The Reuleaux Triangle, the triangle with a constant width

It goes in the square hole

This was also used in Wankel Engine

nah... I don't trust it.

Someone draw a fedora on the first part of the video and turn it in Perry the platypus meme

Rotax engine, no?

Like a rotary engine.

Wankel’s rotary design is based off of Franz Reuleaux’s triangles.

Triangle goes in the square hole