Patent Publication Number: US-2020284326-A1

Title: Continuously variable transmission for ram air turbines

Description:
BACKGROUND 
     The subject matter disclosed herein generally relates to aircraft components, and more particularly to ram air turbines and transmissions thereof. 
     Aircraft may include power generation using turbines in main engines. However, as a safety feature, or for other reasons, alternate power device (e.g., supplementary or backup units) may be arranged on aircraft to supply power (e.g., electric and/or hydraulic) to components of the aircraft, when needed. For example, a ram air turbine is deployable to generate power when sufficient primary power generation is not available. The ram air turbine typically includes a turbine that is deployed into an airstream along (e.g., external to) the aircraft. Rotation of the turbine drives a generator and/or hydraulic pump. The generator and/or hydraulic pump can be mounted at a pivot point of the ram air turbine that is a distance from the turbine deployed within the airstream. Accordingly, a drive arrangement including a gearbox is utilized to transfer power from the turbine to the generator and/or hydraulic pump. The drive arrangement includes a gearbox that provides a desired speed and direction for driving the generator and/or hydraulic pump. Gears, shafts, and other drive components are constrained by limitations in the desired size, weight, and power generation of the ram air turbine. 
     BRIEF DESCRIPTION 
     According to some embodiments, power generation systems for aircraft are provided. The power generation systems include at least one aircraft component and a ram air turbine assembly configured to provide power to the at least one aircraft component. The ram air turbine assembly include a turbine, a power generator operably connected to the turbine, and a continuously variable transmission arranged between the turbine and the power generator, the continuously variable transmission configured to receive an input rotational speed from the turbine and output a constant output rotation speed to enable power generation at the power generator. 
     In addition to one or more of the features described above, or as an alternative, further embodiments of the power generation systems may include that the continuously variable transmission include a first drive shaft operably connected to the turbine and a second drive shaft operably connected to the power generator. 
     In addition to one or more of the features described above, or as an alternative, further embodiments of the power generation systems may include a first pulley operably connected to the first drive shaft and configured to be driven by rotation of the turbine, a second pulley operably connected to the second drive shaft, the second drive shaft operably connected to the power generator, and a drive element operably connecting the first pulley to the second pulley such that rotation of the first pulley causes rotation of the second pulley. 
     In addition to one or more of the features described above, or as an alternative, further embodiments of the power generation systems may include that at least one of the first pulley and the second pulley comprises two cones, wherein the drive element wraps about the two cones. 
     In addition to one or more of the features described above, or as an alternative, further embodiments of the power generation systems may include that one of the two cones is fixedly connected to a respective drive shaft and the other of the two cones is movable along the respective drive shaft. 
     In addition to one or more of the features described above, or as an alternative, further embodiments of the power generation systems may include that the drive element is one of an endless chain and a belt. 
     In addition to one or more of the features described above, or as an alternative, further embodiments of the power generation systems may include that the power generator is an electric power generator. 
     In addition to one or more of the features described above, or as an alternative, further embodiments of the power generation systems may include that the power generator is a hydraulic pump. 
     In addition to one or more of the features described above, or as an alternative, further embodiments of the power generation systems may include that the power generator includes an electric power generator and a hydraulic power generator. 
     In addition to one or more of the features described above, or as an alternative, further embodiments of the power generation systems may include that the at least one aircraft component comprises a hydraulic component of the aircraft. 
     In addition to one or more of the features described above, or as an alternative, further embodiments of the power generation systems may include that the at least one aircraft component comprises an electronic component of the aircraft. 
     According to some embodiments, aircraft are provided. The aircraft include at least one aircraft component and a ram air turbine assembly configured to provide power to the at least one aircraft component, wherein at least a portion of the ram air turbine assembly is deployable between a stowed position and a deployed position external to the aircraft. The ram air turbine assembly include a turbine, wherein the turbine is positioned in an airstream external to the aircraft when in the deployed position, a power generator operably connected to the turbine, and a continuously variable transmission arranged between the turbine and the power generator, the continuously variable transmission configured to receive an input rotational speed from the turbine and output a constant output rotation speed to enable power generation at the power generator. 
     In addition to one or more of the features described above, or as an alternative, further embodiments of the aircraft may include that the continuously variable transmission includes a first drive shaft operably connected to the turbine and a second drive shaft operably connected to the power generator. 
     In addition to one or more of the features described above, or as an alternative, further embodiments of the aircraft may include a first pulley operably connected to the first drive shaft and configured to be driven by rotation of the turbine, a second pulley operably connected to the second drive shaft, the second drive shaft operably connected to the power generator, and a drive element operably connecting the first pulley to the second pulley such that rotation of the first pulley causes rotation of the second pulley. 
     In addition to one or more of the features described above, or as an alternative, further embodiments of the aircraft may include that the drive element is one of an endless chain and a belt. 
     In addition to one or more of the features described above, or as an alternative, further embodiments of the aircraft may include that the power generator is an electric power generator. 
     In addition to one or more of the features described above, or as an alternative, further embodiments of the aircraft may include that the power generator is a hydraulic pump. 
     In addition to one or more of the features described above, or as an alternative, further embodiments of the aircraft may include that the power generator includes an electric power generator and a hydraulic power generator. 
     In addition to one or more of the features described above, or as an alternative, further embodiments of the aircraft may include that the at least one aircraft component comprises a hydraulic component of the aircraft. 
     In addition to one or more of the features described above, or as an alternative, further embodiments of the aircraft may include that the at least one aircraft component comprises an electronic component of the aircraft. 
     The foregoing features and elements may be combined in various combinations without exclusivity, unless expressly indicated otherwise. These features and elements as well as the operation thereof will become more apparent in light of the following description and the accompanying drawings. It should be understood, however, the following description and drawings are intended to be illustrative and explanatory in nature and non-limiting. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The following descriptions should not be considered limiting in any way. With reference to the accompanying drawings, like elements are numbered alike: 
         FIG. 1  is a schematic illustration of an aircraft that may employ embodiments of the present disclosure; 
         FIG. 2  is a schematic illustration of a ram air turbine assembly that may employ embodiments of the present disclosure; 
         FIG. 3  is a schematic illustration of elements a continuously variable transmission in accordance with an embodiment of the present disclosure; 
         FIG. 4  is a schematic illustration of a ram air turbine assembly in accordance with an embodiment of the present disclosure; 
         FIG. 5  is a schematic illustration of a ram air turbine assembly in accordance with an embodiment of the present disclosure; and 
         FIG. 6  is a schematic illustration of a ram air turbine assembly in accordance with an embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     A detailed description of one or more embodiments of the disclosed apparatus and method are presented herein by way of exemplification and not limitation with reference to the Figures. 
     As shown in  FIG. 1 , an aircraft  100  typically includes one or more engines  102  for driving flight and powering the aircraft. The engines  102  are typically mounted on wings  104  of the aircraft  100 , but may be located at other locations depending on the specific aircraft configuration. In some aircraft, the engine(s) may be tail mounted, or housed within the body of the aircraft, or otherwise arranged as will be appreciated by those of skill in the art. 
     Each engine  102  of the aircraft  100 , regardless of location, may include one or more attached or connected generators, as appreciated by those of skill in the art. The generators may provide electrical power to various components of aircraft, as will be appreciated by those of skill in the art. In some configurations, the generators may be operably connected to an output shaft of the engine which drives a stator/rotor to generate electricity. In other configurations, a shaft from the engine may interface to a gearbox, and generators may be mounted, as an accessory, to the gearbox. 
     In addition to the power generated by the traditional or main engines (i.e., engines  102 ), additional power generation systems may be arranged on an aircraft. One type of such alternative, backup, or supplemental power generation may be a ram air turbine. The ram air turbine may be located in a nose portion of the aircraft, or at some other location, as will be appreciated by those of skill in the art (e.g., wing, wing-to-body fairing, etc.). 
     Referring to  FIG. 2 , a ram air turbine assembly  200  is illustrative shown. The ram air turbine assembly  200  is movable between a stowed position within an aircraft  202  (e.g., a nose or other part of the fuselage) and a deployed position. The deployed position is illustratively shown in  FIG. 2 . The ram air turbine assembly  200  includes a turbine  204  with airfoils  206  (e.g., blades) that rotate responsive to airflow. The turbine  204  is suspended on a strut  208  that moves between the deployed and stowed positions. The strut  208  supports a gearbox  210  that transmits power from the turbine  204  to a generator  212  within a generator housing  214 . The strut  208  is attached to the generator housing  214  within which the generator  212  is supported. The example, illustrative ram air turbine assembly  200  shown in  FIG. 2  includes the generator  212 . However, ram air turbine assemblies of the present disclosure could also be utilized to drive a hydraulic pump or other power generator or conversion device, as will be appreciated by those of skill in the art. 
     For example, in some embodiments, the ram air turbine can include a hydraulic power conversion device. Hydraulic power conversion device may, for example, be capable of converting rotation from the turbine into hydraulic pressure and flow. The hydraulic power conversion device can include a hydraulic pump and coupled to one or more hoses capable of transmitting unpressurized hydraulic fluid to the hydraulic power conversion device and pressurized hydraulic fluid from the hydraulic power conversion device to hydraulic components of aircraft, as will be readily appreciated by those of skill in the art. Ram air turbine may further comprise, for example, an electrical power conversion device. The electrical power conversion device is configured to convert rotation from the turbine into electrical energy (e.g., with a generator). Further, in some embodiments, a combination of both hydraulic and electric power generation/conversion can be implemented, without departing from the scope of the present disclosure. 
     The gearbox (e.g., gearbox  210 ) of the ram air turbine assembly (e.g., ram air turbine assembly  200 ) is configured to receive and transmit rotation from a turbine shaft to a drive shaft. For example, the gearbox may be configured to receive the turbine shaft which rotates at a turbine rotational velocity and convert the rotation to a different speed drive shaft rotational velocity (e.g., higher or lower than the turbine rotational velocity). The drive shaft may be operably connected to the hydraulic/electrical conversion devices and drive operation thereof. Operable connections between the turbine and a power converter (or generator) may be a direct connection, a gearbox (as shown), or some other connection. For example, in a typical arrangement, a gear set may be provided within a gearbox to provide increased or decreased rotational speeds, depending on the specific application. 
     In one non-limiting example of a conventional ram air turbine assembly, a fluid filled, right-angle gearbox is configured to increase a turbine shaft speed into a generator (electrical) and/or pump (hydraulic). Typical gear ratios range from 1:1 to 1:2.5. As the turbine spins up, the full driveline spins with it. This adds inertia to the driveline which increases start time (especially at cold conditions where driveline bearing tare losses and gearbox fluid viscous losses are the highest). Additionally, because the gear ratio is fixed, the governing capability of the system may be limited to the turbine. Further, a fluid filled gearbox may be prone to leakage and thus may require periodic maintenance checks and/or inspection. 
     Embodiments of the present disclosure are directed to replacing the traditional gear set with a continuously variable transmission. In some embodiments that require an angled gearbox, a continuously variable transmission can be added. A continuously variable transmission can provide a secondary governing feature to the ram air turbine system. As such, tighter output shaft speed ranges and/or control may be achieved. For example, for electric ram air turbine systems, a tighter (i.e., narrower) frequency band may be achieved, thus enabling a more controlled power supply from the ram air turbine system to electrical systems of an aircraft. In some embodiments, although inclusion of a continuously variable transmission within a ram air turbine system may increase the system weight, such weight increase at the transmission may be offset by electrical devices on the aircraft by being able to design for narrower frequency band operation. 
     In accordance with some embodiments, a flyweight engaged continuously variable transmission is employed within a ram air turbine assembly. In some such embodiments, the continuously variable transmission will include two pulleys coupled by a belt or chain (e.g., “V” pulleys). As noted, the continuously variable transmission could replace the gearbox or may be added to a geared system (e.g., dependent upon the layout of the ram air turbine assembly). In addition, in some embodiments, a clutch can be added to one of the pulleys to allow engagement to occur at a certain speed to aid turbine start-up. The clutch may be configured to engage when the turbine approaches a low end of a governing range (e.g., within 10%). Such configuration would allow for the turbine to spin up relatively quickly by reducing the driveline inertia and tare losses. 
     Referring to  FIG. 3 , a schematic illustration of a continuously variable transmission  300  in accordance with an embodiment of the present disclosure is shown. The continuously variable transmission  300  includes a pair of friction pulleys  302 ,  304  coupled by a drive element  306  (e.g., chain, belt, etc.). Each pulley  302 ,  304  includes a fixed cone  308 ,  310  and a moveable cone  312 ,  314 , respectively. The moveable cone  312 ,  314  moves axially toward or away from the respective fixed cone  308 ,  308  along respective shafts  316 ,  318 . The first movable cone  312  of the first friction pulley  302  may be moved or driven along the first shaft  316  by a first actuator  320  operably connected to the first movable cone  312 . Similarly, the second movable cone  314  of the second friction pulley  304  may be moved or driven along the second shaft  318  by a second actuator  322  operably connected to the second movable cone  314 . The actuators  320 ,  322 , in some embodiments, may be flyweight actuators. 
     The motion of the movable cones  312 ,  314 , caused by the actuators  320 ,  322 , places the drive element  306  at varying radial positions on the pulleys  302 ,  304 . The actuators  320 ,  322 , in some embodiments, may be hydraulic, mechanical, or electromechanical. The changing radial position of the drive element  306  varies a transmission ratio between the first drive shaft  316 , which may for example be the output of a gearbox driven by a ram air turbine, and the second drive shaft  318 , which may, for example, be driven to power an electric generator. Between the two pulleys  302 ,  304  where the drive element  306  is connected to the pulleys  302 ,  304 , the drive element  306  is in an unclamped space  324  (i.e., the drive element  306  is not in physical contact with the pulleys  302 ,  304 ). In the continuously variable transmission  300 , the transmission ratio may vary without steps, continuously, between two predetermined limits (e.g., extents of the cones of the pulleys  302 ,  304 ). Although described with respect to  FIG. 3  as a drive element  306 , other connecting or operating structures can be employed between the pulleys of a continuously variable transmission of the present disclosure. For example, in some embodiments, the drive element  306  may be replaced by a belt or other similar component, as will be appreciated by those of skill in the art. 
     Turning now to  FIG. 4 , a schematic illustration of a ram air turbine assembly  400  in accordance with an embodiment of the present disclosure is shown. The ram air turbine assembly  400  is a turbine assembly for the generation of power for use on an aircraft, as shown and described above. The ram air turbine assembly  400 , in this embodiment, is configured to generate electrical power using an electrical generator  402 . The power generation at the electrical generator  402  is provided from rotation of a turbine  404 , similar to that shown and described above. Located between the electrical generator  402  and the turbine  404  is a continuously variable transmission  406 . 
     The continuously variable transmission  406  is operably configured between the electrical generator  402  and the turbine  404  to provide controlled rotational speed to enable an efficient generation of power at the electrical generator  402 . As shown, the continuously variable transmission  406  includes a first pulley  408  and a second pulley  410  that are operably connected by a drive element  412  (e.g., a drive chain, drive belt, etc.). The first pulley  408  is connected to the turbine  404  by a first drive shaft  414  such that rotation of the turbine  404  will cause rotation of the first pulley  408 . As the first pulley  408  is rotated, the drive element  412  will be driven to cause rotation of the second pulley  410 . The second pulley  410  is operably connected to the electrical generator  402  by a second drive shaft  416 . As will be appreciated by those of skill in the art, the first drive shaft  414  may be referred to as an input shaft of the continuously variable transmission  406  and the second drive shaft  416  may be referred to as an output shaft of the continuously variable transmission  406 . 
     Each of the pulleys  408 ,  410  may be formed of two cones, as described above, with, for example, a movable cone arranged adjacent to a fixed cone. The drive element  412  may wrap about the cones of each of the pulleys  408 ,  410  to enable operable connection therebetween. The ratio between the first pulley  408  and the second pulley  410  may be adjusted or controlled. In some embodiments, actuators may be arranged in operable connection with the movable cones of the pulleys  408 ,  410 . Further, in some embodiments, and as shown, the first pulley  408  and/or the first drive shaft  414  may be configured with a clutch  418 . The clutch  418  may be configured to enable engagement of the first drive shaft  414  with the first pulley  408  at specific or predefined speeds. As such, the clutch  418  may enable improved start-up efficiency of the turbine (i.e., the driving of the first pulley  408  does not impact the initial rotation of the turbine  404 ). 
     The electrical generator  402  may be arranged in electrical communication with one or more components or systems of an aircraft. Accordingly, the electrical generator  402  can be arranged to provide electrical power to such components and/or systems, as will be appreciated by those of skill in the art. During operation of the ram air turbine assembly  400 , the rotational speed of the turbine  404  may be variable, and thus the output from such turbine  404  may cause variability in the electrical power generated by the electrical generator  402 . However, because of the inclusion of the continuously variable transmission  406  between the turbine  404  and the electrical generator  402 , the rotational speed input by the turbine  404  at the first pulley  408  can be adjusted, regulated, and/or otherwise controlled such that the output from the second pulley  410  is constrained within a desired range, allowing for consistent and improved tolerance electrical power generation at the electrical generator  402 . 
     For example, a typical electrical generation ram air turbine assembly may generate electrical power having a frequency tolerance of ±10%-20% or greater. This variance in the electrical frequency output requires the aircraft systems and devices powered by the ram air turbine to be arranged and configured to receive such variable frequency. Accordingly, additional electrical conditional elements may be required at the aircraft systems (e.g., electronic devices). However, advantageously, the continuously variable transmission implementation of the present disclosure can enable reduction of the variability of electrical frequency to ±5% or less, thus reducing the amount of conditioning required of the electrical frequency output from the electrical generator. 
     Turning now to  FIG. 5 , a schematic illustration of a ram air turbine assembly  500  in accordance with an embodiment of the present disclosure is shown. The ram air turbine assembly  500  is a turbine assembly for the generation of power for use on an aircraft. The ram air turbine assembly  500 , in this embodiment, is configured to generate hydraulic power using a hydraulic pump  502 . The power generation at the hydraulic pump  502  is provided from rotation of a turbine  504 , similar to that shown and described above. Located between the hydraulic pump  502  and the turbine  504  is a continuously variable transmission  506 . 
     The continuously variable transmission  506  is operably configured between the hydraulic pump  502  and the turbine  504  to provide controlled rotational speed to enable an efficient generation of power at the hydraulic pump  502 . As shown, the continuously variable transmission  506  includes a first pulley  508  and a second pulley  510  that are operably connected by a drive element  512  (e.g., a drive chain, drive belt, etc.). The first pulley  508  is connected to the turbine  504  by a first drive shaft  514  such that rotation of the turbine  504  will cause rotation of the first pulley  508 . As the first pulley  508  is rotated, the drive element  512  will be driven to cause rotation of the second pulley  510 . The second pulley  510  is operably connected to the hydraulic pump  502  by a second drive shaft  516 . As will be appreciated by those of skill in the art, the first drive shaft  514  may be referred to as an input shaft of the continuously variable transmission  506  and the second drive shaft  516  may be referred to as an output shaft of the continuously variable transmission  506 . 
     Each of the pulleys  508 ,  510  may be formed of two cones, as described above, with, for example, a movable cone arranged adjacent to a fixed cone. The drive element  512  may wrap about the cones of each of the pulleys  508 ,  510  to enable operable connection therebetween. The ratio between the first pulley  508  and the second pulley  510  may be adjusted or controlled. In some embodiments, actuators may be arranged in operable connection with the movable cones of the pulleys  508 ,  510 . Further, in some embodiments, and as shown, the first pulley  508  and/or the first drive shaft  514  may be configured with a clutch  518 . The clutch  518  may be configured to enable engagement of the first drive shaft  514  with the first pulley  508  at specific or predefined speeds. As such, the clutch  518  may enable improved start-up efficiency of the turbine (i.e., the driving of the first pulley  508  does not impact the initial rotation of the turbine  504 ). 
     The hydraulic pump  502  may be arranged in hydraulic communication with one or more components or systems of an aircraft. Accordingly, the hydraulic pump  502  can be arranged to provide hydraulic power to such components and/or systems, as will be appreciated by those of skill in the art. During operation of the ram air turbine assembly  500 , the rotational speed of the turbine  504  may be variable, and thus the output from such turbine  504  may cause variability in the hydraulic power generated by the hydraulic pump  502 . However, because of the inclusion of the continuously variable transmission  506  between the turbine  504  and the hydraulic pump  502 , the rotational speed input by the turbine  504  at the first pulley  508  can be adjusted, regulated, and/or otherwise controlled such that the output from the second pulley  510  is constrained within a desired range, allowing for consistent and improved tolerance hydraulic power generation at the hydraulic pump  502 . For example, with a variable displacement hydraulic pump, a relatively controlled or tight range of operating speeds may be advantageous. The displacement range (e.g., wobbler plate angle) could be smaller as compared to traditional system. Such reduced displacement range may allow for a smaller block size by reducing the piston stroke and/or diameter. This may, in turn, result in a better performing and more efficient pump. 
     Turning now to  FIG. 6 , a schematic illustration of a ram air turbine assembly  600  in accordance with an embodiment of the present disclosure is shown. The ram air turbine assembly  600  is a turbine assembly for the generation of power for use on an aircraft. The ram air turbine assembly  600 , in this embodiment, is configured to generate both electrical and hydraulic power using an electrical generator  602   a  and a hydraulic pump  602   b  (collectively power generators  602 ). The power generation at the power generators  602  is provided from rotation of a turbine  604 , similar to that shown and described above. Located between the power generators  602  and the turbine  604  is a continuously variable transmission  606 . 
     The continuously variable transmission  606  is operably configured between the power generators  602  and the turbine  604  to provide controlled rotational speed to enable an efficient generation of power at the power generators  602 . As shown, the continuously variable transmission  606  includes a first pulley  608  and a second pulley  610  that are operably connected by a drive element  612  (e.g., a drive chain, drive belt, etc.). The first pulley  608  is connected to the turbine  604  by a first drive shaft  614  such that rotation of the turbine  604  will cause rotation of the first pulley  608 . As the first pulley  608  is rotated, the drive element  612  will be driven to cause rotation of the second pulley  610 . The second pulley  610  is operably connected to the power generators  602  by a second drive shaft  616 . As will be appreciated by those of skill in the art, the first drive shaft  614  may be referred to as an input shaft of the continuously variable transmission  606  and the second drive shaft  616  may be referred to as an output shaft of the continuously variable transmission  606 . In some embodiments, the second drive shaft  616  may be operably connected to both the electrical generator  602   a  and the hydraulic pump  602   b . In other embodiments, the second drive shaft  616  may be operably connected to the electrical generator  602   a , which in turn may be operated to drive operation of the hydraulic pump  602   b.    
     Each of the pulleys  608 ,  610  may be formed of two cones, as described above, with, for example, a movable cone arranged adjacent to a fixed cone. The drive element  612  may wrap about the cones of each of the pulleys  608 ,  610  to enable operable connection therebetween. The ratio between the first pulley  608  and the second pulley  610  may be adjusted or controlled. In some embodiments, actuators may be arranged in operable connection with the movable cones of the pulleys  608 ,  610 . Further, in some embodiments, and as shown, the first pulley  608  and/or the first drive shaft  614  may be configured with a clutch  618 . The clutch  618  may be configured to enable engagement of the first drive shaft  614  with the first pulley  608  at specific or predefined speeds. As such, the clutch  618  may enable improved start-up efficiency of the turbine (i.e., the driving of the first pulley  608  does not impact the initial rotation of the turbine  604 ). 
     The electrical generator  602   a  may be arranged in electrical communication with one or more components or systems of an aircraft. Accordingly, the electrical generator  602   a  can be arranged to provide electrical power to such components and/or systems, as will be appreciated by those of skill in the art. During operation of the ram air turbine assembly  600 , the rotational speed of the turbine  604  may be variable, and thus the output from such turbine  604  may cause variability in the electrical power generated by the electrical generator  602   a . However, because of the inclusion of the continuously variable transmission  606  between the turbine  604  and the electrical generator  602   a , the rotational speed input by the turbine  604  at the first pulley  608  can be adjusted, regulated, and/or otherwise controlled such that the output from the second pulley  610  is constrained within a desired range, allowing for consistent and improved tolerance electrical power generation at the electrical generator  602   a.    
     The hydraulic pump  602   b  may be arranged in hydraulic communication with one or more components or systems of an aircraft. Accordingly, the hydraulic pump  602   b  can be arranged to provide hydraulic power to such components and/or systems, as will be appreciated by those of skill in the art. During operation of the ram air turbine assembly  600 , the rotational speed of the turbine  604  may be variable, and thus the output from such turbine  604  may cause variability in the hydraulic power generated by the hydraulic pump  602   b . However, because of the inclusion of the continuously variable transmission  606  between the turbine  604  and the hydraulic pump  602   b , the rotational speed input by the turbine  604  at the first pulley  608  can be adjusted, regulated, and/or otherwise controlled such that the output from the second pulley  610  is constrained within a desired range, allowing for consistent and improved tolerance hydraulic power generation at the hydraulic pump  602   b.    
     In some embodiments having both an electrical generator and a hydraulic pump for power generation, the output shaft of the continuously variable transmission may provide a single output rotational speed for both the electrical generator and the hydraulic pump. However, in other embodiments, a gear box may be arranged along the output shaft between the electrical generator and the hydraulic pump to enable a change in rotational speed of the output shaft for the specific power generator. Moreover, although shown as an arrangement of electrical generator upstream from the hydraulic pump, in other embodiments, the hydraulic pump may be arranged upstream from the electrical generator, or a dual shaft arrangement may enable parallel operation instead of series. In some embodiments, a hydraulic pump connected to the ram air turbine may be configured to power an electrical generator. Furthermore, in some embodiments and as shown in  FIG. 6 , an optional clutch  620  may be arranged on the output shaft such that one or the other of the electrical generator and the hydraulic pump may be operated independently of the other. 
     In operation, embodiments of the present disclosure enable a variable input at the turbine to be converted into a constant or relatively constant output to enable generation of, for example, constant-frequency electrical power. As will be appreciated by those of skill in the art, the ram air turbine assemblies and systems described herein can provide power (e.g., electric and/or hydraulic) to one or more aircraft components. For example, without limitation, aircraft components that can be powered by the ram air turbine assemblies and systems described herein can include airfoil actuators, ailerons and other flight control surfaces (flaps, slats, etc.), and electrical and/or electronic components, including, but not limited to flight-critical instrumentation, navigation, heaters, and/or communication equipment. 
     Advantageously, embodiments provided herein enable efficient and controlled power supply for an aircraft during operation of a ram air turbine assemblies for supplemental and/or emergency power generation. The ram air turbine assemblies provide improved power generation through the inclusion of a continuously variable transmission operably arranged between a turbine and a power generator of the ram air turbine assembly. The continuously variable transmission can enable controlled output shaft speed rotation, and thus enable relatively constant and/or controlled power generation. For example, with an electrical generator, the frequency of the electrical power generated may have a variation of ±5% or less about a desired power level. This is in contrast to prior ram air turbine assemblies that would generate power having up to 20% variability in electrical frequency output. This benefit may also be realized with systems that generate hydraulic power and/or both hydraulic and electrical power, as described above. By improving the quality (tolerance) of the frequency output from the generator(s) of the ram air turbine assemblies, frequency conditioning elements on the aircraft may be reduced in size or even completely eliminated, thus providing weight and space savings on an aircraft. 
     The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, element components, and/or groups thereof. 
     While the present disclosure has been described with reference to an exemplary embodiment or embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the present disclosure. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the present disclosure without departing from the essential scope thereof. Therefore, it is intended that the present disclosure not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this present disclosure, but that the present disclosure will include all embodiments falling within the scope of the claims.