Jet airliner
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A jet airliner (or jetliner, or jet) is an airliner powered by jet engines (passenger jet aircraft). Airliners usually have two or four jet engines; three are less common.
Most airliners today are powered by jet engines because they are capable of high speeds and generate sufficient thrust to power large capacity aircraft. Early airliners, introduced in the 1950s, used the simpler turbojet engine, quickly supplanted by turbofans, which have lower noise levels and fuel consumption.
Contents
Early history
The first airliners with turbojet propulsion were experimental conversions of the Avro Lancastrian piston-engined airliner, which were flown with several types of early jet engine, including the de Havilland Ghost and the Rolls-Royce Nene. They retained the two inboard piston engines, the jets being housed in the outboard nacelles. The first airliner with jet power only was the Nene-powered Vickers VC.1 Viking G-AJPH, which first flew on 6 April 1948.
The early jet airliners had much lower interior levels of noise and vibration than contemporary piston-engined aircraft, so much so that in 1947, after piloting a jet powered aircraft for the first time, Wing Commander Maurice A. Smith, editor of Flight magazine, said, "Piloting a jet aircraft has confirmed one opinion I had formed after flying as a passenger in the Lancastrian jet test beds, that few, if any, having flown in a jet-propelled transport, will wish to revert to the noise, vibration and attendant fatigue of an airscrew-propelled piston-engined aircraft"[1]
First generation
The first purpose-built jet airliner was the British de Havilland Comet which first flew in 1949 and entered service in 1952. Also developed in 1949 was the Avro Canada C102 Jetliner, which never reached production; however the term jetliner came into use as a generic term for passenger jet aircraft.
These first jet airliners were followed some years later by the Sud Aviation Caravelle, Tupolev Tu-104 (2nd in service), Boeing 707, Douglas DC-8, and Convair 880. National prestige was attached to developing prototypes and bringing these first generation designs into service. There was also a strong nationalism in purchasing policy, so that US Boeing and Douglas aircraft became closely associated with Pan Am, while BOAC ordered British Comets.
These two airlines, with the help of advertising agencies and their strong nautical traditions of command hierarchy and chain of command (retained from their days of operating flying boats), were quick to link the "speed of jets" with the safety and security of the "luxury of ocean liners" in the public's perception.
Aeroflot used Soviet Tupolevs, while Air France introduced French 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 metal fatigue problems), Canadian, British and European airlines could not ignore the better operating economics of the Boeing 707 and the DC-8, while some American airlines ordered the Caravelle.
Boeing became the most successful of the early manufacturers. The KC-135 Stratotanker and military versions of the 707 remain operational, mostly as tankers or freighters. The basic configuration of the Boeing, Convair and Douglas aircraft jet airliner designs, with widely spaced podded engines under slung on pylons beneath a swept wing, proved to be the most common arrangement 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 while the Caravelle pioneered engines mounted either side of the rear fuselage.
Second generation
In the 1960s, when jet airliners were powered by slim, low-bypass engines, many aircraft used the rear-engined, T-tail configuration, such as the BAC One-Eleven, Douglas DC-9 twinjets; Boeing 727, Hawker Siddeley Trident, Tupolev Tu-154 trijets; and the paired multi-engined Ilyushin Il-62, and Vickers VC10. This engine arrangement is still used for jetliners with a maximum takeoff weight of less than 50 tons.[2] However, other developments, such as rocket assisted takeoffs (RATO), water-injection, and afterburners (also known as reheat) used on supersonic jetliners (SSTs) such as Concorde and the Tupolev Tu-144, have been superseded.
Present day
Airliners are commonly classified as the generally long-haul widebody aircraft, and narrow-body aircraft.
See also
- Airliner
- Aviation
- Business jet
- Freight aircraft
- Jet aircraft
- Wide-body aircraft
- List of jet airliners
