Abstract:
A launch system in which an unmanned aerial vehicle is secured to a platform in a watertight tube adapted to be launched from a submerged platform. Once launched, side panels on the tube are jettisoned and a flotation device is deployed to bring the tube to the surface. The flotation device maintains the tube in a vertical position when rising to and at the surface. After surfacing, a top-sealing cap of the tube is opened. A lifting mechanism within the tube raises the vertically oriented platform assembly up within the tube. Guide rails maintain the vertical orientation of the assembly during lifting. At the topmost point of travel, the assembly is raised clear of the tube and is disengaged from the guide rails, allowing the assembly to pivot about its attachment to the lifting mechanism and assume an orientation favorable for launching the UAV.

Description:
STATEMENT OF GOVERNMENT INTEREST 
     The invention described herein may be manufactured and used by or for the Government of the United States of America for Governmental purposes without the payment of any royalty thereon or therefore. 
    
    
     BACKGROUND OF THE INVENTION 
     (1) Field of the Invention 
     The present invention relates to subsurface launched unmanned aerial vehicles (UAVs) and is directed more particularly to a deployment system for launching a vertical take off and landing (VTOL) UAV or a fixed-wing UAV. 
     (2) Description of the Prior Art 
     The launching of UAVs from submarines, or other subsurface platforms, is known in the art, e.g., the launching of cruise missiles and other types of missiles and high-speed vehicles. For some purposes, slower speed UAVs are preferred and launch systems for such UAVs are being developed. Some slower speed UAV systems have disadvantages and/or limitations. 
     One system relies on buoyancy to provide the UAVs initial upward momentum to separate the UAV from a launcher. Thus, once released from the underwater platform, one commonly used launcher does not allow for a time-delayed launch of the UAV, which can compromise or reveal the position of the underwater platform. Additionally, the launcher relies on a booster or the like to initially power the UVA once it is separated. This launching mechanism creates a flame or smoke plume, referred to as a “flame datum”, which also compromises the platform location. Two typically used launchers cannot be launched at submarine test depth or in shallow water due to risks of the capsules striking the hull of the submarine or other underwater platform. 
     Accordingly, there is a need for a deployment system for launching a UAV from a subsurface platform, which allows for a time delayed launch without a significant flame or smoke plume, that can launch a UAV at test depth or in shallow water and that can accommodate a variety of UAVs, such as VTOL UAVs and fixed-wing UAVs. 
     SUMMARY OF THE INVENTION 
     It is therefore a general object and a primary purpose of the present invention to provide a deployment system adapted to be launched from a submerged platform at varying depths, to convey a UAV to the surface and to deploy a surface platform for launching the UAV. 
     It is a further object of the present invention to provide a deployment system adapted to accommodate delayed deployment of the surface platform and launching of the UAV without a flame datum. 
     In order to attain these objects, there is provided a watertight tube or capsule that can be launched from a submerged platform and that encapsulates a UAV and a UAV launch platform. The UAV is secured to the platform and the UAV-platform assembly is oriented along a longitudinal axis of the tube. Once launched from and clear of the submerged platform, side panels on the tube are jettisoned and a flotation device, such as a flotation collar, is deployed to bring the tube to the surface. The flotation device is configured such that the tube is maintained in a vertical position when rising to the surface and when the tube and flotation device are at the surface. 
     Upon surfacing, or after a predetermined delay, and preferably at a time when sensors on and/or within the tube determine that surface conditions are satisfactory, the top-sealing cap of the tube is opened. A lifting mechanism within the tube, such as a winch or other powered lift, raises the vertically oriented UAV-platform assembly within the tube. Guide rails within the tube maintain the vertical orientation of the assembly during lifting. At the topmost point of travel, the assembly is raised clear of the tube and is disengaged from the guide rails, allowing the assembly to pivot about its attachment to the lifting mechanism and assume an orientation favorable for launching the UAV. For a VTOL UAV, the platform and UAV assembly can be configured to assume a generally horizontal orientation. For a fixed wing UAV, the orientation may be inclined, e.g., at angles of between 32 and 45 degrees, so as to provide a ramp for launching the UAV. 
     In one embodiment, a system for deploying an Unmanned Aerial Vehicle (UAV) from a platform submerged in a medium includes a capsule enclosing the UAV in a watertight manner when submerged, a floatation device attached to the capsule, the floatation device providing buoyancy to the capsule to bring the capsule to a surface of the medium after launch of the capsule from the submerged platform, a hatch forming an opening in the capsule after the capsule reaches the surface to allow the UAV to exit the capsule, a lifting means within the capsule for moving the UAV from within the capsule, through the hatch and to a position exterior to the capsule and a cradle for releasably supporting the UAV, the cradle and UAV rotating between an interior orientation and a launch orientation when the UAV reaches the position exterior to the capsule. 
     In one aspect, the system includes guide means to maintain the interior orientation of the cradle and UAV during movement of the UAV within the capsule. The guide means can include one or more rails fixed within the capsule and one or more extensions of the cradle that slidably mate with the guide rail. The guide means can include bearings, such as linear bearings, to facilitate the sliding movement between the extension and the rail. 
     In another aspect, the floatation device forms a collar at least partially surrounding the capsule when the floatation device is inflated. The collar is offset from a center of gravity of the capsule to maintain a longitudinal axis of the capsule in a substantially vertical position when the capsule reaches the surface. The floatation device can include a plurality of chambers. Removable panels that conform to the shape of the capsule can cover the floatation device during launch from the submerged platform and prior to inflation of the floatation device. 
     In a further aspect, the lifting means can include a motorized winch and a cable attached at one end to the winch and at the other end to the cradle; such that when the cable is wound on the winch the cradle and UAV move within the capsule. In other aspects, the lifting means can be selected from one of a winch and cable system, a hydraulic piston, rack and pinion gearing, a screw drive and/or a chain drive. 
     In another aspect, the system can include a power source within the capsule for providing power for operation of the system, controls for controlling operation of system and sensors for obtaining measurements of ambient conditions at least one of within and exterior to the capsule. The sensors can measure a depth of the medium for determining when the floatation device is to be activated. The sensors also can measure sea state conditions exterior to the capsule when the capsule reaches the surface for determining when the hatch is to be opened. 
     In still other aspects, the UAV is a vertical take-off and landing UAV and the launch orientation is substantially horizontal. In yet another aspect, the UAV is a fixed-wing UAV, the cradle includes a ramp structure on the cradle with the fixed-wing UAV being releasably attached to the ramp structure such that the launch orientation of the fixed-wing UAV slopes upward away from the surface and a launching mechanism assists the fixed-wing UAV in moving up the ramp structure during launch. The lifting surfaces of the UAV can be stored in a folded position within the capsule. 
     In one embodiment, a system for deploying an Unmanned Aerial Vehicle (UAV) from a submerged platform includes a watertight elongated cylindrical capsule enclosing the UAV, a floatation device providing buoyancy to the capsule to bring the capsule to a surface after launch of the capsule from the submerged platform, the floatation device maintaining a longitudinal axis of the capsule substantially vertical, a lifting means within the capsule for moving the UAV vertically within the capsule, a removable cap forming an opening in the capsule, the lifting means moving the UAV through opening and a cradle for releasably supporting the UAV, the cradle and UAV rotating between a vertical interior orientation and a substantially horizontal launch orientation upon the UAV passing through the opening. 
     In one aspect, the system includes one or more guide rails fixed within the capsule, one or more extensions of the cradle that slidably mate with the guide rails and bearings to facilitate sliding movement between the extensions and the rails. In another aspect, the lifting means can include a motorized winch, a cable attached at one end to the winch and at the other end to the cradle, wherein the cable is wound on the winch to move the cradle and UAV within the capsule. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A more complete understanding of the invention and many of the attendant advantages thereto will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings wherein: 
         FIG. 1  illustrates a schematic sectional view of a UAV deployment system of the present invention; 
         FIG. 2  illustrates a flotation device of the UAV deployment system of the present invention; 
         FIG. 3  illustrates the UAV deployment system upon reaching the surface and beginning to deploy the UAV; 
         FIG. 4  illustrates the UAV secured to a launch platform and pivoting to a launch position; 
         FIG. 5  illustrates the UAV being launched from the launch platform; and 
         FIG. 6  illustrates a fixed-wing UAV being launched from the launch platform. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     To provide an overall understanding, certain illustrative embodiments will now be described; however, it will be understood by one of ordinary skill in the art that the systems and methods described herein can be adapted and modified to provide systems and methods for other suitable applications and that other additions and modifications can be made without departing from the scope of the systems and methods described herein. 
     Unless otherwise specified, the illustrated embodiments can be understood as providing exemplary features of varying detail, and therefore, unless otherwise specified, features, components, modules, and/or aspects of the illustrations can be otherwise combined, separated, interchanged, and/or rearranged without departing from the disclosed systems or methods. Additionally, the shapes and sizes of components are also exemplary and unless otherwise specified, can be altered without affecting the disclosed systems or methods. 
     Referring to  FIG. 1 , there is shown a schematic sectional view of a UAV deployment system  10  of the present invention. The deployment system  10  includes an encapsulating tube or capsule  12 , which is configured for launch from an underwater platform, such as a submarine or other mobile or stationary platform. Preferably, the capsule  12  can be a modified version of an existing capsule that may be launched from an underwater platform, e.g., a modified Harpoon Missile Capsule. However, it is understood that the capsule  12  can be configured with any shape and size to suit the intended purposes described herein. 
     In operation, the capsule  12  forms a watertight seal for a UAV  14  and other components contained therein. The UAV  14  can be releasably mounted on a support platform or cradle  16 . For the orientation of the capsule  12  illustrated in  FIG. 1 , the cradle  16  and the UAV  14  mounted thereon are movable in a vertical direction within capsule. For ease of illustration, but not for limitation, the means for moving the cradle  16  and UAV  14  is illustrated in the exemplary embodiments shown in the figures and described herein as having a winch drum  18  that is turned by a motor  20 . Cable  22  is attached at one end to the drum  18  and attached at the other end to the cradle  16  via pulleys  24 . As the drum  18  is turned by the motor  20 , the cable  22  is wound onto the drum  18  and in turn pulls the cradle  16  and the UAV  14  mounted thereto in a vertical direction. Lifting or moving means other than that shown in the figures may be utilized; including but are not limited to hydraulic pistons, screw and/or chain drives, rack and pinion gearing, and/or combinations thereof. For ease of explanation and generalization, further reference herein to the drum  18  or lifting means will be understood to refer to any of the above lifting means. 
     Guide means  26  can maintain the proper orientation of the cradle  16  and the UAV  14  during movement. For the exemplary embodiment of  FIG. 1 , guide means  26  can include one or more tabs  26   a  on the cradle  16  that mate with a slot  26   b  in rail  26   c  that is mounted to interior surface  12 a of the capsule  12 . For ease of travel, bearings, rollers or the like may be incorporated into rails  26   c  or tabs  26   a.  Other configurations of guide means as are known in the art may be contemplated. For example, but without limitation, the cradle  16  may be configured with rollers, which contact the interior surface  12   a  of the capsule  12 , or the interior surface may include rollers or linear bearings to guide the cradle  16 . It will be understood that other combinations and/or configurations of rails, tabs, rollers, bearings and the like may be used. 
     Additionally, the capsule  12  can include electronic controls  28 , sensors  30  and a power source  32  for operation of the components of the deployment system  10 . The configuration shown in  FIG. 1  for the controls  28 , the sensors  30  and the power source  32  is for illustrative purposes and it is understood that the controls, the sensors and power source may be configured at various locations within capsule  12  as suitable for the overall configuration of the deployment system  10 . Furthermore, the exterior of the capsule  12  includes two or more retaining panels  34 , which cover floatation device  36 , shown un-inflated in  FIG. 1 . The panels  34  may serve to protect the floatation device  36  during a launch of the capsule  12 . 
     Referring now to  FIG. 2 , an isometric view of the capsule  12  is illustrated after the panels  34  have been separated therefrom and the floatation device  36  is deployed. Deployment of the floatation device  36  may be at a predetermined depth, as may be determined by the sensors  30 . The panels  34  may be securely but releasably attached to the capsule  12  by explosive bolts that discharge at the predetermined depth. Other means known in the art may be used, including without limitation, spring-loaded latches, magnetic catches, solenoids and the like. Once the panels  34  are detached from the capsule  12 , the floatation device  36  inflates to preferably form a generally circumferential collar about the capsule. However, it is to be understood that the floatation device  36  need not be fully circumferential. In some embodiments, the force against the panels  34  as the floatation device  36  expands is sufficient to fully or partially detach the panels  34  from the capsule  12  without the need to use explosive bolts or the like, in the manner that an airbag is deployed from within a hidden compartment in an automobile. The placement of the floatation device  36  about the capsule  12  and the total floatation capacity of the floatation device are such as to bring the capsule  12  to the surface in a generally vertical orientation. The floatation device  36  may include more than one compartment and/or may include a number of separate devices for protection against loss of floatation if one compartment or device fails to inflate or is damaged. 
       FIG. 3  illustrates the capsule  12  being held afloat at a surface by means of the floatation device  36  as deployment of the UAV  14  has begun. Preferably, but not necessarily, the sensors  30  (shown in  FIG. 1 ) may determine when the capsule  12  has breached the surface and if conditions exterior to the capsule are satisfactory for deployment. For example, weather gauges, accelerometers, tiltmeters and/or other sensors  30  can gauge the surrounding sea state. To initiate deployment, a hatch or cap  38  is fully or partially detached from the capsule  12 , as shown in  FIG. 3 . Detachment may be by means similar to one of those described for detachment of the panels  34  (shown in  FIG. 2 ), or the deployment of the UAV  14  may cause the cap  38  to detach. The lifting or moving means, such as the drum  18  and cable  22  shown and described with relation to  FIG. 1 , but not shown in  FIG. 3  for clarity, is operated to cause the cradle  16  with attached the UAV  14  to rise within the capsule  12  and to partially extend above the capsule. 
       FIG. 4  illustrates a partial view of the capsule  12  being held afloat at a surface of a medium by means of the floatation device  36 . In the exemplary illustration of  FIG. 4 , lifting means  18  (not shown in  FIG. 4  for clarity) has an extended cradle  16  and the UAV  14  vertically such that guide means  26  (illustrated in  FIG. 4  as tabs  26   a ) are at least partially disengaged. The cradle  16  may pivot about attachment point  40 , as indicated by arrows  42 . The lifting means  18  may include limit switches or the like that can stop operation of the lifting device when the cradle  16  reaches its vertical limit. In some embodiments, the weight and position of the center of gravity of the UAV  14  on the cradle  16  in relation to the attachment point  40  can allow the cradle  16  and the UAV to pivot without further mechanical input once the guide means  26  are disengaged. In other embodiments, the guide means  26 , the lifting means  18 , and/or other source may provide a force against the cradle  16  to the pivot cradle  16  about the attachment point  40 . 
     In some embodiments, a stop means  44  may prevent the cradle  16  from over rotation. For illustrative purposes, the stop means  44  is shown in  FIG. 5  as a tether between the guide means  26  and the cradle  16 , although other attachments may be contemplated. For example, the attachment of the cable  22  to the cradle  16  may serve as the stop means  44 . Other stop means  44  may be used, including without limitation, a rotary damper at the attachment point  40 , hydraulic cylinders, tabs within the capsule  12  that engage the cradle  16  as it pivots, and/or combinations of these and other stop means as are known in the art. The action of the stop means  44  can provide a dampening effect, including without limitation, dampening such as provided by hydraulic cylinders, rotary or other dampers, elastomeric material, springs and the like, to reduce impact forces as the cradle pivots. In addition or alternately, the combination of the position of the center of gravity, the stop means  44  and/or its dampening effect may generally maintain the cradle  16  and the UAV  14  in proper orientation for launch as wave action causes the capsule  12  to tilt. Furthermore, the floatation device  36  may be sized to better stabilize the capsule  12  in varying sea states. 
       FIG. 5  illustrates a partial view of the capsule  12  in which the UAV  14  is launched from a launch platform or the cradle  16 , as indicated by direction arrow  46 . Once the UAV  14  attains a launch position, as described with relation to  FIG. 4  and shown in  FIG. 5 , the UAV  14  can be activated, detached from the cradle  16  and deployed, as illustrated in  FIG. 5 . Attachment and detachment of the UAV  14  to the cradle  16  may be by means similar to one of those described for detachment of the panels  34 , including without limitation, explosive bolts, spring loaded latches, magnetic catches, solenoids and the like. The power and/or control connections from electronic controls  28 , sensors  30  and/or power source  32  to the UAV  14  may include a break-away or other type of releasable connector  48  that detaches from the UAV  14  at launch, as is known in the art. 
     For the embodiment illustrated in  FIG. 5 , the UAV  14  is a vertical take off and landing (VTOL) UAV, such as a small helicopter sized to fit within the capsule  12 . In other embodiments, such as illustrated in  FIG. 6 , a fixed-wing (FW) UAV  114  may be launched. For accommodation within the capsule  12 , lifting surfaces or blades  50  of the VTOL UAV  14  or wings  150  of the FW UAV  114  may be stored in a folded position prior to flight. For the FW UAV  114  of  FIG. 6 , cradle  116  may include a ramp structure  152  that maintains an inclined orientation such that the FW UAV  114  may be launched at an angle suitable for the FW UAV  114  to attain flight. A launching mechanism  154  may be provided to assist FW UAV  114  in attaining flight, such as a stored energy device including without limitation spring-loaded devices, stretched elastomeric bands, pressurized pistons, and/or other known stored energy devices or combinations thereof. While launching mechanism  154  may also or alternately include such devices as rocket boosters and the like, such devices may provide unwanted heat traces. However, the choice of such devices may depend on the mission being accomplished. As an example, a search and rescue mission may not be impacted by having such a heat trace. 
     While preferred embodiments of the deployment systems and methods for subsurface launched UAVs have been described in detail above, various modifications and variations of the invention are possible in light of the above teaching, a number of which have been described herein. It is therefore understood that within the scope of the appended claims the invention may be practiced otherwise and above described.