An improved device useful for hurling baseballs or the like to players in practice ball-hitting sessions has been developed. It provides multi-directional spin control to make a ball curve in any chosen direction from a normal trajectory path, as well as speed control, and it can be carried as a substantially lighter-weight and more easily portable package than the massive and expensive electric-powered curve-ball hurlers such as are now used by professional teams. The spin control is provided by attaching one end of a strap to the ball-holding pouch of an elastic-powered slingshot, or catapult, such that the loose end of the strap may be wrapped in any chosen direction around the ball as it is nested into the pouch, and the strap will induce a spinning motion on the ball when it flies out. The speed control is provided by a light-weight flexible cord that limits the length to which the elastic members of a slingshot may be stretched back; variable settings are possible. Weight reduction and easy portability is further improved by having a relatively thin and flat framework designed to hold the forward ends of the elastic members in a spaced-apart and elevated position, and having one or more relatively light-weight guy lines reaching forward from the framework to one or more suitable anchor points, such as stakes driven into the ground. The guy line(s) works in tension to resist the pull on the elastic members and hold the framework in a near vertical position.

INTRODUCTORY BACKGROUND 
This relates to a device to hurl baseballs or the like to a player during 
practice ball-hitting sessions. 
It is known that skilled baseball pitchers normally put a controlled spin 
on almost every ball thrown, causing the ball to curve away from an 
otherwise normal trajectory, curving either up, down, or to either side, 
depending upon the direction of the spin. Skilled tennis players likewise 
hit the ball to make it spin and curve. Curve-balls are more difficult to 
hit in contests such as baseball games and tennis matches. 
For baseball batting practice sessions there are electric-powered 
ball-throwing machines available which can be adjusted to throw curve 
balls at various set speeds, but these are relatively expensive and heavy 
to transport to a field for non-professional team practice, and electric 
power is generally not available at the pitcher's mound at most amateur 
practice sites. Electric-powered devices to hurl tennis balls are likewise 
available, but expensive and heavy. 
Elastic-powered slingshots and catapults are well known, but none are known 
which provide multi-directional spin control. U.S. Pat. No. 5,123,643 
describes a slingshot system capable of putting a spin on a baseball, but 
it is limited to a down-spin exclusively. U.S. Pat. No. 4,261,319 
describes a slingshot for spinning a non-standard football out from a 
guide rod centered through the length of the ball, but this is clearly not 
applicable for baseballs, tennis balls, and the like. 
It is the object of this invention to provide an easily portable, 
light-weight, non-electrical and relatively inexpensive device that has 
the ability to throw a baseball, tennis ball or the like with a controlled 
spin in any chosen spin direction, and with various settings for a 
controlled maximum forward velocity. 
SUMMARY OF INVENTION 
This will describe improvements to elastic-powered ball-hurling devices to 
provide: (1) the ability to make a spherical ball spin in any direction, 
(2) the ability to limit or control maximum hurling speed, and (3) 
improved light-weight portability. 
A preferred system embodying these improvements includes the typical 
components of a slingshot, namely: 1-resilient elastic members which can 
be pulled back or elongated by a force and then released to accelerate and 
hurl a projectile, 2-a framework to hold the forward ends of the elastic 
members in a relatively fixed position when the slingshot is operated, and 
3-a pouch attached to the rear, or loose ends, of the elastic members; 
this pouch serving to hold the projectile when the elastic members are 
stretched back and when they are released to accelerate the projectile, 
and then serving to release the accelerated projectile when the pouch 
decelerates. 
For spin control, an important part of this invention is a novel pouch 
system. This pouch system includes a strap having one of its ends 
connected to the pouch, such that the rest of the strap may be wrapped in 
an optional direction around a ball as the ball is nested into the pouch. 
In operation, when the accelerated ball has gained momentum to fly out of 
the decelerating pouch, the strap can cause the ball to spin in a definite 
direction, either up, down, or sideways, depending on the direction the 
strap was wrapped around the ball and set into the pouch. It is possible, 
of course, to operate this slingshot without wrapping the strap around the 
ball, in which case the ball will be hurled without significant spin, 
equivalent to what a baseball pitcher calls a knuckle-ball. 
For speed control, novel adjustable means have been developed to limit the 
stretch of the elastic, which in turn limits the force which can be 
accumulated in the elastic, the force to accelerate the ball, and the 
resulting speed of a standard-weight ball. 
For easy portability and weight reduction, a flat framework has been made 
to hold the forward ends of the elastic members in an elevated and 
spaced-apart condition, improved by one or more light-weight guy lines to 
hold this framework in a relatively-fixed near-vertical position when 
forces are applied to the stretch the elastic and to hurl a ball at high 
speed.

DETAILED DESCRIPTION 
The novel strap in the pouch system preferably is long enough to partly 
overlap itself around the ball, to better grip the ball and impart a 
maximum spin on the ball, but a shorter strap may be used within the scope 
of this invention. It has been found that a shorter strap can still spin a 
baseball when the strap has been frictionized or treated such as with a 
rubber coating to make it grip the ball better. An all-rubber or elastic 
strap is also satisfactory. The strap preferably is between a half inch 
and one and a half inches wide simply to facilitate easy wrapping around 
the ball, but any wider or narrower strap could be utilized within the 
scope of this invention. The term "strap" should be broadly interpreted to 
include any flexible material which may have one end wrapped around a ball 
and cause the ball to rotate when the other end is pulled away. It could 
be a fish line, a cord, or a length of chain, but a length of ribbon or 
strap is preferred as the means to impart a spin on a ball. 
The pouch need not be a soft-sided pouch as illustrated; rigid or 
semi-rigid cups, funnels or rings, may also be used with the novel strap 
somehow attached. The strap preferably is attached either to the bottom of 
the pouch or, as illustrated in FIG. 1, connected behind it to reach 
through an opening in the bottom of the pouch. The open bottom system has 
two advantages. One, it provides greater flexibility for orienting the 
direction of strap wrap when the ball is nested in the pouch. Two, for a 
powerful hurling device intended for baseballs or softballs, it can 
prevent smaller objects such as golf balls and small stones from being 
hurled at high velocity by an irresponsible operator. A rigid cup or 
semi-rigid ball-holding pouch is more appropriate than a soft-sided pouch 
for use with a catapult where the pouch is attached to a relatively rigid 
arm that is pivoted to swing and accelerate the ball. 
The means to limit the stretch of the elastic members, which in turn limits 
the force accumulated in the elastic, and the speed of a standard weight 
ball, has been identified as including a "stretch-limit/speed-limit 
flexible cord". However, it should be understood that other flexible 
materials such as straps, chains, or the like, could be used within the 
scope of this invention. Preferably it will be relatively light weight, or 
have a low mass, compared to the weight (mass) of the pouch and elastic 
members, and be relatively flexible. It will have a means to adjust the 
limit the length of cord between the framework and the pouch system. With 
the back end of a fixed-length cord fastened to the pouch system, the 
forward end may be connected to any one of a number of fastening points on 
the framework. Different types of common latching devices and fastening 
points, other than holes as illustrated, may be used to set different 
stretch limits and speed limits. Other common means to shorten the length 
of cord behind the panel may be used, such as looping part of the forward 
end of the cord around alternative pegs. Preferably the means to adjust 
the stretch-limit of the elastic members should be visible to a person 
forward of the framework and thereby indicate to that person the potential 
maximum speed of a ball to be hurled. 
The novel use of one or more guy lines is desirable for package weight 
reduction considering that a force of perhaps 150 pounds, more or less, 
may be applied to the elastic member to accelerate a standard baseball or 
softball to relatively high speed. Guy lines working in pure tension can 
weigh substantially less than equally strong structural members working in 
compression or to resist flexure or torque. The forward end(s) of the 
guy(s) may be attached to any suitable anchor, other than stakes in the 
ground, within the scope of this invention. 
It should be obvious that other arrangements and configurations could be 
used within the scope of this invention.