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1

The static thrust value is with the engine fixed in place in still air. Imagine the engine on an outdoor test stand, or on an airplane with the brakes on or tied down. As soon as the airplane starts to move, the thrust value declines and the static thrust value no longer applies. The static thrust value at sea level is used because it provides a ...


0

Turbofans use a gas turbine core to drive the low pressure fan which produces most of the thrust by moving large volumes of air. This requires large amounts of torque which the low pressure turbine extracts from the hot exhaust gases exiting the gas turbine's core. To develop more power you burn more fuel which means more heat. Low pressure gas turbine ...


6

Most jet nacelles contribute little or no lift, but there is at least one highly notable exception. The airflow inside the nacelle is dominated by the engine and any chance to create differential pressure between upper and lower leading sections is kept negligible in order not to disrupt the intake flow. The outside is more of a stubby fuselage than an ...


0

The ambient temperature limit is the highest ambient temperature at which the engine will be able to provide listed Sea Level Static Thrust. If the air temperature is higher, the engine will reduce its thrust to prevent exceeding the maximal permissible temperature in the turbine. The ambient temperature limit is important in aircraft operation, because at ...


5

Almost any sort of body, conveniently oriented in a fluid flow, can produce lift. A ball is one of the few exceptions... Please note that lift and drag do never cancel out, because they are –by definition– vectors at 90º... There are wingless, heavier-than-air aircraft, like this one, for example: https://en.wikipedia.org/wiki/Wainfan_Facetmobile


26

Turning the engine with one finger is not necessarily recommended, because the leading edges of the fan blades are quite sharp. But it is possible. For some experimental vibration measurements, it is preferable to keep the rotors turning slowly to avoid the bearings "sticking" in one position and confusing the results. A common way to do this is ...


0

It would result in vortices forming at the blade tips, generating drag. Those vortices are the same that come off of the wingtips of airplanes and the blade tips of helicopters. Aircraft manufacturers have made winglets pretty much standard to minimize this drag, and not allowing the blade tips to give off those vortices (by putting them very close to the ...


6

All three engines you show are for fighter jets flying at supersonic speeds. These engines need a low bypass ratio: Why do military turbofan engines use a low bypass ratio? To achieve more thrust at lower bypass ratios, the bypass air needs to be accelerated more, which requires more than one fan stage because axial compressors can only add a limited ...


42

Yes, large turbofans can be turned by hand without too much force. On smaller aircraft this is regularly done as part of the preflight walkaround. You can see an example in this YouTube video of an A320 walkaround: Admittedly, the pilot turns the engine with four fingers here, but you can see that not much force is required. Turning it with a single finger ...


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