Turboprop aircraft rely on gas driven turbine engines to power the aircraft propeller and activate movement for the vehicle. A turbine (or fan) uses rotary power from a hydraulic or pneumatic flow source to generate energy in much the same way as a windmill does. In turbine engines for aviation, the combustion of jet fuel provides flow for the turbine. The turbine engines of turboprop aircraft are connected to a gearbox that turns the propellers wheels and pushes the plane. As opposed to turbojet and turbofan aircraft (which both use turbine engines) most of the propulsion of a turboprop aircraft is derived from the propeller. On the other hand, the propulsion of a turbojet aircraft relies solely on thrust from engine exhaust while a turbofan aircraft uses a large front-end fan to send streams of air into a combustor and around the engine core to provide thrust and engine cooling.
Due to the propeller-centricity of turboprops, these aircraft use less fuel than average jet thrust aircraft but are typically smaller and slower with a lower altitude ceiling (typically 35,000 feet maximum). Propellers lose utility as speed increases and are typically not seen on high speed aircraft. Most turboprops have a maximum speed of approximately 600 miles per hour, with optimal speed being under 450 miles per hour. However, the slower wing creates more lift for the aircraft which is conducive to longer gliding and slower approach. As a result, turboprops are generally more ideal for STOL (short take-off and landing) assignments because they require less runway.
The first American turboprop engine was General Electric’s T31, debuting in 1945. Despite their slight performance limitations, turboprop engines are used in many current, technologically advanced aircraft – including the U.S. military’s C-130J Super Hercules transport, the U.S. Navy’s P-3 Orion maritime patrol aircraft, and the airborne early warning E-2 Hawkeye. However, turboprops are most common in civilian aircraft for short-haul, regional commuter purposes. Some prominent companies which currently manufacture turboprop aircraft include ATR and Bombardier.