Type of aircraft is a broad term that can refer to many different types of aircraft. An autogyro, which has 8 letters, is an aircraft that uses an unpowered rotor in free autorotation to develop lift, and an engine-powered propeller to provide thrust. A turboprop, which has 9 letters, is an aircraft powered by a turbine engine driving a propeller. Finally, STOL, which has 4 letters, stands for Short Takeoff and Landing, and refers to aircraft with very short takeoff and landing capabilities.