Why crabbing is correct and side slipping isn't (was Flying Technique Question of the Day

Yikes! I feel like I'm trapped in an argument with Cliff Claven. There
is no winning, so why bother to continue the debate.

Alas, I've broken my own rule against discussing subjects on the ras
that have life-threatening consequences. My apologies for inviting
such an outwelling of misconceptions and fallacies. I hope they don't
ultimately hurt anyone.

My last word, go back to your primers and make up your own mind.

Apologies to all for my impatience. I've chatted with several pilots
on this subject. I've come to the conclusion that most pilots
misunderstand the control inputs they are making to initiate a side
slip as opposed to a forward slip. This has resulted in misconceptions
about the forces at work while initiating and during a side slip, to
wit, that the banked wing counteracts the effect of crosswind.

This is not the right forum for me to develop what is essentially a
new way to understand side slips. I've started a power point
presentation to codify my ideas. I'll develop this into an article and
submit it to Soaring and to AOPA. If you are interested in peer review
during development of the article, drop me a note at oscar_charlie at
msn.com. Don't respond unless you are willing to put some time and
effort into the process (a couple of hours). I'll need well reasoned,
thoughtful criticism. Priority to the first three respondents, then
the next three based on credentials.

The more I look at this problem, the more certain I am that we've
happened onto something really interesting during the course of this
thread. I jumped into a few books over the past 24 hours, and none
offered a full explanation of the dynamics of the side slip... rather
their treatments featured application, either implying reasons, or
glossing over them without carefully explicating the process of
initiating a turn from base to final during a crosswind approach.

Good stuff.

OC

(Chris OCallaghan) wrote in message . com...
Yikes! I feel like I'm trapped in an argument with Cliff Claven. There
is no winning, so why bother to continue the debate.

Alas, I've broken my own rule against discussing subjects on the ras
that have life-threatening consequences. My apologies for inviting
such an outwelling of misconceptions and fallacies. I hope they don't
ultimately hurt anyone.

My last word, go back to your primers and make up your own mind.

(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. One is used during final for crosswind landings in order
to align the fuselage with the runway throughout the final leg of you
pattern. However, it is, in term of how you use the controls, exactly
the same as any other slip. The difference is that you are executing
the slip along with a crab. That is, if you exit the slip, you will
have a crab angle that aligns your track with the runway.

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. Only crab angle compensates
for crosswind with respect to the ground.



This is where you are wrong. Slipping is just another way to go sideways.
Some people like to slip, some like to crab!!!!





The slip simply aligns the
fuselage with the runway, at the cost of some glide performance.

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

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.

To sum up:

A slip is aerodynamically the same, regardless of wind.

A slip always increases drag.

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.

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

Cheers.