Patent Publication Number: US-7712702-B2

Title: Methods and apparatuses for launching unmanned aircraft, including releasably gripping aircraft during launch and breaking subsequent grip motion

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a divisional of U.S. patent application Ser. No. 10/808,725, filed Mar. 24, 2004, which claims priority to U.S. Provisional Application No. 60/554,824, filed Mar. 19, 2004, and is a continuation-in-part of U.S. patent application Ser. No. 10/758,955, filed Jan. 16, 2004, which claims priority to U.S. Provisional Patent Application No. 60/440,727 filed Jan. 17, 2003. The disclosures of these applications are incorprated herein by reference in their entirety. 
    
    
     TECHNICAL FIELD 
     The present disclosure describes methods and apparatuses for launching unmanned aircraft, including methods and apparatuses for releasably gripping aircraft during launch and braking subsequent grip motion. 
     BACKGROUND 
     Unmanned aircraft or air vehicles (UAVs) provide enhanced and economical access to areas where manned flight operations are unacceptably costly and/or dangerous. For example, unmanned aircraft outfitted with remotely controlled cameras can perform a wide variety of surveillance missions, including spotting schools of fish for the fisheries industry, monitoring weather conditions, providing border patrols for national governments, and providing military surveillance before, during and/or after military operations. 
     Existing unmanned aircraft systems suffer from a variety of drawbacks. For example, existing unmanned aircraft systems (which can include the aircraft itself along with launch devices, recovery devices, and storage devices) typically require substantial space. Accordingly, these systems can be difficult to install and operate in cramped quarters, such as the deck of a small fishing boat, land vehicle, or other craft. Another drawback with some existing unmanned aircraft is that, due to small size and low weight, they can be subjected to higher acceleration and deceleration forces than are larger, manned air vehicles, and can accordingly be prone to damage. Still another drawback with existing launch devices is that they may not absorb the energy associated with a launch in a manner that effectively prevents or limits loads placed on the launch device and/or the aircraft, exposing the launch device and the aircraft to damage. 
     SUMMARY 
     The present invention is directed generally toward methods and apparatuses for launching unmanned aircraft. An apparatus in accordance with one aspect of the invention includes a support, a launch carriage movably carried by the support, and a gripper movably coupled to the launch carriage. The gripper can include at least one grip portion positioned to releasably engage an unmanned aircraft. The gripper can be movable relative to the launch carriage between a first position with the at least one grip portion positioned to contact the aircraft, and a second position with the at least one grip portion positioned to be out of contact with the aircraft. A brake can be positioned at least proximate to the gripper and can be changeable from a first configuration in which the brake inhibits motion of the gripper by a first amount, and a second configuration in which the brake does not inhibit motion of the gripper, or inhibits motion of the gripper by a second amount less than the first amount. Accordingly, the brake can control the motion of the gripper after the aircraft has been released. 
     An apparatus in accordance with another aspect of the invention includes a first launch member, a second launch member positioned at least proximate to the first launch member, and a launch carriage having support positioned to releasably carry an unmanned aircraft during a takeoff operation. The launch carriage can include a first portion in contact with the first launch member and a second portion in contact with the second launch member. The launch carriage can be movable relative to the launch members between a first launch carriage location and a second launch carriage location as at least one of the first and second launch members moves relative to the other, or at least one of the carriage portions moves relative to the other, or both. 
     A method in accordance with a further aspect of the invention includes releasably supporting an unmanned aircraft with a launch carriage, releasably engaging the aircraft with a gripper carried by the launch carriage and accelerating the launch carriage along a launch axis. The method can further include disengaging the gripper from the aircraft by moving the gripper relative to the launch carriage from a first position to a second position, releasing the aircraft from the launch carriage for flight, and at least restricting motion of the gripper relative to the launch carriage after disengaging the gripper. 
     A method in accordance with another aspect of the invention includes releasably supporting an unmanned aircraft with a launch carriage that is movably carried by and in contact with a first launch member and a second launch member. The launch carriage can be accelerated from a first launch carriage location to a second launch carriage location by moving at least one of the first and second launch members relative to the other while the launch members contact the launch carriage, or by moving at least one portion of the launch carriage relative to the other while the launch members contact the launch carriage, or both. The method can further include releasing the unmanned aircraft from the launch carriage for flight. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1A-1C  illustrate an arrangement for launching an unmanned aircraft in accordance with an embodiment of the invention. 
         FIG. 2  illustrates an embodiment of the arrangement shown in  FIGS. 1A-1C  after having been reset for a subsequent launch. 
         FIGS. 3 and 4  illustrate systems for launching an aircraft with a carriage that carries both the aircraft and an actuator. 
         FIG. 5  illustrates a predicted carriage acceleration associated with an embodiment of the invention. 
         FIG. 6  is a partially cut-away illustration of a gripper and gripper brake for releasably supporting an aircraft during launch. 
         FIGS. 7A-7E  are partially schematic illustrations of an apparatus having at least one movable launch member for launching an unmanned aircraft in accordance with another embodiment of the invention. 
         FIGS. 8A-8B  are partially schematic illustrations of an apparatus having a movable launch member for launching an unmanned aircraft in accordance with another embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION 
     The following disclosure describes systems and methods for launching aircraft, for example, unmanned aerial vehicles (UAVs). Certain specific details are set forth in the following description and in  FIGS. 1A-8B  to provide a thorough understanding of various embodiments of the invention. Well-known structures, systems and methods often associated with aircraft launch systems have not been shown or described in detail below to avoid unnecessarily obscuring the description of the various embodiments of the invention. In addition, those of ordinary skill in the relevant art will understand that additional embodiments of the present invention may be practiced without several of the details described below. 
       FIG. 1A  illustrates a launch system  110  having a launch guide  140  and a carriage  120  that together accelerate and guide an aircraft  150  along an initial flight path  111  at the outset of a flight. The launch guide  140  can include a support structure  141  carrying a first or upper launch member  142  (e.g., a track) and a second or lower launch member  143 , both of which are generally aligned with the initial flight path  111 . The support structure  141  can be mounted to a vehicle (e.g., a trailer or a boat) or to a fixed platform (e.g., a building). Portions of the first launch member  142  and the second launch member  143  can be non-parallel to each other (e.g., they can converge in a direction aligned with the initial flight path  111 ) to accelerate the carriage  120 , as described below. 
     The carriage  120  can include a gripper  180  having a pair of gripper arms  181  that releasably carry the aircraft  150 . The carriage  120  can also include a first or upper portion  122  and a second or lower portion  123 , each of which has rollers  121  (shown in hidden lines in  FIG. 1A ). The rollers  121  can guide the carriage  120  along the launch members  142 ,  143  while the carriage portions  122 ,  123  are driven toward each other. Accordingly, normal forces applied to the rollers  121  can drive the rollers  121  against the launch members  142 ,  143 , drive the carriage portions  122 ,  123  together, and drive the carriage  120  forward, thereby accelerating the aircraft  150  to flight speed. 
     An actuator  113  can be linked to the carriage  120  to provide the squeezing force that drives the carriage portions  122 ,  123  toward each other and drives the carriage  120  along the launch guide  140 . Many actuators  113  that are configured to release energy fast enough to launch the aircraft  150  also have a spring-like behavior. Accordingly, the actuators  113  tend to exert large forces at the beginning of a power stroke and smaller forces as the power stroke progresses and the carriage  120  moves along the launch guide  140 . An embodiment of the system  110  shown in  FIG. 1A  can compensate for this spring-like behavior by having a relative angle between the first launch member  142  and the second launch member  143  that becomes progressively steeper in the launch direction. In one example, the force provided by the actuator  113  can decrease from 6000 lbs to 3000 lbs as the carriage  120  accelerates. Over the same distance, the relative slope between the first launch member  142  and the second launch member  143  can change from 6:1 to 3:1. Accordingly, the resulting thrust imparted to the carriage  120  and the aircraft  150  can remain at least approximately constant. 
     At or near a launch point L, the carriage  120  reaches the launch speed of the aircraft  150 . The first launch member  142  and the second launch member  143  can diverge (instead of converge) forward of the launch point L to form a braking ramp  144 . At the braking ramp  144 , the carriage  120  rapidly decelerates to release the aircraft  150 . The carriage  120  then stops and returns to a rest position at least proximate to or coincident with the launch position L. 
     In one embodiment, the actuator  113  includes a piston  114  that moves within a cylinder  115 . The piston  114  is attached to a flexible, elongated transmission element  116  (e.g., a rope or cable) via a piston rod  117 . The transmission element  116  can pass through a series of guide pulleys  145  (carried by the launch guide  140 ) and carriage pulleys  124  (carried by the carriage  120 ). The guide pulleys  145  can include first guide pulleys  145   a  on a first side of the support structure  141 , and corresponding second guide pulleys  145   b  on a second (opposite) side of the support structure  141 . The carriage pulleys  124  can also include first carriage pulleys  124   a  on a first side of the carriage  120  and second pulleys  124   b  on a second (opposite) side of the carriage  120 . One or more equalizing pulleys  146 , located in a housing  147  can be positioned between (a) the first guide pulleys  145   a  and the first carriage pulleys  124   a  on the first side of the support structure  141 , and (b) the second guide pulleys  145   b  and the second carriage pulleys  124   b  on the second side of the support structure  141 . 
     In operation, one end of the transmission element  116  can be attached to the first side of the support structure  141 , laced through the first pulleys  145   a ,  124   a , around the equalizing pulley(s)  146 , and then through the second pulleys  145   b ,  124   b . The opposite end of the transmission element  116  can be attached to the second side of the support structure  141 . The equalizing pulley(s)  146  can (a) guide the transmission element  116  from the first side of the support structure  141  to the second side of the support structure  141 , and (b) equalize the tension in the transmission element  116  on the first side of the support structure  141  with that on the second side of the support structure  141 . 
     When the transmission element  116  is tensioned, it squeezes the carriage portions  122 ,  123  together, forcing the carriage  120  along the converging launch members  142 ,  143 . The carriage pulleys  124  and the rollers  121  (which can be coaxial with the carriage pulleys  124 ) are secured to the carriage  120  so that the carriage  120  rides freely along the initial flight path  111  of the aircraft  150  as the carriage portions  122 ,  123  move together. 
       FIG. 1B  illustrates the launch of the carriage  120  in accordance with an embodiment of the invention. The carriage  120  is held in place prior to launch by a trigger device  139 , e.g., a restraining shackle. When the trigger device  139  is released, the carriage  120  accelerates along the launch members  142 ,  143 , moving from a first launch carriage location to a second launch carriage location (e.g., to the launch point L). At the launch point L, the carriage  120  achieves its maximum velocity and begins to decelerate by rolling along the braking ramp  144 . In this embodiment, one or more arresting pulleys  148  can be positioned along the braking ramp  144  to intercept the transmission element  116  and further decelerate the carriage  120 . 
     As shown in  FIG. 1C , once the carriage  120  begins to decelerate along the braking ramp  144 , the aircraft  150  is released by the gripper arms  181 . Each gripper arm  181  can include a forward contact portion  182   a  and an aft contact portion  182   b  configured to releasably engage a fuselage  151  of the aircraft  150 . Accordingly, each contact portion  182  can have a curved shape so as to conform to the curved shape of the fuselage  151  In other embodiments, the gripper arms  181  can engage different portions of the aircraft  150  (e.g., the wings  152 ). Each gripper arm  181  can be pivotably coupled to the carriage  120  to rotate about a pivot axis P. The gripper arms  181  can pivot about the pivot axes P to slightly over-center positions when engaged with the aircraft  150 . Accordingly, the gripper arms  181  can securely grip the fuselage  151  and resist ambient windloads, gravity, propeller thrust (e.g., the maximum thrust provided to the aircraft  150 ), and other external transitory loads as the carriage  120  accelerates. In one aspect of this embodiment, each pivot axis P is canted outwardly away from the vertical. As described in greater detail below, this arrangement can prevent interference between the gripper arms  181  and the aircraft  150  as the aircraft  150  is launched. 
     At least a portion of the mass of the gripper arms  181  can be eccentric relative to the first axis P. As a result, when the carriage  120  decelerates, the forward momentum of the gripper arms  181  causes them to fling open by pivoting about the pivot axis P, as indicated by arrows M. The forward momentum of the gripper arms  181  can accordingly overcome the over-center action described above. As the gripper arms  181  begin to open, the contact portions  182   a ,  182   b  begin to disengage from the aircraft  150 . In a particular aspect of this embodiment, the gripper arms  181  pivot downwardly and away from the aircraft  150 . 
     An advantage of a gripper arrangement described above with reference to  FIG. 1C  is that the gripping action provided by the gripper arms  181  can be distributed fore and aft over the fuselage  151 , thus distributing the gripping load. A further advantage of embodiments of the foregoing arrangement is that the gripper arms  181  can be configured to quickly and completely rotate out of the way of the aircraft  150  as the aircraft  150  takes flight. Still a further advantage of the foregoing arrangement is that no additional hardware (with associated weight and drag), need be provided to the aircraft  150  to allow it to be releasably carried by the carriage  120 . In still further embodiments, the motion of the gripper arms  181  after the aircraft  150  has been released can be controlled, as described in greater detail below with reference to  FIG. 6 . 
     After the aircraft  150  is launched, a pull-back winch  149  can be used to cock the launch system  110  (e.g., return the carriage  120  to its launch position) in preparation for the next launch.  FIG. 2  illustrates the system  110  in the cocked position. A rope or strap extends from the pull-back winch  149  to the trigger device  139  which engages with the carriage  120 . The actuator  113  can then be energized (e.g., by pressurizing the cylinder  115 ), prior to the next launch. 
       FIG. 3  illustrates a launch system  110  configured in accordance with another embodiment of the invention. In one aspect of this embodiment, the system  110  includes a carriage  320  having carriage portions  322 ,  323  coupled to each other with an actuator  313  that is carried by the carriage  320 . As the actuator  313  contracts, it draws the two carriage portions  322 ,  323  toward each other which, because the launch members  142 ,  143  converge, causes the carriage  320  to roll forward on the rollers  121 . 
     In one aspect of this embodiment, the actuator  313  includes a spring that links the carriage portions  322 ,  323 . The mass of the carriage  320  accordingly includes that of the actuator  313 , and the energy requirements are correspondingly larger than that of the carriage  120  described above with reference to  FIGS. 1C . On the other hand, the carriage  320  shown in  FIG. 3  requires no transmission element  116  or pulleys  145 ,  124  ( FIG. 1A ). 
     In yet another embodiment, (shown in  FIG. 4 ) the carriage  320  carries an actuator  413 , but at least a portion of the energy required by the actuator  413  is provided to the actuator  413  from a ground-based link  418  (e.g., a hose or wire). Accordingly, in one aspect of this embodiment, the actuator  413  can include a pneumatic or hydraulic actuator. In other embodiments, the actuator  413  can include an electric linear actuator or a lead screw actuator. 
     Embodiments of the present invention can include a relatively small spring (or other actuator) and no rotating cam system to achieve a constant force launch acceleration. Embodiments of the present invention can also employ a movable carriage (or shuttle), and an actuator that strokes through only a fraction of the carriage stroke. The “gain” or amplification of this motion amplifier can correspond to the slope of one launch member relative to one or more opposing launch members. For example, in one embodiment, the piston  114  described above with reference to  FIG. 1A  can stroke through a distance of two feet, while accelerating the carriage  120  with a constant force over a distance of ten feet. 
       FIG. 5  illustrates a graph of predicted carriage acceleration as a function of launch member length for an existing system having a single track and a spring or spring-like actuator, along with a system having two non-parallel launch members (e.g., as shown in  FIG. 1A ), also with a spring-like actuator. As shown in  FIG. 5 , by tailoring the relative angle between the non-parallel launch members to compensate for the reduced force provided by the actuator over the length of the launch guide, the force applied to the carriage (and therefore the acceleration of the carriage) can be maintained at a constant or nearly constant level until the carriage is deliberately decelerated to launch the aircraft. An advantage of this arrangement is that it can significantly reduce the peak force applied to the aircraft without significantly increasing the energy required by the launch mechanism, or the distance required to accelerate the aircraft to launch velocity. 
       FIG. 6  is a partially cut-away illustration of an embodiment of the carriage  120  as the gripper  180  supports the aircraft  150  prior to release. For purposes of illustration, only one of the gripper arms  181  is shown in  FIG. 6 . The carriage upper portion  122  can include a pivot post  693  extending along the pivot axis P. The gripper arm  181  can include an upper portion  688  and a lower portion  687 . A gripper sleeve  699  can be attached to the upper portion  688  and disposed coaxially about the pivot post  693 . One or more bearings  686  can support the gripper sleeve  699  relative to the pivot post  693 . Accordingly, the gripper arm  181  can rotate smoothly about the pivot axis P as indicated by arrow M. 
     As discussed above, the gripper arm  181  can pivot both downwardly and outwardly away from the aircraft  150  during release so as to reduce the likelihood that the gripper arm  181  will strike the aircraft  150  as the aircraft  150  takes off. To further reduce the likelihood that the gripper arm  181  will strike either the aircraft  150  or the opposing gripper arm, the system  110  can include a gripper brake  690  that arrests the rotational motion of the gripper arm  181  once the aircraft  150  has been released. 
     The gripper brake  690  can include a first brake member  691   a  that is fixed relative to the pivot post  693 , and a second brake member  691   b  that is fixed to the gripper sleeve  698  to rotate with the gripper arm  181 . The second brake member  691   b  can also move axially toward the first brake member  691   a  along the pivot axis P during braking. The first brake member  691   a  can include a first brake surface  685   a , and the second brake member  691   b  can include a second brake surface  685   b . As the second brake member  691   b  moves toward and rotates relative to the first brake member  691   a , the brake surfaces  685   a ,  685   b  contact each other and halt the rotation of the gripper arm  181 . Accordingly, the brake  690  can be changeable between a first configuration in which it inhibits motion of the gripper  181  by a first amount (e.g., after launch) and a second configuration in which it does not inhibit motion of the gripper arm  181 , or inhibits motion of the gripper arm  181  by a second, lesser amount (e.g., prior to launch). 
     To control the motion of the second brake member  691   b  relative to the first brake member  691   a , the gripper brake  690  can further include a first threaded member  692   a  that can be generally fixed relative to the pivot post  693  and can be supported with a first threaded member support  694 . The first threaded member  692   a  can include external threads  695   a  that engage internal threads  695   b  of a second threaded member  692   b , carried by the gripper sleeve  699 . As the gripper arm  181  rotates about the pivot axis P, it rotates the second threaded member  692   b  relative to the first threaded member  692   a . The first threaded member  692   a  and the second threaded member  692   b  can have left-hand threads, so that the second threaded member  692   b  moves axially downwardly as it rotates. This axial motion drives the second brake member  691   b  into engagement with the first brake member  691   a . As the second threaded member  692   b  continues to rotate, it drives the second brake surface  685   b  against the first brake surface  685   a  with increasing pressure. This action stops the gripper arm  181  from rotating. A corresponding pair of threaded members on the opposite gripper arm can have right-hand threads to provide a generally similar brake action to that gripper arm. 
     In a particular embodiment, the position of the second brake member  691   b  relative to the first brake member  691   a  when the gripper arm  181  is in the gripping position (as shown in  FIG. 6 ) can be adjusted so that there is at least a slight gap (or, in one embodiment, no gap, but little or no pressure) between the second brake surface  685   b  and the first brake surface  685   a . Accordingly, the gripper sleeve  699  can include an adjustment flange  689  having multiple adjustment holes  697 . The second threaded member  692   b  can include an alignment hole  696  that can be selectively aligned with any of the adjustment holes  697  as the second threaded member  692   b  is rotated independently of the gripper arm  181 . Accordingly, a user can rotate the second threaded member  692   b  about the first threaded member  692   a  until a small gap exists between the second brake surface  685   b  and the first brake surface  685   a . The user can then lock the second threaded member  692   b  relative to the gripper arm  181  by inserting a pin or other fastener through the alignment hole  696  and into a corresponding adjustment hole  697  of the adjustment flange  689 . If, over the course of time, the first and second brake surfaces  685   a ,  685   b  move apart from reach other (e.g., as a result of wear), the initial gap between the brake surfaces  685   a ,  685   b  can be readjusted by simply repositioning the second threaded member  692   b  relative to the adjustment flange  689 . 
     The materials of at least some of the system components described above can be selected to reduce and/or eliminate interference caused by differential thermal expansion of one component relative to another. For example, the first threaded member support  694 , the pivot post  693 , and/or the first threaded member  692   a  can be formed from the same material as the gripper arm  181 . Accordingly, the position of the second brake member  691   b  relative to the first brake member  691   a  can be less likely to change as the ambient temperature changes. In other embodiments, the materials selected for these or other components can be selected to increase the life expectancy of the components. For example, the first threaded member  692   a  can be selected to include steel and the second threaded member  692   b  can be selected to include brass. In other embodiments, these components can have other material properties and/or arrangements. For example, the gripper brake  690  can brake the gripper arms  181  via an action different than the axial and rotational action described above. 
     A feature of an embodiment of the system described above with reference to  FIG. 6  is that the gripper brake  690  can rapidly, predictably, and repeatably stop the motion of the gripper arm  181  as it pivots away from the aircraft  150  during release. An advantage of this arrangement is that the gripper arm  181  can be less likely to strike either the aircraft  150  or the opposing gripper arm (not shown in  FIG. 6 ). 
     In the embodiments of the launch system  110  described above, the portions of the carriage  120  move relative to each other while the launch members  142 ,  143  remain fixed. In other embodiments, the launch members can move, in lieu of, or in addition to the movement of the carriage portions.  FIGS. 7A-8B  illustrate launch systems having moving launch members in accordance with further embodiments of the invention. Beginning with  FIG. 7A , a launch system  710  in accordance with one embodiment of the invention can include a base  730  carrying two or more supports  731  (shown in  FIG. 7A  as a first support  731   a  and a second support  731   b ). The base  730  can be configured to incline relative to the ground (for example, with a jack  732 ) to orient the aircraft  150  for launch. 
     The launch system  710  can further include a first launch member  742  (e.g., a first track) and a second launch member  743  (e.g., a second track), both of which support a carriage  720 , which in turn carries the aircraft  150  via a releasable gripper  780 . At least one of the first launch member  742  and the second launch member  743  is movable relative to the other. For example, in one embodiment, the first launch member  742  can be fixed relative to the base  730 , and the second launch member  743  can be movable relative to the base  730 . In other embodiments, the first and second launch members  742 ,  743  can have different arrangements. In any of these embodiments, the movement of at least one of the first and second launch members  742 ,  743  can accelerate the carriage  720  to launch the aircraft  150 , as described in greater detail below. 
     In one embodiment, the second launch member  743  can translate and/or rotate relative to the first launch member  742 . In a particular aspect of this embodiment, the motion of the second launch member  743  relative to the first launch member  742  can be controlled by a pin  729 , which depends from the second launch member  743  and which is received in an elongated guide slot  728  of the second support  731   b . The motion of the second launch member  743  can be further controlled by a block and tackle  733 . In one embodiment, the block and tackle  733  can include a coupling line  735  attached to the second launch member  743  at a first line attachment point  736   a . The coupling line  735  passes through a series of pulleys  745   a - 745   e  to a second attachment point  736   b , also on the second launch member  743 . In other embodiments, the second launch member  743  can be supported relative to the first launch member  742  in other arrangements. 
     The carriage  720  can engage both the first launch member  742  and the second launch member  743 . For example, in one embodiment, the first launch member  742  can include a first roller surface  737   a  (which engages first rollers or wheels  721   a  of the carriage  720 ), and the second launch member  743  can include a second roller surface  737   b  (which engages second rollers or wheels  721   b  of the carriage  720 ). Carriage arms or links  725  can support the second wheels  721   b  relative to the first wheels  721   a.    
     The second roller surface  737   b  can have a curved profile (or other shape) to control the acceleration of the carriage  720 . Accordingly, the carriage  720  can travel (from left to right as shown in  FIG. 7A ) along the first roller surface  737   a  while engaging the second surface roller surface  737   b . In a particular aspect of this embodiment, the second roller surface  737   b  an be inclined relative to the first roller surface  737   a  and can move in a wedge fashion, so as to force the carriage  720  from left to right to launch the aircraft  150 . 
     The force required to move the second launch member  743  relative to the first launch member  742  can be provided by an actuator  713 . The actuator  713  can be coupled with an actuator line  716  to the second launch member  743 , after passing around an actuator pulley  745   f . In one aspect of this embodiment, the actuator  713  can include a compressed gas cylinder, having a piston that retracts the actuator line  716  to draw the second launch member  743  downwardly away from the first launch member  742 , as described in greater detail below with reference to  FIG. 7B . In other embodiments, the actuator  713  can have other arrangements, including a hydraulic cylinder, a bungee, or a spring. In any of these embodiments, the actuator  713  can move the second launch member  743  relative to the first launch member  742 , forcing movement of the carriage  720  from left to right. 
     The launch system  710  can include a carriage return crank or winch  749  having a carriage return line  718  with a releasable trigger  739  connected to the carriage  720 . The launch carriage  720  is held back in a pre-launch position by the carriage return line  718  while a launch force is applied to the launch carriage  720 . The releasable trigger  739  is then disengaged, allowing the launch carriage  720  to accelerate. After launch, the carriage return line  718  can be used to reset the carriage  720 . 
       FIG. 7B  illustrates the launch system  710  after the carriage  720  has been accelerated to launch the aircraft  150 . In one aspect of this embodiment, the actuator  713  has rapidly drawn the second launch member  743  downwardly in a manner controlled by the block and tackle  733  and the pin  729  positioned in the slot  728 . As the second launch member  743  moves downwardly relative to the first launch member  742 , the carriage  720  is forced from left to right at a high rate of speed, until the second wheels  721   b  engage a braking portion  744  of the second roller surface  737   b . Accordingly, the angle between the second roller surface  737   b  and the first roller surface  737   a  changes at the braking portion  744 . At this point, the carriage  720  rapidly decelerates, while the gripper  780  releases, allowing the aircraft  150  to continue forward as it is launched into flight. 
     Once the actuator  713  has moved the second launch member  743 , it can be effectively decoupled while an operator couples the carriage return line  718  to the launch carriage  720  and activates the carriage return crank  749  to return the carriage  720  to the position shown in  FIG. 7A . For example, when the actuator  713  includes a gas powered piston, the volume of the cylinder in which the piston moves can be opened to atmospheric pressure so that the operator does not need to compress the air within the cylinder when returning the carriage  720  to the launch position. Once the carriage  720  has been returned to the position shown in  FIG. 7A , the actuator  713  can be readied for the next launch, for example, by charging the cylinder in which the piston operates with a compressed gas. In other embodiments, the energy of deceleration can be used to reversibly regain energy to be used during the next launch. In still further embodiments, the actuator  713  can be recharged by the carriage return crank  749 . As the carriage return crank  749  is actuated, it can force the second launch member  743  to its original position as the carriage  720  returns. This movement can also force the piston of the actuator  713  to its starting position and restore gas pressure in the actuator  713 . 
       FIG. 7C  is a partially schematic illustration of a portion of the launch system  710  illustrating the first launch member  742 , along with the second launch member  743  (shown in its pre-launch configuration in solid lines and in its post-launch configuration in dashed lines). As shown in  FIG. 7C , the portion of the second launch member  743  to which the coupling line  735  is attached can move by distance 3X, which is three times the distance X moved by the right-most portion of the second launch member  743 . The wedge angle between the first launch member  742  and the second launch member  743  increases by translating and pivoting the second launch member  743  relative to the first launch member  742 . By increasing the wedge angle during the launch process, the carriage  720  is accelerated at a constant or nearly constant rate, even as the force from the actuator  713  decreases near the end of the actuator&#39;s power stroke. 
       FIG. 7D  is a graph illustrating predicted acceleration and velocity values for a, carriage  720  propelled by a launch system  710  in accordance with an embodiment of the invention. In one aspect of this embodiment, the launch system  710  can provide a generally constant acceleration to the carriage  720 , which instantaneously reverses (when the carriage  720  reaches the braking portion  744  described above). This acceleration profile can provide a generally uniform increase in velocity, as is also shown in  FIG. 7D , up to at least the take-off velocity of the aircraft  150 . In other embodiments, the carriage  720  can be propelled in manners that result in different acceleration and velocity profiles. 
       FIG. 7E  is a partially schematic illustration of a launch system  710   a  configured in accordance with another embodiment of the invention and having many characteristics in common with the launch system  710  described above with reference to  FIGS. 7A-7C . In one aspect of this embodiment, the launch system  710   a  includes a first link  719   a  and a second link  719   b  coupled between the first launch member  742  and the second launch member  743 , in lieu of the block and tackle  733  and pin  729  described above. The motion of the second launch member  743  relative to the first launch member  742  can be generally similar to that described above with reference to  FIGS. 7A and 7B , to provide acceleration and velocity profiles generally similar to those described above with reference to  FIG. 7D . 
       FIGS. 8A-8B  illustrate a launch system  810  configured in accordance with still another embodiment of the invention. In one aspect of this embodiment, the launch system  810  can include a first launch member  842  coupled to a second launch member  843  at a pivot point  827 . An actuator  813  can be coupled to the first launch member  742  and the second launch member  743  with actuator rods  814  to force the first and second launch members  842 ,  843  apart from each other in a transverse plane. A carriage  820  can carry the aircraft  150  and can engage a first roller surface  837   a  of the first launch member  842  with first wheels  821   a . The carriage  820  can also engage a second roller surface  837   b  of the second launch member  843  with second wheels  821   b.    
     Referring now to  FIG. 8B , the actuator  813  can be activated to spread the first launch member  842  and the second launch member  843  apart from each other, forcing the carriage  820  from left to right. When the carriage  820  reaches braking portions  844  of the first and second launch members  842 ,  843 , it rapidly decelerates, causing a gripper  880  to open (as indicated by arrows M) while the aircraft  150  continues forward and is launched into flight. In other embodiments, the launch system  810  can have other arrangements. 
     One feature of embodiments of the launch systems described above with reference to  FIG. 1A-8B  is that the “wedge action” of the first and second members relative to each other can rapidly accelerate the carriage (and therefore the aircraft  150 ) in a relatively short distance. An advantage of this arrangement is that the launch systems can be used in cramped quarters, including the deck of a fishing vessel or a towed trailer. 
     Another feature of embodiments of the launch systems described above is that the wedge angle between the first and second members can increase as a function of distance (e.g., as shown in  FIGS. 1A-5 ) and/or time (e.g., as shown in  FIGS. 7A-8B ). This arrangement can provide a constant or nearly constant acceleration to the carriage (and the aircraft  150 ), even if the force provided by the actuator decreases near the end of the actuator&#39;s power stroke. An advantage of this arrangement is that the aircraft  150  is less likely to be subject to sudden changes in acceleration, which can damage the aircraft  150 . 
     Yet another feature of the launch systems described above with reference to  FIGS. 7A-8B  is that they can include a braking portion that rapidly and safely decelerates the carriage carried by the launch system. An advantage of this feature is that the system length required for deceleration can be short relative to that required for acceleration, and the overall length of the system can be correspondingly limited. 
     Another feature of embodiments of the launch systems described above is that the number of components that move at high speed during the launch process is relatively small. For example, in a particular embodiment (e.g., as shown in  FIGS. 7A-8B ), the only rolling elements that are traveling at high speed are the carriage wheels, and no high speed pulleys are included. Accordingly, the potential losses associated with components moving at high speed, including losses caused by ropes attached to the carriage suddenly accelerating and decelerating (e.g., “rope slurping”) can be reduced and/or eliminated. 
     From the foregoing, it will be appreciated that specific embodiments of the invention have been described herein for purposes of illustration, but that various modifications may be made without deviating from the spirit and scope of the invention. For example, the systems described above can be used to launch aircraft having arrangements different than those described above. In other embodiments, these systems can handle projectiles or other airborne devices Aspects of the systems described in the context of particular embodiments can be combined or eliminated in other embodiments. For example, the system described above with reference to  FIG. 1A  can be arranged transversely, as described above with reference to  FIGS. 8A-8B . The gripper brake can also have arrangements different than those described above Further details of related systems and methods are described in the following co-pending U.S. application Ser. No. 10/760,150 entitled “Methods and Apparatuses for Launching Unmanned Aircraft, Including Methods and Apparatuses for Launching Aircraft with a Wedge Action,” filed Jan. 16, 2004 and incorporated herein in its entirety by reference. Accordingly, the invention is not limited except as by the appended claims.