Introduction
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Working through the checklist before the start is obligatory. Of course, you should understand what effects the individual points can have too. |
A pilot does not necessarily need to grasp the scientific causes of flight in detail. Only a few aerodynamic correlations are important for a pilot. He must interpret wind and weather correctly and be in a controlled flying position at all times. The most difficult part is and remains take-off and landing. The most important thing here is to maintain a minimum speed in order to avoid a dangerous lift collapse (stall).
This is precisely why pilots should want to understand the basics of physics. There are countless attempts to explain why an aeroplane flies. But most explanations end up being a mixture of aerodynamic effects and theories. Are all effects causal, or only some? Which theory comes closest to reality? Conventional explanations (based on fluid mechanics) sound logical, but they are not. When it comes to the "supreme discipline" of aerodynamics - the stall - there are no well-founded, physically correct explanations.
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Lift collapse (stall) in the flow tunnel, a real image leads to false conclusions because the inertial system has been swapped. |
It is true that fluid mechanics has its justification, is complex and can be applied to "real" flows. However, using it as a basis for explaining dynamic lift leads to a dead end. There is no horizontal flow on an aeroplane wing; therefore there is no reasonable explanation for dynamic lift and for stall in particular.
Mathematics can be used to calculate physical relationships, but mathematics cannot be used to discover relationships. First comes the realisation, then a theory, then the practical proof and finally a mathematical formula. A wind tunnel is an experimental set-up, not reality. What is observed and measured is real, but because the inertial system is reversed, the result does not quite correspond to reality.
As flying is a dynamic air pressure system, e.g. the airfoil, and the small displacement paths of air particles are in no way proportional to the movement of the wing itself, the term "flow" is misleading. Until further consideration, "pressure distribution" (the flow => the pressure spread or, more precisely, the dynamic pressure spread) and "lift collapse" (the stall => the lift collapse) are proposed.
You will find the physical evidence on the following pages, which go into more detail. One chapter builds on the next.
That's Why an Airplane Fly | ⇒ Cause and Effect