Information about
Baseball HR Simulator

See a separate page (opens in this same window) for suggested experiments you can do with this program, particularly one concerning the new NCAA rule on bats.

This program solves the differential equations governing the flight of a baseball based on the model developed by Robert Adair in his book "The Physics of Baseball". See the bottom of this page for details.

The Hit button lauches a ball with the current values of the input parameters after checking that the parameters are within an allowed range given below. The Clear button removes the displayed trajectories and redisplays the current parameters.

The program enforces the following limits:

A warning is issued when your input value falls outside the legal range and has been replaced with a legal max or min value. You only get one warning if you make errors in several different input fields for the same hit. If you use the "Enter" key after changing a value, that input will be checked and displayed along with any warning.

You also get a warning if the total of the ball speed and wind speed exceeds 150 mph, because the coefficients in use may not be reliable in that situation.

General suggestions and information:

The model used is not perfect so it is best to use it to see the effect of relative changes rather than for absolute predictions. That is, you can use it to estimate the range of angles that will produce a home run for a given ball speed, and how that range would increase or decrease if the ball speed increased or decreased by some percentage.

Common problems such as lack of sufficient colors or poor color mapping are to be expected based on my tests. Feedback or suggestions on colors that might map better, or any other problems, are solicited.

About the program:

This program solves the differential equations governing the flight of a baseball based on the model developed by Robert Adair in his book "The Physics of Baseball". It was first developed/written in Fortran to analyze J.D. Drew's monster 550' home run back in February 1997. The Java version has been checked against that original program and graphs in Adair's book but is not in final form.

The program has other (hidden) options that can be chosen by altering the PARAM specified when the applet is invoked. The default is the one used here, where you can vary the wind. At present the only other option is to hold the wind fixed at zero and vary the relative size of the Magnus effect that results from the rotation of the batted ball.

I plan to write some notes on how the program implements the model described by Adair, but have not done so yet.

My other college baseball material is on a "just the facts" web page, all of which is a sidelight to my usual work of teaching physics.