uniform viewing system
(The aircraft is moving - not the other way around)The invention of wind tunnels made aerodynamic tests easier. In the wind tunnel, the object stands, the air mass is in motion. The results of measurements are similar to the reality. If you do blow in the moving air smoke you can see the path of the moving air particles, the image of an airflow can be recognized.
But that is not the reality when flying in reality. The wind tunnel is an experimental arrangement. Every pilot knows that he usually is moving his plane and almost the air is standing still. If headwind prevails, then the whole system air mass is in motion, so the viewing system itself moves.
Air molecules give their impulses to other air molecules further. To understand the affect at solids the understanding the air and the air parts of itself and its behavior is necessary. Therefore, selecting the right viewing system is so important. Without medium (air), there is no aerodynamic fly, an aircraft can not fly in a vacuum.
Experimental test arrangements use other media such as gases with higher density or liquids such as Water. If the parameters are selected accordingly in consideration of the Reynolds number you get similar results as in air. An airplane is only one of many objects which flying. Therefore aerodynamics can not be moored at the viewing system aircraft but must be based on the medium, in our case it is the medium of air.
Modern mathematical approaches use the three-dimensional Fenite elements method but this is possible only by powerful computers. The extent to which not only the pressure conditions in the individual elements can be calculated accurately enough, but also characterized indexed relative movements of the elements, is not yet known to the author. For the prediction of the resulting relative movements such as vortex is in addition to the static pressure spread and the relative dynamics of interest.
To understand what happens at an aircraft, and more particularly at an profile of an aircraft wing, imagine what happens with a single air particle (not a series of permanent new air particles like a smoke plume). It is not the same what position one takes (air or plane).
At the profile of an aircraft wing there not occur such flow, as is suggested by the plume of smoke. Bernoulli effects not disclose the basic principle of flying because on flying an airflow according to Bernoulli does not exist in this manner - there is no flow, the aircraft is in motion, the air stands). Into the dynamical flying system the energy is in the airplane (potential energy will be transformed to motion energy) and not in the air. In tests with the blown piece of paper or table tennis balls higher energy air (supplied speed) is used, which has nothing to do with reality when flying.
animated image source: Jan Peter Apel Flugtheorie.de
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