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The impact of thrust lapse rate upon a low specific thrust (e.g., civil) engine is even more severe. At high flight speeds, high-specific-thrust engines can pick up net thrust through the ram rise in the intake, but this effect tends to diminish at supersonic speeds because of shock wave losses.
Specific thrust is the thrust per unit air mass flowrate of a jet engine (e.g. turbojet, turbofan, etc.) and can be calculated by the ratio of net thrust/total intake airflow. [ 1 ] Low specific thrust engines tend to be more efficient of propellant (at subsonic speeds), but also have a lower effective exhaust velocity and lower maximum airspeed.
[16] [17] A low disc loading (thrust per disc area) increases the aircraft's energy efficiency, and this reduces the fuel use. [18] [19] [20] The Rolls–Royce Conway turbofan engine, developed in the early 1950s, was an early example of a bypass engine. The configuration was similar to a 2-spool turbojet but to make it into a bypass engine it ...
The JT8D is an axial-flow front turbofan engine incorporating a two-spool design. There are two coaxially-mounted independent rotating assemblies: one rotating assembly for the low pressure compressor (LPC) which consists of the first six stages (i.e. six pairs of rotating and stator blades, including the first two stages which are for the bypass turbofan), driven by the second (downstream ...
The Ivchenko-Progress AI-322 (Ukrainian: AI-322, Russian: АИ-322) are a family of low-bypass turbofan engines developed from the AI-222 engine. Design and development [ edit ]
Turbofan engines with a bypass ratio of less than 2 (usually less than 1). These engines were commonly used on narrow body jet airliners of the 1960s and 1970s, some business jets from the same time period, and on modern fighter aircraft.
The F-14A's thrust-to-weight ratio was similar to the F-4 Phantom II; however, the new fuselage and wing design provided greater lift and a better climb profile than the F-4. The TF30 was found to be ill-adapted to the demands of air combat and was prone to compressor stalls at high angle of attack (AOA), if the pilot moved the throttles ...
Overall, a turbofan can be much more fuel efficient and quieter, and it turns out that the fan also allows greater net thrust to be available at slow speeds. Thus civil turbofans today have a low exhaust speed (low specific thrust – net thrust divided by airflow) to keep jet noise to a minimum and to improve fuel efficiency.