Hi ya'all,
This will relate to all other posts that we have had discussion
with, save me the effort to do more than once, OK?
To begin anything you need to understand the medium with which you are working with aircraft of course it is air.
Air is a fluid. Fluids vary from extremely gaseous to almost solid
grease being an example. other end example would be Helium.
Fluids have density and it is that which relegates their position
in the spectrum. Helium being the least dense. Air and water are
near the least.
Fluids are composed of molecules whose composure relates to
the nature of the substance.
Easy to say the molecules are suspended, that is for the most
part they do not touch each other, there is space between them.
The greater the spacing the "lighter" the fluid. The spacing can be
reduced by applying pressure, compressed?
If compressed a force is created, example>compressed air in
your auto tires. Force is great enough to raise the car?
Knowing the above we can relate to an aircraft's use of air.
We need to go to Webster for a diffinition of two common nouns.
First Aerodynamics> This is a branch of physics which is concerned with objects MOVING THROUGH air. Note not with air
moving past the object (wind?)
There are four major forces which effect and/or create flight.
They are> gravity; drag; lift and thrust. The first two are negative
forces, the others are positive. We need to understand them all.
Second> Gravity, no one seems to know it's exact nature but
for aircraft purposes it is a strong force that acts on everything on
or near earth. The force is always perpindicular to the earth's
surface, this never changes.
Thirdly> Drag. this is a force created by some other force. Example; anything moving through a fluid does the moving by
application apllication of force. Drag is the equal and opposite
resultent of that force.
Fourth> Lift is a force which opposes Gravity basically but it can
also be applied otherwise.
Fifth> Thrust; this is a force applied to anything with the intention
of moving it. Can be applied in any direction.
example> airplane; propeller or turbine> helicoptor, rotor>
Auto gyro; propeller and rotor.
Thrust is normally created by a mechanizm but it also can be
created by lift as with rotorary wiings or a lifting device facing the
line of flight,
So, the average modeler is not a professional engineer but can
be an amatuer one if he understands the medium and forces he
is working with, the presented information was done in the realm
of the average modeler and for his benefit only.
Now that the forces envolved are understood one really needs
to know how they are created and used.
That will be explained on a seperate post in this forum to avoid
confusion, see you there?
Others additions and/or discussion of this info is welcome of course!

Hal [email protected]