Complex sentence: In radio-controlled modeling, a model engine is an internal combustion engine used to power a radio-controlled aircraft, radio-controlled car, radio-controlled boat, free flight and control line aircraft, and tether car models also use these engines.
Split into simpler sentences: In radio-controlled modeling, a model engine is an internal combustion engine used to power a radio-controlled aircraft, radio-controlled car or radio-controlled boat. Other forms of aeromodeling, such as free flight and control line aircraft, and ground-running tether car models also use these engines.