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#161 SLIPS

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(Written in July of 2016)

(No, this article has nothing to do with Elizabeth Taylor or Susan Sarandon)

At Tailwheel Town, I’ve found that it’s important to design a maneuver for every issue a flyer may have.  The two maneuvers described here will help the flier learn to deal with crosswinds.

This little article also has to do with the fact that all the maneuvers taught at Tailwheel Town have something in common…. SOMETHING is always constant.  Let’s take the most common maneuver taught here, the alternating sideslip.  For those of you who have a copy of “Brian’s Flying Book”, it used to be called “The Portuguese Roll” but I changed it because everyone was confusing it with the “Dutch Roll”.

What’s constant in the alternating sideslip?  Heading.  In fact, when the most common error in performing this maneuver is made, the maneuver becomes the least taught one in my bag o’ tricks, The Alternating Forward Slip!  And what’s the constant in the alternating forward slip?  Course.

Let’s describe these two maneuvers, staring with the Alternating Sideslip:

The airplane is on its left side of the runway and it’s right wing is down as it sideslips to the right…
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The airplane has now slipped over to the right side of the runway and has just put it’s left wing down to begin the slip back to the left side of the runway. Notice that no matter what side of the runway it is, it’s heading has remained constant… the runway heading. (photos by Jim Mateski, who risked his life by standing on the centerline!)

First of all, remember that, for all landings, coordination is thrown out the window as we cross the airport fence.  Heading is controlled by rudder and course is controlled by aileron.  Performed at low altitude, the alternating sideslip is actually performed in a low approach… we will not touch down.  We begin the maneuver, lined up right over the runway lights on one side of the runway.  Our heading is the same as runway heading.  Now we bank the airplane to begin a slip to the other side of the runway.  But in order to maintain runway heading, we must use opposite rudder… CAREFUL!  NOT TOO MUCH!  Most of us use too much opposite rudder.  If we fall for that, our heading will no longer be runway heading.  Instead it is a heading which is the opposite of our new course over to the other side of the runway.  As you back off on that rudder in order to hold runway heading, remember the error you just made, because it will be an important part of the next maneuver.  Suffice it to say that while performing the alternating sideslip, our heading will remain the same as runway heading and our course will run back and forth as we move the airplane from one side of the runway to the other.

Now for the other one, the alternating FORWARD SLIP:  Keeping our course constant will be easy because someone painted a nice, long dashed line down the runway.  They call it the Centerline.  We call it the Course line.  Our airplane’s course will be constant, which means that we will be straddling that centerline from one end of the runway to the other.  But our heading will change from one side to the other.  Not only is this maneuver a lot easier to perform, but it is also a lot of fun and when you do it right is one of the most graceful maneuvers we do.  As the plane proceeds down the runway, we will use a poopload of rudder on one side.  In order to keep the airplane from making a skidding turn in that direction, we will use opposite aileron, banking the airplane in the opposite direction.  The result is a forward slip, with the plane right over the center line.  As soon as we’ve achieved a forward slip with that heading, we will smoothly change the bank to the other side and the rudder to the opposite side as well.  The result is a graceful change from a forward slip with one wing down to a forward slip with the other wing down… and the course never changed.

A couple of details:  The purpose of the alternating sideslip is to give you lots of practice doing exactly the same thing you’ll do to land in a crosswind.  But the purpose of the alternating forward slip is to increase your proficiency by practicing a maneuver which has virtually no other purpose!

With the alternating forward slip, we have to be aware of wind.  The reason is obvious, but might be missed.  Our average heading (the heading which is between the two headings the airplane assumes during the maneuver) will be one that is directly into the wind, not necessarily runway heading.

The practice of these two maneuvers will almost guarantee a much improved ability to handle a crosswind.  They’ll also relieve you of ever having to think too much about slips.  All you have to remember is “Rudder for heading, aileron for course”.  Period.