|What's the difference with a Mazda rotary engine?
The rotary engine was supposed to revolutionize automobiles when it was first introduced several decades ago. Instead of a piston and cylinder, it has a triangular shaped object that wobbles around the inside of a hollow chamber. This object traps a fuel and air mixture, compresses it, ignites it, extracts energy from it, and releases it into the outside air, just as a normal engine does. But it uses the wobbling motion of the triangle, rather than the reciprocating motion of the piston and cylinder. The rotary engine has fewer moving parts to wear out, but it evidently has other issues that have prevented its wide adoption.