Yoke deflection, load factor & stall

dtuuri said:
THIS party realizes it. He can point to an unimpeachable source to back him up too: Stick and Rudder, page 221.
THIS pilot has a couple thousand hours legally teaching these things to mostly primary students too.

dtuuri
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No doubt, but both you and Stick And Rudder are assuming coordinated level turns, and are ignoring propwash. Nothing is wrong with either of those, but it is not the only way to describe this problem. Your opponent made a different choice.

If you include propwash, your feet directly measure what you're trying to describe, in a much more general context. And among student pilots, assuming coordinated turns isn't the best assumption....
 
gismo said:
I'm stuck with the concept that as long as the tail is flying the same arc as the wing, the angle between a tangent to the circle will have the same angle to the tail a and wing as they have when generating the same amount of lift in level flight. To me that means the "authority" of the elevator would be the same in either case.
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I appreciate that you're trying to see my point. How about the wing itself, then. Two-thirds of it is behind the CG, at a slightly (very slightly) higher angle of attack. The forward third is less than at the CG. Does this not produce more of a nose-down moment than in straight flight where all three areas are at the same AoA?

dtuuri
 
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MAKG1 said:
No doubt, but both you and Stick And Rudder are assuming coordinated level turns, and are ignoring propwash.
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Actually, I'm not. See my post #26 where I discuss propwash. Coordination plays no part of my explanation for why the OP's observations happen.

MAKG1 said:
Nothing is wrong with either of those, but it is not the only way to describe this problem. Your opponent made a different choice.
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FlyingRon? Opponent? Antagonist is more like it.

MAKG1 said:
If you include propwash, your feet directly measure what you're trying to describe, in a much more general context.
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I was trying to describe 'g' force as the result of AoA. Propwash affects elevator in my discussion; where your feet are have nothing to do with why the plane doesn't stall. Might have had something to do with why it stalled violently, but he didn't ask that (or I didn't reply to that if he did).

MAKG1 said:
And among student pilots, assuming coordinated turns isn't the best assumption....
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Now there's something I can agree with. :wink2: Amen brother! Now I know you've BTDT.

dtuuri
 
dtuuri said:
That's apparently what the captain on Colgan Air in Buffalo thought too. Check out the control wheel excursions after the stall on the FDR traces:dtuuri
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I don't care what he did. Without reading the report, I figure out that aileron was used DURING stall, before stall recovery. I said very clearly that you return wings level using ailerons AFTER you recovered, not during stall. Why do you select my statements from posts context to look like being wrong?
 
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Richard_SWave said:
I don't care what he did. Without reading the report, I figure out that aileron was used DURING stall, before stall recovery. I said very clearly that you return wings level using ailerons AFTER you recovered, not during stall. Why do you select my statements from posts context to look like being wrong?
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It can be done either way. I use rudder during stall recovery to level the wings. My stalls always drop straight ahead. That can only be done by using rudder during the stall - unless you get very lucky and the plan just happens to drop the nose without dropping a wing - which is rare unless...wait for it....wait for it...wait for it...you use the rudder during the stall.
 
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Richard_SWave said:
I don't care what he did. Without reading the report, I figure out that aileron was used DURING stall, before stall recovery. I said very clearly that you return wings level using ailerons AFTER you recovered, not during stall. Why do you select my statements from posts context to look like being wrong?
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You should care a lot. Read the report too. "After the stall" was taken by me to mean "After the break". You apparently mean "back in normal flight". One of us is having problems with English.
EDIT: After re-reading your post, I see now what you meant. The first time I couldn't understand the first sentence at all ("And I guess you meant with after the stall, after stall entry during stall, not after the stall recovery"), so I disregarded it. Sorry 'bout that.

dtuuri
 
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dtuuri said:
"After the stall" was taken by me to mean "After the break". You apparently mean "back in normal flight".
dtuuri
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Don't know what you mean with "break", but I guess "break the stall", as an expression, means to push forward to unstall the wing. So, "after the break" should be "back in normal flight", shouldn't it?
 
Richard_SWave said:
Don't know what you mean with "break", but I guess "break the stall", as an expression, means to push forward to unstall the wing. So, "after the break" should be "back in normal flight", shouldn't it?
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(sigh)

dtuuri
 
EdFred said:
It can be done either way. I use rudder during stall recovery to level the wings.
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I think the main reason for not being recommended is that you induce yaw when you use the rudder. So, why to induce yaw in the opposite way during a stall? Assuming you were coordinated when you stalled, the wing drop is not because of yaw towards the low wing. So, no need to coordinate or to cancel any yaw imbalance. Push forward to unstall, after that when you are not anymore stalled, level the wings using ailerons.
 
Richard_SWave said:
Don't know what you mean with "break", but I guess "break the stall", as an expression, means to push forward to unstall the wing. So, "after the break" should be "back in normal flight", shouldn't it?
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You've suggested that you've finished primary training. I'm having some trouble believing that. In fact, that you're missing basic terminology at every turn suggests you have very little time, if any, at all. These questions are natural and expected after ground school and/or a lot of reading, but not after going through a complete primary training regimen. In particular, you seem never to have experienced a real stall (at least, while at the controls). And that's part of every PP-ASEL practical test I've ever heard of.

PTS VIII.B.6. and VIII.C.6.

A stall break is the (possibly quite small) uncommanded nose drop that indicates a fully developed stall.
 
Richard_SWave said:
I think the main reason for not being recommended is that you induce yaw when you use the rudder. So, why to induce yaw in the opposite way during a stall? Assuming you were coordinated when you stalled, the wing drop is not because of yaw towards the low wing. So, no need to coordinate or to cancel any yaw imbalance. Push forward to unstall, after that when you are not anymore stalled, level the wings using ailerons.
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Because enough aileron use can stall a wingtip, leading to a much worse stall, particularly with power on (182s are notorious for this at full power). You can't do that with the rudder. The change in heading is usually pretty small, if done reasonably well. And, frankly, the point is practicing what happens on base-to-final or departure if you screw up bad. The direction you're going afterward is usually far less important than just to still be going afterward.

Controlling with the rudder is very much recommended in a stall.

You need to get up with an instructor to a reasonable altitude and practice this.
 
MAKG1 said:
Because enough aileron use can stall a wingtip, leading to a much worse stall, particularly with power on (182s are notorious for this at full power). You can't do that with the rudder.
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Oh, yeah, for sure, you are not going to induce a much worse stall by unnecessary misusing the rudder during stall, but you are going to induce a much worse stall if you use the ailerons when you are not stalled. Really funny. To not say anymore that the wing stall first at the root and other aspects. Let's ban using the ailerons in slow flight, would you agree? I guess so.
 
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Richard_SWave said:
Oh, yeah, for sure, you are not going to induce a much worse stall by unnecessary misusing the rudder during stall..
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Nope, just a spin. I don't know what a "much worse" stall is.

Richard_SWave said:
...but you are going to induce a much worse stall if you use the ailerons when you are not stalled.
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Oh really? Have you ever tried to stall an airplane from a full deflection slip, simulating a slip to land?

Guys, hope you have learned a lesson here...never argue with a 120 hr 172 pilot. ;) I'm just hard-headed I guess.
 
I'm sorry if you have not noticed the irony in reply to the above message. I was not the one who says what a much worse stall is. Read the posts above if you really want to get the point, don't come and read the last message and then reply meaningless.


MAKG1 said:
Because enough aileron use can stall a wingtip, leading to a much worse stall, particularly with power on (182s are notorious for this at full power). You can't do that with the rudder.
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Have you read it?
 
Swave guy...

Since you are not adressing the questions, I will say this...

1) Aileron input (up to max) can aggravate a stall, but not always

2) Rudder input (up to max) can aggravate a stall, but not always

3) Sometimes it's impossible to produce a spin with full rudder

4) Sometimes it's possible to produce a spin with NO rudder

Sorry if you don't understand these points or disagree with them. These things are true. If your instructor cannot explain these things, then that's not necessarily surprising. You currently live in the low-level minimum PTS standards of basic PPL training. You speak in generalities. Flight is too complex to generalize. And you continue to argue with those who have much more experience than you because you don't understand the complexities...because you have not experienced them. You seem to feel you have gained as much knowledge and experience as anyone after spending 120 hours in a 172.

If you come back and read this thread after a 1000 more hours, I'll bet you'll wish you had zipped it earlier.
 
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You may be right, I have some ideas about all those points, but probably I don't understand them at all. What if you would help me and write a little about each one of them? I would really appreciate.
 
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Richard_SWave said:
You may be right, probably I don't understand those points at all. What if you would help me and write a little about each one of them? I would really appreciate.
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No thanks, you have not shown much receptiveness to anything contrary or in addition to what your instructor has taught you...or to anything that you "know" to be true at this point in your extremely short flying career.
 
RoscoeT said:
or to anything that you "know" to be true at this point in your extremely short flying career.
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Because there were recommendations that were not relied on anything conclusively, eventually, searching now on the Internet, surprising we are not the only ones who argue on this topic, it is a hard debated issue and I found that this technique to pick-up the wing using rudder is more like an obsolete one still unnecessary used by some instructors perhaps because it was taught in their times, I don't know. Eventually this technique might be used to arrest any further roll, but not necessary to push it further to level the wings.
 
Richard_SWave said:
You may be right, I have some ideas about all those points, but probably I don't understand them at all. What if you would help me and write a little about each one of them? I would really appreciate.
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There are several already in existence. Probably the best for pilots is the Stick and Rudder book by Langewiesche.

It may be old, but stick and rudder flying is remarkably similar to his time (except maybe that tailwheels are the exception now, rather than the rule).

When you're not willing to listen to others, it's not reasonable to expect the same people to teach you for free.
 
Hold up a minute, gotta get more popcorn.
 
Richard_SWave said:
You may be right, I have some ideas about all those points, but probably I don't understand them at all. What if you would help me and write a little about each one of them? I would really appreciate.
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Over the past few days, I believe it seems like years, alot was put out there to you about all of this....and good reading suggestions (especially stick and rudder). The crux of the whole issue was angle of attack and coordinating the aircraft as much as possible in whatever phase of flight and/or recovery you may be in.

I have to ask, how old are you, because the manner in which you keep reaching for information seems very awkward, almost child-like. Over analysis isn't going to help you. Experience will. You need to put alot more time under your belt and challenge yourself, with an instructor, to see how all the theoretical issues you seem to need to discuss to distraction actually work.

Quite frankly, nothing personal, I'm far from perfect, but I am being honest here, I would be scared sh*tless to be in an aircraft, at this point in time, where you are PIC and had to face making a crucial decision in flight, to react to an unexpected event...because you just can't over analyze everything that happens in the aircraft. You become a passenger rather than the PIC.

Go out and just fly, fly some more, and then some more.
 
remember, its no the Gs that make an airplane stall. Its the ANGLE OF ATTACK!!! You can be doing 3 times Vs and bank until your angle of attack is above critical by maintaining altitude and you will stall. However, you feel Gs because as you are banking you loose lift and thus you pull back to maintain altitude. The faster you are going the harder you need to pull back the stabilizer and thus the bigger angle of attack causes the wing to stop flying. AOA not airpseed!
 
MAKG1 said:
An airplane is a dirty system that really doesn't lend itself well to simplification. For instance, the rudder doesn't really just yaw the aircraft, but will roll it as well.
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It rolls mostly because the outside wing is now going faster than the inside wing, and producing more lift.

Picking up the wing with rudder is the proper phraseology taught by instructors, but its not quite 100% accurate.

I once demonstrated a power on stall for an instructor and got reprimanded for using aileron to pick up a wing. What did I do wrong? Nothing. I dropped the nose, stopped the turn with opposite rudder, and the moment I felt the plane come out of the stall and start flying again, I rolled in some aileron as well.

Its true that you should not use aileron while the airplane is stalled. It can lead to or worsen a spin. But with practice you can feel exactly when the plane becomes un-stalled and starts flying agin.
 
RoscoeT said:
Oh really? Have you ever tried to stall an airplane from a full deflection slip, simulating a slip to land?
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Now that the gopro is back in action I need to go play with a few of these. After one of the great slip to land vs stabilized approach debates on here, I went out and shot some footage at altitude stalling the plane in a full deflection slipping vs a skidding turn. One was a wild ride, the other not so much. Unfortunately the go pro broke and the footage got erased.
 
I thought the issue with slipping vs. skidding stalls was that the slipping stall was more difficult to produce and would dip the inside wing, where recovery means taking your foot off the rudder. The skidding stall would dip the outside wing and recovery is a problem because you already have too much rudder in that direction.
 
MAKG1 said:
I thought the issue with slipping vs. skidding stalls was that the slipping stall was more difficult to produce and would dip the inside wing, where recovery means taking your foot off the rudder. The skidding stall would dip the outside wing and recovery is a problem because you already have too much rudder in that direction.
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Other way around. A skidding stall drops the inside wing.

In a descent, the inside wing is already at a higher AOA even when the airplane is coordinated. Skidding it increases that AoA difference, making the inside wing stall much sooner than the outside wing and leading to the spin.

Go to this thread http://www.pilotsofamerica.com/forum/showthread.php?t=40070&highlight=AoA+table&page=4 and scroll down to post #93 to see the pictures.

Dan
 
Dan Thomas said:
In a descent, the inside wing is already at a higher AOA even when the airplane is coordinated. Skidding it increases that AoA difference, making the inside wing stall much sooner than the outside wing and leading to the spin.

Go to this thread http://www.pilotsofamerica.com/forum/showthread.php?t=40070&highlight=AoA+table&page=4 and scroll down to post #93 to see the pictures.

Dan
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Very impressive visual aid you have there! I'm envious. It illustrates the "boom effect" nicely. It also exaggerates the nose-down moment I mentioned in post #82, where the aft 2/3 of the wing is at a higher AoA than the forward 1/3. In fact, that's what seems to be the point of your model, not what you say in your post. But I should be careful not to argue with an aeronautical engineer--:eek: you aren't one, I hope, are you? I have a hard time convincing myself that the inside edge of the coil spring sitting on my desk magically has a steeper slope than the outside edge. Would climbing a spiral staircase near the inside be a steeper climb than farther out?

I would need to compare the same point on each wing instead of the trailing edge vs. the leading edge. Since the upper surface appears to have a triangular shape, perhaps placing the plane under the rails so the apex is pivoting on the rails would be a more accurate way to consider this? Also, is there dihedral built into the wing? Dihedral should decrease the AoA of the inside wing and increase it on the outside in a skid--exactly opposite of what your pictures appear to show.

dtuuri
 
dtuuri said:
Very impressive visual aid you have there! I'm envious. It illustrates the "boom effect" nicely. It also exaggerates the nose-down moment I mentioned in post #82, where the aft 2/3 of the wing is at a higher AoA than the forward 1/3. In fact, that's what seems to be the point of your model, not what you say in your post. But I should be careful not to argue with an aeronautical engineer--:eek: you aren't one, I hope, are you? I have a hard time convincing myself that the inside edge of the coil spring sitting on my desk magically has a steeper slope than the outside edge. Would climbing a spiral staircase near the inside be a steeper climb than farther out?

I would need to compare the same point on each wing instead of the trailing edge vs. the leading edge. Since the upper surface appears to have a triangular shape, perhaps placing the plane under the rails so the apex is pivoting on the rails would be a more accurate way to consider this? Also, is there dihedral built into the wing? Dihedral should decrease the AoA of the inside wing and increase it on the outside in a skid--exactly opposite of what your pictures appear to show.

dtuuri
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The dihedral doesn't change things much. The angle of incidence is still the same, so the AoA is about the same.

Yes, a spiral staircase is steeper on the inside. You climb the same amount with each step, but travel less distance. The handrails make it really clear.

I'm not an aeronautical engineer.

Dan
 
Dan Thomas said:
The dihedral doesn't change things much. The angle of incidence is still the same, so the AoA is about the same.
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There's a significant difference to my eye. See 'dihedral' in Stick and Rudder.

Dan Thomas said:
Yes, a spiral staircase is steeper on the inside. You climb the same amount with each step, but travel less distance. The handrails make it really clear.
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So which way is more difficult, the steeper slope or the shallow one?

Dan Thomas said:
I'm not an aeronautical engineer.
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Great! Me neither.

dtuuri
 
dtuuri said:
So which way is more difficult, the steeper slope or the shallow one?
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The steeper one, but only because the stairs are so narrow. You foot can slip off if the staircase is wound tightly enough around the vertical axis.

Dan
 
Dan Thomas said:
The steeper one, but only because the stairs are so narrow. You foot can slip off if the staircase is wound tightly enough around the vertical axis.

Dan
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I've been out all day and, with tired mind, sat here to contemplate this again. I can see the person farthest from the center having to cover more ground in the same time as the person closest to the center, so the outside shallower slope would seem to mean more effort (power) is required, which is counter-intuitive to me. Probably not germane to the AoA discussion either...

Compared to your model, a more realistic scale would be if the plane were small enough in wing span to fit within a hollow 1/4 inch rail located where your's is the farthest from the center. I'm trying to wrap my mind around the true magnitude of the difference in the two wings' AoAs. And why should the pull of gravity, from ahead in a descent to behind in a climb, make a difference? Too brain-dead tonight, though. Maybe somebody like gismo will jump in.

dtuuri
 
During flare, after using the crab method to compensate for a crosswind, when you de-crab you are cross-controlling close to stall speed, why there's no wing drop or even an incipient spin behaviour? I figure out it may be a slip here, but you are wings levek, not banked as in a slip and being so close to stall, why opposite aileron doesn't increase the angle of attack of the opposite wing?
 
Richard_SWave said:
Interesting, I figure out if you don't have enough authority in an emergency (too aft CG, elevator control problem etc.) to avoid a stall, you might be more able to handle it somehow banking hard, maybe toward a knife edge attitude, or I'm entirely wrong?
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You're wrong and if you try it in a c172 the result will not be good.

Now, go find an aerodynamics course at your local college then come back and review this thread. You'll understand more of it.

G's don't matter. Speed don't matter. AoA is the only physical constraint that matters.
 
MAKG1 said:
Mr. Swave, I think a lot of these questions could be resolved if you grabbed an instructor and tried a few stalls. Meanwhile, try to visualize the angle of attack. You'll have it right when the horizon doesn't matter. AoA is the angle between wing chord and your 3D velocity.
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I'm still trying to figure out the original question.
 
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