First published in German, January. 17. 2003
by J. Peter Apel

Revised July, 13, 2004
Translated May, 8, 2008

The physically aerodynamic Base Formula

An airplane flies by the kinetic laws of Newton. By this arise a force only when a mass is accelerated. It is therefore necessary that a wing accelerates air mass down. This makes a wing with an angle of attack α by quickly moved forward, as shown in the following sketch.
A wing not only accelerates air with its bottom down, but by the sloping rear top and its freed up space also with its top side. With the results of this both arise a common effluent of air far-reaching do up and down, the so-called down wash. It is fixed in the air at each position where a plane is moved through.
Flying is generat by a plane, it must provide the required energy, namely, to accelerate air downwards. This determine the coordinate system of flying: it's the air in its continued state without any influence of a plane.
An air flow on an aircraft does not exist. It is the wind of moving, which is a fictitious movement of air. That does not matter for technical, but for physics, in there is an  aircraft moving, not the air, just as it can be observed in nature.

The calculation for this lift-force results from the Newton law for forces by constant velocity:

L = m delta Vvertical down wash

The through flow of air masses is determined. It is the product of the wing span and the aircrafts velocity. It is defined as Sair:


Sair = wing span Vplane . . . . . Dimension m2

The fact that the generated flow deviates in the angle of attack, α, perpendicularly in relation to the course line has an impact on the effective area of discharge flow-through. Where the air is flowing perpendicular to area of discharge flow-through it is lowered by the factor Cosinus α.

The accorded velocity for the down wash Vdown wash results from the following drawing with V sin α.

The flow of masses per second perpendicular to the plane results with ρair as the specific mass of air:

m dt = ρair Sair Vplane cos α sin α

The basic-formula for forces is:

Total Aerodynamic Force (TAF) = m dt Vdown wash

The formula for the total aerodynamical force is:

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TAF = ρair Sair (Vdifferent between plane and air)2 (sin α)2 cos α 1 [ s ]
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Lift is the force in the vertically to the earthground:


The flight-formula for lift by stationary horizontal flight is:

L = ρair Sair (Vdifferent between plane and air)2 (sin α)2 (cos α)2 1 [ s ]


Forces emerge in the air only according to the Newton Laws and are airflows that are generated by planes. There is no other possibility to generate dynamic forces. This is also effective when a „stream“ collides with a solid plane: the plane generates identical airflows, exactly the same way the plane would move in the air. Only the perspective is different. For example: the rotor blades of a windmill generate the same down wash in/against the blowing wind like the wings of a glider generate down wash in/against the vertically thermal „wind“.

The relative event between a plane and air is the same in all cases.

These formulas results only by new thinking, without any historical knowledges or experiments.

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