Aerodynamic question for you engineers

D Ramapriya wrote in
:

On Jan 25, 7:19 pm, Bertie the Bunyip wrote:
D Ramapriya wrote
innews:8e2786b5-d92c-4fb3-b950-2d9346494a87@
1g2000hsl.googlegroups.com
:



On Jan 25, 10:22 am, Pete Brown wrote:
If a conventional aircraft is in stable level flight and the stick
is pulled back, all of the texts I have read indicate that the
aircraft pitches up, rotating through the CG.

Is this exactly correct or is it a very useful approximation good
for all practical purposes?

Most aircraft have the CG located slightly forward of the center
of pressure ( CP or center of lift) for positive pitch stability.
I was wondering if the actual point of rotation is displaced
somewhat aft of the CG, someplace close to the CG but in fact some
small distance towards the CP.

When the aircraft is subject only to the force of gravity, any
displacement will cause it to rotate around the cg but in flight
its subject to gravity as well as the aerodynamic forces which act
through the CP, suggesting to me that the point of rotation is not
quite on the CG.

It's tempting to think that it could be somewhere near the center
of the balance arm but it's hard to logically argue against the CG,
isn't it?

They're the same thing.


By balance arm, I meant the distance between CG and CP. Missing
something, am I?

Well, that'd be a misdefinition. Also, CP really should read CL


Bertie