What does a rotary engine sound like? A Mazda, that’s what. Ugh, that triggered me more than it should.

I’m a little confused, aren’t they just referring to aircraft rotary engines with the cylinders arranged radially? Or what’s the triggering part?

Rotary engines are wankel engines. Pretty much only Mazda still uses them. If the cylinders are arranged radially it’s called a radial engine. IIRC, one of the very few helicopters to have a radial motor was the Sikorsky S-58, which saw action in the Vietnam War.

Yup, I know, it doesnt check out at all, you wouldn’t put a rotary on a helicoptor. But “rotary” engines were indeed used on aircraft, since they also refer to a radial cylinder configuration where the engine housing moves and the axis is fixed. So I think it’s likely they were referring to the common WWI plane engine. I didnt think of a wankel at all till you mentioned it! Interestingly enough, modern wankel engines are also sold for helicopters.