes a controller communicatively coupled to the first high speed motor generator and the third high speed motor generator, wherein the controller is configured to execute program instructions to selectively direct the power augmentation system to transmit power from the third high speed motor generator to the first high speed motor generator. 
         [0056]    In yet still another refinement, the third high speed motor generator is electrically coupled to the second high speed motor generator. 
         [0057]    In a further refinement, the gas turbine engine power augmentation system further includes a controller communicatively coupled to the second high speed motor generator and the third high speed motor generator, wherein the controller is configured to execute program instructions to selectively direct the power augmentation system to transmit power from the third high speed motor generator to the second high speed motor generator. 
         [0058]    In a still further refinement, the third high speed motor generator is electrically coupled to both the first high speed motor generator and the second high speed motor generator. 
         [0059]    In yet still a further refinement, the second spool is a gas producer spool, and the third high speed motor generator includes a motor generator rotor mounted on the main shaft of the gas producer spool. 
         [0060]    In an additional refinement, the second spool is a gas producer spool, and the third high speed motor generator includes a motor generator rotor integral with the main shaft of the gas producer spool. 
         [0061]    Embodiments also include a system for augmenting power in an engine powered air vehicle, comprising: means for rotating an output shaft of the engine to provide a first mechanical power at the output shaft; means for converting the first mechanical power at the output shaft into a first electrical power; means for converting the first electrical power into a second mechanical power; means for storing the second mechanical power in the form of an inertial energy; means for converting the inertial energy into a second electrical power; and means for converting the second electrical power into a third mechanical power at the output shaft. 
         [0062]    In a refinement, the system also includes means for rotating a gas producer shaft of the engine to provide a fourth mechanical power; means for converting the fourth mechanical power into a third electrical power; and means for transmitting the third electrical power to one of: the means for converting the first electrical power into a second mechanical power; and the means for converting the second electrical power into a third mechanical power at the output shaft. 
         [0063]    In another refinement, the system further includes means for providing a fourth electrical power from a static power source to the means for converting the first electrical power into the second mechanical power. 
         [0064]    In yet another refinement, the system further includes means for powering a weapon system using the means for converting the inertial energy into the second electrical power. 
         [0065]    While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment(s), but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims, which scope is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures as permitted under the law. Furthermore it should be understood that while the use of the word preferable, preferably, or preferred in the description above indicates that feature so described may be more desirable, it nonetheless may not be necessary and any embodiment lacking the same may be contemplated as within the scope of the invention, that scope being defined by the claims that follow. In reading the claims it is intended that when words such as “a,” “an,” “at least one” and “at least a portion” are used, there is no intention to limit the claim to only one item unless specifically stated to the contrary in the claim. Further, when the language “at least a portion” and/or “a portion” is used the item may include a portion and/or the entire item unless specifically stated to the contrary.