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A JT9D turbofan jet engine installed on a Boeing 747 aircraft. Jet engines power jet aircraft, cruise missiles and unmanned aerial vehicles. In the form of rocket engines they power model rocketry, spaceflight, and military missiles. Jet engines have propelled high speed cars, particularly drag racers, with the all-time record held by a rocket car.
A tip jet is a jet nozzle at the tip of some helicopter rotor blades, used to spin the rotor, much like a Catherine wheel firework. [1] Tip jets replace the normal shaft drive and have the advantage of placing no torque on the airframe, thus not requiring the presence of a tail rotor.
Some radio-controlled helicopters and smaller, helicopter-type unmanned aerial vehicles, use electric motors or motorcycle engines. [11] Radio-controlled helicopters may also have piston engines that use fuels other than gasoline, such as nitromethane. Some turbine engines commonly used in helicopters can also use biodiesel instead of jet fuel ...
A jet aircraft (or simply jet) is an aircraft (nearly always a fixed-wing aircraft) propelled by one or more jet engines. Whereas the engines in propeller-powered aircraft generally achieve their maximum efficiency at much lower speeds and altitudes, jet engines achieve maximum efficiency at speeds close to or even well above the speed of sound .
Diagram of a typical gas turbine jet engine. Air is compressed by the compressor blades as it enters the engine, and it is mixed and burned with fuel in the combustion section. The hot exhaust gases provide forward thrust and turn the turbines which drive the compressor blades. 1. Intake 2. Low pressure compression 3. High pressure compression ...
Today (2015), most jet engines have some bypass. Modern engines in slower aircraft, such as airliners, have bypass ratios up to 12:1; in higher-speed aircraft, such as fighters, bypass ratios are much lower, around 1.5; and craft designed for speeds up to Mach 2 and somewhat above have bypass ratios below 0.5.
An aircraft engine, often referred to as an aero engine, is the power component of an aircraft propulsion system. Aircraft using power components are referred to as powered flight . [ 1 ] Most aircraft engines are either piston engines or gas turbines , although a few have been rocket powered and in recent years many small UAVs have used ...
The Pratt & Whitney JT9D engine was the first high bypass ratio jet engine to power a wide-body airliner. [46] The lower the specific thrust of a turbofan, the lower the mean jet outlet velocity, which in turn translates into a high thrust lapse rate (i.e. decreasing thrust with increasing flight speed). See technical discussion below, item 2.