Aerodynamic question for you engineers

Tina wrote:
Sorry. Rigid bodies do NOT rotate around their cg if an external force
is applied whose vector goes thru it.

No need to be sorry. I agree with that and not sure what I wrote that
would imply otherwise.

Drop a yardstick, cg at the 18 inch mark, so that its zero inch edge
hits a table. The center of rotation as a reaction to that force is
the table edge.

You may write an equation that descibes rotation around its cg, and
another that describes translation, but a center of rotation, to many
who deal with such things, is that point on a rotating body whose
translational motion does not include rotation, the body appears to
rotate around it.

In the case I just described, such a point is at the end of the
yardstick.

You are obviously defining center of rotation differenrtly than I am,
but my American Institute of Physics Handbook on page 2-9 talks about
rotation "in which some axis or point remains fixed in space". That is
the center of rotation. In the several examples I've given that axis,
the center of rotation, is not at the center of gravity.

I can't speak for anyone else posting to this thread, but I don't believe
I used the term "center of rotation" as such. And I don't disagree with
anything you've written above.

I am sure the math and classical physics folks use the same
definition. It's perfectly fine to talk abou other ways of describing
rotation, but engineers who think about it a little, even if they are
pilots, would tend, I expect, tend to agree with AIP handbook if they
are trying to communicate with other engineers.
.
As I claimed earlier, if allowed thusters on a rigid body, I can make
it rotate around ANY point. The table edge in my example could be
replace by such a thruster.

Definite agreement. But if you were given only one thruster and it is at
the end of your yardstick pointing downwards like so:

|
=====================V

The yardstick would rotate around the CG when the thruster is turned on.

Now, if the forces are removed, you will get no argument from me that
rotation is about the CG. The forces are not removed in the OP's
question.

Okay. The original post asked whether pulling back the stick causes the
plane to rotate about the CG or some other point. That is a tad more
analogous to my yardstick drawing above with only one thruster than the
other situations mentioned. Of course there is the complications of the
motion through the air and what happens as the angle of attack of the
wings is changed as the rotation starts to occur. But that resulting
complex motion first begins with the plane starting its rotation about
its center of gravity.

My BSc in physics may be a bit rusty, and I don't try to presume to speak
for engineers, but I'm not sure there is much disagreement left here
worth arguing about. And even if there were, I'm not sure it would
accomplish anything anyway! :-)