On 5 Dec 2006 10:49:02 -0600, T o d d P a t t i s t
wrote:

Ron Wanttaja wrote:

Airplanes fly relative to the atmosphere. Since the atmosphere moves with the
Earth's spin, aircraft see no advantage from eastward flight.

Airplanes fly relative to whatever frame of reference you
want to use. If you use the spinning earth as a frame of
reference, then any motion in that frame produces
centrifugal or Coriolis force. Those forces affect the
amount of lift the plane must produce (unless they are
entirely horizontal.) The amount of lift affects the amount
of drag, and that affects fuel consumption. For relatively
low speeds, the effect on fuel consumption is tiny, but it
is measurable.

two comments on your posts

centrifugal force does not exist. it is an engineering misconception.
the force involved is inertia.

aeroplanes fly relative to the atmosphere they fly in.
mathematical abstractions are based on frames of reference.
the two are not the same.
wantajja's post was correct.
Stealth Pilot