Stalls full rudder crossed control

[FlyingMonkey]

I'm not concerned when I'm slipping, skidding is how I enter a spin,   Too much bank is ok, too little is risky, right?

 

Yeah, the canonical base-to-final stall spin happens when somebody overshoots the turn and then tries to tighten it up with rudder instead of increased aileron, thus with the airplane in a skid with inside aileron and inside rudder both in play.

[Ed Cesnalis]

Yeah, the canonical base-to-final stall spin happens when somebody overshoots the turn and then tries to tighten it up with rudder instead of increased aileron, thus with the airplane in a skid with inside aileron and inside rudder both in play.

 

Actually the scenario is inside rudder to deal with the overshoot and outside aileron to limit the bank to 30°.  Now you have a skid with crossed controls. 

 

Limiting bank is done by "High-siding" the stick.

[FlyingMonkey]

Actually the scenario is inside rudder to deal with the overshoot and outside aileron to limit the bank to 30°.  Now you have a skid with crossed controls. 

 

Limiting bank is done by "High-siding" the stick.

 

Wait a minute.  Crossed controls are by definition a slip, a skid occurs when you have too much rudder in the direction of the turn.  Unless you are talking about insufficient aileron to counter the rudder.

[Ed Cesnalis]

I'm talking about high siding the stick to limit bank.  Left traffic base to final, correcting for overshoot with left rudder and limiting bank with right aileron.

 

Pilot is crossing the controls to skid the turn with a 30degree bank  where a 45degree bank was needed to remain coordinated. 

 

Crossed controls is how you enter and maintain a slip but it is not the definition of a slip.

 

Another example of crossed controls while not slipping would be a left climbing turn on departure.  Right rudder and left aileron resulting in a coordinated climbing left turn.

[FlyingMonkey]

I understand what you are saying,  You are talking about cross control positions where one control (rudder) dominates the overall condition of the airplane, because there is not enough deflection of the other control (aileron) to bring the airplane into a slip .  But if you cross the controls enough you *will* be in a slip.  Unless speeds are so slow there is insufficient control response.

[Ed Cesnalis]

I understand what you are saying,  You are talking about cross control positions where one control (rudder) dominates the overall condition of the airplane, because there is not enough deflection of the other control (aileron) to bring the airplane into a slip .

 

I'm disputing what you said about crossed controls being the definition of a slip.  I think a slip is a turn or condition with too much bank to be coordinated.  Even when slipping I think of the rudder as the 'fixer' not the dominate control.  The rudder can be thought of as the fixer in all phases of flight where the other control surfaces have jobs so I see those as dominant.  

 

I maintain that crossed controls are needed in various phases of flight.

 

 But if you cross the controls enough you *will* be in a slip.  Unless speeds are so slow there is insufficient control response.

 

 

If you are in a cross controlled skid and you take the controls to the stops you will more likely spin than transition to a slip, no?

 

If you are flying at 120kts and suddenly raise the nose and cross controls to the stops you will likely snap roll ( another spin ) rather than slip.

 

Maybe your statement is true if you don't enter a spin before achieving a slip?

[FlyingMonkey]

If you take the controls to the stops in a cross control fashion, I'd say you can't be in anything other than a slip.

 

I would say you cannot snap roll and enter an incipient spin without being in a yawed condition, however brief, before the snap happens (since it requires a yaw component to happen).  So I would say that you are slipping, or at least had the yaw portion of the slip in place, when the stall happened.   Though this is starting to sound like a "chicken v. egg" argument.  

 

Can you get in a skid with the controls crossed?  Sure, if the rudder is deflected more than the ailerons.  Can you slip without crossing the controls?  Sure, in level flight stomp the rudder and the airplane will turn in that direction with ball all the way outside.  My comment was only meant to say that crossing the controls is the correct control input to enter a slip; what you are defining is to me, simply using too much rudder for the bank of turn you have dialed in.  You can call it cross controlled, but you can get the same condition with the stick neutral, so without actual inputs opposite each other, I would not call that a "cross controlled" condition so much as a condition of excess inside rudder, which is a skid. 

 

I did not mean to say that the position of each control individually is what determines the condition of the airplane, but the overall relation they have to each other.  If you have the rudder to the stops to the left and the stick slightly to the right you have cross controlled inputs, but the rudder is so overpowering the slight aileron input that you are in a skid as far as airplane condition.

[Ed Cesnalis]

The skid is more dangerous than the slip if the airplane is close to a stall. In the slip, the raised wing — the left one if the airplane is turning to the right — will stall before the lowered one, and the airplane will reduce the bank angle, which prevents the stall. In the skid, the lowered wing will stall before the raised one, and the airplane will tighten the turn, and the stall can develop to a spin.

 

Stall / slip results in level wings where stall / skid results in spin entry.  You are contending that there is a slip in between the skid and spin, I don't see it.

 

More precise definitions:

1. A skid is where the rate of turn is too great for the angle of bank.
2. Conversely, a slip is where the angle of bank is too great for the rate of turn.

Ask yourself, as you skid base to final all the way to stall / spin, somewhere in the middle did you transition from #1 to #2?

[FastEddieB]

Posted before but worth repeating (from Stick And Rudder):

 

 

 

 

[FlyingMonkey]

 

Stall / slip results in level wings where stall / skid results in spin entry.  You are contending that there is a slip in between the skid and spin, I don't see it.

 

 

 

Maybe I was not clear or didn't understand you.  I just meant that if you go from one condition to the other with the stall happening in the transition, there has to be a yawed condition to facilitate the spin.

 

I think we agree on what's going on, we're just using slightly different terms.

 

And yes, the skid is the killer because of the yaw to the low wing that wants to roll the airplane on its back, instead of the slip that rolls the plane through wings level and enables much more time for recovery before the spin can develop.

[FlyingMonkey]

Thanks for the stick and rudder pics, Eddie.  That sequence is exactly why I'm very conscious to never use the rudder to move the nose around or make turns in the pattern or at low altitude.  I use aileron exclusively for turning and only use enough the rudder to keep the ball centered.

[Ed Cesnalis]

http://www.empire-aviation.com/flight-instructors/john-e-mclain/slips-and-skids-an-explanation-of-the-terms-is-necessary.html

 

One very common explanation of a spin is that it results from an uncoordinated stall. This is only a half-truth. A spin requires two things to be maintained. They are stall and yaw. So, yes, if the airplane is yawing as it stalls, a spin could result. However, only a skid, not a slip, involves yaw. Therefore, a stall while in a slip will not result in a spin.

 

I hope this explanation will alleviate the fears of some readers who thought that a spin could result from a properly executed slip, such as to lose altitude or land in a crosswind. It is just not true. There are, however, some problems that a slip could produce, although in my opinion they are not nearly as significant as what a skid or yaw could produce. So let’s look at these.

 

Without going into a lengthy explanation, let me just say that a stall out of a slip will normally result in the high wing stalling first, which is what most pilots refer to as an over-the-top stall.

 

Let me walk you through one. You are slipping to the right. The right wing is down, and you are holding left rudder to keep the nose going straight. For some unexplained reason, you increase the pitch angle sufficiently to induce a stall. In this case the high wing will stall first and the low wing will start to rise. You will then be returning to a wings level position. The application of proper stall recovery technique will result in a minimum loss of altitude. Compare this to a stall out of a skid, where the low wing stalls first and you are pointed directly at the ground. You will lose much more altitude in the recovery.

[FlyingMonkey]

Thanks CT, I had read that a slip would not result in a spin, but never confirmed that.  It seems counterintuitive there is no yaw in a slip, but I guess we are talking yaw vs the relative wind instead of yaw in the airframe relative to its centerline.

[Tom Baker]

Something else to remember is if you tighten the turn by making a steeper bank your stall speed goes up, and sometimes the increased stall speed will intersect with the slow approach speed.

[FastEddieB]

That sequence is exactly why I'm very conscious to never use the rudder to move the nose around or make turns in the pattern or at low altitude.  I use aileron exclusively for turning and only use enough the rudder to keep the ball centered.

Of course, that's the goal, and the mental image we all have as far as how we think we fly all the time. We're all good "sticks" and we all know better than to rush turns with rudder.

 

But fatigue, stress, distractions all can lead to skidding turns.

 

No pilot who ever spun out of a skidded turn likely ever thought he was the type to do that. Until he did. And it only takes once.

 

Best to humbly accept that it can happen to anyone, and then try to train to avoid that deadly chain of events.

[Runtoeat]

A good discussion.  I have been working with my forward slips to improve my ability to loose altitude quickly for short fields with trees at the threshold or when I come in too high and need to loose altitude on my final.  The attitude while doing the slip is something I had to become comfortable with since it isn't a "normal" feeling with the rudder held opposite to the aileron.  One always reads about crossed controls on the base to final being a well recognized "killer".  This discussion clears up some misunderstandings I've had about slipping.  One thing I always pay attention to is my airspeed during my slips and it is good to understand better the distinction between stalling in a slip compare to stalling in a skid.

[Ed Cesnalis]

Dick,

 

On a BFR the instructor asked me to land short enough to exit the runway at the 1st turnoff, its about 500'.  He also called my base and it was way to soon, just beyond abeam the numbers.  With full flaps and a big slip on base, base to final turn and final it was quite easy to do.  Until then I didn't realize that turns in the pattern while slipping was a useful technique.

[FlyingMonkey]

I have a tendency to be a little high on final, which I think is better/safer than being low.  It rarely is a problem, and I'm getting good at slipping the CTSW to land it where I want it.

[FastEddieB]

I have a tendency to be a little high on final, which I think is better/safer than being low.  It rarely is a problem, and I'm getting good at slipping the CTSW to land it where I want it.

 

I tell my students that if they're too high, the have a whole complement of tricks to get down - more flaps, slips, S-turns, that sort of thing.

 

But if they're too low, they have one and only one tool to make the runway - power.

 

I'd much rather see the former, and over a career of flying someday it just might save somebody's a**!

[Anticept]

I had a discussion with a DPE about the slope. He was always adamant being on target with the slope, because both runway overruns and underruns result in deaths. I made the counter point that a person should know their plane, and situate themselves in the slope in which they know the plane will make it if the engine looses power. I also made the point as FaatEddieB said, I can use a lot of tools to get down from a high angle, but we're going in if I lose power while low, and that's why I like to stay slightly above the slope (in VFR). He then said as long as I can prove that I know my plane well enough, he would be fine with a slightly high approach.

[FastEddieB]

Similarly, when I trained to be a Cirrus Standardized Instructor, the young lady instructor routinely told me I was too high on my approaches. I was putting the plane right where I wanted to, but she wanted a flatter approach, carrying more power.

 

Rather than argue, I did them that way. 

 

Until I got my certificate, then back to the way I like them.