I have a Tamiya Sherman Tank that has a sound sythisizer in it so the technology is out there. The engine idles at rest and changes sound on acceleration. It also has the turret motor noise not to mention the machine gun and cannon. They made recordings of a real Sherman to get the sounds. I'm sure its doable for an electric airplane if you could find the right hardware. There are several tapes and CDs of different airplanes out there for the sounds. Don