cbire880

http://en.wikipedia.org/wiki/Slip_(aerodynamic)
Wrong, forward slip is to lose altitude, side slip is to correct side drift while keeping the longitudinal axis aligned with the runway.

If you were taught something wrong, your instructor can expect to get an earful from the examiner. At the CFI level, you better be able to backup all of your answers with textbook or regulation references. There isn't much of an execuse for being taught something "wrong" at the CFI level. Technique issues are a different story.

As far as the CFI ride goes, relax, its just another flight. My ride was a breeze, so maybe you'll get lucky.

coldpilot

Uh, last time I checked doing a cross wind landing is a side slip. It counter intuitive because the longitudinal axis is pointed down the runway and you are tracking a straight line. In a forward slip you are still traveling forward and tracking a straight line but you are essentially "sideways." The picture of the forward slip is correct in the AFH on page 8-11. The one of the side slip is not. Read the paragraphs on pages 8-10 and 8-11 then you will understand what I am saying.

PFGiardino

Thanks, this makes sense. The difference is the relative wind, correct? The relative wind is from straight on in the side slip, but from the side in a forward slip...

Cubdriver

Not quite. You may be getting confused about which technique is used in a crosswind and which one is used in normal winds. The oncoming (relative) wind in both manuevers is from the side, whether it be a normal wind or a crosswind. Here's another rundown of both manuevers. Both of them are slips, as the nose is turned away from the oncoming wind. Both airplanes are tracking straight to the runway. I use the term "steer" rather than "add aileron" because it's clearer.

1) "Slip". Encountering a crosswind, pilot needs to do something to correct for it lest she be blown off the runway centerline. They put the upwind wing down using the yoke, and add as much rudder as needed to keep the aircraft from flying in the direction the wind is coming from. If crosswind is from right, turn yoke to the right, right wing will be down left wing will be high, add some left rudder to align airplane with the runway. Fly down the extended runway centerline. Airplane touches runway on upwind wheel first, then settles down on the downwind wheel.

2) "Forward slip". This is primarily in non-crosswind conditions to lose altitude. Rudder drives the manuever, in contrast to above where rudder merely compensated for off-alignment. Choose a rudder, doesn't matter which, stomp hard on it to get a big yaw. Left rudder causes a left yaw for example. Airplane turns sharply left, push hard on yoke to get rapid descent, and counter the tendency to go left by steering a little right as required. 100 feet or above the runway drop the control inputs and straighten the airplane.

A variation of this manuever occurs when one has both a need to lose altitude and a crosswind at the same time. Select the rudder that yaws the airplane away from the oncoming wind, so to get maximum side exposure to oncoming wind. Right wind, use left rudder. Everything else is the same, except it will take a lot more right steering to keep from going left. Do not make the mistake of stomping on the upwind rudder pedal, as this will remove drag rather than add it. This would actually set up a crab or a skid, rather than a slip, and rapid altitude loss due to increased drag will not happen.

Another altitude losing technique, which also serves to slow the airplane down and take up time, is the S-turn. Turn left then turn right, then rinse, wash, and repeat. This adds drag with all the banking, adds time with the added distance, and loses altitude for both the above reasons. It doesn't look or feel very good, it tends to result in youtube vidoes, so for this reason is not preferred. If no one is around and you did a sloppy job of setting up your approach you can use it, otherwise you had probably better go around.

Cubdriver

I don't think it does have a higher AOA, but due to the aerodynamic shape resembling a swept wing more than a square one the tip stalls earlier.

Let's say the crosswinds you were slipping against were to magically disappear and you were to roll level and forget to take your rudder input out. You are flying sideways at first, and the airplane will go in the direction of the remaining rudder input.

Pilots do this on ILS approaches in leiu of making actual aileron heading corrections, because the airplane can be given very small heading changes with the rudder at only a minor cost to coordination.

So you are going off-course when you take those ailerons out and roll level. And when this happens, there is no skid or slip as long as the airplane turns with the rudder. Tricky one.

Explained above, the purposes are different and the control inputs are executed in different magnitudes to solve different needs, but they are similar.

detpilot

"By the way side slip is when your airplane is not flying straight. It's flying sideway when you are trying to lose altitude. Forward slip is when your airplane is flying straight for example when you are doing a corss wind landing. Although you are using rudder your longitudinal axis of the airplane is aligned with the runway. Plus go by things your instructor tells you that way if the examiner finds you wrong you might just get to slide. Some times if you say something wrong and you can prove you were tought it wrong like this examiner will let you slide saying ok I'll tell you the right way and from now on go by my way. That happened to a friend of mine."


You've got it backwards, my friend. est of luck to both of you, I'll be taking my CFI initial in about 2 weeks.