Jet aircraft

A jet aircraft (or simply jet) is an aircraft (nearly always a fixed-wing aircraft) propelled by jet engines (jet propulsion).

Whereas the engines in propeller-powered aircraft generally achieve their maximum efficiency at much lower speeds and altitudes, jet engines and aircraft achieve maximum efficiency (see specific impulse) at speeds close to or even well above the speed of sound. Jet aircraft generally cruise at faster than about M 0.8 (609 mph, 981 km/h or 273 m/s) at altitudes around 10,000–15,000 metres (33,000–49,000 ft) or more.

Frank Whittle, an English inventor and RAF officer, developed the concept of the jet engine in 1928,Hans von Ohain in Germany, a decade later developed the concept independently at the end of the 1930s. He wrote in February 1936 to Ernst Heinkel, telling him of the design and its possibilities. However, it can be argued that the English engineer A. A. Griffith, who published a paper in July 1926 on compressors and turbines, also deserves credit.

Business jet

A business jet, private jet, or bizjet, or simply B.J., is a jet aircraft designed for transporting small groups of people. Business jets may be adapted for other roles, such as the evacuation of casualties or express parcel deliveries, and some are used by public bodies, government officials or the armed forces.

History

1950s first flight

The Lockheed JetStar, seating ten passengers and two crew, first flew on 4 September 1957. 204 aircraft were produced from 1957 to 1978, powered by four 3,300 pounds-force (15 kN) Pratt & Whitney JT12 turbojet engines, then Garrett TFE731 turbofan for a 44,500 pounds (20.2 t) MTOW, then two General Electric CF700 turbofans.

The smaller, 17,760 pounds (8.06 t) MTOW North American Sabreliner first flew on 16 September 1958. Powered by two Pratt & Whitney JT12 turbojet engines then Garrett TFE731, more than 800 were produced from 1959 to 1982.

1960s first flight

The 25,000 pounds (11 t) MTOW British Aerospace 125 first flew on 13 August 1962, powered by two 3,000 pounds-force (13 kN) Armstrong Siddeley Viper turbojets. Its engine were replaced by Garrett TFE731, then Pratt & Whitney Canada PW300 turbofans. Almost 1,700 aircraft were produced between 1962 and 2013 after being marketed as the Hawker 800.