Jet aircraft
From Wikipedia, the free encyclopedia
A jet aircraft is an aircraft propelled by jet engines. Jet aircraft fly much faster than propeller-powered aircraft and at higher altitudes -- as high as 10,000 to 15,000 meters, about 33,000 to 49,000 feet (14,900 m). At these altitudes, jet engines achieve maximum efficiency over long distances. The engines in propeller powered aircraft achieve their maximum efficiency at much lower altitudes.
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[edit] Historical examples
The first jet-propelled aircraft ever built was the Coanda-1910, piloted by its Romanian inventor Henri Coandă in 1910. Its engine, unlike modern jet engines, used a piston engine rather than the turbine itself to drive the compressor that made the compressed air needed to produce the jet flame. The aircraft crashed during its first and only demonstration but remained intact.
The first turbine-equipped jetplane was the Heinkel He 178 (Germany), piloted by Erich Warsitz on August 27, 1939.
The British flew their Gloster E.28/39 powered by Sir Frank Whittle's turbojet on May 15, 1941, and piloted by Flt Lt PG Sayer. When the United States, learned of the British work, it produced the Bell XP-59, with a version of the Whittle engine built by General Electric which flew on September 12, 1942 piloted by Col L. Craigie.
The first operational jet fighter was the Messerschmitt Me 262, piloted by Fritz Wendel. It was the fastest conventional aircraft of World War II - only the rocket-powered Messerschmitt Me 163 Komet was faster. Mass production started in 1944, too late for a decisive impact on the outcome of the war. About the same time, the United Kingdom's Gloster Meteor was limited to defense of the UK against the V1 flying bomb and in ground-attack operations over Europe in the last months of the war. The Imperial Japanese Navy also developed jet aircraft in 1945, including the Nakajima J9Y Kikka, partially inspired by German designs.
On November 8, 1950, during the Korean War, United States Air Force Lt. Russell J. Brown, flying in an F-80, intercepted two North Korean MiG-15s near the Yalu River and shot them down in the first jet-to-jet dogfight in history.
BOAC operated the first commercial jet service, from London to Johannesburg, in 1952 with the de Havilland Comet jetliner.
The fastest military jet plane was the SR-71 Blackbird at Mach 3.2. The fastest commercial jet plane was the Tupolev Tu-144 at Mach 2.35.
[edit] Modern jets
Modern jets cruise at speeds of 0.75 to 0.85 Mach, or 75% to 85% of the speed of sound (420 to 580 mph/ 680-900 km/h). The speed of sound predominantly depends on air temperature (hardly at all on pressure), so the speed of a jet also varies with atmospheric conditions. NASA and the US Federal Aviation Administration have been promoting Very Light Jets, small general aviation aircraft seating 4 to 8 passengers.
[edit] Other jets
Most people use the term 'jet aircraft' to denote gas turbine based airbreathing jet engines, but rockets and scramjets are both also propelled by jets.
The fastest airbreathing jet aircraft is the unmanned X-43 scramjet at around Mach 9-10.
The fastest manned (rocket) aircraft is the X-15 at Mach 6.85.
The Space Shuttle, while far faster than the X-43 or X-15, is not regarded as an aircraft during ascent (although aerodynamic lift is used during some parts of this phase of operation[citation needed]), and is unpowered when flying as an aircraft during reentry and landing. Thus it is not considered a jet aircraft at either time.
