Jan
Peter Apel
Mystery of Circulation
Almost
no pilot can understand what the so-called circulation is. It is the
basis invented by Kutta-Joukowski to enable calculations and make with
it Bernoulli theory to scientific. It is intended to answer the
question of why the air flows faster on the upper side of the wing.
That the air does this is only an observation from the wind tunnel, and
thus in the coordinate system of the moving airplane. There is no
explanation for this, only the assumption that because the air does so,
there must be a fictitious circulation flow of air circling around the
wing profile. The cause would be the so-called start-up vortex, which
would create this counter-vortex according to the thesis that a vortex
always needs a counter-vortex.
How is the truth found?
The correct cause of the ability to fly can
be represented with a normal, horizontally arranged plate. It is the
ideal structure to show the basis of flying. It has the least possible
drag to horizontal movement in the air, but a maximum to vertical
movement in the air.
The picture shows how the air moves when the plate is moved
vertically downwards. It presses air down with its underside, but air
also escapes upwards on the sides. Of course, the top of the plate also
sucks in air from above, which also sucks in the amount of air flowing
around the edges of the plate from below. Air flows like a vortex
around the side edges of the plate upwards.
Basicly arised an
overpressure on the underside of the plate and a negative pressure on
the top of the plate. Both pressures arise by the accelerations of air
mass and together lead to an buoyancy in the vertical direction. Due to
this buoyancy, a plate falls down more slowly.
Please
note during this process: the plate moves, the air is passive. The
plate must provide the energy to move air so that buoyancy is created.
The energy that the plate has here is its potential energy. It is the
same one that a glider flies with.
It should also be noted that
everything a body does in the air with the air happens in the
coordinate system of the air. The air, that is still untouched by these
local processes around the plate (airplane), is the absolute reference
point for flying.
In
Figure 2, the plate not only performs a vertical downward movement, but
also a faster horizontal movement. The lateral flow around the plate
edges caused by the vertical movement of the plate also occurs here.
In
the direction of movement to the front, this flow occurs at the front
edge, as is known, but it then extends into the upper plate surface.
This is a condition that arises in an airplane wing when the airplane
flies too slowly and threatens to crash.
If an airplane flies
fast enough, 3rd image, the front vortex extends from the air that
swells up to the rear edge of the plate (wing), where its air volume is
accelerated downwards together with that air, that is accelerated down
by the inclined plane of the plate (wing) by its angle of attack in
relation to the moving direction.
The
vortex from the upswelling air from the rear edge of the plate can be
seen at the right at the start of the movement. It is the so-called
start-up vortex that would supposedly start the circulation. But the
circulation is a myth that does not exist.
There are two
movements above the plate (wing) from the viewpoint of the plate (wing,
wind tunnel): the fiktiv airstream out of the moving plate and the air
movement from the vortex from the front edge. Only the sum of the two
is detectable. The airstream out of the moving plate is not a flow of
air, it represent only the speed of the plate (wing). Only the increase
in air velocity in the coordinate system of the plate (wing, wind
chanel), arised out of the vortex around the plate's leading edge, is a
real flow. This vortex is shown in the following animation using the
upper air particle. The absolut movement of the air particle of the
flow vortex from front to back (shown in red) only takes place during
the time in which the plate (wing) moves through the air in this
location. 
There
are basic physical laws for movements. Only movements that are
invariant are effective, so that they are true or real. Invariant
motion quantities are only those, that are contained in all possible
views, i.e. all possible coordinate systems. When flying, two views are
used: the view from the aircraft, i.e. the coordinate system of the
aircraft, which is also the wind tunnel view, and the view from the
ground, the coordinate system of the ground. The right view, the right
coordinate system, is the air in and with which a flying object
interacts. When there is no wind, the view from the ground is identical
to that from the air. In wind, the entire process of flying moves
unchanged with the entire air mass above the earth's surface. There are
two possible views for flying: the coordinate system of the aircraft
and that of the surrounding air mass, regardless of whether it is
moving as a wind or not.
Wind on the moving plate (wing) is an
air movement in the coordinate system of the airplane. But it does not
exist in the coordinate system of the air. So head wind is not an
invariable, but a variable movement, therefore relative and ineffective.
The
supposedly fictitious movement of the circulation, in reality the true
air flow that swells up in front of the wing, is an invariant and
therefore effective air flow. It is directly present in the coordinate
system of the air, in the coordinate system of the airplane it only
leads to an increase in the head wind.
According
to the physical rules, which are neglected in teaching, it is forbidden
to add invariant and variant movement quantities from two coordinate
systems, which differ in their movements!
The
apparent increase in the speed of the air from the head wind and
the real flow of the air of the vortex from the front edge in the
coordinate system of the airplane must not be regarded as a common air
movement.
The faster "airflow" over a wing, which can be felt in the
wind tunnel and from the relative point in the view of a pilot or
occupant, is not a real airflow in the physical sense, but only a
relative observation from the airplane's moving coordinate system, but
which is the wrong. The plane is the actor, it provides the energy,
i.e. the action force, only the air accelerated downwards by the plane
generates the buoyancy force as a reaction force.
The
real air flow from the vortex from the front edge is only a tenth of
the head wind. In there can according to the physical laws (pressure
profiles in flow paths) arise a Bernoulli effect. And this even happens
and increases the negative pressure around the wing nose as a narrowing
of the cross-section, but until the end at the rear edge there is then
a diffuser effect with pressure increase, which compensates the
negative pressure on the nose. Thus there is no influence on the level
of lift due to the recoil force of the downward accelerated air, so
that the resulting buoyancy force moves forward.
According to Newtonian physics, every flying object heavier than air,
from paper planes to jet fighters and fruit flies to bumblebees,
"rides" on reaction forces by down accelerated air mass.
