Can leaf stalls be taught in a 172???

Bill

Bill

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After trying leaf stalls in the Citabria, I was wondering if leaf stalls could be done in a typical training aircraft like a 172?

I haven't been spun yet, but even the leaf stalls really help drive home how helpful top rudder can be in a stall situation. Seeing that most PP students won't get a chance to spin, why not at least let them do leaf stalls and experience that?
 
Can you explain what a Leaf Stall is?
 
Greebo said:
Can you explain what a Leaf Stall is?
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I think he's describing what's more commonly known a falling leaf stall. It starts as a standard power off stall then just hold the yoke back at the stop after the break occurs. The nose will oscillate up and down (kind of like a leaf falling off a tree if you will) and you'll stay at real low airspeed until you relieve back pressure. In the meantime it's ready to drop off on one side given the opportunity so you really have to stay on top of the rudder to keep the ball in the center by looking outside for indications of roll or turn. The first time you do it through a couple oscillations, you're realize there's no point in fooling with the ailerons and the rudder has a lot more authority than you ever gave it credit for previously.

And yes, you can do them in CE172's. BTDT
 
fgcason said:
And yes, you can do them in CE172's. BTDT
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Yes, you sure can. It is how I was taught to relax my legs and use my feet in the Skyhawk.
 
They are fun in a skyhawk, and went a long way toward helping me get comfortable with stalls. I have done them in both older Hawks and a 172SP. The planes all handled them well.

Jim G
 
I've done 'em in a Archer too. Lots of fun and gets you quick in the feet.

The technique we used for the falling leaf stall was to bring it into a stall then dance back and forth on the rudder to have the wings alternate falling. Instructors who want the students to gain lots of confidence in the aircraft do teach this in primary, mine did.

Missa
 
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Interesting - I'd forgotten about this topic.

What is the purpose of training in falling leaf stalls?
 
Greebo said:
Interesting - I'd forgotten about this topic.

What is the purpose of training in falling leaf stalls?
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I think mainly to develop fast feet. Once you stall wings level, you put in a little rudder (which normally would cause you to spin), and then catch it the other way. Once started, you must continually dance on the pedals to keep the craft up, it really wants to fall hard to either side.

My instructor said to think of the airplane balanced on the end of a pencil, and by working the rudder, you're trying to keep it balanced.

Good way to see how top rudder works.
 
Bill Jennings said:
After trying leaf stalls in the Citabria, I was wondering if leaf stalls could be done in a typical training aircraft like a 172?

I haven't been spun yet, but even the leaf stalls really help drive home how helpful top rudder can be in a stall situation. Seeing that most PP students won't get a chance to spin, why not at least let them do leaf stalls and experience that?
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Sure, we do them in C172s all the time until we get tired of them. Helps take some of the surprises out of stalls/recoveries & really helps show where the aerodynamic lines are.
 
Do you do this with the stick all the way back? I find in my taildragger, that the pitch excursions get more and more agressive, eventually getting fairly violent. I don't remember that behavior in a Skyhawk.
 
Yep, you can do them in a Skyhawk. You can do them in a Warrior or an Archer or just about any other trainer too.

I do them with my students from time to time, especially if, as one inherited student said to me on one of our first flights, "you know, I've never really understood exactly what the rudder is for in a stall." Hmmmm, well, let's go find out! :)

I also give my students the opportunity to do spin training if they so desire. If they're training in an Archer or other non-spinnable aircraft, we use a Cessna for the day. I don't push them into it, but always make the opportunity available. Most wind up doing a lesson at some point.

Carolyn
 
lancefisher said:
Do you do this with the stick all the way back? I find in my taildragger, that the pitch excursions get more and more agressive, eventually getting fairly violent. I don't remember that behavior in a Skyhawk.
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In the Citabria, we did it full stick back. I don't recall any pitch excursions, the plane held her nose high. The back and forth motion did get more violent as the airspeed continued to bleed off, which makes sense as the rudder has less airflow, thus less authority.
 
Every one of my students does this maneuver. C140, C172, C150. Engage slowflight stall horn chirping. Pitch back until one wing drops- pick up with rudder. hold it there until the other one drops- same. Stop when altitude cushion gets less than cushy. Maybe the student will add power and try to continue... :)
 
Bill Jennings said:
In the Citabria, we did it full stick back. I don't recall any pitch excursions, the plane held her nose high. The back and forth motion did get more violent as the airspeed continued to bleed off, which makes sense as the rudder has less airflow, thus less authority.
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The Decathlon doesn't want to stall unless the stick is all the way back. Sometimes I think it's all the way there, but it's not -- got to be really forceful with it. I've done this kind of stall, but had just a little side to side movement, not much. Is the amount of swing different in different airplanes?
 
I remember them well when I was begining my training. It is a great way to learn and feel rudder effectiveness in near stall to stall flight. The early Champs were so fun to fly these. When I can I still get out and practice them. The 172 is a great plane to do these.

John J
 
I was searching for more references for Tristan and guess what comes up? :)
 
Greebo said:
What is the purpose of training in falling leaf stalls?
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Bill Jennings said:
I think mainly to develop fast feet.
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"Fast" feet isn't really the goal...the goal is to learn to use rudder to pick up a wing IN a stall (not immediately prior to--that's still supposed to be a coordinated action.)

Particularly with older airplanes, an attempt to pick up a wing with aileron in a stall can result in a spin. The "proper" way to pick up a wing or stop a spin in that situation is with rudder.

More "modern" airplanes, the 172 included, can still be used to teach falling leaf stalls, but the reason behind the maneuver is more difficult to demonstrate...they have enough washout in the wings that in the initial phases of a stall, the wingtips (and ailerons) are still flying, so you can normally get away with using aileron to pick up the wing. Older designs, such as Champs and Cubs, don't have enough washout to keep the ailerons flying, and often don't have the differential aileron with its associated benefits, so they're much more likely to get you in trouble if you use aileron to try to pick up a wing in the stall. And I HAVE seen a student snap-roll a 152 with aileron input, so modern airplanes can still get you in trouble with poor technique.

Fly safe!

David
 
I've only done it in a J3, which is well-suited for practicing that. I agree with David- it helps your footwork in general, but the real purpose is to get a feel for controlling roll when the wing is stalled (or so close to stalled that the ailerons will not help).
It's also a lot of fun. :D

As my Cub instructor explained it, with that type of plane especially, there is a point in a "deep stall" where aileron will not only not do what you want, it can have the opposite effect!
 
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I've done them in a 152 in which they are very fun, However; to get really good at rudder my CFI has me do the dutch roll maneuver.
 
I was taught to do them during my Tiger checkout. I was told that in that airplane they work well, and it's more important to keep a wing from falling off during the stall because when they spin, they tend to spin flat.
 
MauleSkinner said:
Particularly with older airplanes, an attempt to pick up a wing with aileron in a stall can result in a spin. The "proper" way to pick up a wing or stop a spin in that situation is with rudder.

More "modern" airplanes, the 172 included, can still be used to teach falling leaf stalls, but the reason behind the maneuver is more difficult to demonstrate...they have enough washout in the wings that in the initial phases of a stall, the wingtips (and ailerons) are still flying, so you can normally get away with using aileron to pick up the wing. Older designs, such as Champs and Cubs, don't have enough washout to keep the ailerons flying, and often don't have the differential aileron with its associated benefits, so they're much more likely to get you in trouble if you use aileron to try to pick up a wing in the stall. And I HAVE seen a student snap-roll a 152 with aileron input, so modern airplanes can still get you in trouble with poor technique.
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Y'know, I know what you say is true, but now I'm having trouble making sense of it for some reason.

The reason we don't want to pick up a wing with aileron is because the down aileron increases angle of attack and thus might stall first/more and drop the wing instead of raising it, right?

But if we raise the wing solely with rudder, we're gonna be very uncoordinated for a moment, so doesn't THAT risk making the airplane spin? In fact, that would be a skid - And aren't skids worse than slips even in a "nice" airplane like the 172?

So, wouldn't the proper action be a coordinated input of rudder and aileron, recognizing that the deflections might not be exactly what we're used to in more normal flight regimes?
 
flyingcheesehead said:
But if we raise the wing solely with rudder, we're gonna be very uncoordinated for a moment, so doesn't THAT risk making the airplane spin?
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Only if you get it wrong. The reason the wing is dropping in the stall is that you're already uncoordinated. If you pick it up with the rudder, you're simply reestablishing coordinated flight. If you're not uncoordinated, you can't spin.
 
jmaynard said:
Only if you get it wrong. The reason the wing is dropping in the stall is that you're already uncoordinated. If you pick it up with the rudder, you're simply reestablishing coordinated flight. If you're not uncoordinated, you can't spin.
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I would think that enough rudder to stop the wing drop (ignoring any overbanking tendency) would be the amount that should have been applied to begin with, and that enough rudder to actually lift the wing, with no application of any aileron at all, would be uncoordinated in the opposite direction.

The scenario here, of course, is a power-on stall without right rudder. Stall, left wing drops first, I would think that the proper control input would be enough rudder to counteract the left-turning tendencies, plus aileron to actually lift the wing, plus enough additional rudder to counteract the adverse yaw effects of the aileron input.

I would think that once the wing drops, an input of rudder ONLY in a fashion to return to coordinated flight should result in a coordinated turn at the same bank angle (again, ignoring overbanking and such).
 
flyingcheesehead said:
I would think that enough rudder to stop the wing drop (ignoring any overbanking tendency) would be the amount that should have been applied to begin with, and that enough rudder to actually lift the wing, with no application of any aileron at all, would be uncoordinated in the opposite direction.
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I take it you haven't played this game.

I would think that once the wing drops, an input of rudder ONLY in a fashion to return to coordinated flight should result in a coordinated turn at the same bank angle (again, ignoring overbanking and such).
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When I've done this, it's been straight and level.

Being "coordinated" is to prevent a wing from dropping. Once one starts to drop (stall more deeply than the other wing) for other reasons, you need to pick it back up to prevent the stall from converting into a spin. using aileron increases the angle of attack of the dropping wing which just pushes it further down the back side of the lift curve (deeper into the stall). In an aircraft that is reluctant to spin, this is the kind of thing you do to help it get into a spin.
 
Capt. Geoffrey Thorpe said:
I take it you haven't played this game.
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I have, and I know how the airplane reacts, but I'm trying to understand the "why" better.

Being "coordinated" is to prevent a wing from dropping. Once one starts to drop (stall more deeply than the other wing) for other reasons, you need to pick it back up to prevent the stall from converting into a spin. using aileron increases the angle of attack of the dropping wing which just pushes it further down the back side of the lift curve (deeper into the stall). In an aircraft that is reluctant to spin, this is the kind of thing you do to help it get into a spin.
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Right... But why does the application of rudder with no aileron, which (I think) results in being uncoordinated in the opposite direction, not cause problems as well?
 
flyingcheesehead said:
I have, and I know how the airplane reacts, but I'm trying to understand the "why" better.
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You are on the back side of the lift curve where increasing the angle of attack DECREASES lift (you are on the right hand part of the curve below). This is an unstable situation - if a wing starts to drop just a little, the angle of attack increases which causes a reduction of lift which causes the wing to drop faster which causes...

Aileron doesn''t work because it increases the angle of attack which (unlike in normal flight) decreases lift.
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Right... But why does the application of rudder with no aileron, which (I think) results in being uncoordinated in the opposite direction, not cause problems as well?
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Forget about coordination - you are trying to balance the lift between the two wings. So, if the right wing drops, pushing on the left pedal speeds up the right wing which decreases the angle of attack (as well as making it go faster than the left wing) and lets it generate more lift and you pick it back up.

Being coordinated helps avoid dropping into a spin at the time that you stall, but once the wing is stalled and you are operating on the back side of the lift curve, the way the wings react to changes in angle of attack are different...
 
flyingcheesehead said:
Right... But why does the application of rudder with no aileron, which (I think) results in being uncoordinated in the opposite direction, not cause problems as well?
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No...when a wing drops in the stall, it's an incipient spin. You're simply doing a spin recovery before the spin gets very far along. Applying rudder actually puts you in a slip rather than a skid, but will become a skid if you hold it long enough, and of course must be stopped before it becomes a skid...and holding the stall while balancing aerodynamically with the rudder is what we're doing with the falling leaf stall.
 
Bill Jennings said:
After trying leaf stalls in the Citabria, I was wondering if leaf stalls could be done in a typical training aircraft like a 172?
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I had to demonstrate them in the '150 for my 3rd class SODA checkride (I walk with a limp). Hold the yoke back, keep the wings as level as possible while it bobs up and down.
 
Capt. Geoffrey Thorpe said:
Forget about coordination - you are trying to balance the lift between the two wings. So, if the right wing drops, pushing on the left pedal speeds up the right wing which decreases the angle of attack (as well as making it go faster than the left wing) and lets it generate more lift and you pick it back up.
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That's how I've always heard it explained, too...
 
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What you are really doing in using rudder while holding the stick full back is cancelling out adverse yaw. If you keep adverse yaw from developing, you can just sit there with the stick full back and the nose will bob up and down. You can lose a lot of altitude pretty fast that way. As long as you keep the adverse yaw from developing, the airpland won't spin. If you let the airplane yaw a little, it will swing back and forth while descending, just like a leaf falling.
 
My DPE demonstrated it during my Private Pilot check ride.. C-150 way back when (1974). Then he had me try it, no problems at all. Turns out the DPE always likes to "teach something" during the check rides if all is going well.
 
somorris said:
What you are really doing in using rudder while holding the stick full back is cancelling out adverse yaw. If you keep adverse yaw from developing, you can just sit there with the stick full back and the nose will bob up and down. You can lose a lot of altitude pretty fast that way. As long as you keep the adverse yaw from developing, the airpland won't spin. If you let the airplane yaw a little, it will swing back and forth while descending, just like a leaf falling.
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I think you're misusing the term "adverse yaw" unless you are referring to use of the rudder along with aileron deflection. If the ailerons aren't being moved off center, there can be no adverse yaw.

I wanted to add a couple other points about the maneuver.

One is that lowering the aileron on a "dropped" wing doesn't by itself necessarily cause an increase in AoA, what you are actually doing is increasing the camber. With both wings partially stalled, the use of aileron will generally still raise the low wing if you apply some rudder with the aileron, especially if you aren't too agressive with the ailerons. (edit: deleted nonsense about rising wing increasing AoA).

The other is that no matter what you do with ailerons, if you keep the airplane from yawing it cannot spin. Doing this with rudder you may end up with some significant swings in roll, but as long as you keep the nose pointed in the same direction there will be no spin.
 
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gismo said:
I wanted to add a couple other points about the maneuver.

One is that lowering the aileron on a "dropped" wing doesn't by itself necessarily cause an increase in AoA, what you are actually doing is increasing the camber. Indirectly though the AoA does increase as soon as the wing starts to rise (think relative wind here, wing goes up making the relative wind vector come from further below).
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This sounds backwards. When the wing starts to rise, the AoA will be reduced, as the relative wind will be coming from a higher spot as the wing travels upwards.
 
Wahtorskeer: You're right. I should have simply said "yaw" not "adverse yaw." Good catch -- thank you.
 
flyingcheesehead said:
This sounds backwards. When the wing starts to rise, the AoA will be reduced, as the relative wind will be coming from a higher spot as the wing travels upwards.
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It is backwards. I don't know what I was thinking, blame it on a hard day of skiing in the mountains. I'll see if I can edit the post to make sense.
 
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