An engine is a machine that converts energy into useful mechanical motion. The type of engine can vary depending on the application. A turbojet engine is an internal combustion engine that uses a turbine to compress air and create thrust. It is commonly used in aircraft propulsion. A DIESEL engine is an internal combustion engine that uses compression ignition to generate power. It is often used in large vehicles such as trucks and ships. A turbine engine is an internal combustion engine that uses a turbine to generate power. It is commonly used in power plants and in some aircraft.