Hi Sir.
I think both statements are correct, though they may appear to conflict...
With the greatest respect, I have wanted to ask the following question.
Several times I have been present at a demonstration of the Harrier. I have a friend whose first experience with one is an interesting tale, but for now....
In the hover, one can easily see the application of the Newton Third Law.
Disregarding the dozens of airfoils providing "lift" from Pegasus, the reaction and work is readily apparent.
As you ease into aerodynamic flight, when exactly, does Newton fade away, and Bernoulli replace him? Can Newton yet apply to and through the "transition"?
Most grateful Sir
HazelNuts39
"Physically it doesn't really matter whether you place yourself in the airplane and describe the airflow moving by, or you place yourself in air at rest and look at the airplane flying past you."
Yes, of course. However. This came up as a response to my initial post that posited the wing as the source of energy in the standard diagram seen in the paper under discussion....
The authors purpose in writing the paper was to generate interest in evolving the basic introduction to the Physics of Flight. It is my view that an introduction should be basic, elemental, and exquisitely explicit.
I share that with the authors, imo. So why introduce 'latitude' ("it makes no difference") when restraint is required? To what end? Without a purpose, offering alternate suppositions to frame of reference is gratuitous, and opens the gate to erroneous knowledge.
My drawing has the thrust arrow "within" the wing, denoting motion of the airfoil, not "in front of" the leading edge. The wing is not passive, yet that is the almost universal conclusion students make when first introduced to the "standard" diagram.
Now Camber. The authors show in an elegant way why camber is not necessary in forming a teaching model. They intimate the importance of shape, but dismiss shape as a fundamental necessity, I agree.
The authors show, again simply, why Bernoulli assumes a closed system. As a practical matter, that is deceptive, again for the beginning student.
So off we always go, as the scientists impatiently require a long list of illogical assumptions of their audience, and then recoil in anger as some refuse.
Newton does not 'fail' in any way, throughout the flight envelope, imo....
to awblain..... Thank you indeed for introducing the word 'keel' to the discussion....
Last edited by Lyman; 15th Nov 2012 at 17:30.