A Pratt & Whitney F100 turbofan engine for the F-15 Eagle and the F-16 Falcon is tested at Robins Air Force Base, Georgia, USA. The tunnel behind the engine muffles noise and allows exhaust to escapeSimulation of a low bypass turbofan's airflow
A jet engine is a reaction engine that discharges a fast moving jet of fluid to generate thrust in accordance with Newton's laws of motion. This broad definition of jet engines includes turbojets, turbofans, rockets, ramjets, pulse jets and pump-jets. In general, most jet engines are internal combustion engines[1] but non-combusting forms also exist.
In common usage, the term 'jet engine' generally refers to a gas turbine driven internal combustion engine, an engine with a rotary compressor powered by a turbine ("Brayton cycle"), with the leftover power providing thrust via a propelling nozzle. These types of jet engines are primarily used by jet aircraft for long distance travel. The early jet aircraft used turbojet engines which were relatively inefficient for subsonic flight. Modern subsonic jet aircraft usually use high-bypass turbofan engines which help give high speeds as well as, over long distances, giving better fuel efficiency than many other forms of transport.
Historical examples
Heinkel He 178, the world's first aircraft to fly purely on turbojet power
Frank Whittle's memorial showing a full-scale model of the Gloster E28/39
The first turbine-equipped jetplane was designed on paper in late 1929 when Frank Whittle of the British Royal Air Force sent his concept to the Air Ministry to see if it would be of any interest to them. The first manufactured turbine jetplane was the Heinkel He 178 turbojet prototype of the German Air Force (Luftwaffe), piloted by Erich Warsitz on August 27, 1939.
The first flight of the Italian Caproni Campini N.1 motorjet prototype was on August 27, 1940. Test pilot Major Mario De Bernardi of the Italian Royal Air Force (Regia Aeronautica) was at the controls.
The British flew their famous Gloster E.28/39 prototype on May 15, 1941, powered by Sir Frank Whittle's turbojet, 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 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.
Virgin Atlantic Airbus A340-600 landing
Bahrain Royal Flight Boeing 747SP
Modern
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 Mach number for 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.
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 a jet aircraft during ascent (although aerodynamic lift is used during some parts of this phase of operationneed nor during reentry and landing (as it is unpowered during this phase of operation).
Jet aircraft
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.
Two engineers, Frank Whittle in the United Kingdom and Hans von Ohain in Germany, developed the concept independently during the late 1930s, although credit for the first turbojet is given to Whittle.
Although the concept had already been discussed as early as August 1928 by Frank Whittle at Flying School, Wittering, Hans von Ohain wrote In February 1936 to Ernst Heinkel, telling him of the design and its possibilities.
It can be argued that A. A. Griffith, who published a paper in July 1926 on compressors and turbines, which he had been studying at the RAE, also deserves priority credit, perhaps more than either
The Boeing 747
A Boeing 747-400 jumbo jet of Air New Zealand
The Boeing 747 was the original jumbo jet. The 747 was the first wide-body airliner, first to use the twin-aisle concept, and the first airliner to use high bypass turbofan engines. Major features are:
triple decks - the lowest used by some airlines for galleys as well as cargo
distinctive profile - the hump over the forward fuselage makes this airliner easily distinguishable from others.
Other jumbo jets
Informally, the Airbus A380, nicknamed the "Super Jumbo"
Informally, wide-body aircraft
Informally, very large aircraft such as the Lockheed C-5 Galaxy, Antonov An-124, Shuttle Carrier Aircraft, Boeing 747 Large Cargo Freighter, and Antonov An-225
Air force
RAF Eurofighter Typhoon, an advanced 21st century aircraft
USAF F-22 stealth aircraft.
USAF B-2 Spirit stealth strategic bomber.
An air force, also known in some countries as an air army or historically an army air corps , is in the broadest sense, the national military or armed service that primarily conducts aerial warfare. The term "air force" may also refer to a tactical air force or numbered air force, which is an operational formation within a national air force.
Air forces typically consist of a combination of fighters, bombers, helicopters, transport planes and other aircraft. Many air forces are also responsible for operations of military space, intercontinental ballistic missiles (ICBM), and communications equipment. Some air forces may command and control other air-defense assets such as antiaircraft artillery, surface-to-air missiles, or anti-ballistic missile warning networks and defensive systems.
