Why stall it?

Cooter

Cooter

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Cooter
What is the reasoning behind flying into a stall before touchdown? Does anyone teach to fly it onto the runway a few knots above stall speed? I just want to get different perspectives, if there are any.
 
You don't stall it. You set off the stall warning. BIG difference.

You want the airplane to stop flying when the wheels are on the ground.
 
I don't think many people actually fully stall on landing, even a three point on a taildragger, you still got a little juice left if it's a good landing IMO

MAKG1 said:
You don't stall it. You set off the stall warning. BIG difference.

You want the airplane to stop flying when the wheels are on the ground.
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Yup

Good short field / soft field you should be hearing the stall born on most GA singles on short final.
 
The "full stall" landing is a misnomer. Most aircraft (tricycle or conventional) aren't stalled if the mains are touching (or nearly so).
 
The only time my stall horn is making noise is when I'm doing my monthly practice flight, during which I purposefully practice short/soft field landings, and power on/off stalls. Otherwise, I come in with a little extra energy. I have better control, and my landings are smoother, which makes the wife happy.

I think we're taught to land on the verge of a stall so that we know how, in case we need to. I don't always fly perfect patterns either.
 
If something, anything, goes wrong on the landing, extra energy is the enemy.

Hitting something or swerving out of control at 55kts can cause a lot more damage and/or injury than the same incident at 50kts, let's say.

Every Private Pilot had to demonstrate a normal landing at approximately stall speed. It's a valuable skill that far to many pilots get lazy about once they have their licenses, and we get to see the results on a fairly regular basis.
 
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.
 
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...
 
Kritchlow said:
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...
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I was under the impression that you are in the majority, I was taught that the perfect landing was one where you stall it just slightly off the ground. But, I choose to do it differently. I was curious as to what people's reasoning was behind their technique.
 
Cooter143 said:
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.
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Well, I would hope that all instructors teaching to the Practical Test Standards teach that way - if they don't they can expect their students to bust checkrides with some regularity.

What students do afterwards is beyond their control.
 
pigpenracing said:
If it isn't stalled it is still flying....
What are you going to do? Fly it in the hangar????
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The AoA will decrease after landing, kind of preventing the classic definition of stall. Right?
 
FastEddieB said:
Well, I would hope that all instructors teaching to the Practical Test Standards teach that way - if they don't they can expect their students to bust checkrides with some regularity.

What students do afterwards is beyond their control.
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"Approximate" leaves room for interpretation and certainly excludes full stall as a hard requirement.
 
pigpenracing said:
If it isn't stalled it is still flying....
What are you going to do? Fly it in the hangar????
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I agree with a small airplane, but you could make the same statement about a jet.
Trust me, you don't want to full stall a jet.... Ever.
 
Cooter143 said:
"Approximate" leaves room for interpretation and certainly excludes full stall as a hard requirement.
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Sure.

It's a goal.

A few knots over will likely pass muster with most examiners. A few knots more is probably risking a pink ticket,

My goal in most light planes is to have the stick/yoke hit the rear stop as the mains touch. I usually come close*, but only occasionally hit it perfectly.

Oh, and my working assumption is we're talking light GA piston aircraft, and not jets or anything exotic.

*As I think most here have seen in my Sky Arrow landings.
 
Kritchlow said:
I agree with a small airplane, but you could make the same statement about a jet.
Trust me, you don't want to full stall a jet.... Ever.
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Can some of the reasoning behind not stalling a larger aircraft on landing not be applied to light GA aircraft? I understand not touching down 10kts over, but what about targeting 2-4kts above stall?
 
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I'm not sure how to explain it. Not sure if it's the sheer weight, or a function of a swept wing (ailerons generally stall before root). Possibly a combo of both.
 
Kritchlow said:
I'm not sure how to explain it. Not sure if it's the sheer weight, or a function of a swept wing (ailerons generally stall before root). Possibly a combo of both.
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I always thought it was because the stall, when it occurs, is more abrupt. Also many jets have shakers, and some have pushers. On one of my first landings in a Lear 35 I got the shaker. The captain looked at me and said something like, "You know what comes after the shaker..."
 
Kritchlow said:
I'm not sure how to explain it. Not sure if it's the sheer weight, or a function of a swept wing (ailerons generally stall before root). Possibly a combo of both.
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Never flown a jet.

I thought it had to do with high AOA affecting airflow into the engines, combined with needing to carry power since turbines take so long to spool up on a missed approach/go around.

Happy to be schooled if those are not correct.
 
I don't know about other jets, but in the ones I've flown (which are all business jets, not airliners), by the time you touch down you are at idle thrust.
 
FastEddieB said:
Never flown a jet.

I thought it had to do with high AOA affecting airflow into the engines, combined with needing to carry power since turbines take so long to spool up on a missed approach/go around.

Happy to be schooled if those are not correct.
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I think it differs for each aircraft. Turbojets spool up rather quickly, and most modern jets won't have too many problems with compressor stalls at idle. The weight issue might be part of it, but some will drag the tail if you hold it off too long. Personally, it's just uncomfortable to hold it off and get that slow. The flight controls lose effectiveness and it is hard to make corrections when you're nearly out of flying speed. There's less room for drift or touchdown aim point errors when your doing 130 instead of 60.

The large majority of my flight time is in jets, I am trying to think through the implications of treating light aircraft similarly.
 
FastEddieB said:
Never flown a jet.

I thought it had to do with high AOA affecting airflow into the engines, combined with needing to carry power since turbines take so long to spool up on a missed approach/go around.

Happy to be schooled if those are not correct.
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Well we do land power off.. (Airbus retard) :D
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.
 
I attempt to stall my Cub as the wheels touch. The gear geometry of the RV-4 makes it a bit more difficult. If I hold it off enough to full stall it, I will hit tailwheel first, but the mains immediately come down, lowering the AoA. Even then, with stick full back, it won't fly anymore.
 
As they say, if you're going to crash, might as well crash slow.
 
It's possible that in many jets a tail strike would occur prior to stall.
 
Kritchlow said:
Well we do land power off.. (Airbus retard) :D
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.
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will the bus fully stall in normal law? In the Falcon the FCS will lower AOA if the stall warning is ignored and prevent the full stall.
 
It seems a LOT of people confuse stall with stall warning.

I've seen the results of a 172 that really stalled onto the runway. Bent firewall, prop strike, cracked mains, and a loose carburetor (broken mounting bolts?). It's still sitting on the ramp at Palo Alto if anyone wants to see it. Been three years or so. It's a total loss.

You want it to be NEAR stall so you can transition through it when the mains touch. Not stalled. If you cut it too close, you'll strike the tail.
 
NJP_MAN said:
will the bus fully stall in normal law? In the Falcon the FCS will lower AOA if the stall warning is ignored and prevent the full stall.
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Probably not. Definitely not from pilot input, be natures input yes it's possible.

That said, more to your question... We don't bring the Bus close to the normal law limits or we would scrape the tail.
 
PS- the Bus laws in flair eff with you. I hate it. It changes at 50 feet.
 
N3368K said:
I attempt to stall my Cub as the wheels touch. The gear geometry of the RV-4 makes it a bit more difficult. If I hold it off enough to full stall it, I will hit tailwheel first, but the mains immediately come down, lowering the AoA. Even then, with stick full back, it won't fly anymore.
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Put bigger wheels on the cub :)
 
MAKG1 said:
I've seen the results of a 172 that really stalled onto the runway. Bent firewall, prop strike, cracked mains, and a loose carburetor (broken mounting bolts?). It's still sitting on the ramp at Palo Alto if anyone wants to see it. Been three years or so. It's a total loss.
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That's a 172 that stalled at some significant height above the runway.

When the stall occurs as the mains touch, or with the mains just a few inches above the surface, believe me no damage has to occur - I've done thousands in a pretty wide variety of aircraft - including 172's - and they remained undamaged.

I don't have stats to back me up, but in my subjective opinion, one sees far more "Bent firewall, prop strike, cracked mains..." from aircraft allowed to touch down too fast that got into a porpoising/PIO mode. We've had more than one Cirrus fatal that started out that way and ended up in fatals and ended in botched go arounds.

Just watching GA planes land at a busy GA airport, my general impression is that many pilots land WAY fast and flat. It's not rare to see all three gear touch the ground simultaneously (talking nose dragger, of course). As I said before, since they all had to demonstrate landings at approximately stall speed to get their licenses, my working assumption is that at some point they just got lazy and/or lost proficiency. And we'll continue to see the effects of that in accident reports with numbing regularity going forward.
 
All right, one size does not fit all. Planes do differ. The way I land a no rudder pedals Ercoupe differs from how I land a Fly Baby (which has only the tires as a shock absorber -- the landing gear are solid wooden sticks), and it differs from the landing in an Archer.

And gusts, crosswinds, make a difference, too.

Each landing is a unique experience.
 
One issue is nose wheels. They have a lot of problems. Attempt to touch down too fast, and you "wheelbarrow" which can result in converting the airplane into a ball of aluminum scrap. A little slower and you land "flat", but it doesn't take much to get into the boing boing mode and stuff the nose gear through the firewall. Too slow and you drop it - depending on how far and the type of airplane, this can be an issue. Plus passengers seem to think a big drop and bounce is a bad landing (go figure). So, the solution is to land somewhere near (but not below) stall speed with the nose up - that protects the fragile nose gear, lets you touch down reasonably softly, and the airplane is less likely to try and fly again.

With a taildragger, you don't have the nose wheel problems so you can wheel land at a bit higher speed and still stick to the runway - no big deal. Under some conditions, in some aircraft, that is the easier way to land.
 
FastEddieB said:
Just watching GA planes land at a busy GA airport, my general impression is that many pilots land WAY fast and flat. It's not rare to see all three gear touch the ground simultaneously (talking nose dragger, of course). As I said before, since they all had to demonstrate landings at approximately stall speed to get their licenses, my working assumption is that at some point they just got lazy and/or lost proficiency. And we'll continue to see the effects of that in accident reports with numbing regularity going forward.
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I don't think that's the only explanation. I believe there's a lot of complacency in this area among instructors, and apparently DPEs.
 
Capt. Geoffrey Thorpe said:
One issue is nose wheels. They have a lot of problems. Attempt to touch down too fast, and you "wheelbarrow" which can result in converting the airplane into a ball of aluminum scrap. A little slower and you land "flat", but it doesn't take much to get into the boing boing mode and stuff the nose gear through the firewall. Too slow and you drop it - depending on how far and the type of airplane, this can be an issue. Plus passengers seem to think a big drop and bounce is a bad landing (go figure). So, the solution is to land somewhere near (but not below) stall speed with the nose up - that protects the fragile nose gear, lets you touch down reasonably softly, and the airplane is less likely to try and fly again.

With a taildragger, you don't have the nose wheel problems so you can wheel land at a bit higher speed and still stick to the runway - no big deal. Under some conditions, in some aircraft, that is the easier way to land.
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Think lots of those issues are with the pilots not the design.

With proper instruction even a solo student should be able to preform touch and goes, crossing the fence at VREF, touching the mains, adding power and taking back off without ever letting the nose wheel touch.
 
It depends on the plane, but with all the one's Ive flown, truth is, you don't have to. Instructors like to make students do it so the student gets the ability, but smooth, safe landings can occur above stall that is for sure.

Short field you should full stall it so you land at slowest possible speed (and plop it on, shorter if it bounces a bit)....Best short fields are hard. Not too hard though :)
 
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mscard88 said:
Exactly what I was thinking. Never had any damage stalling within say a foot of the runway during landing.
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It didn't stall. It just sank. Big difference.

The AoA of a wing in the three-point attitude, such as a Citabria, is 12°. Stall happens around 17°. A typical trike won't come any closer than that even if it bashes the tail on the runway. An exception might be the Zenair 701/801 or the Kodiak, which are designed for very high landing attitudes.

Stall speed also drops in ground effect. The surface inhibits the tip vortices and reduces the incoming upwash, reducing drag and increasing lift.

Take your XX-stall speed airplane up and do a power-off stall in it. Keep the altitude level until the stall by steadily bringing the nose up, and see what the ASI says when it breaks. It will indicate considerably lower than what the book value is just because of pitot position error.

Maybe there's a video somewhere of a tufted-wing airplane in a "full-stall" landing. Be interesting to see the tufts behave.
 
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