I was working on a project where I have to launch a ball. The current design has two wheels that are side by side with the ball going between them. I noticed that in almost every commercial ball launcher, the wheels are stacked on top of one another rather than side by side.

I don't understand what advantage this has over my current system. It seems a lot more accurate and precise, but I don't see why.

  • $\begingroup$ because horizontal precision is much more important than vertical precision. $\endgroup$ Jan 23, 2017 at 8:56
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    $\begingroup$ I'm struggling to picture this - sketches would help. $\endgroup$
    – AndyT
    Jan 23, 2017 at 11:21
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    $\begingroup$ Your question cannot be answered until we understand what your desired outcome is. Why are you launching a ball, what's the intended use, etc? There's a big difference between launching curve balls for batting practice and launching spheroids to hit military targets, for example. $\endgroup$ Jan 23, 2017 at 15:50

1 Answer 1


Quite a few of the machines allow to tilt the pair of wheels to arbitrary angle too. Some allow tuning speed of the two motors separately.

It's all about curveballs and Magnus Effect. One wheel going faster will give the ball a spin on top of the forward speed - and the ball trajectory will curve in direction perpendicular to rotation axis and current velocity vector. "Stacked" layout allows to pitch the ball a longer distance, by counter-acting gravitational drop, and keeping the trajectory more straight. Sideways placement will tend to curve the ball to a side. Which you want depends on how you want to train.


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