Patent Publication Number: US-7219817-B2

Title: Fluid slug launcher

Description:
This application claims the benefit of U.S. Provisional Application No. 60/326,355, filed on Oct. 1, 2001. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates generally but not exclusively to toy projectile launchers, and in particular to a mechanism which will hurl substantially intact “slugs” of fluid through the air. 
     2. Description of the Prior Art 
     From the dawn of time, humans have sought to create devices to launch solid projectiles. These devices were originally used for survival in hunting, attack, and defense. They may by now be a part of the human psyche. As such, projectile launchers are an eternally popular child&#39;s toy. 
     In one prior art variant of such toys, a gun-like launcher supports one or more projectiles, which are launched either through a spring-loaded launching mechanism or an air pressure driven launching device. The projectiles have enjoyed equally varied shapes and have included ping-pong balls, foam resilience balls, lightweight missiles and foam bodied arrows or missiles. Exemplary of such prior art solid projectile launchers are those described in U.S. Pat. No. 4,892,081 (1990) issued to Moormann and U.S. Pat. No. 4,694,815 (1987) issued to Moormann. 
     Many prior art water launchers also exist. The toy industry is highly competitive, and hundreds of different water launchers have been developed over the years in an attempt to profit from the toy&#39;s inherent popularity. However, in the prior art, the water launched has never appeared to be a solid, compact projectile. Instead, the shape of the water launched has fallen into one of three basic categories. The first category is a continuous stream of water interrupted periodically, such as that produced by the basic Squirt Gun. The second category launches an elongated, broken, or irregular mass of water, similar to the pattern produced by throwing water from a cup or bucket. Lastly, there are devices which launch a plurality of droplets. No toy device has, as yet, launched a slug of water which is so substantially free of accompanying droplets that it resembles a stone flying through the air. 
     One example of the “continuous stream” launcher is described in U.S. Pat. No. 5,074,437 (1991) of D&#39;Andrade, et al. In this device, air pressure is built up and stored by a pumping action, and then selectively used to pressurize stored water. When the trigger is activated, the movement of the pressurized water through the narrow nozzle produces a stream of propelled water. This stream continues while the trigger is engaged, and ceases when the trigger is disengaged or when the driving pressure of the water equals atmospheric pressure. A second example of the “continuous stream” launcher is described in U.S. Pat. No. 5,433,646 (1995) of Tarng. This device automatically interrupts the water stream at a substantially high frequency, without requiring recycling of the trigger. 
     An example of the “irregular mass of water” launcher is found in U.S. Pat. No. 5,339,987 (1994) of D&#39;Andrade. This invention provides a triggered mechanism for controlled flow with a bursting release of water. The shape of this burst is elongated, irregular and consists of multiple sub-packets of water. 
     An example of the “multiplicity of droplets” launcher is provided by U.S. Pat. No. 5,662,244 (1997) of Liu, et al. This patent states that “The present invention provides the popular advantages of traditional water guns, but projects a water charge that may be in the form of a burst or shower of water that is more likely to land on the intended target without the need for precision in aiming.” 
     While the foregoing described prior art devices have provided some measure of enjoyment and amusement for the user, they have disadvantages, and there remains a continuing need in the art for ever more interesting and improved launchers. Some disadvantages of the prior art for solid projectile launchers are:
         (a) Solid projectiles are easily lost, thus rendering the launcher useless or limited in play value.   (b) Solid projectiles must be retrieved, thus interrupting play.   (c) Solid projectiles can cause pain or injury upon impact.   (d) Solid projectiles add additional manufacturing cost to the toy.       

     On the other hand, prior art water launchers cannot launch water as a discrete, compact, visibly recognizable “slug”. In play, this presents the following disadvantages:
         (a) A child has difficulty pretending he or she is launching a solid object such as a stone or bullet.   (b) The launched water provides no sensation of being struck by an object, and no satisfying “thud” upon impact.   (c) Because it does not resemble a discrete projectile, the water launched by prior water launchers is not well suited to traditional target games.       

     SUMMARY OF THE INVENTION 
     Accordingly, the drawbacks of the prior art are overcome by the present invention, which launches an airborne liquid projectile which looks and behaves like a solid flying object. 
     The theory behind the present invention is that in order for a single slug of liquid to remain intact while flying through a vacuum, each molecule of said liquid must travel in the same direction and at the same speed (that is, without turbulence). To achieve this state, the preferred embodiment of the present invention seeks to first load a predetermined quantity of liquid into a moveable container, and then to accelerate said container so that each molecule of liquid moves in the same direction and at the same speed, without turbulence. Finally, the present invention provides a means to release the slug from its container, also without inducing turbulence. It achieves this result by structuring the side walls of the container to minimize turbulence as the liquid flows by them and exits the container, and by releasing the vacuum between the rear containment wall and the liquid at the moment of deceleration of said rear containment wall. The result of such a release is an airborne, substantially intact slug of liquid, in which all molecules are moving at the same speed and in the same direction. 
     Objects and Advantages 
     Accordingly, several objects and advantages of the present invention are:
         (a) Water can be used for the projectiles, and is generally available in abundant supply. This eliminates the danger of losing manufactured projectiles and thus destroying the usefulness of the toy.   (b) The pattern of play is not interrupted by the necessity of retrieving projectiles.   (c) The launcher can be sold without manufactured projectiles, reducing consumer expense.   (d) Although the projectile may be composed of water, a child can pretend he or she is launching a solid object such as a stone or bullet.   (e) The slug launched, being composed of a liquid, is not likely to cause pain or injury upon impact.   (f) Unlike prior art water launching toys, the present invention fires a projectile which simulates a solid object. This provides a sensation of being “hit”, and the sound of a “thud” upon impact.   (g) The present invention can be applied to target games which were designed for use with solid projectiles.   (h) A discrete slug of water many times the volume of a raindrop can be launched through the air. Since a water slug of this size is rarely seen in nature, the effect is magical, and creates the opportunity for an exciting and saleable toy. The magical quality also provides the opportunity for compelling television commercials and packaging graphics.   (i) Both solid projectile launchers and water squirters have been hugely successful products in the marketplace. The present invention combines the advantages of both, creating a unique new product niche.       

     Further objects and advantages of the present invention will become apparent from a consideration of the drawings and ensuing description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the detailed description of the invention presented below, reference is made to the accompanying drawings, in which: 
         FIG. 1-A  is a perspective view of a “moving cylinder and moving piston” version of the present invention, in the “ready-to-fire” position; 
         FIG. 1-B  is a cross-sectional side view of  FIG. 1-A ; 
         FIG. 1-C  is a perspective view of the “moving cylinder and moving piston” version of the present invention, in the “just-fired” position; 
         FIG. 1-D  is a cross-sectional side view of  FIG. 1-C ; 
         FIG. 2-A  is a perspective view of a “moving cylinder and rear opening” version of the present invention, in the “ready-to-fire” position; 
         FIG. 2-B  is a cross-sectional side view of  FIG. 2-A ; 
         FIG. 2-C  is a perspective view the “moving cylinder and rear opening” version of the present invention, in the “just-fired” position; 
         FIG. 2-D  is a cross-sectional side view of  FIG. 2-C ; 
         FIG. 3  shows a perspective left side view of the preferred embodiment of the present invention, in the “ready-to-fire” position, with the left side panel removed; 
         FIGS. 4 ,  5 , and  6  respectively show perspective, front, and cross-sectional left side views of the launcher assembly of the preferred embodiment, in the “ready-to-fire” position; 
         FIG. 7  shows a perspective left side view of the preferred embodiment, in the “just-fired” position, with the left side panel removed; 
         FIGS. 8 ,  9 , and  10  respectively show perspective, front, and cross-sectional left side views of the launcher assembly of the preferred embodiment, in the “just-fired” position; 
         FIG. 11  is a break-away right side perspective view, showing the components of the safety door assembly in the “just-fired” position; 
         FIG. 12-A  is a cross-sectional side view of a “fixed container and moving piston” version of the present invention, in the “ready to accelerate piston” position; 
         FIG. 12-B  is a cross-sectional side view of the “fixed container and moving piston” version of the present invention, in the “release piston” position; 
         FIG. 12-C  is a cross-sectional side view of the “fixed container and moving piston” version of the present invention, in the “stop piston” position; 
       
         
           
             
                 
               
                 
                     
                 
                 
                   Reference Numerals In Drawings 
                 
                 
                     
                 
               
              
                 
                     
                 
              
             
             
                 
                 
                 
              
                 
                     
                   15 
                   moving container and moving piston 
                 
                 
                     
                     
                   liquid slug launcher 
                 
                 
                     
                   16 
                   container 
                 
                 
                     
                   17 
                   piston 
                 
                 
                     
                   18 
                   liquid slug 
                 
                 
                     
                   19 
                   stop 
                 
                 
                     
                   20 
                   longitudinal axis (of container 16) 
                 
                 
                     
                   21 
                   rear collar (of piston 17) 
                 
                 
                     
                   22 
                   moving container and rear opening liquid 
                 
                 
                     
                     
                   slug launcher 
                 
                 
                     
                   23 
                   axis (of container 24) 
                 
                 
                     
                   24 
                   container 
                 
                 
                     
                   25 
                   valve 
                 
                 
                     
                   26 
                   liquid slug 
                 
                 
                     
                   27 
                   stop 
                 
                 
                     
                   28 
                   water slug launcher 
                 
                 
                     
                   29 
                   launcher assembly 
                 
                 
                     
                   30 
                   container 
                 
                 
                     
                   31 
                   water slug 
                 
                 
                     
                   32 
                   piston 
                 
                 
                     
                   33 
                   compression spring 
                 
                 
                     
                   34 
                   elastic drive band 
                 
                 
                     
                   35 
                   housing 
                 
                 
                     
                   36 
                   opening 
                 
                 
                     
                   37 
                   housing rails 
                 
                 
                     
                   38 
                   catch 
                 
                 
                     
                   39 
                   arm (of piston 32) 
                 
                 
                     
                   40 
                   safety door 
                 
                 
                     
                   41 
                   door push spring 
                 
                 
                     
                   42 
                   elastic door return spring 
                 
                 
                     
                   43 
                   valve axis 
                 
                 
                     
                   44 
                   water tank 
                 
                 
                     
                   45 
                   draw tube 
                 
                 
                     
                   46 
                   one-way draw valve 
                 
                 
                     
                   47 
                   pump body 
                 
                 
                     
                   48 
                   one-way delivery valve 
                 
                 
                     
                   49 
                   delivery hose 
                 
                 
                     
                   50 
                   pump lever 
                 
                 
                     
                   51 
                   pump lever pivot pin 
                 
                 
                     
                   52 
                   pump piston 
                 
                 
                     
                   53 
                   pump piston pivot pin 
                 
                 
                     
                   54 
                   pump spring 
                 
                 
                     
                   55 
                   sliding handle 
                 
                 
                     
                   56 
                   notches in container 30 
                 
                 
                     
                   57 
                   catch pivot pin 
                 
                 
                     
                   58 
                   catch spring 
                 
                 
                     
                   60 
                   flange 
                 
                 
                     
                   61 
                   angled surface 
                 
                 
                     
                   62 
                   container bottom protrusion 
                 
                 
                     
                   63 
                   elastic stop band 
                 
                 
                     
                   64 
                   container side protrusion 
                 
                 
                     
                   65 
                   door axis 
                 
                 
                     
                   66 
                   fixed container and moving 
                 
                 
                     
                     
                   piston liquid slug launcher 
                 
                 
                     
                   67 
                   fixed container 
                 
                 
                     
                   68 
                   axis of container 
                 
                 
                     
                   69 
                   piston 
                 
                 
                     
                   70 
                   liquid slug 
                 
                 
                     
                   71 
                   rear collar 
                 
                 
                     
                     
                 
              
             
           
         
       
     
    
    
     DETAILED DESCRIPTION OF THE PRESENT INVENTION 
     An Explanation of the Physics of Projecting a Slug of Liquid Through the Air 
     The present invention propels a discrete slug of liquid through the air, with few or no accompanying droplets. The effect is unique, because airborne slugs of liquid substantially larger than raindrops are rarely seen in nature. The description of this invention therefore begins with a discussion of the physics of airborne liquids. 
     It is known that raindrops break into smaller droplets if they accumulate too much size as they fall. Indeed, equations have been developed to calculate what the maximum size of a water droplet will be, as it falls toward earth. The variables in these equations are primarily based on the droplet&#39;s shape, its mass, the speed at which it is moving, and the density of the air through which it is passing. In common terms, as a slug of water traveling through the air increases in speed, the pressure of the air against the advancing face of the water slug will eventually cause it to flatten out and break into smaller droplets. These smaller droplets may continue to flatten and break, until the resultant droplets are small enough that their terminal velocity in freefall is not sufficient to break them. 
     The preferred embodiment of this invention launches a cylindrical water slug of approximately 2 cubic centimeters in volume. As the slug travels through the air, the pressure of the air against its advancing face, and the internal attractive forces within the liquid itself, cause it to originally gather into a somewhat spherical shape. However, if the liquid slug continues to move at too high a speed, the pressure of the air against its advancing face will ultimately cause it to flatten and break. 
     Experiments with prototypes of the invention showed that when the volume of the water slug was increased, the maximum velocity at which the slug broke decreased. Inversely, when the volume of the water slug was decreased, the maximum velocity at which the slug broke increased. In another experiment, by varying the airborne speed of the water slug, the maximum velocity of the cylindrical 2 cc. slug before breakage was found to be about 22 miles per hour, at sea level air pressure. This information was used to select a drive spring for the prototype which released the liquid slug at just below 22 miles per hour. 
     Our attention now turns to the problem of accelerating and releasing a single slug of liquid into the air, with little or no accompanying droplets. The problem is solved by the realization that in order for a liquid slug to stay intact when it is released, each molecule of liquid within the slug should move at the same speed and in the same direction. If this condition is met, there will be no force except air pressure to break the slug. However, if the liquid slug is released while in a state of turbulence, that is, if its molecules are moving at dissimilar velocities, the liquid may split off into different pieces which move in different directions. The first problem solved by the present invention is that of accelerating the liquid slug without inducing turbulence. The second problem overcome is that of releasing it without inducing turbulence. 
     The solution which the present invention provides to the first problem is to accelerate the slug while it is retained within the fixed walls of a container. Since the container walls are rigid, the seams are sealed, and there is no compressible liquid such as air within or behind the slug, there is no place for the liquid molecules to move, and thus no turbulent flow is induced. Even if the front of the container is left open, the liquid molecules will not tend to flow in that direction, since the force of acceleration presses them to the rear. Therefore, when the liquid slug has been accelerated and is ready to be released from the container, all liquid molecules are moving at the same speed and in the same direction. 
     The solution to the second part of the problem, how to release the liquid slug without inducing turbulence, is provided in the present invention by two measures. The first measure is to release the vacuum at the rear of the slug after acceleration ceases so that the liquid can freely leave the container. The second measure is to construct the side walls of the container so that they are substantially parallel to the direction of acceleration of the container. This allows the molecules of the liquid slug which are in contact with the container walls to leave the container without substantially changing their speed or direction. 
       FIGS. 1A ,  1 B,  1 C, and  1 D illustrate one embodiment of the present invention,  FIGS. 2A ,  2 B,  2 C, and  2 D illustrate a second embodiment, and  FIGS. 12A ,  12 B, and  12 C illustrate yet a third. All three utilize the previously stated principles to launch liquid slugs. 
     First Apparatus to Accelerate and Release a Liquid Slug 
     Referring now to  FIG. 1A  and  FIG. 1B , there is shown respectively a perspective and side-cut view of a “moving container and moving piston liquid slug launcher”  15  in the “ready-to-fire” position, which is referred to as Phase One. In this embodiment, launcher  15  includes a container  16  for liquid, with the side walls of container  16  parallel to a longitudinal axis  20  of container  16 , an opening at the right end of axis  20 , and a second opening at the left end of axis  20 . The opening at the left end is sealed against liquid leakage by a seated piston  17 . A liquid slug  18  is shown inside container  16 . In this orientation, a vacuum at the rear and sides of liquid slug  18  tends to prevent it from exiting the right opening of container  16 . 
     In what is referred to as Phase Two of the present invention&#39;s operation, a force is applied to container  16 , causing it to accelerate along axis  20  and in the direction indicated by the arrow of  FIG. 1D . Since piston  17  and liquid slug  18  are retained by container  16 , they will accelerate at the same rate as container  16 . Therefore, in this phase, all three components move at the same velocity. 
     In Phase Three, container  16  strikes a stop  19 . This causes container  16  to decelerate, while piston  17  and liquid slug  18  continue to travel at their previous velocities. 
       FIG. 1C  and  FIG. 1D  show Phase Four, the “just fired” position, wherein liquid slug  18  is released into flight. At this point in time, container  16  has decelerated and piston  17  and liquid slug  18  have moved forward together, until the forward motion of piston  17  is slowed due to a rear collar  21  proximally attached via a stem to piston  17  striking the end of container  16 . Since liquid slug  18  and the tip of piston  17  are outside container  16  when this occurs, the only vacuum which retains liquid slug  18  is at the tip of piston  17 . In this position, liquid slug  18  can break away from the slower moving piston  17 , with relatively little resistance. If desired, the tip or leading edge of piston  17  may be shaped to minimize friction and disturbance to liquid slug  18  as it breaks away. 
     In Phase Five, piston  17  is drawn back to the original position described in Phase One, and a fresh slug of liquid is loaded into container  16 . At this time the launching cycle may recommence. 
     Second Apparatus to Accelerate and Release a Liquid Slug 
       FIG. 2-A  and  FIG. 2-B  respectively show a perspective and side-cut view of a second embodiment of the present invention. In this embodiment, the left end of a container  24  opens at the moment of deceleration. “Moving container and rear opening liquid slug launcher”  22  is shown in the “ready-to-fire” position, now called Phase A. Launcher  22  includes container  24  for liquid, with the side walls of container  24  parallel to a longitudinal axis  23  of container  24 , an opening at the right end of axis  23 , and a second opening at the left end of axis  23 . The opening at the left end is sealed against leakage by a valve  25 , which is rotatable about a valve axis  43 . The inertial properties of valve  25  are such that the product of the distance of the center of mass of valve  25  below valve axis  43  multiplied by the mass of valve  25  below valve axis  43  will significantly exceed the product of the distance of the center of mass of valve  25  above valve axis  43  multiplied by the mass of valve  25  above valve axis  43 . A liquid slug  26  is shown inside the container. In this position, a vacuum at the rear and sides of liquid slug  26  tends to prevent it from exiting the right opening of container  24 . 
     In operation, during Phase B of this embodiment, a force is applied to container  24 , causing container  24 , valve  25 , and liquid slug  26  to accelerate along axis  23  and to the right. Under acceleration, the greater moment of the mass of valve  25  below valve axis  43  than above it creates a clockwise moment about valve axis  43 , pressing valve  25  more tightly against the left opening of container  24  and thus sealing against leakage. In this phase, container  24 , valve  25 , and liquid slug  26  all move at the same velocity at any point in time. 
     In Phase C, container  24  decelerates after striking a stop  27 . At the same time, the greater moment of mass below the axis of valve  25  will cause it to open by rotating counterclockwise, while the inertia of liquid slug  26  will cause it to continue traveling forward. Since the only vacuum retaining liquid slug  26  is at the surface of valve  25 , liquid slug  26  will break away from the retreating valve  25  with relatively little resistance, deformation, or induction of turbulence. If desired, the surface of valve  25  which is in contact with liquid slug  26  may be shaped to minimize friction and to allow liquid slug  26  to break away smoothly and with as little disturbance as possible. 
       FIG. 2-C  and  FIG. 2-D  show Phase D, the “just-fired” position. Container  24  has decelerated, valve  25  has opened, and liquid slug  26  has been released into flight, in the direction of the arrow. 
     In Phase E, means is provided to rotate valve  25  back to the original position described in Phase A, and a fresh slug of liquid is loaded into container  24 . The launching cycle can now recommence. 
     Third Apparatus to Accelerate and Release a Liquid Slug 
     Referring now to  FIG. 12A , there is shown respectively a side-cut view of a “fixed container and moving piston liquid slug launcher”  66  in the “accelerate piston” position, referred to as Phase One. In this embodiment, launcher  66  includes a fixed container  67  for liquid, with the side walls of container  67  parallel to a longitudinal axis  68  of container  67 , an opening at the right end of axis  68 , and a second opening at the left end of axis  68 . The opening at the left end is sealed against liquid leakage by a seated piston  69 . A liquid slug  70  is shown inside container  67 . In this orientation, a vacuum at the left and sides of liquid slug  70  tends to prevent it from exiting the right opening of container  67 . 
     In what is referred to as Phase Two of operation, container  67  is held stationary while a force is applied to piston  69 , causing piston  69  to accelerate along axis  68  and in the direction indicated by the arrow. Since liquid slug  70  is retained by container  67 , it is forced to accelerate at the same rate as piston  69 . Therefore, in this phase, both components always move at the same velocities. 
     The “release piston” position is illustrated by  FIG. 12B . In this third phase, the accelerating force is discontinued, allowing piston  69  and liquid slug  70  to continue moving unimpeded at constant velocity. 
     Finally,  FIG. 12C  shows Phase Four, the “stop piston” position, wherein liquid slug  70  has been released into flight in the direction indicated by the arrow. At this point in time, the forward motion of piston  69  has been halted due to a rear collar  71  of piston  69  striking the left end of fixed container  67 . This causes liquid slug  70  to break away from piston  69  and continued on, unimpeded. 
     In Phase Five, piston  69  is drawn back to the original position described in Phase One, and a fresh slug of liquid is loaded into container  67 . At this time the launching cycle may recommence. 
     The Preferred Embodiment Launcher Assembly 
       FIG. 3  shows a perspective side view of the preferred embodiment of the present invention, a water slug launcher  28 , in the “ready-to-fire” position, and with the left side panel removed. 
       FIGS. 4 ,  5 , and  6  respectively show perspective, front, and side-section views of a launcher assembly  29 , in the “ready-to-fire” position. Assembly  29  comprises a container  30 , a water slug  31 , a piston  32 , a compression spring  33 , and an elastic drive band  34 . These are the principle moving parts which operate to launch water slug  31 . 
       FIGS. 8 ,  9 , and  10  respectively show perspective, front, and side-section views of launcher assembly  29 , in the “just-fired” position. Piston  32  has been halted in its forward position, with its tip protruding from container  30 . Water slug  31  has broken free from the tip of piston  32 , and is airborne in the direction of the arrow of  FIG. 10 . 
     Referring now to  FIG. 3 , at the front of a housing  35  there is an opening  36 , through which water slug  31  will emerge after launching. Assembly  29  is retained within housing  35  by notches  56  on each side of container  30 , which are engaged with and slide freely on housing rails  37 , thereby allowing assembly  29  to reciprocate within housing  35  from right to left and back again. 
     Assembly  29  is shown in the “ready-to-fire” position, with drive band  34  stretched taut between container  30  and the front of housing  35 . Although drive band  34  is exerting a force to pull assembly  29  forward, assembly  29  is restrained from moving by a catch  38 , which is locked against an arm  39  of piston  32 . 
     The Preferred Embodiment Safety Door Assembly 
       FIGS. 3 ,  7 , and  11  show the components of the safety door assembly. A safety door  40  prevents a person from inserting an improvised projectile into container  30 , or in the path of assembly  29 , thus assuring that only liquids can be launched. 
     Now referring to  FIG. 11 , which is a break-away perspective view of the components of the safety door assembly in the “just-fired” position, the components shown are door  40 , a door axis  65 , a door push spring  41 , an elastic door return spring  42 , assembly  29 , and a container side protrusion  64 . During operation, when container  30  travels to the front of launcher  28 , protrusion  64  strikes push spring  41 . As protrusion  64  continues to move forward, door  40  is rotated open about door axis  65  by the force of protrusion  64 , transmitted by push spring  41  against the rear of door  40 . While door  40  is open, water slug  31  passes through opening  36 , unimpeded. As an elastic stop band  63  completely arrests the forward motion of assembly  29 , and then pulls assembly  29  back toward the right end of housing  35 , the pressure exerted against door  40  by push spring  41  is thereby released, and spring  42  quickly closes door  40 . 
     One advantage provided by this arrangement of components is that the length, spring rate, and initial tension of push spring  41  and the length, spring rate, and initial tension of return spring  42  can be adjusted to cause door  40  to remain open only for the instant in which the speeding water slug  31  passes through the region of door  40 . This very short period of time prevents a person from reacting quickly enough to catch door  40  in the open position, hold it open, and then insert an improvised projectile into launcher  28 . A second advantage is that in its rest position, door  40  cannot be opened to insert an improvised projectile, since there is insufficient space provided between housing  35  and door  40  to insert a finger behind door  40  and thereby pull it open. Once again, this will prevent the subsequent insertion of an improvised projectile. A third advantage is that door  40  prevents a person&#39;s finger from being inserted into the path of assembly  29  and thus being struck by assembly  29 . A fourth advantage is that if a finger is inserted into opening  36 , or held against the front of door  40 , no significant impact will be felt when launcher  29  is fired. This is because push spring  41  possesses a spring rate which is so low that it exerts only a soft force against door  40 , even when protrusion  64  strikes the opposite end of push spring  41 . 
     The Preferred Embodiment Charge-and-Release Mechanism, and Water Delivery System 
     Also depicted in  FIG. 3  is a water delivery system, which transports water from a water tank  44  into container  30 . In one complete cycle of operation, the water flows sequentially from tank  44 , through a draw tube  45 , through a one-way draw valve  46 , into the inner chamber of a pump body  47 , through a one-way delivery valve  48 , through a delivery hose  49 , and thereafter into the internal chamber of container  30 . It should be noted that when the internal chamber of container  30  is loaded with water, and container  30  is tilted downward toward its opening, the water load is restrained from running out of container  30  by the vacuum seal at the rear of the container chamber, and also by the seal provided by valve  48 . Valve  48  is sealed due to its initial cracking pressure, which in the case of this preferred embodiment exceeds the pressure of a ten inch column of water. Experiments with prototypes of this embodiment showed that when these seals are intact, the water load will not run out of the container chamber if the diameter of the chamber opening is less than about 0.32 inches. 
     Referring again to  FIG. 3 , a pump lever  50  is attached, by a pump lever pivot pin  51  at its left end, to housing  35 . A pump piston  52  is attached by a pump piston pivot pin  53  to lever  50 . In the “water delivery” stage, lever  50  is raised as assembly  29  is drawn to the right, rotating lever  50  counterclockwise about pivot pin  51 . This drives piston  52  into the inner chamber of pump body  47 , forcing the water contents of said inner chamber into hose  49 . As this occurs, water is prevented from moving into tube  45  by valve  46 . Since the water delivery system has already been primed, a slug of water equal in volume to that displaced from the inner chamber of pump body  47  is therefore forced into container  30 . In the “water draw” stage, a pump spring  54  pushes against lever  50 , rotating lever  50  clockwise about pin  51 . As a result, a quantity of water is drawn by vacuum from tank  44 , through tube  45  and valve  46 , and into pump body  47 . As this occurs, valve  48  prevents water from being drawn into pump body  47  through hose  49 . 
     The Firing Cycle of the Launcher 
     A sliding handle  55  is mounted below housing  35 , in this embodiment utilizing notches on the sides of handle  55  which engage with rails in housing  35 . The rails are not pictured. This configuration allows handle  55  to slide freely back and forth in the same directions of motion as assembly  29 . The following sequence of events describes one complete launching cycle, assuming that a water slug has just been launched: 
     The cycle commences with assembly  29  resting at the left side or front of housing  35 , and the handle resting at the rear of housing  35 . The operator pushes handle  55  from the rear of housing  35  to the front. At that point, catch  38 , which is pivoted within handle  55  by catch pivot pin  57  and continually biased upward by a catch spring  58 , slides underneath the lower portion of arm  39  of piston  32 , and then snaps back upward, engaging arm  39  at its left extremity. 
     Next, the operator pulls handle  55  to the right, or toward the rear of housing  35 . As this occurs, elastic drive band  34 , which is connected between the front of housing  35  and container  30 , is drawn increasingly taut. Additionally, as handle  55  moves to the right, the following actions occur sequentially: 
     Container  30  remains in place, while piston  32  moves to the right, until the head of piston  32  contacts a flange  60  within container  30 . This orientation of components is shown in  FIG. 6 . Referring again to  FIG. 3 , container  30  now begins to move to the right also, being pulled by the head of piston  32 . As it travels to the right, container  30  slides under lever  50 , raising lever  50  gradually. Lever  50  raises piston  52 , which pushes water from pump body  47 , through valve  48  and hose  49 , and into container  30 . Thereafter, an angled surface  61  of housing  35 , shown at the bottom rear of housing  35 , forces catch  38  downward, releasing the arm  39  of piston  32  and thus allowing elastic drive band  34  to pull assembly  29  forward. 
     Next, container  30 , piston  32 , and water slug  31  are all accelerated to the left by drive band  34 . Although this acceleration causes the pressure in hose  49  to increase, water is prevented from flowing back into tank  44  by valve  48  and valve  46 . Lever  50 , now unsupported, is pushed downward by pump spring  54 , thus drawing another load of water into pump body  47 . As assembly  29  comes to the front of housing  35 , a container bottom protrusion  62  strikes stop band  63 , causing container  30  to decelerate, while piston  32  and water slug  31  continue on unimpeded. 
     Piston  32  now moves forward within container  30 , until it is decelerated when arm  39  strikes spring  33 , which is mounted within container  30 . Referring to  FIG. 11 , at about the same time, container protrusion  64  on the right side of container  30  strikes the left end of push spring  41 . Door  40  is pushed open by the force exerted by side protrusion  64  against push spring  41 . At this point in time, the position of all components of the present embodiment are shown in  FIGS. 7 ,  8 ,  9 ,  10 , and  11 . Both water slug  31  and the tip of piston  32  are outside the walls of container  30 . Since spring  33  has decelerated piston  32  but not water slug  31 , the inertia of water slug  31  forces it to break away from the slower moving piston  32 . While this is occurring, the smooth conical tip of piston  32  aids in preventing water slug  31  from breaking apart as it is released, by allowing the rear portions of water slug  31  to slide gradually off the tip of piston  32 . Spring  33  also assists in allowing water slug  31  to be released without breaking, by reducing the shock when piston  32  strikes container  30 . Water slug  31  is thus released into flight. 
     Finally, stop band  63  completely arrests the forward motion of container  30  and piston  32 , and they are pulled back toward the rear of housing  35 , by the spring force of stop band  63 . The pressure exerted against door  40  by door push spring  41  is thereby released, and spring  42  closes door  40 . All moving components have now come to rest, and the operator can move sliding handle  55  forward again to begin another launching cycle. 
     Modifications and Variations 
     Obviously, numerous modifications and variations of the present invention are possible in the light of the above teachings. For example, although the embodiment shown in drawings  2 A,  2 B,  2 C, and  2 D utilizes an inertia-driven rotatable valve  25  to open the rear of container  24 , the rear of container  24  could also be opened by a linear inertia valve, or by a flat plate which is able to move sideways and is opened by a spring and trigger mechanism at the instant of the container&#39;s deceleration. 
     Additionally, the elements and features disclosed can be adapted for use in any number of fluid projectile launching devices. For example, the principles of the present invention could be used to create a product line of toy weaponry, such as a waterslug pistol, waterslug machine gun, waterslug mortar, waterslug shotgun, and a waterslug bow-and-arrow. As a second example, the invention could be utilized in a water theme park, to hurl large balls of water at participants. As a third example, the invention could become part of a miniature toy action-figure playset utilizing water weaponry, such as miniature cannons, rocket launchers, hand held weapons, and attack planes. As a fourth example, the invention could be used to launch smoke rings or other gaseous shapes. Nor does the present invention need to be limited to a gun-type device. For example, its principles could be used to create a sporting goods item which pitches a ball of water to a batter, and is activated either manually or via a garden hose. Or, it could become a toy water sprinkler for summer play which intermittently flings balls of water at playing children. Finally, the invention could be used for devices entirely outside the field of toys; for example, for a decorative water fountain which launches balls of water into the air, for a lawn waterer, or for an industrial purpose utilizing slugs of liquid other than water. It is therefore understood that within the scope of the appended claims, the invention may be practiced, and the function and result achieved, otherwise than as specifically described in the embodiments herein.