Abstract:
A projectile launching device includes self-timing without cam lean. The projectile launching device may include a rail, a riser, two energy storing components, (such as two limbs), two cams, a launch string, and at least one cable. The ends of the launch string are attached to the two cams. Opposing ends of first and second cables may be coupled to the rail or riser. A mid-portion of the first and second cables are slideably engaged with the first and second cams, respectively. Alternatively, a single cable may replace the first and second cables. The two cams are preferably built as mirror images of each other at a centerline of the rail. The two cams include a launch string track, having identical, but mirrored, upper and lower cable tracks.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to archery and more specifically to a shooting bow with a unique cable arrangement, which allows a portion of first and/or second cables to be slidably engaged to first and second cams, and the ends of the cable(s) to be coupled back to first and second posts. This arrangement enables the device to have self-timing. The present invention may alternately use components other than flexible limbs for storing energy prior to launching the projectile. 
     2. Discussion of the Prior Art 
     Historically, archery bows and crossbows have been used for war, survival, sport, and recreation. A specific component of a compound style shooting bow are the cables. Typically, each cable includes a power end and a control end. The manner in which the cables interact with the cams and limbs of the bow is of particular importance. Typically, the power end of the cable is coupled to the cam on one limb, and the control end of the cable is often coupled to the opposite limb or opposite cam. A very good way to accomplish efficiency is through a binary cam system, wherein the cables are connected to opposing cams, and as one of the cams wraps the cable on the power track, the opposite cam pays out cable from the control track. While all of these methods work to some extent, all have significant issues with performance related to cam lean, and/or assembly and cost. Due to the crossing of cables and the need to keep the cables from interfering with the flight of the arrow, the cables often are off-angle, which in turn creates twisting and torque in a cam axle, thus creating cam lean. 
     U.S. Pat. No. 4,457,288 to Ricord discloses a cam lever compound bow, where a bow utilizes single string wrapping pulleys journaled to the ends of the bow limbs, and the ends of the string are coupled to a cam device mounted upon the bow riser. Although, this method does remove the problem of the cables being in the way, it is very inefficient, and timing issues from one limb to the other is a factor. U.S. Pat. No. 7,637,256 to Lee discloses a compound bow, which provides a shooting bow that removes the issue of cables interfering with the flight of the arrow. However, the inefficient use of tensioning devices severely limits the potential of this device. U.S. Pat. No. 8,651,095 to Islas discloses a bowstring cam arrangement for compound crossbow, which provides a method of removing the cables from the path of the string. U.S. Pat. No. 9,494,379 to Yehle discloses a crossbow, where Yehle relies on four cables. However, Yehle claims a helical cable track. Issues are created by having separate cables above and below the string track on each cam. If the cables are not of exact length, or if the upper cable stretches more than the lower cable, or visa-versa, the cables must be adjusted by the user to stay in time with each other. Timing of the cables can be a time consuming and a very difficult process. 
     The above inventions try to keep four cables in proper timing, as opposed to two. The present invention deals with the manner in which the cables are coupled to the cams of the bow or crossbow. 
     Accordingly, there is a clearly felt need in the art to provide a shooting bow, which allows a mid-portion of first and second cables to be slidably engaged to first and second cams, and a first end of a cable coupled to a post above the plane of the launch string, and a second end of a cable coupled to a post below the plane of a shooting string, respectively. The cables do not cross the centerline of the shooting bow, or alternately a shooting bow with a launch string and having a single cable, which replaces two cables. 
     SUMMARY OF THE INVENTION 
     The present invention provides a self-timing cam and cable configuration for a projectile launching device. The present invention includes at least one cable, which does not anchor to the cam(s), and also reduces or eliminates cam lean. The projectile launching device with self-timing and without cam lean (projectile launch device) may be applied to either a crossbow or vertical bow. The projectile launch device preferably includes a first cam, a second cam, a launch string and two cables, collectively known as a harness system, where neither end of the cable is anchored to a cam. This configuration allows opposing ends of a first cable to be anchored to first and second cable posts, and opposing end of a second cable to be anchored to third and fourth cable posts. Preferably, the first and second cables do not cross a centerline of the shooting bow. In a second preferred embodiment, the projectile launching device preferably includes a string latch housing, a bow riser, a rail, a first energy storing device (such as a first limb), a second energy storing device (such as a second limb), a first cam, a second cam, at least one bowstring, and two cables. 
     A third preferred embodiment uses a launch string and only one cable. One end of the cable is coupled to a first cable post, wherein a portion of the cable is slidably engaged with a first transitional portal; crosses to the second cam; another portion of the cable is slidably engaged with a second transitional portal; and an opposing end of the cable is coupled to the second cable post. The term “limb” may refer to what are known as solid limbs, split-limbs, tube-limbs, or any other flexible energy storing component. The bow riser is enjoined with the rail. One end of the first limb extends from a first end of the bow riser and one end of the second limb extends from a second end of the bow riser. The first cam is pivotally retained on the first limb and the second cam is pivotally retained on the second limb. A first end of the launch string is retained by the first cam and a second end of the launch string is retained by the second cam. A first set of first and second cable posts are located on a first side of a centerline of the rail and a second set of first and second cable posts are located on a second side of the centerline of the rail. The first cam includes a first cam launch string track, an upper first cam cable track, located above the launch string track, a first cam transitional portal, and a lower first cam cable track, located below the launch string track. The second cam includes a second cam launch string track, an upper second cam cable track, located above the launch string track, a second cam transitional portal, and a lower second cam cable track, located below the launch string track. The first set of first and second cable posts are located above the plane of the launch string, and the second set of first and second cable posts are located below the plane of the launch string. 
     A first end of the first cable is coupled to the first cable first cable post; a segment of the first cable before a middle of the first cable partially engages the first cam first cable track; the middle of the first cable partially wraps the first transitional portal; a segment of the first cable after the middle of the first cable partially engages the first cam second cable track; and a second end of the first cable is coupled to the first cable second cable post. A first end of the second cable is coupled to the second cable first cable post; a segment of the second cable before a middle of the second cable partially engages the second cam first cable track; the middle of the second cable partially wraps the second transitional portal; a segment of the second cable after the middle of the second cable partially engages the second cam second cable track; and a second end of the second cable is coupled to the second cable second cable post. 
     When the launch string is drawn from a rest position to a ready to fire position, the first cam rotates in a first direction and the second cam rotates in a second direction. As the first and second cams rotate, the launch string is unwound from the first and second launch string tracks. Simultaneously, the first and second cables wind into the first and second cable tracks of the first and second cams. 
     A unique feature of the present invention is that the first and second cables are not firmly fixed to the cams in any way, rather they “float” or slide relative to the first and second cam transitional portals. The first and second cables are of one piece, and as the cable stretches, it self-centers itself. 
     In a preferred embodiment, the launch string may be releasably retained in the ready-to-fire position by mechanisms known as a string latch assembly or a string release. 
     In a first preferred alternative embodiment, the launch string may be held in the ready-to-fire position and released by the users&#39; fingers. 
     In a second preferred alternative embodiment, a rail-less crossbow design may be used. 
     In a third preferred alternative embodiment, the same harness system configuration may be used on projectile launching devices utilizing energy storing components other than flexible limbs. These other types of energy storing components include spring(s), hydraulics, or pressurized cylinder(s). For clarity, the word coupled is being defined as a way to connect an object, such as a bowstring or cable, with another object, be it directly or indirectly, such as directly to a post or pulley, or indirectly as in from the end of a string or cable, to an intermediate object, and then to a limb or axle. The term “transitional portal” is the opening in the surface of the cam that the cable(s) is inserted, to allow the cable to transition from a first side of the cam to the second side of the cam, said transitional portal also confines and restricts the movement of the cable(s) 
     Accordingly, there is a clearly felt need in the art for a projectile launching device with no cam lean, having a first cam, a second cam, a launch string and one or two cables, collectively known as a harness system, where neither end of the cable is rigidly attached to the cam. 
     These and additional objects, advantages, features and benefits of the present invention will become apparent from the following specification. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side view of a vertical bow of the present invention, having a first and second cam, a first cable, and a string, wherein the cable does not anchor to the cam. 
         FIG. 1A  is a partial rear view of a vertical bow of the present invention, having a first and second cam, a first and second cable, and a string, wherein the cables do not anchor to the cam. 
         FIG. 1B  is a partial rear view of a vertical bow of the present invention, having a first and second cam, a cable, and a string, wherein the cable does not anchor to the cam. 
         FIG. 2  is a top view of a reverse draw crossbow of the present invention in a cocked position, having first and second cams; first and second cables; and a string, wherein the ends of the limbs are cut away to illustrate the first and second cable wrapping the cam pulleys, wherein the cables do not anchor to the cam. 
         FIG. 2A  is a top view of a conventional limb crossbow with inverted cams of the present invention in an at-rest position, having first and second cams; first and second cables; and a string, wherein the cables do not anchor to the cam. 
         FIG. 2B  is a top view of a compact conventional limb crossbow with inverted cams of the present invention in an at-rest position, having first and second cams; first and second cables; and a string, wherein the cables do not anchor to the cam. 
         FIG. 2C  is a top view of a conventional limb crossbow with conventional-draw cams of the present invention in an at-rest position, having first and second cams; first and second cables; and a string, wherein the cables do not anchor to the cam. 
         FIG. 2D  is a top view of a reverse draw crossbow of the present invention in an at-rest position, having first and second cams; first and second cables; and a string, wherein the cables do not anchor to the cam. 
         FIG. 2E  is a top view of a reverse draw crossbow of the present invention in an at-rest position, having first and second cams; first and second cables; and a string, said string comes off a back side of the cam, wherein the cables do not anchor to the cam. 
         FIG. 2F  is a top view of a compact reverse draw crossbow of the present invention in the at-rest position, having first and second cams; first and second cables; and a string, wherein the cables do not anchor to the cam. 
         FIG. 2G  is a side view of a reverse draw crossbow of the present invention in an at-rest position, having first and second cams; first and second cables; and a string, wherein the cables do not anchor to the cam. 
         FIG. 3A  is a top view of a first one-piece cam with round cable tracks of the present invention, wherein a transition portal is illustrated, wherein the cables do not anchor to the cam. 
         FIG. 3B  is an exploded side view of a first one-piece cam with round cable tracks of the present invention, having bearings and a transition portal illustrated, wherein cables do not anchor to the cam. 
         FIG. 3C  is a bottom view of a first one-piece cam with round cable tracks of the present invention, a transition portal is illustrated and wherein the cables do not anchor to the cam. 
         FIG. 3D  is an exploded bottom side view of a first one-piece cam with round cable tracks of the present invention, having bearings and a transition portal is illustrated, wherein the cables do not anchor to the cam. 
         FIG. 3E  is a top view of a second one-piece cam with round cable tracks of the present invention, a transition portal is illustrated and wherein the cables do not anchor to the cam. 
         FIG. 3F  is an exploded side view of a second one-piece cam with round cable tracks of the present invention, having bearings and a transition portal is illustrated, wherein the cables do not anchor to the cam. 
         FIG. 3G  is a bottom view of a second one-piece cam with round cable tracks of the present invention, a transition portal is illustrated and wherein the cables do not anchor to the cam. 
         FIG. 3H  is an exploded bottom side view of a second one-piece cam with round cable tracks of the present invention, having bearings and wherein a transition portal is illustrated, wherein the cables do not anchor to the cam. 
         FIG. 4A  is a top view of a first multi-piece cam with non-circular cable tracks of the present invention, a transition portal is illustrated; a string and cable are illustrated with the cam, wherein the cables do not anchor to the cam. 
         FIG. 4B  is a bottom view of a first multi-piece cam with non-circular cable tracks of the present invention, a transition portal is illustrated; a string and cable are illustrated with the cam, wherein the cables do not anchor to the cam. 
         FIG. 4C  is a side cut-away view of a first multi-piece cam with non-circular cable tracks of the present invention, a transition portal is illustrated with first cable transitioning from a first side of the cam to a second side of the cam, a string and cable are illustrated with the cam, wherein the cable does not anchor to the cam. 
         FIG. 4D  is an exploded side view of a first multi-piece piece cam with non-circular cable tracks of the present invention having first and second mirror image modules and a transition portal illustrated, wherein the cables do not anchor to the cam. 
         FIG. 5A  is a top view of a second multi-piece cam with non-circular cable tracks of the present invention, the transition portal is illustrated; a string and cable are illustrated with the cam, wherein the cables do not anchor to the cam. 
         FIG. 5B  is a bottom view of a second multi-piece cam with non-circular cable tracks of the present invention, the transition portal is illustrated; a string and cable are illustrated with the cam, wherein the cables do not anchor to the cam. 
         FIG. 5C  is an exploded side view of a second multi-piece piece cam with non-circular cable tracks of the present invention having a first and second mirror image modules; a transition portal is illustrated, wherein the cables do not anchor to the cam. 
         FIG. 5D  is a side cut-away view of a second multi-piece cam with non-circular cable tracks of the present invention, a transition portal is illustrated with first cable transitioning from a first side of the cam to a second side of the cam; a string and cable are illustrated with the cam, wherein the cable does not anchor to the cam. 
         FIG. 6A  is a top view of first and second multi-piece cams with non-circular cable tracks of the present invention; a transition portal is illustrated, modules have been removed for illustrative purposes; a string and cable are illustrated with the cam in a drawn position, wherein the cables do not anchor to the cam. 
         FIG. 6B  is a bottom view of first and second multi-piece cams with non-circular cable tracks of the present invention, a transition portal is illustrated; modules have been removed for illustrative purposes; a string and cable are illustrated with the cam in a drawn position, wherein the cables do not anchor to the cam. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     With reference now to the drawings,  FIGS. 1, 1A and 1B  show views of a vertical bow-type projectile launching device  2 . The projectile launching device  2  preferably includes a bow riser  10 , a first limb  14 , a second limb  16 , a first cam  18 , a second cam  20  and a launch string  22 . One end of the first limb  14  is attached to a first end of the bow riser  10  and one end of the second limb  16  is attached to a second end of the bow riser  10 . The first cam  18  is pivotally retained on an opposing end of the first limb  14  with a first axle  31  and the second cam  20  is pivotally retained on an opposing end of the second limb  16  with a second axle  32 . 
     With more specific reference to  FIG. 1A , the disclosed embodiment illustrates a vertical bow  2  having a first cable  44  and a second cable  46 , wherein a first end of the first cable  44  is anchored to a first cable first post  24 , and a second end of the first cable  44  is anchored to a first cable second cable post  26 . A first end of the second cable  46  is anchored to a second cable first cable post  25  and a second end of the second cable  46  is anchored to a second cable second post  27 . A first cable spanner bar  82  is coupled to the riser  10  on a first side of the launch string  22 , and a second cable spanner bar  83  is coupled to the riser  10  on a second side of the launch string  22 . The cable spanner bars  82  and  83  displace the first and second cables  44  and  46  a distance away from the launch string  22  to allow clearance for an arrow  33 . 
     With more specifically referring to  FIG. 1B , the disclosed embodiment illustrates a vertical bow  2  having a single cable  45 , wherein said first end of the single cable  45  the first post  24 , and a second end of the single cable  45  is anchored to the cable post  25 . The first spanner bar  82  is coupled to the riser  10  on the first side of the launch string  22 , and the second spanner bar  83  is coupled to the riser  10  on the second side of the launch string  22 . The first and second spanner bars  82 ,  83  displace the single cable  45  a distance away from the launch string  22  allow clearance for the arrow  33 . 
       FIGS. 2 and 2A-2G  illustrate a crossbow  1  of the current invention. The bow riser  10  may be joined with the rail  12  in any method known to join two pieces, as well as the rail  12  and the riser  10  being formed together as a single unit. The projectile launching device  1  preferably includes the riser  10 , the rail  12 , a first limb  14 , a second limb  16 , a first cam  18 , a second cam  20  and a launch string  22 . 
     A first end of the first limb  14  is coupled to a first end of the bow riser  10  and a first end of the second limb  16  is coupled to a second end of the bow riser  10 . The first cam  18  is pivotally retained on an opposing end of the first limb  14  and the second cam  20  is pivotally retained on an opposing end of the second limb  16 . The crossbow  1  includes a first cable  44  and a second cable  46 . With reference to  FIGS. 2 and 2G , the first end of the first cable  44  is anchored to the first cable first post  24  extending from a top of the riser  10 . The second end of the first cable  44  is anchored to the first cable second cable post  25  extending from a bottom of the riser  10 . The first end of the second cable  46  is anchored to the second cable first cable post  26  extending from a top of the riser  10 . The second end of the second cable  46  is anchored to the second cable second post  27  extending from a bottom of the riser  10 . 
     With reference to  FIGS. 2B-2G , the first cable first post  24  extends from a first side of the rail  12 , above a centerline of the rail  12 . The first cable second post  25  extends from the first side of the rail  12 , below the centerline of the rail  12 . The second cable first post  26  extends from a second side of the rail  12 , above the centerline of the rail  12 . The second cable second post  27  extends from the second side of the rail  12 , below the centerline of the rail  12 . 
     With reference to  FIGS. 3A-3D , the first cam  18  includes a first launch string track  19 , a first cam upper cable track  40 , a first cam launch string post  61 , a first cam transitional portal  34 , and a first cam lower cable track  41 . A first upper bearing  84  is pressed into the first cam upper cable track  40  and a first lower bearing  85  is pressed into the first cam lower cable track  41 . With reference to  FIGS. 3E-3G , the second cam  20  includes a second launch string track  21 , a second cam upper cable track  42 , a second cam launch string post  63 , a second cam transitional portal  35 , and a second cam lower cable track  43 . A second upper bearing  86  is pressed into the second cam upper cable track  42  and a second lower bearing  87  is pressed into the second cam lower cable track  43 . A first end of the launch string  22  is retained by the first cam launch string post  61 ; a portion of the span of the launch string  22  at least partially wraps around the first cam  18  in the first cam launch string track  19 ; a portion of the span of the launch string  22  at least partially wraps the second cam  20  in the second cam launch string track  21 , and a second end of the bowstring  22  is retained by the second cam launch string post  63 . 
     The first end of the first cable  44  is coupled to the first cable first cable post  24 ; a segment of the first cable  44  partially engages the first cam upper cable track  40 ; the middle of the first cable  44  is inserted through the first cam transitional portal  34 ; a segment of the first cable  44  partially engages the first cam lower cable track  41 ; and the second end of the first cable  44  is coupled to the first cable second cable post  25 . The first cable  44  does not cross the rail  12 . A first end of the second cable  46  is coupled to the second cable first cable post  26 ; a segment of the second cable  46  partially engages the second cam upper cable track  42 ; the middle of the second cable  46  is inserted through the transitional portal  35 ; a segment of the second cable  46  partially engages the second cam lower cable track  43 ; and the second end of the second cable  46  is coupled to the second cable second cable post  27 . The first and second cable first cable posts  24 ,  26  are located above a horizontal plane of the first and second cams  18 ,  20 . The first and second cable second cable posts  25 ,  27  are located below a horizontal plane of the first and second cams  18 ,  20 . The second cable  46  does not cross the rail  12 . 
     With reference to  FIGS. 6A and 6B , when the launch string  22  is drawn from a rest position to a ready to fire position, the first cam  18  rotates in a first direction, and the second cam  20  rotates in a second direction. As the cams  18  and  20  rotate, the launch string  22  is unwound from the first and second launch string tracks  19  and  21 . Simultaneously, the cables  44  and  46  wind into the first and second upper cable tracks  40  and  42  and the first and second lower cable tracks  41  and  43  of the first  18  and second  20  cams. When the launch string  22  has been drawn to the ready-to-fire position, it may be held in this the position by an operably releasable catch located in a housing  56 . The first cable  44  is slideable relative to the first cam transitional portal  34  and the second cable  46  is slideable relative to the second cam transitional portal  35 . An alternate embodiment uses the launch string  22  and a single cable  45 . With reference to  FIG. 1B , a first end of the single cable  45  is attached to the single cable first cable post  24 , a span of the single cable  45  is retained in the first cam transitional portal  34  of the first cam  18 ; crosses a center-line of the rail  12 ; is retained in the second cam transitional portal  35  of the second cam  20 , and the second end of the single cable  45  is attached to the single cable second cable post  25 . The single cable  45  replaces first and second cables  44 ,  46 . 
       FIGS. 3A-3H  illustrate an embodiment of a cam of the current invention, without string and cable(s), wherein the cam is constructed of a unitary type construction. In this type of construction, the first and second side of the first cam  18  and the second cam  20  are mirror images of each other, and the first cam  18  is identical and interchangeable with the second cam  20 . Specifically,  FIG. 3A  is a top view of the first cam  18 ;  FIGS. 3B and 3D  is a side view of a first cam  18 ; and  FIG. 3C  is a bottom view of a first cam  18 .  FIG. 3E  is a top view of the second cam  20 ;  FIGS. 3F and 3H  are side views of the second cam  20 ; and  FIG. 3G  is a bottom view of the second cam  20 . The upper cable track  40 , the lower cable track  41 , the upper cable track  42  and the lower cable track  43  may be generally circular, or non-circular. 
       FIGS. 4A-4D and 5A-5D  illustrate an embodiment of the first cam  18  of the current invention with string and cable(s), wherein the first cam  18  is constructed of a modular type construction. In this type of construction, the first and second side of the first cam  18  and the second cam  20  are mirror images of each other, and the first cam  18  is identical and interchangeable with the second cam  20 . The first cam  18  includes a first module  70  and a second module  75 . The first and second modules  70 ,  75  are mirror images of each other. The first and second modules  70 ,  75  are identical and are interchangeable with a first module  72  and a second module  77  of the second cam  20 . Specifically,  FIG. 4A  is a top view of the first cam  18 ,  FIG. 4B  is a bottom view of the first cam  18 ,  FIG. 4C  is a cut-away view of the first cam  18  with the string  22  and the cable  44 . The first module  70  and the second module  75  may be generally non-circular, or circular.  FIG. 4C  illustrates how the cable  44  passes through the first transitional portal  34 . 
       FIGS. 5A-5D  illustrate an embodiment of the second cam  20  of the current invention, with string and cable(s), wherein the second cam  20  is constructed of a modular type construction. In this type of construction, the first and second side of the second cam  20  and the first cam  18  are mirror images of each other, and the first cam  18  is identical and interchangeable with the second cam  20 . The first module  72  and the second module  77  are mirror images of each other, and the first and second modules  70  and  75  are identical and interchangeable with the first and second modules  72  and  77 . Specifically,  FIG. 5A  is a top view of the second cam  20 ,  FIG. 5B  is a bottom view of the second cam  20 ,  FIG. 5C  is a cut-away view of a second cam with the string  22  and the cable  46 . The first module  72  and the second cable module  77  may be generally non-circular, or circular.  FIG. 5D  illustrates how the cable  44  passes through the first transitional portal  35 . 
       FIG. 6A  illustrates a top view of the first cam  18  and the second cam  20 , in the drawn position.  FIG. 6B  illustrates a bottom view of the first cam  18  and the second cam  20 , in the drawn position.  FIGS. 6A and 6B  are identical to each other and not just mirror images, as described previously in  FIGS. 5A-5D . This feature allows for an easier method of manufacture and assembly. With reference to  FIGS. 2 and 2G , a first end of the first cable  44  is anchored to a first cable first cable post  24 ; the second end of the first cable  44  is passed through the first cam transitional portal  34 ; and anchored to the first cable second cable post  25 . A first end of the second cable  46  is anchored to a second cable first cable post  26 ; the second end of the second cable  46  is passed through the second cam transitional portal  35 ; and anchored to the second cable second cable post  27 . A first end of the launch string  22  is anchored to the first cam string post  61 ; a segment of the launch string  22  partially wraps cam  18  in the string track  19 ; the string crosses the center of the riser  10 ; and partially wraps the second cam  20  in the string track  21 ; and the second end of the launch string  22  is anchored to the second cam string post  63 . 
     With reference to  FIGS. 4A-4D and 5A-5D , the center of the first and second cables  44 ,  46  slideably engage the first and second transitional portals  34 ,  35 , which allows the first and second cables  44 ,  46  to “self-center” themselves relative to a first side and a second side of the first and second cams  18  and  20 . The self-centering feature of the cables  44 ,  46  provides for automatic cable timing, which eliminates cam lean, and timing issues. As the launch string  22  is drawn, the launch string unwraps, or “pays out” from the first and second cams  18 ,  20 . Simultaneously, the first and second cables  44 ,  46  wrap the respective first cable tracks  70 ,  75  and the second cable tracks  72 ,  77 . 
     With reference to  FIGS. 3A-3G , it is preferable for both single and double cable designs that a vertical distance between the lower cable tracks  41 ,  43  relative to the string launch tracks  19 ,  21  have an equal vertical distance as the upper cable tracks  40 ,  42  relative to the string launch track  19 ,  21 . However, the projectile launching device  1  could still function satisfactorily without the above vertical distance conditions. It is also preferable that the cables  44 ,  45 ,  46  not be parallel to the launch string  22 . However, the projectile launching device  1  will function satisfactorily without the non-parallel conditions. It is preferable that the first ends of the first and second cables  44 ,  46  not be anchored to the same post. However, the first and second cables  44 ,  46  will still function satisfactorily if anchored to the same post. It is preferable that the second ends of the first and second cables  44  and  46  not be anchored to the same post. However the first and second cables  44 ,  46  will still function satisfactorily if anchored to the same post. 
     While the preferred embodiment of the invention has been illustrated and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from the invention in its broader aspects, and therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of the invention.