Aerodynamic question for you engineers

Bertie the Bunyip wrote:
Jim Logajan wrote:
As I understand it, the force of the tail plane's elevators typically
moves the center of lift forward and backward along the airplane's
axis as the elevators are moved up and down (as well as changing the
lift magnitude a little - though that is secondary). One presumably
enters stable flight when the center of lift is moved to coincide
with the center of gravity.


That's exactly the case if you include the stab in the CL equation. If
you're just referring to it on the wing itself, providing the AoA and
speed remain the same it doesn;t shift. It's a matter of definition.

Just checked one of my references[*] for proper terminology - where I used
"center of lift" it uses the phrase "total lift" with the symbol L. For the
lift of the main wings it uses Lw and for the lift of the tail it uses Lt.
[*] "Aerodynamics, Aeronautics, and Flight Mechanics" by Barnes W.
McCormick.

Jim Logajan wrote in
:

Bertie the Bunyip wrote:
Jim Logajan wrote:
As I understand it, the force of the tail plane's elevators
typically moves the center of lift forward and backward along the
airplane's axis as the elevators are moved up and down (as well as
changing the lift magnitude a little - though that is secondary).
One presumably enters stable flight when the center of lift is moved
to coincide with the center of gravity.


That's exactly the case if you include the stab in the CL equation.
If you're just referring to it on the wing itself, providing the AoA
and speed remain the same it doesn;t shift. It's a matter of
definition.

Just checked one of my references[*] for proper terminology - where I
used "center of lift" it uses the phrase "total lift" with the symbol
L. For the lift of the main wings it uses Lw and for the lift of the
tail it uses Lt.


Sounds about right. I haven't read that stuff in years, though.


Bertie