What factors contribute to wing drop?

MAKG1 said:
That makes all kinds of sense for a power-on stall, but I don't understand how it's a factor at idle power. P-factor should be negligible if the engine is throttled.
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True, but an idling engine is still producing some thrust that must be corrected for. Walk behind an idling prop- gotta hold your hat.

MAKG1 said:
Now, I'm certain I'm missing something, as there sure seems to be very noticeable left turning tendency in a 182 during flare. Maybe gyroscopic effect? The engine may not be producing that much thrust, but it's still spinning at almost half speed.
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The 182 is where I first began to notice the left turning during flare, since the prop is still producing a noticeable amount of thrust and left yaw due to P-Factor.
...and started noticing it even in a 152 on calm mornings when the new student would flare and yaw left slightly, which he wouldn't see, and the yaw isn't quite enough for a new student to see, and the subsequent slightly yawed landing is perceived as passable.

The gyroscopic effect is happening only during the actual moments that you are pulling the yoke. During those moments, the spinning gyro tries to go right , so a smooth continuous pull would counter the increasing left pull of the P-Factor yaw. But it hardly ever works out that way. Usually you are floating a bit with the nose high and pulling left.

...and so, to sum it all up, between all four torque forces; p-factor, gyro effect, corkscrewing, and lack of engine torque, and squirrely winds, the main point to learn in stalls, and landings, is to focus on keeping the nose straight with rudder. All the time. No matter what it takes. You cannot accurately predict a set direction or amount of neeeded rudder pressure because of all the variables that are also interacting with each other.

That's why the old tailwheel was such a good trainer. You had to, had to, have a positive control of yaw with rudder to land straight before you solo'ed.
You had to. And you knew you had to.
 
CTLSi said:
A cross wind will kick a wing up, lowering the opposite wing. When you nose over after the stall, note if a cross wind exists and press the rudder a little into it as you go over the hump.
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We just got back from a hot-air balloon flight. Nice flight, wind wasn't bad except the crosswind messed up my hair. :yes:
 
nosehair said:
True, but an idling engine is still producing some thrust that must be corrected for. Walk behind an idling prop- gotta hold your hat.
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While flying, the thrust is negative. The air is pushing the prop, rather than the other way around. The evidence is that your engine "idles" at glide faster than it idles on the ground.

nosehair said:
The gyroscopic effect is happening only during the actual moments that you are pulling the yoke. During those moments, the spinning gyro tries to go right , so a smooth continuous pull would counter the increasing left pull of the P-Factor yaw. But it hardly ever works out that way. Usually you are floating a bit with the nose high and pulling left.
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Well, I don't float much at all in a 182 with 40 flaps and an idle engine; they slow down in a big hurry. So, I'm "pulling" all the time during the flare. And I get that the gyroscopic effect goes the other way. Left as you pull the nose up, right as you let it down.

Now, in slow flight, you can clearly feel the P-factor. But that's at high power.
 
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MAKG1 said:
And I get that the gyroscopic effect goes the other way. Left as you pull the nose up, right as you let it down.
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Reverse that - with "normal" turning engines, a pitch up will produce a right gyroscopic force, a pitch down a left force. Though it theoretically exists during landing, it is IMO, virtually undetectable in most airplanes - especially common GA planes, given the low propeller mass to aircraft mass ratio and the fact that the prop is turning very slowly at idle power. Not enough of an effect to really show itself or require correction. Also, the pitch rate during landing is very slow. If you have a metal prop, and could produce a very fast pitch action at very low airspeed at full power, then you might just start to see something. Aerobatic pilots of high power-to-weight ratio ships with metal props are used to making subtle corrections for this effect, but it's not a factor in most other airplanes.

MAKG1 said:
Now, in slow flight, you can clearly feel the P-factor. But that's at high power.
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Yes, just keep in mind for the sake of accuracy that there are two yawing forces - asymmetric prop thrust (P-factor) as well as spiraling propeller slipstream hitting the vertical stab. Two distinctly different forces working in the same direction that some people (not saying you) improperly use "P-factor" as a catch-all for.

In my strong opinion, slipstream is a much more significant yawing force than P-factor in most airplanes. The Ercoupe uses twin vertical stabs outside the propwash to avoid slipstream yaw, but this does not address P-factor. It got along OK with no independent rudder control or ability to control P-factor.
 
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Yeah, can't ever recall feeling any effect on landing, even with a tail dragger, take off, yeah lol.
 
Henning said:
Yeah, can't ever recall feeling any effect on landing, even with a tail dragger, take off, yeah lol.
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"Something" yanks the nose left noticeably while flaring a 182.

I think Roscoe is saying it's spiraling slipstream, which makes some sense at low airspeed. But I don't see why it should be any stronger in a 182 than a 172RG (which also has the CS prop).
 
MAKG1 said:
"Something" yanks the nose left noticeably while flaring a 182.

I think Roscoe is saying it's spiraling slipstream, which makes some sense at low airspeed. But I don't see why it should be any stronger in a 182 than a 172RG (which also has the CS prop).
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Are you flaring with power or idle? I can't imagine residual idle P-factor and slipstream would be enough to cause a significant yaw during the roundout/flare. If you're rounding out/flaring with a touch of power, I could see P-factor and slipstream coming into play. A 182 of course has a little higher power to weight ratio than a 172, so I would expect these forces to be slightly stronger.
 
RoscoeT said:
Are you flaring with power or idle? I can't imagine residual idle P-factor and slipstream would be enough to cause a significant yaw during the roundout/flare. If you're rounding out/flaring with a touch of power, I could see P-factor and slipstream coming into play. A 182 of course has a little higher power to weight ratio than a 172, so I would expect these forces to be slightly stronger.
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When I was originally trained on a 182, I was taught to land with power or less than full flaps. I've since changed that. It's almost always power off with full flaps. I can still feel "something" pulling the airplane left as the nose comes up.
 
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CTLSi said:
A cross wind will kick a wing up, lowering the opposite wing. When you nose over after the stall, note if a cross wind exists and press the rudder a little into it as you go over the hump.
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What about a downwind turn?
 
JoeSelch said:
What about a downwind turn?
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Only a problem if you are trying to maintain a constant reference to the ground at very slow speed. See "moose stall". If you are not referencing the ground then neither applies.
 
As Silvaire has pointed out, this airplane likely has some imperfections in its rigging. The 172 has eccentric bushings in the aft spar attach points that permit the trailing edges of the wing to be adjusted up or down a bit to compensate for any wing-heaviness. If one of the wings has been poorly jigged at the factory it may have more or less washout than the other wing and will cause some wing-heaviness which then gets adjusted out, or the fuselage center section might be off and the incidence is then not quite right, again requiring adjustment. In any case, the wing with higher incidence or with less washout will stall first, usually, and drop.

Still, 172s have a really benign stall and this one is misbehaving. Maybe that turn coordinator isn`t level in the panel. Its screws are in slots for adjustment. Maybe there are some generators of turbulence atop the right wing. Most 172s will drop the left wing in a power-on stall due to prop torque reaction and the higher angle of attack on the left wing root caused by the spiralling slipstream.

Dan
 
Everyone knows the wind only matters in a downwind turn.

OP, I think the important question is, how's your recovery? Deliberately stalling the plane is not a normal maneuver. As long as you can recover from various stalls and incipient spins, it's be happy. The fact that you do the entry "wrong" seems less important. But maybe I'm missing something
 
Lindberg said:
Everyone knows the wind only matters in a downwind turn.

OP, I think the important question is, how's your recovery? Deliberately stalling the plane is not a normal maneuver. As long as you can recover from various stalls and incipient spins, it's be happy. The fact that you do the entry "wrong" seems less important. But maybe I'm missing something
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No, I can recover fine and I enjoy the wing drop. I am nitpicking myself and trying to be more precise in my flying.

My bird always does this big wing drop. I want to be able to stall the plane with minimal "fun". I can't imagine ever accidentally stalling a plane but I want to be able to stall the lane instead of it stalling me so to speak.




I have posted this here before. but this is typical. This is power off

 
SixPapaCharlie said:
I have posted this here before. but this is typical. This is power off

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Is that your instructor or buddy with you? If it's your instructor, he looks a little jumpy. If it's your buddy, tell him to keep his hands off the dang controls. :)

Can you not control the wing drop during the stall with (left) rudder?
 
RoscoeT said:
Is that your instructor or buddy with you? If it's your instructor, he looks a little jumpy. If it's your buddy, tell him to keep his hands off the dang controls. :)
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It was my CFI. This was our first time in this new to us plane. Neither of us expected that much of a drop in a power off stall. He was a good CFI but I suspect a little new. I never asked but I suspect I was one of his first few students.


RoscoeT said:
Can you not control the wing drop during the stall with (left) rudder?
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Next time I go up I am going to do the "point the nose at a cloud" thing versus watching the ball and either release right rudder or throw in some left at the moment I feel that sensation.

I think I may be letting the plane get itself stalled and recovering versus controlling the stall.
 
On a similar note, couple weeks ago I was practicing oscillation stalls in a club 172. One wing (I think the right wing) would drop and I could not bring it up using full opposite rudder. The wing would stay down a bit and the airplane would circle slowly right during the long stall maneuver despite full opposite rudder. This 172 has droop tips to lower stall speed.

So yesterday I went out again and decided to use just a bit of aileron to keep the wings level in addition to some rudder. My reasoning was that the root stalls first and I do not think the stall ever progresses to the full wing in this airplane so a bit of aileron should be OK. That method worked fine and I was able to hold the nose on a heading and the wings level during a long oscillation stall.

BTW, the Kings make a distinction between an oscillation stall and a falling leaf stall. In an oscillation stall we hold the wings level while in the falling leaf stall we let the wing fall quite a bit one way and then the other; the latter is a lot more fun.
 
Lindberg said:
Everyone knows the wind only matters in a downwind turn.
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You're not serious, I hope.

Gravity only works in the vertical. Once you're off the ground the wind has no effect on the airplane, other than the turbulence that might be associated with it. The airplane's horizontal velocity and momentum have nothing to do with the earth's surface.

Go up in a stiff wind, get under the hood with a lookout pilot, and make level, coordinated turns and try to see if you can tell the check pilot if you are turning upwind or down. See if the airspeed changes.

Dan
 
SixPapaCharlie said:
what is an oscillation stall?
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Stall the airplane, continue holding full back elevator and it will oscillate between dropping the nose and stalling repeatedly. Hold heading and wings level during this. Though the 172 I was flying would mostly just mush down at 500-700 fpm.
 
alfadog said:
Stall the airplane, continue holding full back elevator and it will oscillate between dropping the nose and stalling repeatedly. Hold heading and wings level during this. Though the 172 I was flying would mostly just mush down at 500-700 fpm.
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Yeah, some will oscillate, and some will come down smoothly in a steady attitude. I shot this in the Pitts at idle power and full aft stick. 32 seconds from 3,000' to 1,500' - 2,800 FPM. No oscillation. Very stable and tame, despite the misconceptions many have about these airplanes. Just takes a light touch on the rudder and not making any movements when they're not needed. Just like when landing the thing. :)

http://www.youtube.com/watch?v=mLZG2lU0WrQ&list=UUm9cBvavbT4j6vReBu9H8Qg
 
whifferdill said:
Yeah, some will oscillate, and some will come down smoothly in a steady attitude. I shot this in the Pitts at idle power and full aft stick. 32 seconds from 3,000' to 1,500' - 2,800 FPM. No oscillation. Very stable and tame, despite the misconceptions many have about these airplanes. Just takes a light touch on the rudder and not making any movements when they're not needed. Just like when landing the thing. :)

http://www.youtube.com/watch?v=mLZG2lU0WrQ&list=UUm9cBvavbT4j6vReBu9H8Qg
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interesting. Throttle on the left, stick in right hand?
 
It looked like you didn't keep wings level. It looked like you leaned to the left and tried to lift the right wing with aileron. This will create more lift on the right wing and adverse yaw to the right and give you more work for your feet.

Don't do that.
 
SixPapaCharlie said:
interesting. Throttle on the left, stick in right hand?
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Traditional layout for centerline seating as found in single-seaters and tandems. Cubs and Champs and Citabrias are the same.

Dan
 
JohnF said:
It looked like you didn't keep wings level. It looked like you leaned to the left and tried to lift the right wing with aileron. This will create more lift on the right wing and adverse yaw to the right and give you more work for your feet.

Don't do that.
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Mostly what you're doing by applying left aileron during the stall (which it appears was the case) is increasing the AOA and more deeply stalling the right wing, causing it to drop (or drop further) than it otherwise would if ailerons were centered. Don't use any aileron to pick up a wing until you've unloaded, and the wings are unstalled.
 
Lindberg said:
No, I'm not. But I think he was. And many others have been. Reasoning with them never works.
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Well,...it is a fact that gusty winds during the stall (landing) phase will cause varying differentials of lift/drag on various parts of the wings/controls/fuselage. During landings (and upper air stall practice), it is these gusty winds as well as the variable propeller forces that cause a constant shifting of cg, etc, and require constant control manipulation to keep it right on centerline.
And that's what maybe he's talking about during stall practice; is to keep the nose exactly straight- with rudder only, and the wings exactly level, or in a commanded and controlled bank angle with aileron. ...and never mind the ball; it will be all over the place, especially in windy conditions.

To the OP:
When you are in a turn, that is when you want to focus on the ball.

You are not holding a heading, so look at the ball if you have to. But when you are holding a heading, either an instrument heading, or a visual heading, as in when you are lining up with a runway, or pointing towards a cloud for stall (landing) practice, the ball may or may not be centered, depending on so many variables.

Of course, it won't be way out of the cage either, but maybe a half ball out during certain speeds and power conditions. It's a study to be done under the hood- but basically; watch the heading when you're straight, watch the ball when you're turning.
 
6PC: I see what others see, a slight tendency to use the aileron, coupled with a very late reaction on the rudder and not nearly enough of it. Remember, as you slow all the flight controls become less effective. What took a gentle nudge of rudder at 90 knots may take full rudder deflection to create the same results at stall speed.

During your next stall practice, find a bug on the windscreen and park it on something on the horizon and do not let it move at ALL. If the nose is moving, STOP it from moving, not matter how much rudder it takes or how fast or slow you need to move your feet to get the rudder there.

You're suffering from tricycle-gearus-foot-disconectedus-from-brainus. Been there, done that. Got the t-shirt. The guaranteed fix is taildragger time, but you can also use techniques to correct it forever in any airplane.

Grab an old fashioned grease pencil and make a crosshair on the window if you need to. Make it really obvious that your chosen target point is moving and make it stop moving. It'll feel forced at first. Force it. Mash that pedal all the way to the floor if it needs to go there.

And I'm serious about not letting it move at ALL. You may find at first all you can do is keep it in an average position over the chosen landmark point, but work harder focusing on the pedals and how much pressure to use to just nail it to the spot.

If you have rudder trim, note it's effect. Do some MCA and see if you can trim away the movement of your dot. Now change speed to slightly faster. Did you need to reset the trim? It's often completely forgotten in the 182.

In the video, there was about one full second where you could tell there was no input to the rudder while the wing drop accelerated. Gotta catch it sooner than that.

I didn't really get how slow I was and how ginger I was on the rudder pedals until taildragger landings. If the nose is moving you're already behind it in a taildragger rolling on the ground. You don't get one second to fix it. You stop the motion or you pour he power on immediately and go around. There is no real butt puckering equivalent in a tricycle gear Cessna. In the taildragger you're better off over-correcting at first and having to alternate back and forth with the rudder wagging from stop to stop than to let that nose move left or right.

Correct sooner and more heavily. You're stepping on the high side anyway, and in a Ceesna it's very hard to induce a high side over the top spin entry.

When you're doing a falling leaf, put the rudder pedal all the way to the floor and hold it if the thing is still rolling. It'll either stop, or you'll have to put the nose down to recover. Sometimes it'll stop at 20-30 degrees and just stay there in a slip. But at least it stopped. It'll fly crooked like that forever coming done at a high sink rate, if it isn't gusty out.

Positive control is what these drills are all about. Use all available control deflection to put the nose of the aircraft exactly where you want it. Ailerons at stall speed aren't an option, so you use all of the rudder and start as soon as you see it move. All of the rudder. You can always relax the pressure I'd the nose goes the other way.
 
Wow - never had a C172 drop a wing like that! I'm still getting used to the Bo and it will drop the left wing about like that. I have some other 35 pilots that say their airplanes will just buffet and drop the nose. Most likely they are just better on the pedals than I am..
 
brian];1542821 said:
Wow - never had a C172 drop a wing like that! I'm still getting used to the Bo and it will drop the left wing about like that. I have some other 35 pilots that say their airplanes will just buffet and drop the nose. Most likely they are just better on the pedals than I am..
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On a Bo you have an interesting opportunity to adjust the plane out of rig from the pilot's seat. You have the knob in the middle of the control you can turn to directly affect the aileron rigging and the trim tab to indirectly affect it. You can counter balance the two so it flies just fine, but when you lose the trim tab effectiveness near stall, the knob setting will take its set.
 
Henning said:
On a Bo you have an interesting opportunity to adjust the plane out of rig from the pilot's seat. You have the knob in the middle of the control you can turn to directly affect the aileron rigging and the trim tab to indirectly affect it. You can counter balance the two so it flies just fine, but when you lose the trim tab effectiveness near stall, the knob setting will take its set.
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Not on the old ones- no rudder trim. I think the aileron / rudder interconnect is what I'm still getting used to.
 
brian];1543011 said:
Not on the old ones- no rudder trim. I think the aileron / rudder interconnect is what I'm still getting used to.
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Not rudder trim, aileron trim. Do you have a trim tab on your aileron? Do you have the knob at the fulcrum of your yoke? Most Bonanzas do and you can set them in competition of each other with trim losing at stall speed.
 
Henning said:
Not rudder trim, aileron trim. Do you have a trim tab on your aileron? Do you have the knob at the fulcrum of your yoke? Most Bonanzas do and you can set them in competition of each other with trim losing at stall speed.
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No aileron trim - no knob in the middle on the throw over.

I think I can buy a yoke with the knob and just get a log entry, but I'm just not sure of the value. Not sure what year the started adding the aileron trim ...
 
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