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The bypass air is accelerated by the fan at the front of the turbofan engine. This changes its velocity and therefore its momentum, which is the definition of a force (in this case: thrust): $$F = \frac{\text{d}}{\text{d}t} p = m \frac{\text{d}}{\text{d}t} v = m \cdot a$$ This thrust contributes to the total thrust of the engine. How much will depend on ...

9

A bypass fan provides thrust in the same way a propeller provides thrust: by increasing the energy content of the gas mass passing through the disk. The added energy is most effectively converted into thrust by allowing it to expand until internal pressure is equal to ambient pressure, so all added energy is converted into kinetic energy. This expansion ...

7

It doesn't bypass everything, just the combustion chamber. Notably, the air still goes through a fan. High-bypass turbofan engines make most of their thrust from the ducted fan. Very much like a turboprop except the blades are smaller and enclosed by the cowling. @Harper's answer on What is the difference between turbojet and turbofan engines? explains ...

4

Yes, rounded wings have been tested in the past. Probably the most famous example is the Vought XF5U "Flying Flapjack". They work perfectly fine. However, the design as pictured does have some flaws. Efficiency The lower the aspect ratio (i.e. wider front-to-back in comparison to their length left-to-right), the more inefficient the wing. This is ...

4

For airplanes with normally aspirated engines or turbocharged engine above their critical altitude, the engines produce less power as altitude increases as atmospheric air density decreases as altitude increases. As power decreases, the operative engine requires less rudder authority to maintain directional stability due to the reduction in thrust, which ...

4

One place where a reversible aerofoil is used is on the daggerboard of Proas - boats that can be sailed in either direction. They have fixed windward and leeward sides, rather that forward and aft ends, so the foil is always required to generate lift in the same direction, but the flow is reversed. Their shape is very like that in Peter Kämpf's answer.

1

First, let's transform the coordinates to polar coordinates for simplicity by introducing a variable $\theta$ such that: $$z=-s\cos{\theta}$$ In this coordinate, the chord distribution is then: $$c(\theta)=c_C\sin{\theta}$$ Let's write the unknown lift distribution of the bound vortex as a Fourier sine series, again in the $\theta$ coordinate: \Gamma(\...

1

Somewhere on the rcgroups.com website I once saw a post describing where someone took the wing of an rc model airplane and flipped it around so that the trailing edge was in front and attached it to the fuselage with rubber bands. Flight was possible.

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