Jan Peter Apel

How flies a plane?

For each object that can fly, the basic principle of flying applies: air mass push down to get the recoil force as lift force. Subsequently, it is shown how that makes an airplane. (In the next chapter follows, as it makes the bumblebee.)

Only with overview natural processes can understand properly. So must assume the right view, the correct coordinate system. The coordinate system of a natural phenomenon may not be selected at will or expediency, it must be found!

An airplane can fly only if it moves against the air. Whether the air is stationary or moving as a counter, back or side wind above the ground. If an aircraft is too slow against the air, it falls down. So, the air is the natural and only correct coordinate system for flying.
The air does not do anything! If an air jet takes something with upwardly, then is this not a fly, but a fall in the air jet, in which the rate of fall down just less than the air jet velocity by upward. A glider does not fall in a rising thermal air area, but flies in it. For this fly it needs the indispensable energy for a horizontally fly to generate lift. It takes this energy from its height by downhill force. Its flight path is always slightly inclined relative downward to the air. Increases the thermal air faster upwards as it flies in it down so it gains altitude.

How generate a plane lift force? In each case energy is necessary. Air mass must accelerate downward, it mast pushed down. The energy previously required is then included in the down wash. The down wash forms with the surrounding air vortices, that sinks! They are called wake turbulence.

For aircrafts with fixed wings is the specific principle to push air down the operating principle of an inclined plane. The leading edge of the wings are always higher than the trailing edge, so that by moving the wings horizontal the surfaces of the wings will be lowered. This is normally as well as in inverted flight! 

The effect of the wings working as inclined plates can be seen in the following animation. Shown are representative of every other air particles two, as they are accelerated by simplest wings surfaces, caused by its horizontal forward movement and the mechanical action of the inclined plane down. Profils of teh thickness of the wings have signifikations for the technologie and economics, but not for flying ability per se. 

The motions of the air particles are their movements relative to the surrounding air, thus not the relative, which can be observed from the aircraft or in the wind tunnel. Only these changing movements of air mass are effective for flying!

An aircraft wing moving air above and below the wing down. The lower volume of air is pushed down directly from the underside of the wing, the upper air is therefore torn down from above, because the horizontal movement of the inclined plane creates a vacuum on the falling surface to the rear of the wing, which is filled immediately by inflowing air from above. The air down push give birth naturally a positive pressure below the wing, the down tearing of air from the top creates a negative pressure above the wing. The terms "push" and "tearing" are necessary because this is done in only milliseconds! This time is the one that a wing with its forward speed has to pass through each point in the air. Air particles perceive their acceleration down by an aircraft wing like a beat!

The red marked part of swing movement which performs the upper air particles, is an absolute movement of the air to the rear, against the coordinate system of flying, the air, which increases the wind on the wing upper surface (about 10%). This movement results from the fact that the wing of the lower side pressed air downward, that a little bit air swells slightly in front of the wing upwards and flows above the wing to the rear. In this only 10% effective true flow inside the only running wind creates indeed a Bernoulli's negative pressure, which added to the negative pressure previously formed from the drawing down of the upper air. In the rear wing area results by the addition but a reduction of the negative pressure generated by the inclined plane. The reason: the air from the bottom side slows down again until the trailing edge as in a diffuser. This goes so far, that on the trailing edge the total negative pressure is zero. All Bernoulli's pressure changes add up around an airfoil to zero, so that it does produced no lift! In supersonic flight can no more air swell up before the wing. The loss of the Bernoulli's vacuum does not lead to a decrease of lift force, which proves that it previously produced too no increase in lift force. The Bernoulli's pressure influence are only a consequence of the lift force originating by the mechanical principle of an inclined plate. One consequence of a causation, however, can not have influences to its generating process!

The following animation shows, as in reality the downwash flows downward
. The lines at the individual points are wind vanes, showing with there directions  the directions of the air flow and with there lenghts the velocities of the air at these points. The area of downward movement air extends in both distance above and beneath to a distance equal to the wingspan of an airplane.

For flying also applies to aircraft: the aircraft moves to the air and not vice versa! That passenger of an airplane see the air "flow", is an illusion by relative view: they are moving, not the air!

So the explanation of "Why does an airplane fly?" is finished: by pressing
air down. That's the whole secret!

That the explanation of flying of an airplane is as easy, although the teachings complexity are not to exceed, is not an accident, but a MUST! The Nobel Prize winner Paul Dirac presented already noticed: "A physical theory is either short, or false" and Johann Wolfgang von Goethe: "Everything is simpler than one may think, also entangled, as can be understood." In nature it is always so, that the phenomena (symptoms) of their apearances
are confusing, although the underlying causes are quite simple. Therefore, it is so difficult to understand the nature. Whereby add to that is, that we see often relatively, so wrong, how it is especially by flying. Why do we do that? Because we like it, to be the coordinate system. One and a half millennia we spent that the sun circle around us, although we go on earth carousel. Now we spend more than 100 years in the belief, that the air flows backward along our aircraft and not we move with it forward.

Flying is a purely mechanical process, in which by means of energy input air is accelerated downwards. So does not apply the laws of aerodynamics, but the aerokinetics. The essence of the aerodynamic by Bernoulli consists precisely in the fact that no energy may be used. But without transver from energy to the air, no object can fly! A glider takes the required energy from its height to which it was previously raised by use of energy, a powered aircraft has its own engine. In both cases, the energy is require to move the aircraft horizontally through the air. Therefor must overcome the resistance for the displacement of air and the "resistance component", which arise by the function of the wing as an inclined plane.

Out of this correct physics of flying arised the comprehensible formula for lift force.

For flying there are next to the Bernoulli theory two other popular explanations. All three are wrong, which is also evaluated by NASA to see at www.grc.nasa.gov/WWW/K-12/airplane/wrong1.html and following.