Hey HN, I built Spin Lab: a browser-based interactive explainer for table-tennis spin.

It visualizes topspin/backspin, spin rate, ball trajectory, bounce behavior, and why the opponent’s return reacts the way it does.

I built it because spin is central to table tennis, but most explanations are either too hand-wavy or too static. I wanted something you can scrub, slow down, and experiment with.

Are you using flight trajectories with simulated drag and lift from Magnus effect?

You might consider emailing hn@ycombinator.com and asking about the standing of your account.