Let me chime in... ;-)

"Shirl"wrote
Shirl:
The difference is that when the longitudinal axis of the airplane is
not
lined up with the runway centerline (forward slip), there is much more
drag.

I think this is true only in the no-crosswind case when the relative wind
has the same direction as the runway. If there is crosswind, the relative
wind direction is from a direction more or less to the side, depending on
the crosswind component. Therefore, in a crosswind side-slip approach, even
if the airplane's longitudinal axis is aligned with the runway there is some
degree of additional drag as the airplane is not aligned into the relative
wind. (In comparison, in a crabbing approach the airplane is aligned much
closer to the relative wind.)


Jose:
This is true of a side slip too. I suppose if you want to lose
altitude, you cross your controls more, but again, the =airplane=
doesn't see the runway, so the =airplane= can't tell the difference.
It's just cross controlled.

It's true that the action of the pilot is the same; however, in a
forward slip (for loss of altitude) it is cross-controlled to a greater
degree so that the airplane is actually coming down sideways (but in
line with the centerline) so as to expose more of it to the oncoming
wind. Yes, there's drag in a side slip (for crosswind correction) too,
but not as much, and the whole point of the side slip is to keep the
airplane lined up with the runway, not to lose altitude.

Yes, in a forward slip where you want maximum descent speed it's no problem
to use full opposite rudder. In a crosswind side-slip, the crosswind itself
does much of the job the opposite rudder does in a forward slip, so less
rudder is needed.

Did we reach a higher level of confusion? ;-)