(Chris OCallaghan) wrote in message . com...
Dan,

You've got it right, at least the way that most of us are taught. But
let me clarify something that we aren't typically taught.
Aerodynamically speaking, there is no difference between a forward and
a side slip.

I agree, I thought that was implied in my post, ALTHOUGH, for
touchdown, the slip angle is typically small, and for glidslope
control I usually have full rudder application and a severe slip
angle. I would ALMOST call it a different manouver, just because of
the huge amounts of drag you can produce in, say, a Pawnee. Just a
question of degree.

The only reason I bring this up is that I've seen a thread that
suggests that there is a difference between a forward and side slip.
That the forward slip (by tilting the lift vector) somehow compensates
for a crosswind. Of course, it does not.

Seems to me that statement is true. If you hold fusalage alignment
with rudder, and your upwind wing low, you really are "tilting your
lift vector to cancel out the effect of the crosswind" What's wrong
with that statement?

This technique is very useful for smooth crosswind landings in high
wing taildraggers, where there is an advantage to setting one main
gear on the ground rather than both at once.
Or in strong gusty crosswinds, and yes, low wing tail draggers, and
gliders.

It is not nearly so
applicable to gliders, though many of us were taught to compensate for
crosswinds this way.

I think it applies well to everything that doesn't have turbine
engines hanging under the wings, gliders included.

It has some minor advantages... the upwind wing
is "low" at touchdown, less finesse is required with the rudder... but
also has some disadvantages... the controls are crossed, the airspeed
indicator is unreliable, the glider will not achieve maximum
performance if sink or turbulence is encountered, there is some risk
of touching a wingtip if the flair is not properly executed.

So, you're looking at your airspeed indicator at touchdown? And a
crosswind correction makes it unreliable? The only wingtip I ever
touched was the Pawnee with the droop tips on takeoff. Never on a
landing, & never in a glider, and in the strongest crosswinds you'd
ever care to try.

But most important, many pilots seem not to realize that they are, in
fact, using the slip not to compensate for crosswind, but to align the
nose with the runway in order to gain a more "normal" view of the
approach. That is its only real value. Giving a slip different names
based on its application only perpetuates the confusion. And I guess
that's my point.

Those are some weird statements. Is there anyone else out there that
believes the only real value in a slip is to give you a better view?
Does anyone else use their airspeed indicator during touchdown? In
anything?
(Shuttle excluded)

To sum up:

A slip is aerodynamically the same, regardless of wind.
TRUE.. All manouvers are the same regardless of wind, unless part of
the aircraft enters the wind gradiant (Very low turn in wind over
bushes)

A slip always increases drag.
TRUE

A slip can be used to align the nose with the runway during a
crosswind approach (match heading with track), at the cost of
additional drag.

TRUE. but if you don't do it, you'll be CRABBING off the edge of the
runway, and you just might roll the tire off the rim if you touch down
that way.

A tangent to the orignal thread, more concerned with semantics than
application, but I thought I'd turn the discussion in this direction.

Cheers.

I think you have the theory correct, just not the application.
-Dan