01 · Baseball

Magnus

A baseball you can throw in the browser. Change the speed and the spin, and the path changes for real — not like a video game.

Open the park Throw pitches in the browser

The Magnus park at night, with pitch controls and camera views — The park at night. This one is a 94 mph fastball. You can walk around the field.

What you do: Pick a pitch. Move speed and spin.
What you see: The ball’s path through the air.
The yellow line: The same throw, with the spin turned off.
Why it bends: Spin pushes air. Air pushes the ball back.

A slider’s path in white next to a yellow path that does not break as much — A slider. White is the real pitch. Yellow is no spin.

A curveball dropping well below the yellow no-spin path — A curve. Topspin pulls it down. The gap is the spin doing work.

What it is

A 3D interactive baseball pitch physics simulation. You get complete control over the pitch and its environment.

I wanted a tool that makes it easy to see how the flight changes when you adjust ball speed, spin speed, spin direction, or the air around the ball.

How this actually works

A spinning ball drags air around with it. The air on one side moves faster than the other, so the pressure is uneven, and the ball curves. Soccer players use the same idea when they bend a kick. That push is called the Magnus effect.

I do not use a video-game physics engine. The path is walked forward in tiny time steps from published baseball measurements of drag (air slowing the ball) and lift (spin bending it).

The yellow line is the same throw with spin set to zero. The gap is how far spin moved the ball compared to a dead throw. Stat nerds call that induced vertical break.