You have the right derivation and you've broken "helicopter" correctly, but what exactly is a "gyroco"? It seems to me "gyrocopter" was very likely coined in En

You have the right derivation and you've broken "helicopter" correctly, but what exactly is a "gyroco"? It seems to me "gyrocopter" was very likely coined in English from the root "gyro" and the "copter" from "helicopter" as a back-formation.