Turboprop
[1] A turboprop consists of an intake, reduction gearbox, compressor, combustor, turbine, and a propelling nozzle.
[13] Due to the turbine engine's slow response to power inputs, particularly at low speeds, the propeller has a greater range of selected travel in order to make rapid thrust changes, notably for taxi, reverse, and other ground operations.
[14] Due to the pilot not being able to see out of the rear of the aircraft for backing and the amount of debris reverse stirs up, manufacturers will often limit the speeds beta plus power may be used and restrict its use on unimproved runways.
[14] The turboprop is also distinguished from other kinds of turbine engine in that the fuel control unit is connected to the governor to help dictate power.
Since it is more efficient at low speeds to accelerate a large amount of air by a small degree than a small amount of air by a large degree,[16][17] a low disc loading (thrust per unit disc area) increases the aircraft's energy efficiency, and this reduces the fuel use.
For this reason turboprop engines are not commonly used on aircraft[4][5][6] that fly faster than 0.6–0.7 Mach,[7] with some exceptions such as the Tupolev Tu-95.
Subsequent work at the Royal Aircraft Establishment investigated axial compressor-based designs that would drive a propeller.
From 1929, Frank Whittle began work on centrifugal compressor-based designs that would use all the gas power produced by the engine for jet thrust.
[27] The first British turboprop engine was the Rolls-Royce RB.50 Trent, a converted Derwent II fitted with reduction gear and a Rotol 7 ft 11 in (2.41 m) five-bladed propeller.
Two Trents were fitted to Gloster Meteor EE227 — the sole "Trent-Meteor" — which thus became the world's first turboprop-powered aircraft to fly, albeit as a test-bed not intended for production.
The Dart-powered Vickers Viscount was the first turboprop aircraft of any kind to go into production and sold in large numbers.
The world's first single engined turboprop aircraft was the Armstrong Siddeley Mamba-powered Boulton Paul Balliol, which first flew on 24 March 1948.
The Bear would serve as their most successful long-range combat and surveillance aircraft and symbol of Soviet power projection through to the end of the 20th century.
[36] 1964 saw the first deliveries of the Garrett AiResearch TPE331, (now owned by Honeywell Aerospace) on the Mitsubishi MU-2, making it the fastest turboprop aircraft for that year.
[37] In contrast to turbofans, turboprops are most efficient at flight speeds below 725 km/h (450 mph; 390 knots) because the jet velocity of the propeller (and exhaust) is relatively low.
[38] Compared to piston engines, their greater power-to-weight ratio (which allows for shorter takeoffs) and reliability can offset their higher initial cost, maintenance and fuel consumption.
As jet fuel can be easier to obtain than avgas in remote areas, turboprop-powered aircraft like the Cessna Caravan and Quest Kodiak are used as bush airplanes.
Turboprop engines are generally used on small subsonic aircraft, but the Tupolev Tu-114 can reach 470 kn (870 km/h; 540 mph).
[40] Less widespread and older airliners include the BAe Jetstream 31, Embraer EMB 120 Brasilia, Fairchild Swearingen Metroliner, Dornier 328, Saab 2000, Xian MA60, MA600 and MA700, Fokker 27 and 50.
