Forward slip to landing

6 Answers

1. 
   

   
   

   sfryzel on Jan 04, 2018

   In a forward slip to landing, how should the airplane be oriented relative to the wind and why? For example the wind is from the left, do you yaw to the right and put left wing down?

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2. 
   

   
   

   Skyfox on Jan 05, 2018

   If you weren’t doing a slip, you’d have a crab angle to the left to turn the nose into the wind and keep your ground track aligned with the runway. To turn that into a slip, you could point the nose straight forward so the longitudinal axis is aligned with the runway, and use enough left aileron to bank into the wind so the horizontal component of lift counteracts the wind and keeps the ground track also aligned with the runway. If you need more slip you can put in more bank and more yaw, which would help you drop faster but the nose wouldn’t be aligned with the runway anymore.

   Alternatively it would be possible to yaw into the wind and bank to the right so the thrust into the wind counteracts both the crosswind and the horizontal component of lift trying to take you with the wind, but really that would be kind of sloppy. The previous method that banks into the wind and yaws away from it would be preferable because that’s the easiest to recover from once you no longer need the forward slip, or would also be most closely set up for crosswind landing if you had to slip all the way to the threshold.

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3. 
   

   
   

   Brian on Jan 12, 2018

   “The previous method that banks into the wind and yaws away from it would be preferable because that’s the easiest to recover from once you no longer need the forward slip”

   Not to mention actually being aligned with the runway when you touch. Your former method would be even farther out of alignment than just landing in a crab. Eek, I feel bad for the landing gear.

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4. 
   

   
   

   Skyfox on Jan 15, 2018

   True! To be crabbing so far into the wind that it would counteract a bank away from the wind would ruin the landing gear, or even cause a crash if the crosswind and crossed controls were strong enough. Nobody should ever attempt to land like that. Of course, any forward slip should be ended before flaring for touchdown because the increased descent rate would no longer be needed. I was just describing it as a *possible* way to forward slip while on final approach, even if not ideal.

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5. 
   

   
   

   KDS on Jan 15, 2018

   While it wasn’t part of your question, allow me to add something that I do with students.

   Go up to altitude (always a good way to start such things). Then, while flying at approach speed, put in full rudder and counter it with aileron. Note how you run out of rudder before you run out of aileron.

   It will feel extreme when you first do it, but once you become comfortable at the limits, you will be better able to effectively use a slip to land.

   Doing a good slip to land is almost a lost art in aviation. Pilots use flaps (and / or spoilers) to manage their approach angle. That’s good most of the time, but it’s nice to have the slip to land method in your back pocket for the time it can do you some good. For example, you want to steepen your approach, but you don’t want to add more flaps. You can put the slip in, get down to the angle you want, and then take the slip out or reduce it.

   The thing I see pilots do almost consistently is to put a slip in, not be able to control it, and then take it out and repeat that process of putting it in and taking it out.

   One caution with a slip is that depending on your aircraft, the airspeed indicator may become inaccurate. So, take a look at your pitch angle before you put the slip in and don’t let the nose come above that pitch.

   If you ever get a chance to fly with someone who has an airplane that doesn’t have flaps, do it. They will no doubt be quite good at the slip to landing as a way to touch down exactly where they want to.

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6. 
   

   
   

   Brian on Jan 17, 2018

   “Of course, any forward slip should be ended before touchdown…”

   https://www.youtube.com/watch?v=hlsNDtKZqhk

   A proper cross wind technique would be to roll out on one wheel in a slip. And this isn’t taildragger specific. Landing with some degree of slip should be used in all aircraft, it’s just required in a taildrager since side load will end your day very poorly. During rollout the ailerons should be continually displaced till reaching their limit and only at that time should the second wheel touch the ground.

   Recall an aircraft rolling one way produces yaw the opposite way. 😉

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