slips vs skidding turns

[M016576]

I think I should clarify my question. I wasn't talking about turns but, rather, the sort of forward slips that I think most of us were taught to use in order to land in a crosswind.

So, on final, if I've got a right crosswind and, in response, lower the right wing while stepping on the left rudder (in order to remain pointed down the runway) do I risk a spin should my airspeed decay to a stall? Because getting to stall speed, of course, is roughly what I'm trying to do. Sure, I want to stall while 6 inches above the runway, but engaging in a behavior that will produce a spin if my airspeed decays while, say, 10 feet off the runway isn't a pleasant thought.

Wing down, top rudder.

If you do stall, your top wing will stall first. When it does, it will drop about 15- 30 degrees and automatically resume a fly able AoA so long as your instinct isn't to pull back for all you're worth, and instead you apply the appropriate stall recovery procedures: then you'll end up in a wings level attitude (but minus some altitude). You won't end up in a spin unless you pull the aircraft through the wing drop, enter a secondary stall and continue to hold in the cross controlled inputs. Don't forget to smoothly neutralize the rudder and look to regain balanced flight after you release the backstick pressure. Some airplanes have problems with their pitot static system getting blocked during deep slips, causing airspeed inaccuracies. Mooneys have 2 static ports, so we're mostly immune, but your pitot tube will lie a little bit depending on how much AOB you put in (how aggressive the slip is). Best to pad your airspeed a bit in a slip- don't get slow. An AOA indicator can help you here, but only if it's on the top wing (in a slip... Bottom wing if it's a skid). Or you could buy 2 AOA indicators- one for each wing

[PTK]

I think I should clarify my question. I wasn't talking about turns but, rather, the sort of forward slips that I think most of us were taught to use in order to land in a crosswind.

So, on final, if I've got a right crosswind and, in response, lower the right wing while stepping on the left rudder (in order to remain pointed down the runway) do I risk a spin should my airspeed decay to a stall? Because getting to stall speed, of course, is roughly what I'm trying to do. Sure, I want to stall while 6 inches above the runway, but engaging in a behavior that will produce a spin if my airspeed decays while, say, 10 feet off the runway isn't a pleasant thought.

You're referring to a side slip maneuver used to align with the runway.

 

Slips are inherently resistant to stall spin because the rudder is opposite the aileron. And the deeper into the slip the more resistant it is. It feels awkward because the airplane is descending and leaning but nose is not turning. There's not enough rudder as in skids where there's too much rudder. In the slip aileron and rudder are equal and airplane is flying sideways.

 

The airplane is stable and airspeed is controllable without stalling right down to 1.3 Vso. As M016576 said there will be airspeed fluctuations depending on static ports and the angle the pitot tube is making. So forward pressure not to get to slow when slipping to the right.

 

And the beauty of it is things happen in real time just like the crosswind we're trying to cancel! You can maintain this control right down to the last moment before touchdown. This is why the upwind wheel touches down first. If slip is not varied as needed and maintained the crosswind will not be cancelled and the airplane will drift off center-line.

Remember there is a purpose to this. It's to cancel, the crosswind. You're lowering right wing and applying left rudder and varying as needed to cancel out the crosswind.

 

The airplane will come out of the slip just as smoothly as entering it. Ease the pressures and the airplane will exit and fly normally. It's very controllable. The focus is to use it and vary it as needed.

 

[bonal]

_{For me the forward slip is a very needed skill.  since my home is in a valley and many locations we fly to are close to mountains (and because I always fly as high as practical)}

_{the only way for me to get down to pattern altitude with out a lot of 360's is to slip it in. as most of you know a cessna 150 can slip like crazy so when i transitioned into my 20c I was worried that it may not perform as well or be as safe.  NO WORRIES! it slips real well. Normal crosswind at my airport are from the left and i prefer a left down wing so it works out great. i just slip the crap out of her until i get a red and a white PAPI and then adjust for crosswind and slide right in. I guess the long body models its a bigger concern.}

_{i love flying my C it reminds me of an early 1970's 911 RS. I thank My instructor for really teaching me the value of a good slip. plus its fun as hell!}

[scottfromiowa]

I had a lot of fun slipping my Mooney down for a landing (both left and right) with my CFI during my last flight review. Plane performed great. Just an excellent, and simple, way to lose altitude with solid control in my Mooney.

[scottfromiowa]

Great, now I want a '70's 911

[PTK]

1980-1983 911 SC (Super Carrera)!

[bonal]

1972 911 carrera rsr light weight good power and in mid to high speed turns you have to steer with the throttle not the wheel a real drivers car

and no AOA indcator it was pure. Man I want to get the hell out of this office and go flying!

[Yetti]

From my CFI who got me to doing slipping 1 main cross wind landings...   He move to Alaska and found that a certain amount of friction is required to make a 1 wheel main landing.  So on an iced over runway, you will continue to get blown across the runway even when you get the 1 main down. 

 

My question is if as instructed never exceed a standard rate turn in the pattern, and keep my airspeed decent, will I need a AOA to keep me from spinning it into the dirt.

[M016576]

From my CFI who got me to doing slipping 1 main cross wind landings...   He move to Alaska and found that a certain amount of friction is required to make a 1 wheel main landing.  So on an iced over runway, you will continue to get blown across the runway even when you get the 1 main down. 

 

My question is if as instructed never exceed a standard rate turn in the pattern, and keep my airspeed decent, will I need a AOA to keep me from spinning it into the dirt.

The clerics of old-tyme aviation, waving incense, promoting bleeding by leeches and the use of only an airspeed indicator will tell you that an AOA indicator is heresy and cannot help you. They will tell you that you should be able to use book speeds, your 30 year old airspeed indicator with its (up to) 5% gauge error and "feel" well into a gusty flare and stall to precisely determine your touchdown point.

An AOA indicator can help you immensely in just this sort of environment.. But.. Ultimately, you as the pilot must learn and practice these techniques to safely and consistently land your aircraft under these conditions. No number of airspeed indicators or AOA gauges can make up for solid fundamentals, training and airmanship!

[carusoam]

Did he mention landing in the crab works on ice??? Steer right to go left....

No, I don't recommend landing in the crab...

[Yetti]

Speaking of feeling the airplane, is anyone still able to to this?  I grew up racing  small sail boats and learned to feel the boat.  I never liked doing stalls, because I could feel the plane start to mush before the buffet began.  It's the same thing you are doing racing to windward always keeping it on the edge. For the most part you can do it with your eyes closed.  Of course you also have telltales (similar to AOA just lower tech)   There have been a couple times on base where I felt I was too slow and just added throttle. But I can keep what ever speed I want without looking at the ASI if need be.  So fly by the numbers or fly by feel?

[Hank]

Fly by feel, but check the numbers because the feel can fool you.

[Mooneymite]

My Navy primary instructor warned me:  "if you want to avoid a spin, simply keep the ball centered at all times."  Despite the simplification, there's a pretty good general discussion of this topic here:

 

http://faaflighttest.us/Cross-Controlled.pdf

 

Specifically:

 

With reference to a slip:

 

"In this configuration, there is no 

tendency to spin because roll force 

downward into a turn is opposed 

by the rudder force against the turn, 

thus creating a balanced situation."