Jet airliner
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A jet airliner is any airliner powered by jet engines. Most modern long-distance air travel is conducted with jet aircraft, although the fleets of many airlines include a number of smaller turboprop types, typically used for shorter flights to provincial towns, island communities, or airports where topography or adjoining development limits the runway length. Early models were powered by turbojet engines, but all current models use more fuel-efficient turbofans.
The first jet airliner was the de Havilland Comet, which first flew in 1949 and entered service in 1952. it was followed some years later by the enormously successful Boeing 707 and Douglas DC-8, the Sud Aviation Caravelle, Tupolev Tu-104, and Convair 880. Considerable national prestige was attached to developing prototypes and bringing these first generation designs into service. There was a strong nationalism in purchasing policy, such that the Boeing and Douglas products became closely associated with Pan Am, whilst BOAC ordered Comets, Aeroflot used Tupolevs, and Air France introduced Caravelles. Commercial realities dictated exceptions, however, as few airlines could risk missing out on a superior product: American airlines ordered the pioneering Comet (but later cancelled when the Comet ran into fatigue problems, British and European airlines could not ignore the excellent operating economics of the 707 and the DC-8.
Boeing became the most successful of the early manufacturers, partly due to the 707's origin as a well-funded military project. The KC-135 Stratotanker and versions of the 707 remain operational — mostly as tankers or freighters. The basic configuration of the Boeing, Convair and Douglas aircraft, with widely spaced podded engines underslung on pylons beneath a swept wing, proved to be the prevalent arrangement by 1980 and was most easily compatible with the large-diameter high-bypass turbofan engines that subsequently prevailed for reasons of quietness and fuel efficiency.
The de Havilland and Tupolev designs had engines incorporated within the wings next to the fuselage, a concept that endured only within military designs whilst the graceful Caravelle pioneered engines mounted either side of the rear fuselage.
In the 1960s, when jet airliners were powered by slim, low-bypass engines, many aircraft used the rear-engined configuration, such as the Boeing 727, Douglas DC-9, BAC One-Eleven, Hawker Siddeley Trident, Ilyushin Il-62 and Vickers VC-10. It survives into the 21st century on numerous Douglas DC-9 derivatives plus newer short-range jetliners built by Bombardier, Embraer and, until recently, Fokker. For business jets the rear-engined configuration is universal as on small aircraft the wing is too close to the ground to accommodate underslung engines.
The DH106 Comet should not be confused with the earlier piston-engined De Havilland DH.88 racer also known as the Comet.