Why stall it?

[FastEddieB]

I may try to work up a simple Excel spreadsheet later and post it here. Unless somebody beats me to it.

I came up with this in Excel, mostly to help solidify the concept in my mind:

https://dl.dropboxusercontent.com/u/22997486/landing energy.xlsx

Can someone tell me if that link works - you'll need Excel or something compatible to open it.

 

[unsafervguy]

Well we do land power off.. (Airbus retard)
Don't believe it's to do with engines. It's the swept wing and our weight. Did a full stall in the Bus during training and recieved major kudos for recovering in about 3000 feet.

what altitude where you at, if you were up high you are "da man". took me about 5k after stalling it at 390.

bob

 

[LongRoadBob]

I learned many years ago in an aeronca champ, some in a super cruiser. The instructor, a WW2 Stearman instructor,( how many hundreds do you suppose he Taught!?) and later a jug pilot, taught this way. Coming in , you chopped the throttle just past the fence and he would have already clued you to keep the nose a little high and try to be three feet or so above the runway. ( 2200 feet of grass, good approaches) Then he would keep saying....." Dont let it land,keep coming back on the stick " repeating this several times until we touched down in a three point. I caught on to this pretty quick and could land in a three point without much trouble sometimes as the plane touched, more often just a bit above the runway, ( six inches maybe) he explained that one wanted the airplane to STOP FLYING as one flared and touched down. That meant a stall to me and still does. I spent a lot of hours in that aeronca , over a hundred and in the super cruiser. Later I landed a mooney pretty much the same way, a Stearman, , a shrike, taylorcraft, etc. in the Stearman you wanted to be thru flying on touch down as until you were very adept in one, you could wind up anywhere. There was no AOA in many of these aircraft and I never used one anyway. You simply " knew" the right angle and your purifieral ( spelling!) vision did the rest. Simply practice. Over and over. Monkey and the typewriter stuff. Rote.

Thanks for this! The description made a good connection for me. So far I've landed once, and ven then not sure how much was correction by the CFI. We newbies often make landings to be very big deals, maybe too much. Build up in our minds that it is like the single most difficult thing. This idea, specially of inching the nose up to "not let it land" puts a good perspective and I needed to hear that, to think that.

I'm now going over to a Piper PA28 warrior, was reading in the manual that the stall warning horn activates when "5-10 knots over stall speed". So another thing I picked up from this thread was that it (though I see this is being debated, I will ask my CFI and go with that) isn't really stalling, at least not a full stall on landings. That point was confusing me and I had contradictory ideas (stall and not stall but fly to the ground).

Anyway, glad I read this. One question though..."chopped the throttle" just means cut the throttle or is this some other technique or describing opening and closing it as needed?

 

[Kritchlow]

what altitude where you at, if you were up high you are "da man". took me about 5k after stalling it at 390.

bob

I honestly don't remember... In case anyone is wondering, it was in the sim.

 

[FastEddieB]

"Chopping" the throttle just means closing it rapidly.

For most small GA planes, I like to see the power at idle by at least 50' or so - it's then one less thing to worry about during the landing process.

 

[Fearless Tower]

Ok, thanks for the responses. I thought it was common to teach to hold it off until it reached a stall, but I guess not everybody teaches that. I prefer just to hear the stall warning begin in the flare and ease it down from there. I'll add a few knots with a crosswind and use less flaps.

Wait a minute....I thought you were a Navy guy? No one in the Navy does that!

 

[Cooter]

Wait a minute....I thought you were a Navy guy? No one in the Navy does that!

I am sad to say I traded in my Wings of Gold, I've had to relearn and it's not easy. I still prefer to just fly it right into the runway but that doesn't always go over too well! Have you ever ridden on one of the C-9s (now C-40) with a former fighter guy flying?

 

[Fearless Tower]

I am sad to say I traded in my Wings of Gold, I've had to relearn and it's not easy. I still prefer to just fly it right into the runway that doesn't always go over too well! Have you ever ridden on one of the C-9s (now C-40) with a former fighter guy flying?

No, but I have flown a few Delta MD-80s that probably had a former fighter guy at the controls.

 

[Half Fast]

For most small GA planes, I like to see the power at idle by at least 50' or so - it's then one less thing to worry about during the landing process.

My instructor tells me to go to idle once a safe landing is assured. Consequently I wait until I've taxied to the hangar.....

 

[Cooter]

No, but I have flown a few Delta MD-80s that probably had a former fighter guy at the controls.

Chances are you're right, a lot of Navy guys go Delta. I remember a few guys saying landing the MD-80 was counterintuitive because you actually pushed the nose down to soften the landing and if you were coming down too fast, pulling up could make for a harder landing.

 

[Velocity173]

Had a friend who did a rotor wing to fixed wing transition and thought that the stall horn was required to go off on take off. Said every flight he had in the DA-20 with his CFI the horn was chirping on rotation. He continued the practice solo by rotating around stall speed. If he didn't get the horn he actually rotated harder to get it!

I just laughed when he told me that story. His CFI definitely failed to teach him anything on FW aerodynamics.

 

[LDJones]

Only speaking for myself, but when flying a small airplane the goal was indeed a full stall landing. That's the way I flew and the way I taught.

It always worked for me.
Flame away...

Ditto. Hold it off til it can't fly anymore. A perfect landing is one where the yoke hits the aft stop just as the tires kiss the runway.

 

[LDJones]

You pretty much never want to stall an airplane airborne (other than training), so why do it on landing? I agree with working the speed down but personally, I just don't want to stall it and hope I've judged my height above runway exactly right. The airplane gets less and less controllable as it nears stall. I would rather preserve some of that controllability to ease it onto the runway. I'll take the chance that the extra few knots that aid responsiveness won't be the difference in life or death in the event a deer runs out.

Done right you never stall while airborne. You hit the stall at the moment of touchdown. Those "few extra knots" at touchdown cause more grief for pilots than stalling it at the moment of touchdown. Keep in mind the last handful of knots were bled off a foot or less over the runway, so the risks your alluding to are very minimal. But PIO and prop strikes are common when trying to land too fast.

 

[Jimmy cooper]

Done right you never stall while airborne. You hit the stall at the moment of touchdown. Those "few extra knots" at touchdown cause more grief for pilots than stalling it at the moment of touchdown. Keep in mind the last handful of knots were bled off a foot or less over the runway, so the risks your alluding to are very minimal. But PIO and prop strikes are common when trying to land too fast.

Perfect explanation but probably not satisfactory for" cooter " until he gains experience .

 

[Dan Thomas]

Done right you never stall while airborne. You hit the stall at the moment of touchdown. Those "few extra knots" at touchdown cause more grief for pilots than stalling it at the moment of touchdown. Keep in mind the last handful of knots were bled off a foot or less over the runway, so the risks your alluding to are very minimal. But PIO and prop strikes are common when trying to land too fast.

You will not stall at touchdown. The geometry of the airplane itself will prevent it. The most you will get is a sink if you hold it off a little too long.

Think about landing in a bit of a crosswind. You have a little aileron in to keep the upwind wing down and opposite rudder to keep the nose aligned with the runway. This is a classic cross-controlled situation that would cause a wing drop if the airplane stalled. And yet it never does, because the wing doesn't stall in the landing. The people who design airplanes try to avoid a configuration that would let the wing get to stall AoA in the flare. Too many airplanes would get broken.

Think, too, about flaring too high and dropping six feet. If the wing stalled, the nose would fall, but the airplane manages to hit, hard, on the mains. It's just sink.

 

[Jimmy cooper]

You will not stall at touchdown. The geometry of the airplane itself will prevent it. The most you will get is a sink if you hold it off a little too long.

Think about landing in a bit of a crosswind. You have a little aileron in to keep the upwind wing down and opposite rudder to keep the nose aligned with the runway. This is a classic cross-controlled situation that would cause a wing drop if the airplane stalled. And yet it never does, because the wing doesn't stall in the landing. The people who design airplanes try to avoid a configuration that would let the wing get to stall AoA in the flare. Too many airplanes would get broken.

Think, too, about flaring too high and dropping six feet. If the wing stalled, the nose would fall, but the airplane manages to hit, hard, on the mains. It's just sink.

But with experience and proper instruction one doesn't do these things. As the FBO! former corsair pilot who checked me out in my Stearman explained " keep coming back till it quits flying and fly it this way until you really have a handle on the airplane." this is close enough to a stall for me and has worked basically for over 4000 hours, with little variation except for the cessna 195 which had lousy viz so I usually wheel landed it.

 

[Cooter]

Perfect explanation but probably not satisfactory for" cooter " until he gains experience .

Are you one of those people who's afraid of engaging with a different perspective?

 

[LDJones]

You will not stall at touchdown. The geometry of the airplane itself will prevent it. The most you will get is a sink if you hold it off a little too long.

Think about landing in a bit of a crosswind. You have a little aileron in to keep the upwind wing down and opposite rudder to keep the nose aligned with the runway. This is a classic cross-controlled situation that would cause a wing drop if the airplane stalled. And yet it never does, because the wing doesn't stall in the landing. The people who design airplanes try to avoid a configuration that would let the wing get to stall AoA in the flare. Too many airplanes would get broken.

Think, too, about flaring too high and dropping six feet. If the wing stalled, the nose would fall, but the airplane manages to hit, hard, on the mains. It's just sink.

Point taken. I should have said "Touchdown at the point the yoke/stick hits the aft stop and you can't milk any more flight out of the wink." That will still be above the stall speed, but you should be hearing/seeing the stall warning.

 

[Kritchlow]

Are we starting to split hairs here??? I don't think anyone is suggesting stalling the airplane six feet off the runway.
That said, don't forget ground effect plays a role here.

 

[FastEddieB]

The closest to full stall landings I've seen were in my Citabrias.

I found the best landings were when you kept holding off as long as possible. If done right, you could feel the tailwheel roll on slightly first*, then the stick would come firmly back the rest of the way and the mains would drop a few inches to plop on the runway. I loved these because there was little doubt the plane was stalled, or very nearly so - it sure seemed like as one attempted to further increase the AOA at the end it was accompanied by a decrease in lift, and the plane was done flying.

In 3-point landings, there was just a tad more "squirreliness" as the wings still seemed to have a modicum of lift left.


*In fact, "feeling for the runway with the tailwheel" was an image I tried to convey to my tailwheel transition students. It actually works reasonably well in nosewheel aircraft as well, which are generally configured so that actually landing tail first is all but impossible.

 

[flyingron]

Again, holding it off with progressive backpressure until lift dies away and the wheels touch is NOT stalling it. I don't know anybody who holds a stall attitude in the flare. You'd certainly hit the tail first and while Maule suggests landing that way, it's still not usually a stall landing. It's near impossible that you're in a stall if you touch mains first.

Yes, with a minimal energy landing you are pulling further back as you slow and you may run out of aft stick just about the time you have insufficient lift to maintain level flight and sink on the ground. Nobody is arguing that this is the minimal energy landing giving you the shortest landing roll, etc... but you're not stalling the aircraft. The reason that lift is decreasing is NOT that you exceeded the critical AOA (stalling) but because you have been progressively SLOWING DOWN (that's the point) during the manoeuvre.

 

[Dan Thomas]

Landing in a gusty headwind can lift the airplane off again if you get a sudden gust right after touchdown with the nose as high as you can get it. If the wing was stalled, you wouldn't--couldn't--lift off.

I'm sure most of us have experienced this as some time, if we've been at it long enough.

 

[FastEddieB]

The reason that lift is decreasing is NOT that you exceeded the critical AOA (stalling) but because you have been progressively SLOWING DOWN (that's the point) during the ling the aircraft. The reason that lift is decreasing is NOT that you exceeded the critical AOA (stalling) but because you have been progressively SLOWING DOWN (that's the point) during the manoeuvre.

I thought the critical/stall angle of attack was defined as the point where any further increase in angle of attack led to a decrease in lift:

If that's the case, not sure the quoted part of your post makes sense.

 

[flyingron]

I thought the critical/stall angle of attack was defined as the point where any further increase in angle of attack led to a decrease in lift:

If that's the case, not sure the quoted part of your post makes sense.

Exactly. The stall is the point where the increase in AOA stops generating an increase in the coefficient of lift. However, lift is not solely determined by AOA/coefficient of lift. It's also determined by airspeed (and a few other parameters that are essentially constant for this discussion). What is happening while you are flaring in this landing is you are not only INCREASING AOA (and increasing the coefficent of lift) but also DECREASING AIRSPEED. The slower speed dominates and lift decreases.

In fact the decreasing lift is what leads to the apparent "stall speed" where you go slower and slower and you have to increase AOA to make up for the loss of lift due to decrease in airspeed.

 

[Cooter]

I thought the critical/stall angle of attack was defined as the point where any further increase in angle of attack led to a decrease in lift:

If that's the case, not sure the quoted part of your post makes sense.

One way to thing about it is, what's the difference between best glide and maximum range? Both roughly occur at L/D max.

 

[Rykymus]

Getting your stall horn chirping as you touch down is taught to ensure that the new pilot knows how to land the plane at the lowest controllable airspeed, and in the least distance necessary. It's just like the basics of flying the pattern, reducing power abeam the numbers, hitting certain airspeeds at each leg/flap setting, etc... Neither are meant to be strictly adhered to for the rest of your flying days. To me, that's the difference between being a technician, and an artist. There are many ways for me to land my plane, some of them safer than others. But there is no one way that is right every single time, as the conditions are always changing. It's about understanding the dynamics, yes, but it is also about 'feel'. That became obvious to me in the later stages of my training, when I was being allowed to fly my plane from my training airport to my home airport each day. The tower was constantly giving me different entries, extending legs, asking me to get down quick for faster traffic on approach, etc... I realized that following the 1,2,3 steps that I was originally taught to land the plane did not work in all situations. The same is true with getting the stall horn chirping. You need to be able to land the plane safely at just above stall speed, and at 10-20 knots above it. Getting too locked into a 'standard' method of doing things is a recipe for disaster, IMHO.

 

[LongRoadBob]

Getting your stall horn chirping as you touch down is taught to ensure that the new pilot knows how to land the plane at the lowest controllable airspeed, and in the least distance necessary. It's just like the basics of flying the pattern, reducing power abeam the numbers, hitting certain airspeeds at each leg/flap setting, etc... Neither are meant to be strictly adhered to for the rest of your flying days. To me, that's the difference between being a technician, and an artist. There are many ways for me to land my plane, some of them safer than others. But there is no one way that is right every single time, as the conditions are always changing. It's about understanding the dynamics, yes, but it is also about 'feel'. That became obvious to me in the later stages of my training, when I was being allowed to fly my plane from my training airport to my home airport each day. The tower was constantly giving me different entries, extending legs, asking me to get down quick for faster traffic on approach, etc... I realized that following the 1,2,3 steps that I was originally taught to land the plane did not work in all situations. The same is true with getting the stall horn chirping. You need to be able to land the plane safely at just above stall speed, and at 10-20 knots above it. Getting too locked into a 'standard' method of doing things is a recipe for disaster, IMHO.

With my limited knowledge part of your post scares me a bit. It seems to me that 10-20 knots above stall speed is a dangerous maneuver at my ignorant stage of learning.
I do understand already that conditions are rarely the same,and that one needs to learn what and how to adapt, quickly, but everything I'm hearing is saying that in general one does not want extra speed at landing. That it is dangerous. I plan on trying my best to learn emergency procedures in a safe way that may include coming in too fast, but also have definite plans to learn to go around and when to do that when it is appropriate.

I'm a little confused by this idea.

 

[flyingron]

10-20 knots above the stall speed is likely way fast. That's 50% over Vso in things like the Skyhawk and is a bit fast even for an approach speed, let alone a touch down speed.

I disagree about landing with the stall warning chirping (unless your stall warning goes off way early). MCA is *NOT* where you want to be landing either, you want good control throughout the landing.

 

[Cooter]

With my limited knowledge part of your post scares me a bit. It seems to me that 10-20 knots above stall speed is a dangerous maneuver at my ignorant stage of learning.
I do understand already that conditions are rarely the same,and that one needs to learn what and how to adapt, quickly, but everything I'm hearing is saying that in general one does not want extra speed at landing. That it is dangerous. I plan on trying my best to learn emergency procedures in a safe way that may include coming in too fast, but also have definite plans to learn to go around and when to do that when it is appropriate.

I'm a little confused by this idea.

Extra knots isn't necessarily dangerous, but being fast can contribute to other problems. On a calm day with light or steady winds, I might hold it all the way off like some have described. Otherwise, I usually touch down slightly above to at stall horn speed. I also don't usually land full flaps in light GA airplanes unless I need to, which is almost never. For now, just do what your instructor wants and once you get signed off, go practice different ways and test it for yourself. When getting signed off in a new airplane I'd recommend paying close attention to the landing characteristics because some are less forgiving than others, and what works in one may not work well in another.

 

[FastEddieB]

A few of the last several posts echo a depressingly familiar theme.

Of course, a pilot needs flexibility. Landing my Citabria at night in a gusty crosswind with the landing light out, trying to find the full stall attitude with no clear idea where the ground was would have "bad idea" written all over it.

But 40+ years of reviewing accident reports has led me to believe that a very significant number of accidents and fatalities could have been avoided if only the pilot had flown as he or she had been trained to originally. "Strictly adhered" to first principles, and at least Private Pilot Standards, as it were.

Countless porpoising incidents and runway overruns due to being too fast and/or partial flaps. Planes colliding because one felt traffic patterns were just something to show an examiner and then ignore. Planes coming apart or engines failing because checklists are for beginners. Limitations are for losers. And so on, ad nauseum.

But human nature, and Type A personalities, being as they are, I don't expect this to ever change.

So it goes. At least I'll still have plenty of accident reports to consider!

 

[Cooter]

A few of the last several posts echo a depressingly familiar theme.

Of course, a pilot needs flexibility. Landing my Citabria at night in a gusty crosswind with the landing light out, trying to find the full stall attitude with no clear idea where the ground would have "bad idea" written all over it.

But 40+ years of reviewing accident reports has led me to believe that a very significant number of accidents and fatalities could have been avoided if only the pilot had flown as he or she had been trained to originally. "Strictly adhered" to first principles, and at least Private Pilot Standards, as it were.

Countless porpoising incidents and runway overruns due to being too fast and/or partial flaps. Planes colliding because one felt traffic patterns were just something to show an examiner and then ignore. Planes coming apart or engines failing because checklists are for beginners. Limitations are for losers. And so on, ad nauseum.

But human nature, and Type A personalities, being as they are, I don't expect this to ever change.

So it goes. At least I'll still have plenty of accident reports to consider!

Then what you are talking about are tolerances, not technique. Anecdotal evidence can be provided to the contrary as well where slow airspeed contributed to an accident. In Navy flying, there's not much room for error at either end and neither a fast or a slow is tolerated. Getting slow is more dangerous though.

I don't really care if people have different methods of getting it back to the runway, I just like to hear the reasoning behind why they do it. I think there is a time and place for both and a competent pilot can make the right determination for which is appropriate.

 

[Rykymus]

Sometimes I think that I don't explain my thoughts very well, which is surprising since by profession I am a writer. The idea that I was trying to get across is that there is no one way that something should always be done. You should have the skill to do it many different ways, in many different environments, and have the good judgement to use them. I would argue (probably unconvincingly) that strict adherence to the way you were taught to land can be just as dangerous, given conditions that require a different approach. I mean, when you do a simulated engine-out approach, pulling power abeam the numbers, you don't continue on with your 1,2,3 step approach and fly the perfect pattern, you turn early and get her down, then bleed off speed on short final. If the runway is 100' wide and a mile long, landing at just above stall speed with an unpredictable and strong crosswind would be ill-advised. That doesn't mean that you don't need to have the ability to do so. You do, because someday you might be looking at 40'x2,000', in the same winds. But it also doesn't mean that you should always land at or just above Vso. When I'm coming into a full pattern, with big iron coming in behind me, and the tower asks me to put it down quick or go around, I'm glad that I regularly practicing coming in on final at 120kts, and shaving it down to 75 by the time my wheels kiss the runway. But I also regularly practice riding all the way down with the stall horn blaring at least once per month, if not more often.

I agree that you should stick with the way you're taught in the beginning, but it would be idiotic to think that you must fly that way at all times, for the rest of your life. There is always more than one way to skin that cat.

 

[FastEddieB]

Anecdotal evidence can be provided to the contrary as well where slow airspeed contributed to an accident. In Navy flying, there's not much room for error at either end and neither a fast or a slow is tolerated. Getting slow is more dangerous though.

Getting too slow in the approach can be deadly - stall/spin and all that.

In the actual landing, the roundout/flare, too slow is rarely any concern - you're only a foot or so over the runway for most of it. It's there that I think excess speed is far more of a problem than too little.

 

[Cooter]

Getting too slow in the approach can be deadly - stall/spin and all that.

In the actual landing, the roundout/flare, too slow is rarely any concern - you're only a foot or so over the runway for most of it. It's there that I think excess speed is far more of a problem than too little.

You assume only a foot or two off the runway. That's not a given, it's part of the tolerances I mentioned. If you do everything else right, a few knots fast or slow doesn't make much difference in most circumstance. I lean towards preserving controllability until touchdown because I see more potential danger off the ground than on it. And, those extra couple knots can be nice to have in a go-around.

 

[N659HB]

Getting too slow in the approach can be deadly - stall/spin and all that.

In the actual landing, the roundout/flare, too slow is rarely any concern - you're only a foot or so over the runway for most of it. It's there that I think excess speed is far more of a problem than too little.

I think it depends on what you're flying as well. My Luscombe, which is quite light for a certified aircraft, will float and float and float if I have excess speed in the flare. If I pull back too hard on the stick, it balloons! Plus, I can easily tell when the wind has shifted to a tailwind! Different planes will have different characteristics in the flare, but in my mind a slower touchdown equals more control on the ground. Keeping up a higher than normal approach speed is quite different than carrying an extra 20 knots into the flare. It's good to be able to fly a fast approach and slow to normal speed before the flare.

 

[coloradobluesky]

Any airplane will float if you come in fast.
Go up and stall your airplane. Have a friend note airspeed (you can't youre busy stalling)
Land said airplane and stall it just a bit above the runway so it plops on. Have friend note airspeed.
Now you know!

Take a look at this, starting around 30seconds into it.

 

[flyingron]

Any airplane will float if you come in fast.
Go up and stall your airplane. Have a friend note airspeed (you can't youre busy stalling)
Land said airplane and stall it just a bit above the runway so it plops on. Have friend note airspeed.
Now you know!

That would be a foolish way to land. Again, if you get it to a stall AOA you'll be way more nose up than would be safe. Again, SPEED DOESN'T MAKE YOU STALL.

 

[N3368K]

I had to be careful with my Starduster Too when three pointing not to over do the stick back. I could make a perfect three pointer and haul back to "stick" the landing and quickly find myself airborne again about 5-10' in the air when she would just fall out of the sky if one wasn't immediately on the throttle or relaxed the excess back pressure. It landed best slightly tailwheel first and hold the stick and the mains would settle on nicely. If I tried to land with full up elevator as the gear touched, it would be very nose high, t/w first. By definition, it was still flying when the tailwheel touched and the AOA decreased when the mains settled on. As the AOA decreased, the wing continued flying.

My RV-4 has short gear and is easy to land slightly tailwheel first with mains a foot or more high. I cannot pull back enough to run out of full up elevator without getting way too nose high and hitting tailwheel first. If I do it right and get all three down at once and pull the stick back, it will takeoff again.

 

[dmspilot]

In the interest of playing devil's advocate, I will say that a full-stall "style" of landing (which I will decline to participate in the actually-stalled-or-not debate) will result in the nose blocking the view of the runway in a number of airplanes, such as the C150/152. This manner of landing does not seem congruent with attempting to prevent a loss-of-directional-control type of landing accident. Disagreement is welcome.

 

[Dan Thomas]

In the actual landing, the roundout/flare, too slow is rarely any concern - you're only a foot or so over the runway for most of it. It's there that I think excess speed is far more of a problem than too little.

Exactly. Too many pilots forget a basic tenet of aerodynamics: lift is a function of AoA and airspeed. More speed, less AoA required. That means that a fast touchdown happens at a lower AoA, which means that the airplane's attitude is nose-low, which means that the nose wheel can hit first, which can start a porpoise that ends in a busted airplane, or a wheelbarrowing airplane which has now become a really nasty taildragger, or a three-point landing (in a trike) that means there is little weight on the wheels (due to remaining lift from all that speed) so that it runs off the end of the runway, or flat-spots the tires or blows them out with braking.

Of all the bad habits one can develop after licensing, this one seems to show up first. You see it all the time. And I'd bet that way more airplanes are totalled this way than are totalled in stall/spins on approach.