Patent Publication Number: US-11021251-B2

Title: Inset turret assemblies for tiltrotor aircraft

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation of co-pending application Ser. No. 16/522,369 filed Jul. 25, 2019 which is a continuation of application Ser. No. 16/251,571 filed Jan. 1, 2018. 
    
    
     TECHNICAL FIELD OF THE DISCLOSURE 
     The present disclosure relates, in general, to turret assemblies for use on aircraft and, in particular, to rotatable turret assemblies mounted on a nonhorizontal surface and inset in an aperture formed by the nose of the aircraft to reduce the drag experienced by the aircraft during flight. 
     BACKGROUND 
     Aircraft must balance the need for operational payloads, or devices, with flight efficiency requirements including weight, drag and maneuverability requirements. Certain operational payloads such as weapons, sensors and cameras are typically mounted on the underside of the aircraft fuselage to maintain a clear line of sight to their intended target. Such operational payloads are often rotatable about one or more axes to allow for targeting of specific elements in the air or on the ground. One common type of exterior rotatable payload is a gun turret mounted on the underside of an aircraft&#39;s fuselage. Gun turrets typically house a weapon, and sometimes a crew member, while being capable of some degree of azimuth and elevation, or cone of fire, through which the weapon may be aimed and fired. Another type of exterior rotatable payload is a gimballed sensor turret that hangs from the underside of an aircraft&#39;s fuselage and employs sensors to perform airborne observation, surveillance or reconnaissance. 
     One reason why such exterior rotatable payloads are mounted on the underside of the fuselage is because the fuselage underside presents a horizontal surface, which provides an orthogonal and predictable load and center of gravity and sometimes helps to reduce moments on the airframe of the aircraft. Undermounted external payloads, however, do not take advantage of the improved structural strength of modern aircraft airframes and also increase the forward-facing profile of the aircraft, thereby increasing drag and reducing aircraft efficiency. Accordingly, a need has arisen for turret systems that allow rotatable operational payloads to be mounted to aircraft without incurring the drag penalty of existing undermounted turret systems. 
     SUMMARY 
     In a first aspect, the present disclosure is directed to a nose assembly of an aircraft including a nose airframe having a nonhorizontal mounting surface and a turret assembly mounted on the nonhorizontal mounting surface. The turret assembly includes a turret device housing rotatable relative to the nonhorizontal mounting surface. The nose airframe includes a nose skin forming a nose fairing having an apex aperture. The nose skin at least partially covers the turret assembly such that the turret assembly is at least partially inset in the apex aperture of the nose fairing. 
     In certain embodiments, the nonhorizontal mounting surface may be a vertical mounting surface. In some embodiments, the nonhorizontal mounting surface may be disposed inside the nose fairing. In certain embodiments, the turret assembly may protrude from the nonhorizontal mounting surface in a forward direction. In some embodiments, the turret device housing may be a gimballing turret device housing rotatable about at least two axes. In certain embodiments, the turret assembly may include a turret mount coupling the turret device housing to the nonhorizontal mounting surface. In some embodiments, the turret mount may include a base and a forked housing mount, and the base may be disposed inside the nose fairing. In certain embodiments, the forked housing mount may be rotatable about a longitudinal axis parallel to a forward flight direction of the aircraft. In some embodiments, the turret device housing may be rotatably coupled to the forked housing mount about a lateral axis perpendicular to a forward flight direction of the aircraft. In certain embodiments, the forked housing mount may protrude from the nose fairing through the apex aperture. In some embodiments, the turret device housing may be a turret sensor housing including one or more sensors such as an integrated sensor suite. In certain embodiments, the turret device housing may be a turret weapon housing including a weapon. In some embodiments, the turret device housing may be substantially spherical to form a turret ball. In certain embodiments, the nose fairing may substantially cover a rear-facing hemisphere of the turret device housing. 
     In a second aspect, the present disclosure is directed to an aircraft including a fuselage having a nose assembly. The nose assembly includes a nose airframe having a nonhorizontal mounting surface and a turret assembly mounted on the nonhorizontal mounting surface. The turret assembly includes a turret device housing rotatable relative to the nonhorizontal mounting surface. The nose airframe includes a nose skin forming a nose fairing having an apex aperture. The nose skin at least partially covers the turret assembly such that the turret assembly is at least partially inset in the apex aperture of the nose fairing. 
     In certain embodiments, the aircraft may be a helicopter, tiltrotor aircraft or unmanned aerial system. In some embodiments, the nonhorizontal mounting surface may form an acute angle with a horizontal plane of the aircraft. In certain embodiments, the turret device housing may include an outer surface contoured to form an aerodynamic apex of the nose assembly. In some embodiments, the nose fairing may cover at least 30 percent of the turret device housing. In certain embodiments, the aircraft may include a weapons turret mounted on the underside of the fuselage. In some embodiments, the nonhorizontal mounting surface may be a substantially flat and planar nonhorizontal mounting surface. In other embodiments, the nonhorizontal mounting surface may include a multifaceted surface having two or more faceted surfaces, and the turret assembly may comprise a plurality of turret assemblies each mounted to one of the faceted surfaces. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a more complete understanding of the features and advantages of the present disclosure, reference is now made to the detailed description along with the accompanying figures in which corresponding numerals in the different figures refer to corresponding parts and in which: 
         FIGS. 1A-1C  are schematic illustrations of a helicopter having an inset turret assembly in accordance with embodiments of the present disclosure; 
         FIGS. 2A-2C  are side views of horizontally-mounted turret assemblies juxtaposed with an inset turret assembly in accordance with embodiments of the present disclosure; 
         FIGS. 3A-3E  are various views of an inset turret assembly in accordance with embodiments of the present disclosure; 
         FIGS. 4A-4C  are various views of different inset turret assembly configurations in accordance with embodiments of the present disclosure; 
         FIGS. 5A-5C  are schematic illustrations of a tiltrotor aircraft having an inset turret assembly in accordance with embodiments of the present disclosure; and 
         FIGS. 6A-6B  are schematic illustrations of an unmanned aerial system having an inset turret assembly in accordance with embodiments of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     While the making and using of various embodiments of the present disclosure are discussed in detail below, it should be appreciated that the present disclosure provides many applicable inventive concepts, which can be embodied in a wide variety of specific contexts. The specific embodiments discussed herein are merely illustrative and do not delimit the scope of the present disclosure. In the interest of clarity, all features of an actual implementation may not be described in this specification. It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developer&#39;s specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure. 
     In the specification, reference may be made to the spatial relationships between various components and to the spatial orientation of various aspects of components as the devices are depicted in the attached drawings. However, as will be recognized by those skilled in the art after a complete reading of the present disclosure, the devices, members, apparatuses, and the like described herein may be positioned in any desired orientation. Thus, the use of terms such as “above,” “below,” “upper,” “lower” or other like terms to describe a spatial relationship between various components or to describe the spatial orientation of aspects of such components should be understood to describe a relative relationship between the components or a spatial orientation of aspects of such components, respectively, as the devices described herein may be oriented in any desired direction. As used herein, the term “coupled” may include direct or indirect coupling by any means, including by mere contact or by moving and/or non-moving mechanical connections. 
     Referring to  FIGS. 1A-1C  in the drawings, a helicopter is schematically illustrated and generally designated  10 . The primary propulsion assembly of helicopter  10  is a main rotor assembly  12 . Main rotor assembly  12  includes a plurality of rotor blades  14  extending radially outward from a main rotor hub  16 . Main rotor hub  16  is rotatable relative to fuselage  18 . The pitch of rotor blades  14  can be collectively and/or cyclically manipulated to selectively control direction, thrust and lift of helicopter  10 . A tailboom  20  extends from fuselage  18  in the aft direction. An anti-torque system  22  includes a tail rotor  24  that is rotatably coupled to the aft portion of tailboom  20 . Anti-torque system  22  manages the yaw of helicopter  10 . A retractable landing gear system (not shown) may provide ground support for helicopter  10 . 
     Fuselage  18  includes a nose assembly  26  at the forward end of helicopter  10 . Nose assembly  26  is supported by a nose airframe  28  including nose skin  30 . Nose skin  30  forms a nose fairing  32  to provide an aerodynamic forward end of helicopter  10 . Nose fairing  32  forms an apex aperture, or hole,  34  located at the apex and forward end of nose assembly  26 . Apex aperture  34  is illustrated as having a circular shape, but may have any shape depending on the embodiment. Nose airframe  28  also includes a nonhorizontal mounting surface  36  disposed inside nose fairing  32 . In the illustrated embodiment, nonhorizontal mounting surface  36  is vertically oriented so as to be substantially perpendicular to forward flight direction  38  of helicopter  10 . Nonhorizontal mounting surface  36 , however, may form any nonparallel relationship or angle with forward flight direction  38 . 
     Nose assembly  26  includes a turret assembly  40  mounted on nonhorizontal mounting surface  36 . Nose skin  30  partially covers turret assembly  40  such that turret assembly  40  is partially inset in apex aperture  34  of nose fairing  32 . Turret assembly  40  includes turret device housing  42 , which is rotatable relative to nonhorizontal mounting surface  36 . Turret device housing  42  protrudes from apex aperture  34  and is contoured to form an aerodynamic apex for nose assembly  26 . As best seen in  FIG. 1C , the exposed outer contour of turret device housing  42  is substantially flush with nose skin  30  at apex aperture  34  to integrate turret assembly  40  into the aerodynamic nose of helicopter  10 . Turret device housing  42  may include any device(s) suitable for the operation of helicopter  10 . In the illustrated embodiment, turret device housing  42  is a turret sensor housing that includes one or more sensors. The types of sensors that may be included in the turret sensor housing are numerous and may include an infrared sensor, such as a forward-looking infrared (FLIR) sensor, a night vision sensor or other optical sensor, a laser sensor, a sound sensor, a motion sensor, a high resolution camera, a radar or any other type of sensor. Such sensors may have a wide variety of uses including in intelligence, surveillance, target acquisition and reconnaissance (ISTAR) and may form an integrated sensor suite. 
     The direction or orientation of turret device housing  42  may be controlled in a variety of ways. For example, the pilot(s) of helicopter  10  may use manual or voice-activated inputs to rotate turret device housing  42  to direct the device(s) in the turret device housing  42  in a particular direction. In another example, a flight control computer onboard helicopter  10  may direct and control the device(s) in the turret device housing  42  in accordance with a programmed mission, such as a mission to obtain surveillance photographs of a targeted area. In yet another example, ground personnel or computers may remotely communicate with helicopter  10  to provide commands that direct and control the device(s) in the turret device housing  42 . Helicopter  10  may be piloted or unmanned. Helicopter  10  may optionally include a second turret assembly  44  rotatably mounted to the underside of fuselage  18 . In the illustrated embodiment, turret assembly  44  is a gun turret assembly. In other embodiments, gun turret assembly  44  may be excluded and inset turret assembly  40  may be the sole or primary turret assembly of helicopter  10 . 
     It should be appreciated that helicopter  10  is merely illustrative of a variety of aircraft that can implement the embodiments disclosed herein. Indeed, inset turret assembly  40  may be implemented on any aircraft. Other aircraft implementations can include hybrid aircraft, tiltwing aircraft, quad tiltrotor aircraft, unmanned aircraft, gyrocopters, propeller-driven airplanes, compound helicopters, jets, drones and the like. As such, those skilled in the art will recognize that inset turret assembly  40  can be integrated into a variety of aircraft configurations. It should be appreciated that even though aircraft are particularly well-suited to implement the embodiments of the present disclosure, non-aircraft vehicles and devices can also implement the embodiments. 
     Referring to  FIGS. 2A-2C  in the drawings, horizontally-mounted turret assemblies currently employed by aircraft are compared to the nonhorizontally-mounted turret assemblies of the illustrative embodiments. In  FIG. 2A , aircraft  100  includes a turret assembly  102  mounted on a downward-facing horizontal surface  104 . Turret assembly  102  is mounted on the underside of fuselage  106  and protrudes from fuselage  106  in the downward direction. Turret assembly  102  increases forward-facing profile  108  of aircraft  100 , which opposes airflow  110  in forward flight and therefore increases the drag penalty of aircraft  100 . In  FIG. 2B , aircraft  114  includes a turret assembly  116  mounted on an upward-facing horizontal surface  118 . In contrast to turret assembly  102  of  FIG. 2A , turret assembly  116  protrudes in the upward direction. Turret assembly  116  is mounted to a forward appendage  120  protruding from the nose of aircraft  114 , but may alternatively be mounted on an upward-facing horizontal surface of fuselage  122 . Turret assembly  116  is not aerodynamically streamlined or integrated with either the nose assembly of aircraft  114  nor any other portion of aircraft  114 , thus increasing the drag experienced by aircraft  114  in response to airflow  124  during forward flight. 
     In contrast to turret assemblies  102 ,  116  of  FIGS. 2A and 2B , which are mounted on horizontal surfaces  104 ,  118 , turret assembly  126  of aircraft  128  in  FIG. 2C  is mounted to a nonhorizontal, and in this case vertical, mounting surface  130 . Turret assembly  126  is also contoured to form an aerodynamic forward end of aircraft  128  to reduce air resistance to airflow  132  in forward flight, thereby reducing the drag experienced by aircraft  128 . Skin  134  covers a portion of turret assembly  126  to further streamline aircraft  128  in forward flight. The potential to nonhorizontally mount turret assemblies has been overlooked in previous aircraft designs due to the ease, predictability and perceived structural benefits of horizontally mounting turret assemblies. Horizontally-mounted turret assemblies, however, fail to take into account the enhanced maneuverability of modern aircraft, which allows the airframes of such aircraft to withstand loads in various angles and orientations. In the example of  FIG. 2C , nonhorizontal mounting surface  130  may be part of the airframe of aircraft  128  that provides support for both turret assembly  126  and aircraft  128  itself. It will be appreciated by one of ordinary skill in the art, however, that turret assembly  126  is not limited to being mounted only to nonhorizontal airframe elements, and may instead be mounted to structural elements that do not necessarily contribute to the strength of the airframe of aircraft  128  but nonetheless provide support for turret assembly  126 . 
     Referring to  FIGS. 3A-3E  in the drawings, an aircraft including an inset turret assembly is schematically illustrated and generally designated  200 . Nose assembly  202  of fuselage  204  is supported by nose airframe  206 . Nose airframe  206  includes nose skin  208 , which forms nose fairing  210  having apex aperture  212 . Nose airframe  206  also includes nonhorizontal mounting surface  214  on which turret assembly  216  is mounted. Nose skin  208  partially covers turret assembly  216  such that turret assembly  216  is partially inset in apex aperture  212  of nose fairing  210 . Aircraft  200  includes a weapons turret  218  on the underside of fuselage  204 , although in other embodiments weapons turret  218  may be excluded. 
     Nonhorizontal mounting surface  214  is a substantially vertical mounting surface disposed inside nose fairing  210 . Nonhorizontal mounting surface  214  provides a flat plane on which turret assembly  216  may be mounted. In other embodiments, nonhorizontal mounting surface  214  may instead or also include one or more beams, a gantry, a scaffold or any other structure capable of supporting turret assembly  216 . Turret assembly  216  protrudes from nonhorizontal mounting surface  214  in the forward direction. Turret assembly  216  includes a turret device housing  220 , which is rotatable relative to nonhorizontal mounting surface  214 . Turret device housing  220  is substantially spherical to form a turret ball. Turret device housing  220  is rotatably coupled to nonhorizontal mounting surface  214  by turret mount  222 . Turret mount  222  includes a forked housing mount  224  and a base  226 . Base  226  is interposed between forked housing mount  224  and nonhorizontal mounting surface  214  and is disposed inside nose fairing  210 . 
     Turret mount  222  provides a gimbal to allow turret device housing  220  to rotate about at least two axes. In particular, forked housing mount  224  is rotatable about a longitudinal axis  228  parallel to forward flight direction  230  of aircraft  200 , as indicated by rotational motion arrow  232 . Forked housing mount  224  is thus rotatable relative to nonhorizontal mounting surface  214 . Turret device housing  220  is rotatably coupled to forked housing mount  224  about a lateral axis  234  perpendicular to forward flight direction  230  of aircraft  200 , as indicated by rotational motion arrow  236 . Gimballing turret device housing  220  in this manner provides turret device housing  220  wide horizontal and vertical fields of view  238 ,  240 , enabling any device housed by or coupled to turret device housing  220 , such as sensor  242 , to be aimed or swept through a large cone of fire. Depending on the device housed by or coupled to turret device housing  220  and the operational requirements of aircraft  200 , horizontal and vertical fields of view  238 ,  240  may each form an acute angle, right angle, obtuse angle, straight angle or reflex angle. Horizontal and vertical fields of view  238 ,  240  may form congruent or noncongruent angles. 
     The extent to which nose fairing  210  covers turret assembly  216  may vary. In the illustrated embodiment, nose fairing  210  substantially covers a rear-facing hemisphere  244  of turret device housing  220  and a portion of forked housing mount  224  protrudes from nose fairing  210  through apex aperture  212 . In other embodiments, nose fairing  210  may cover 20 percent, 30 percent, 40 percent, 50 percent, 60 percent, 70 percent, 80 percent or other portion of turret device housing  220  and/or turret assembly  216 . Outer surface  246  of turret device housing  220  is contoured to form an aerodynamic apex for nose assembly  202  to reduce the drag experienced by aircraft  200 . Because turret assembly  216  is inset in the nose of aircraft  200 , turret assembly  216  does not adversely contribute to the forward-facing profile of aircraft  200 , thereby reducing drag. In some embodiments, gap  248  between turret assembly  216  and the edge of nose fairing  210  defining apex aperture  212  may include air blocking seals or sweeps to further streamline nose assembly  202  and reduce or prevent airflow from entering nose fairing  210 . 
     Referring to  FIGS. 4A-4C  in the drawings, various configurations of different inset turret assemblies are schematically illustrated.  FIG. 4A  is a side view of a nose assembly  300  including nonhorizontal mounting surface  302  on which turret assembly  304  is mounted. Nonhorizontal mounting surface  302  forms an acute angle  306  with a horizontal plane  308  of the aircraft. Acute angle  306  may be any angle in a range exceeding zero degrees and less than 90 degrees. For example, acute angle  306  may be in a range between 20 and 60 degrees, such as 45 degrees. The downward-facing orientation of nonhorizontal mounting surface  302  causes turret assembly  304  to protrude downward through aperture  310  formed by the underside of nose assembly  300 . Angle  306  may also be a right angle, causing turret assembly  304  to protrude through the apex of nose assembly  300 , or an obtuse angle, causing turret assembly  304  to protrude through the top side of nose assembly  300 . An aperture may be formed by nose assembly  300  at any location from which turret assembly  304  protrudes from the aircraft. 
     The top view of nose assembly  314  illustrated in  FIG. 4B  shows left and right turret assemblies  316 ,  318  mounted to left and right nonhorizontal mounting surfaces  320 ,  322 , respectively. Left and right nonhorizontal mounting surfaces  320 ,  322  face different directions, providing a multifaceted surface on which turret assemblies  316 ,  318  may be mounted. Turret assemblies  316 ,  318  protrude from different portions of nose assembly  314 . Left turret assembly  316  protrudes from a left aperture  324  formed by the left side of nose assembly  314  and right turret assembly  318  protrudes from a right aperture  326  formed by the right side of nose assembly  314 . Nose assembly  314  may include any number of turret assemblies, such as three, five, eight or any other number of turret assemblies. Left and right nonhorizontal mounting surfaces  320 ,  322  are nonperpendicular to longitudinal centerline  332  and each form an obtuse angle  328 ,  330  with longitudinal centerline  332  of the aircraft, respectively. In other embodiments, angles  328 ,  330  may be right or acute angles. While left and right nonhorizontal mounting surfaces  320 ,  322  are illustrated as being substantially vertical, in other embodiments left and right nonhorizontal mounting surfaces  320 ,  322  may be both nonhorizontal and nonvertical to provide an angled surface from which a turret assembly can protrude from nose assembly  314  at any angle. In other embodiments, another turret assembly (not shown) may be mounted on apex  334  at which left and right nonhorizontal mounting surfaces  320 ,  322  meet. 
     In  FIG. 4C , turret assembly  338  of nose assembly  340  includes a turret weapon housing  342  to which weapon  344  is coupled. The types of weapons that may be coupled to turret weapon housing  342  are numerous and may include guns, lasers, missiles or other weapon types. Turret assembly  338  is not limited to including only weapons or sensors and may include any device suitable for the operation of the aircraft including both military or nonmilitary operations. Also, turret device housings may be readily interchanged to alter the purpose of turret assembly  338 . For example, turret weapon housing  342  may be removed from turret assembly  338  and replaced with a similarly-sized multi-sensor turret ball, thereby changing the capabilities of the aircraft. In other embodiments, the device(s) housed by or coupled to turret device housings of the illustrative embodiments may be modular and interchangeable. For example, weapon  344  may be removed from turret weapon housing  342  and replaced with a sensor. 
     Referring to  FIGS. 5A-5C  in the drawings, a tiltrotor aircraft is schematically illustrated and generally designated  400 . Tiltrotor aircraft  400  includes a fuselage  402 , a wing mount assembly  404  and a tail assembly  406 . Tail assembly  406  may have control surfaces operable for horizontal and/or vertical stabilization during flight. A landing gear system (not shown) may provide ground support for tiltrotor aircraft  400 . A wing  408  is supported by fuselage  402  and wing mount assembly  404 . 
     Coupled to outboard ends  408   a ,  408   b  of wing  408  are pylon assemblies  410   a ,  410   b . Pylon assembly  410   a  is rotatable relative to wing  408  between a generally horizontal orientation, as best seen in  FIG. 5A , and a generally vertical orientation, as best seen in  FIG. 5B . Pylon assembly  410   a  includes a rotatable portion of the drive system and a proprotor assembly  412   a  that is rotatable responsive to torque and rotational energy provided by an engine or motor of the drive system. Likewise, pylon assembly  410   b  is rotatable relative to wing  408  between a generally horizontal orientation, as best seen in  FIG. 5A , and a generally vertical orientation, as best seen in  FIG. 5B . Pylon assembly  410   b  includes a rotatable portion of the drive system and a proprotor assembly  412   b  that is rotatable responsive to torque and rotational energy provided by an engine or motor of the drive system. In the illustrated embodiment, proprotor assemblies  412   a ,  412   b  each include three proprotor blade assemblies  414 . It should be understood by those having ordinary skill in the art, however, that proprotor assemblies  412   a ,  412   b  could alternatively have a different number of proprotor blade assemblies, either less than or greater than three. In addition, it should be understood that the position of pylon assemblies  410   a ,  410   b , the angular velocity or revolutions per minute (RPM) of proprotor assemblies  412   a ,  412   b , the pitch of proprotor blade assemblies  414  and the like may be controlled by the pilot of tiltrotor aircraft  400  and/or a flight control system to selectively control the direction, thrust and lift of tiltrotor aircraft  400  during flight. 
       FIG. 5A  illustrates tiltrotor aircraft  400  in a forward flight mode or airplane flight mode, in which proprotor assemblies  412   a ,  412   b  are positioned to rotate in a substantially vertical plane and provide a forward thrust while a lifting force is supplied by wing  408  such that tiltrotor aircraft  400  flies much like a conventional propeller driven aircraft.  FIG. 5B  illustrates tiltrotor aircraft  400  in a vertical takeoff and landing (VTOL) flight mode or helicopter flight mode, in which proprotor assemblies  412   a ,  412   b  are positioned to rotate in a substantially horizontal plane and provide a vertical thrust such that tiltrotor aircraft  400  flies much like a conventional helicopter. During operation, tiltrotor aircraft  400  may convert from helicopter flight mode to airplane flight mode following vertical takeoff and/or hover. Likewise, tiltrotor aircraft  400  may convert back to helicopter flight mode from airplane flight mode for hover and/or vertical landing. In addition, tiltrotor aircraft  400  can perform certain flight maneuvers with proprotor assemblies  412   a ,  412   b  positioned between airplane flight mode and helicopter flight mode, which can be referred to as conversion flight mode. 
     Wing  408  and pylon assemblies  410   a ,  410   b  form part of a propulsion and lift system for tiltrotor aircraft  400 . Fuselage  402  may include a drive system, including an engine, motor and/or transmission, for providing torque and rotational energy to each proprotor assembly  412   a ,  412   b  via one or more drive shafts located in wing  408 . In other embodiments, each pylon assembly  410   a ,  410   b  houses a drive system, such as an engine, motor and/or transmission, for supplying torque and rotational energy to a respective proprotor assembly  412   a ,  412   b . In such embodiments, the drive systems of each pylon assembly  410   a ,  410   b  may be coupled together via one or more drive shafts located in wing  408  such that either drive system can serve as a backup to the other drive system in the event of a failure. In tiltrotor aircraft having both pylon and fuselage mounted drive systems, the fuselage mounted drive system may serve as a backup drive system in the event of failure of either or both of the pylon mounted drive systems. 
     Turret assembly  416  is inset in nose assembly  418  of fuselage  402 , thus demonstrating the wide variety of aircraft types on which the illustrative embodiments may be implemented. Turret assembly  416  includes features similar to those of turret assembly  40  in  FIGS. 1A-1C  and turret assembly  216  in  FIGS. 3A-3E . In yet other embodiments, one or more turret assemblies may be inset on the forward edges or downward sides of wing  408  and/or pylon assemblies  410   a ,  410   b . For example, turret assemblies may be inset in either or both of proprotor assemblies  412   a ,  412   b.    
     Referring to  FIGS. 6A-6B  in the drawings, an unmanned aerial system including an inset turret assembly is schematically illustrated and generally designated  500 . Unmanned aerial system  500  includes fuselage  502  from which wings  504 ,  506  protrude. Wings  504 ,  506  include winglets  508 ,  510 . Fuselage  502  houses a propulsion assembly to propel unmanned aerial system  500  in a forward direction. Nose assembly  512  of fuselage  502  includes inset and rotatable turret assembly  514  mounted on a nonhorizontal surface inside fuselage  502  and having other features as described in the illustrative embodiments. For example, unmanned aerial system  500  may be equipped for reconnaissance missions and turret assembly  514  may include a gimballed multi-sensor turret ball with a wide field of view to detect targeted elements and/or movement on the ground. Because unmanned aerial system  500  does not accommodate an onboard pilot, the orientation of turret assembly  514  may be controlled remotely from the ground or from elsewhere by a person or computer. For example, unmanned aerial system  500  may include a flight control computer, housed within fuselage  502 , to process and send flight commands as well as turret assembly commands that point turret assembly in a particular direction. 
     The foregoing description of embodiments of the disclosure has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure to the precise form disclosed, and modifications and variations are possible in light of the above teachings or may be acquired from practice of the disclosure. The embodiments were chosen and described in order to explain the principals of the disclosure and its practical application to enable one skilled in the art to utilize the disclosure in various embodiments and with various modifications as are suited to the particular use contemplated. Other substitutions, modifications, changes and omissions may be made in the design, operating conditions and arrangement of the embodiments without departing from the scope of the present disclosure. Such modifications and combinations of the illustrative embodiments as well as other embodiments will be apparent to persons skilled in the art upon reference to the description. It is, therefore, intended that the appended claims encompass any such modifications or embodiments.