An RC plane "sound Machine" with the following features :

• play start engine sound when throttle stick leaves "zero" position
• seamlessly increase/decrease motor RPM sound with the throttle stick
• while motor running, play machine gun sound when pressing the gun button on the radio
• play stop engine sound when turning motor off
• The project is also fully documented on my Hackadays pages : https://hackaday.io/project/198182-rc-plane-sound-machine

See (hear) it on the bench here : https://youtu.be/CIiXLgnl6Os