I wanted ot mess a bit further with FM today. I ended up making the world’s ugliest pure data patch. no doubt. Its a space engine sound where you control the RPM. This then drives various parameters on the FM voice. But, in addition i ahve several non-linair distortions added that increase when the RPM is increased. In the future you could also add a throttle, so you could put a load on the the engine and get a more realistic simulation. I dig the sound of ths thing though.