Aerodynamic question for you engineers

On Fri, 25 Jan 2008 17:03:04 -0800 (PST),
wrote:

On Jan 25, 5:40 pm, wrote:
The aircraft will rotate EXACTLY at the CG.
As a side note, the CG will actually lose a little altitude until it stabilizes
at the new attitude.

I think this absolutely has to be the case.

CL is simply the place the overall lift averages out to. It's a FORCE
acting on a body. And so is any force acting on the horizontal tail
surfaces, or acting on any other place on the plane.

The body has a CG and it will rotate at the CG.

Displacement is another matter.

And if the CG is moving horizontally at 100 knots, where
is the rotation point now? As soon as rotation starts, the aircraft
begins to change its flight path, and any determination of rotation
point, whether it's the CG or CP or any other point, becomes very hard
to determine and might be irrelevant. I would prefer to think of the
fixed end of the flight path radius (which is also changing) as the
airplane rotates, just like one of those complicated cabinet door
hinges that has two arms and four pivot points. Where is the rotation
point of that door? There is no fixed point.

Dan

clueless. you'd never have understood the propeller like the wrights
did because you cant simplify situations until the problem becomes
solveable. finding a solution to a problem is often a matter of
thinking about it with just the relevant factors at play.

the answer to your door problem lies in understanding that there are
multiple hinge points that each act in a simple manner.

the frame of reference is moving at 100 knots. the aircraft rotates
about it's centre of gravity (centre of mass).