mechanical baseball launcher project

7/25/2019 Mechanical Baseball Launcher Project

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Design and assumptions

For this design,

1. The links of the machine can be considered to be extra lubed, thus friction

can be neglected.

2. The baseball is also lubed such that drag does not affect its trajectory

through the air; the speed is constant.

3. ar!"ink 1 is stationary.

#. $hen adjusting for trajectory, the entire machine mo%es &ith bar 1.

'. The baseball &ill be launched at the point &hen (# is at )* degrees +Fig. 2

&ith respect to (1.-. The bar on the far right side is one solid, rigid link.

. $hen locked in, the trigger &ill compress the torsional spring a certain angle

defined by (spring +Fig. 2.

/. The adjustable preload for speed control is adjusted by mo%ing the trigger

and trigger arm to the left to tighten the spring back by some %alue. Thus,

the torsional spring, &hen tightened, &ill be released &ith the energy stored

by a compression of (spring 0 (2start (2end. $e &ill compute &hich

angles gi%e &hich %elocities.

). $hen (spring 0 *, the ball &ill launch at #* mph. The maximum allo&ed

(spring &ill launch the ball at /* mph.

For the materials of the baseball launcher, each bar is composed of solid metal

cylinders; specifically aluminum &ith a density of *.*)/ lb!in3. The diameter of

each link &ill be 1 inch. The baseball &ill ha%e a radius of 1.' inches and &eigh #

ounces as specified.



The follo&ing &ritten pages sho&s the &ork for deri%ing the euations

needed for the design to select the proper torsional spring, as &ell as the angles

needed to launch the ball at specific %elocities. The 4atlab code uses the deri%ed

euations to compute the spring constant and angles needed to launch the ball at

specific %elocities gi%en &hate%er chosen lengths. 5arious lengths &ere trialed

before settling on these to maximi6e efficiency.

Conclusions and Comparison to the simple ball launcher design

From the results it can be determined that a %ery strong spring &ill be

needed. 7riginally, steel #2* +bla6e it &as used for the material of the bars and the

spring constant &as o%er one million. 8fter aluminum &as used instead, the spring



constant dropped by --9. 8lso, %arying the arm lengths also helps &ith the

efficiency of the machine. 5arious arm lengths &ere tried and the spring constant

needed &as lo&ered further to its current %alue in the 4atlab code. There is

probably an e%en more efficient combination of bar lengths then the lengths

chosen.

:n comparison to the single bar ball launcher; there are ad%antages and

disad%antages to both. For one, &eight The &eights of the single bar launcher is

much less than that of the # bar launcher; this &ould result in less &ork needed to

produce the same amount of ball %elocity. There is also a snubber in the one bar

design &hich &ould allo& some lee&ay in the calculation of the spring constant,

since the snubber can effecti%ely stop the spring before it tra%els the full distance

&ithout the stop.

mechanical baseball launcher project

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