SLIPS TO A LANDING
Landing in a crosswind is a normal part of flying sailplanes. The question is "What is the best way to teach and to learn how to handle crosswinds?" There are two standard methods taught for landing in a crosswind. One is using a "crab" for compensating against the crosswind. The second method is to use a "sideslip".
Before we go on letís get straight in our heads the difference between a sideslip and a forward slip. These two terms gave me a lot of trouble for many years as their definitions seemed exactly backwards to me. A forward slip is defined to be a slip where the fuselage is not parallel to the line of travel. That is the fuselage is pointed off to one side of the line of travel. A forward slip is used for losing altitude. A sideslip is defined to be a slip where the fuselage is parallel to the line of travel. A sideslip is used for landing in a crosswind. Where is the world did these names for slips come from; a forward slip and the fuselage is pointed off to the side, a sideslip and the fuselage is pointed straight forward? Confusing, huh? Well, here is one explanation that has helped me understand the definitions. These terms came from the English. They sometimes have what we consider a strange way of saying things. When the wind is blowing across the runway they called it a "side" wind and, hence, the slip used to offset this wind is called a sideslip. The forward slip is used when traveling generally forward and simply trying to lose altitude. Is this explanation right? I donít know, but at least it helps me and more important, it help my students keep the two terms correct in our minds.
Now, letís move on the sideslips versus crabs. Many students are taught the crabbing method to offset a crosswind. A crab is where the wings of the sailplane are kept level and the nose is pointed with the rudders into the wind enough to make the plane track straight down the runway. There is a problem with using a crab for crosswinds. You cannot land with the nose of the plane pointed off to one side. Just before touching down you are to come out of the crab. Between the time you come out of the crab and the actual touch down the plane will start to drift with the wind. The longer the time interval between coming out of the crab and touch down the more the plane will drift with the wind. I once saw and pilot in a power plane "kick out" of a crab too early and float totally off the runway before the plane touched the ground. When it did touch down it was in a ditch. It was at that point in time that I decided I wanted to avoid that scenario. I needed to learn and get good at using a sideslip instead of a crab.
A sideslip is when the wing on the side of the plane where the wind is coming from is lowered to offset the tendency of the plane to drift sideways downwind. The rudders are used to simply keep the nose pointed straight down the runway. The ailerons are used totally to keep the plane from drifting either into or with the wind. If the plane is drifting into the wind raise the wing a little. If the plane is drifting downwind then lower the wing some more. Raising or lowering the wing will require a rudder adjustment to keep the nose pointed straight down the runway. While somewhat more difficult to master, this method allows the pilot to land without any last minute adjustments before touchdown. That is, the plane is flared and landed with the wing down and the nose pointed straight down the runway.
Getting good at handling crosswind landings, like anything else, requires practice. However, this practice needs to be done safely. That means with an experienced flight instructor. Go practice and get good with handling crosswinds. It will make you a better and safer pilot.
Fly Safely and Have FUN!
Bermuda High Soaring